Energy waste in buildings, especially commercial buildings, is a classic example of a market failure. Complicated lease structures separate the entity that pays for energy in commercial buildings – usually the tenant – from decisions about the original design and ongoing operation of the building. Additionally, energy use, especially during peak demand times, has large costs that are socialized across all energy consumers.

Source: California Energy Commission. Energy Action Plan, 2008 Update.

Policy makers at local, state and federal levels have decided that the societal costs of wasted energy are high enough that the government should do something to safeguard the public (just like with vehicle fuel mileage standards). Energy efficiency codes are the primary and heretofore most effective method for reducing energy waste in buildings. California is the poster child for this. Since passage of California’s landmark building energy code, Title 24, in 1978 and appliance standard, Title 20, in 1976 the state’s per capita energy usage has remained almost flat while energy use in the rest of the country has continued to rise by over 30%. This reduction in energy waste has saved Californians from spending over $66 billion in energy costs and building approximately 20 power plants.[1,2,3]

Energy codes are enacted state to state. Many states have had minimal or non-existent codes until recently when having such codes was made a requirement in order to receive certain portions of the American Recovery and Re-investment Act (ARRA) funding. So hopefully we will see a leveling out of energy use across the country in the years to come.

All this sounds great, right? The thing about building codes, though, is that they only impact new construction and substantial renovations. Until recently, financial incentives for voluntary efficiency improvements seemed like the only way that jurisdictions could encourage energy efficiency in existing buildings. That was until a few cities pioneered the way with new legislation that required some combination of regular energy benchmarking, disclosure of Energy Star ratings and energy audits for commercial buildings.

You can think of these laws as the equivalent of tracking the miles per gallon (benchmarking) and getting a smog test for your building (auditing). So far six cities (Austin, D.C., New York City, Philadelphia, San Francisco and Seattle) have passed such rules. San Francisco’s was enacted in February 2011.

Each city ordinance has its own nuances, which were developed through long multi-stakeholder negotiating processes involving the environmental and real estate communities. I personally participated in the negotiations in New York as part of the New York State Energy Research and Development Authority (NYSERDA). One of the many issues that we had to consider was if there were enough qualified professionals available to perform the benchmarking and auditing services in the legislated timelines. Of course that also meant that we had to define what a qualified professional was (sneak peak to the next installment of this series: Carbon Lighthouse is a qualified energy auditor for compliance in San Francisco).

The laws, all of which share similar frameworks, do some pretty great things from an environmental perspective. For starters, there will be widely available and up-to-date data on the amount of energy being used across a huge population of buildings. Prospective owners and tenants will be able to use that data to evaluate new properties and owners of underperforming buildings will feel pressure to become more efficient, both in terms of energy and operating costs. The audits go a step further to get building owners to buy in – literally – to the idea of energy efficiency. The mandated audits will help owners and managers understand where improvements could be made in their building, though they stop short of requiring that those upgrades are made.

If you are a data-obsessed building nerd, like we all are here at Carbon Lighthouse, this is all great news. The downside, however, is that benchmarking and audits aren’t free to building owners and knowing how to comply can be really confusing. The next two posts will cover how to comply if you are a building owner and how to make sure that you are investing in your building rather than just paying a tax to the data collectors.

[1] California Energy Commission. Building Energy Efficiency Standards, Frequently Asked Questions.
[2] California Energy Commission. AB 758 Comprehensive Energy Efficiency Program for Existing Residential and Nonresidential Buildings.

There are many topics in here, so if you only have time to read part of it, try to read a few lines rather than skim to the bottom, realize how long it is, and mutter to yourself, “Oh #*%$, I felt like trying to do something good for the environment, but this is way too long. I’ll never be able to do this.” Instead, try picking a bullet point at random and if it works for you, embrace it. Hopefully it can be a good starting point. This post is not going anywhere; you can always come back to it for more suggestions.

There are two main sections below: actions to take in your residence, and actions to take with your transportation. The focus is on energy since that is the main source of the average person’s carbon footprint. There are many other environmental topics we could have included such as food choice (i.e. the emissions impact of eating steak every day) or product packaging. But we limit ourselves to energy you directly consume, lest this turn into a book.

I. In Your Residence

THE EASY STUFF AT HOME

Lighting upgrades: The most cost-effective measures are replacing:
• Incandescent bulbs with compact fluorescents or Energy Star-rated LEDs
• Large halogens, in most homes these are a PAR30 type lightbulb, with compact fluorescents or energy star rated LEDs
• Little halogens, in most homes these are MR16 type lightbulbs, with energy star rated LEDs

Some people are concerned about light color (warm yellow vs. white) when switching from incandescents. If you like the warm, yellow glow of incandescents, you should make sure to choose a warm color compact fluorescent. These exist but you often need to ask! Color is measured in degrees kelvin (K), so a 2700 K compact fluorescent is a nice warm yellow light, while a 4500 K light bulb will be a bright white light.

Thermostats: If you have a thermostat for your heating and cooling, make sure it is programmed properly. Then check again. And again. Vast amounts of energy are wasted conditioning your home when no one is around. If you do not have a programmable thermostat, have one installed; some utilities will supply and install one for free.

Power Strips: Almost all devices in your home use power even when they’re not on. If you go to this list, the average number of watts used is roughly the same as dollars saved annually; multiply by 4 and you get pounds of carbon saved annually. It’s small, but it adds up and is easy to do.

Weather-stripping: Very cheap, small foam strips that seal gaps in doorframes and windows. They help keep warm air inside in the winter and cool air inside in the summer.

Hot-water line insulation: If you have a domestic water heater, make sure the hot water lines coming out of it are insulated. Insulating the exposed pipes is cheap and easy and saves heating energy.

Window shades: Insulated window shades should be mounted as close to the glass as possible. The air gap between the shade and the window creates an insulating layer of air, the same principle that makes double-pane windows work.

No Cost activities:
• Turn off lights when you leave a room. An oldie but a goodie.
• Close your newly-installed sun-facing window shades on hot days.
• Open your newly-installed sun-facing window blinds on sunny, winter days.
• Because air flow impacts our perception of heat, on hot days, you can achieve the same comfort level with much less energy by using fans as much as possible before switching on the A/C.
• Keep the back of your refrigerator clear. An open area behind the refrigerator allows the condenser coil to dump heat efficiently, reducing the work your compressor does.
• Defrost freezers when ice is ¼” or thicker
• Take a shower instead of a bath to reduce hot water usage.
• Wash only full loads in the dishwasher to conserve hot water.

THE HARDER STUFF AT HOME

Whole House Studies: It is often advisable to undertake a comprehensive home energy study. This is especially true if you feel your home is always drafty in the winter and/or you cannot keep it cool in the summer. These studies involve a comprehensive analysis of energy flows within your home. Often, a blower door test is conducted to test your home for leaks. It is a cool, simple test. To have such a study conducted contact your local electric utility.

Attic and Wall Insulation: These comprehensive studies will likely recommend improving your home – especially your attic – insulation. There are many types of insulation including: fiberglass batts, blown-in cellulose, and rigid foam boards. What matters most is that you insulate at all. The more the merrier!

Window upgrades: Installing double-paned or triple-paned windows is a much-touted energy savings measure. Since the average home’s wall space is only 10-15% windows, wall and attic insulation are usually more important and are likely a better first investment. When deciding whether to upgrade your windows for energy savings reasons, details matter a lot. If you live an area with extreme weather and high electricity prices (for example, Boston, MA) then window retrofits are more likely to be a good investment compared with a temperate region with low energy prices. There’s only one way to find out if a window retrofit is cost-effective for you and unfortunately it’s the hard way: call three contractors, get bids, do a reality check of their proposed savings numbers compared to your actual electricity and natural gas/fuel oil bills, ask the contractors how they arrived at their savings numbers’ predictions, make sure they are using energy modeling software derived from DOE-2 or an alternative that is as good, and if you are capable and willing, do your own energy modeling to check their numbers. Yeah, not that easy.

Though not perfect, here is a way to approximate your maximum possible energy savings from a windows upgrade. First, look at your monthly gas/fuel oil bills for a year, and see how much they increase in the winter vs. the summer. That is your space heating load. It’s unlikely more than 25% of your heating load is going through your windows and your new double-pane windows might be three or four times as effective as your existing windows. So to calculate your maximum possible winter savings take 25% of your heating load and multiply by 0.8. Then do the same process with the difference between your electric bill from the summer vs. winter to calculate your space cooling load. Add up these winter and summer savings, and that is the maximum your annual savings could be from a windows replacement.

Appliances: If your washing machine, refrigerator, dishwasher, TV, or other energy appliance is at the end of its life, you have an easy fix: buy the most energy efficient replacement machine that you can. Energy Star is a helpful rating system available throughout the United States, but there are more and less efficient devices even within Energy Star. So make sure to buy the appliance that uses the fewest Watts or Watt-hours for the amount of washing/cooling/entertainment that you need.

If your equipment is not near the end of its life cycle, the calculation becomes more complex. A good rule here is if your appliance is pre-1995, you are probably better off replacing it as several appliance efficiency standards began kicking in in the early 1990′s. Energy efficiency is good, but buying new appliances every year is neither cost-effective nor great for the planet (it takes energy to gather the parts of the machine, assemble it, and then ship it).

RENEWABLE ENERGY AT HOME

For many homes in urban areas in North America, the optimal renewable electricity solution is a solar array. Small wind solutions exist, and can be a fit; however, the comparative economics between residential-scale solar and wind are complex calculations. So caveat emptor: if you do not understand concepts like “$/kWh” and “capacity factor,” you should probably avoid doing your own shop-at-home comparison. Solar solutions come with the benefit that the residential market has rapidly matured.

Solar arrays for your home will have multiple payment options. You can purchase your own solar array outright. Alternatively, you can have it financed through a lease or a power purchase agreement in which you pay for the energy you use. You capture more financial benefit if you buy your own system, but you have to put in the up-front money yourself as well as be responsible for maintenance. Solar companies that provide you with financing solutions benefit from the tax-advantaged solar asset depreciation write-off that non-businesses, like you the homeowner, cannot use.

Solar installations are an area of rapid innovation. Items like virtual net-metering, new feed-in-tariffs, and other items mean there are likely to be an increasing variety of ways to go solar at home.

When selecting a solar firm, remember that this is a competitive market like any home improvement task. Whatever companies you solicit bids from it is advisable to find an organization that:
• Has a strong reputation
• Explains clearly all tax-related benefits
• Provides a monitoring solution so you can see the power being produced
• Provides you with the warranty info for your panels (these should be at least 20 years)
• Provides you with the warranty info and explanation of replacement costs (if any) for your inverters
• Explains to you how net-metering and true-ups work in your utility region

Solar hot water heating is another good renewable energy option. Solar hot water makes better use of the sun (solar how water panels are closer to 80% efficient, while solar electric panels are only 20% efficient) and will reduce your hot water heating bill. It’s more complicated to measure than solar electric. Solar hot water, however, can be used on a greater number of homes like those with roofs facing many angles or that have some shading.

II. Transportation

DRIVING

What type of car to buy
If you are in the market for a car, the short answer is you should buy the car that uses the least amount of gasoline. Hybrid cars are an impressive innovation but just because a car is a hybrid does not mean it is more efficient than all other non-hybrid cars. Many hybrid cars provide excellent city mileage, but others do not; luxury hybrids in particular frequently use more gasoline than a standard fuel-efficient, gasoline-only sedan.

Plug-in hybrids and all electric vehicles are among the most environmentally-beneficial solutions, often better than a hybrid car. How environmentally beneficial your electric car is depends upon the carbon intensity of the electric grid you use for your power. In part because an electric engine is three times more efficient than an internal combustion one, driving an electric car like a Nissan Leaf (an all electric car with a 100-mile range) or a Chevy Volt (a plug-in hybrid with a 40-mile electric range) will have environmental benefits no matter where you get your electricity.

No-cost driving changes
There are also many ways that cost you nothing to reduce your environmental impact form driving. Some of these will be familiar:
• Relax and enjoy the ride: Because of air drag, driving 55 mph uses 21% less fuel than driving 75 mph. Every 5 mph faster you drive, is like paying an extra $0.25/gallon.
• Straight and steady: drive at a constant rate, accelerate slowly, and do not tailgate. On highways, aggressive driving lowers efficiency as much as 33%.
• Charge! Accelerate before a hill rather than on it.
• Roll hard: inflate all tires to the maximum recommended limit.
• Clear out excess items from your trunk. Removing 100 pounds increases efficiency 2%.

PUBLIC TRANSPORTATION

If you have the convenience of mass transit, whether bus or trains, taking them instead of driving will substantially reduce your environmental impact. Carpools are a great thing, too.

AIR TRAVEL

Unfortunately, reducing the carbon intensity of your air travel is an area where business solutions are limited. New technologies are sorely needed. Biofuel-powered planes are one future option but they are not in widespread use for commercial air activities and biofuels bring with them other challenges, too. Electric planes are unlikely any time soon given the weight of batteries.

Minimizing air travel through tele-conferencing is one way to reduce the impact.

If you are a captain of industry, then eschewing private planes in favor of commercial-ones will substantially reduce the carbon intensity of your trip. The emissions from a large plane are larger than from a small one but are spread across a much greater number of people. The carbon intensity of a cross-United States airplane ride on a commercial jet is the same as if you drove a Toyota Prius c by yourself that same distance (in fact, if you are on a jet with 200 or more people, flying is probably less carbon intensive).

BECOMING CARBON-NEUTRAL

When you’ve exhausted all your options for changes in your own lifestyle, then you can try to reduce your environmental impact through carbon allowances or carbon credits.

Carbon allowances are pollution permits. Carbon Lighthouse Association, a non-profit organization, independently governed from Carbon Lighthouse LLC (carbonlighthouse.com), competes with power plants for pollution permits and then retires those permits, unused, on your behalf. All permits are mandatory and are enforced by state governments. You can use the tool on the Carbon Lighthouse Association website to calculate your carbon footprint. Then purchase allowances on the website and balance your residual carbon footprint to become carbon-neutral.

If you would like to invest in a carbon mitigation project the non-profit Carbon Fund has a list of projects. US-based, renewable energy and methane flaring projects are among the most reliable and verifiable carbon offset projects.

Final Thoughts

The impacts human beings are having on the planet are difficult to overstate. The seven billion of us enjoy the fruits of industrial-age, human ingenuity through the consumption of vast amounts of fuels. While this consumption is economically sustainable for the time being, it will become increasingly less so as we further stress our environment. Little steps lead to bigger ones, and a few individuals taking action lead to larger groups joining in. We hope this post has been a helpful, no-nonsense summary of the opportunities available to you as an individual to help the planet.

Although cleantech companies do not recruit at career fairs or through personal networks at the same scale as Fortune 500 companies, there are still tons of ways to find great cleantech companies offering a variety of jobs.

If you want to work for Carbon Lighthouse, then email your resume and cover letter to careers {at} carbonlighthouse {dot} com. Whether we’re actively hiring now or not, we’ll add you to our database and you’ll be the first to know about new positions.

If you want to work elsewhere, what follows is a system you can follow to find pretty much any green job you can think of. Here’s the system:

0. Green Job Boards. There are a few of these. Social Good Jobs is one of them, and they even keep a list of other green job boards here. There’s also the Green Jobs Network, which keeps a pretty comprehensive list here. This is a very easy place to start because you can just apply to jobs like any normal person: look up people who are hiring, and apply. These will be competitive jobs, however, because they are so easy to find. So if you need or want to look beyond what is easily findable on jobs boards, go on to step 1.

1. Greentech Media (GTM) is an excellent place to start. Their stories cover everything cleantech, with particular detail on companies that recently raised venture capital funding. Venture capital funding is good news for you because one of the first things a CEO does with the sudden influx of millions of dollars is hire people. Conveniently, Greentech Media has sorted their coverage into categories like solar, grid, energy efficiency, etc. Spend an hour browsing through the different categories to figure out which ones interest you the most, and then start compiling a list of companies that sound interesting.

Many of the companies covered will be based in the San Francisco Bay Area, but don’t be concerned; the food is fantastic and you can still drive to the mountains to enjoy winter if you like. There are also 100+ companies based throughout the country and world that Greentech Media covers, so you should have no problem creating a list of companies east of Yosemite.

2. Industry Groups. These are great for developing target company lists since they often have a list of their member companies. The American Solar Energy Society has a list of State Chapters. Click on the State you’d like to work in, and the contact info for someone in that State who’s familiar with every solar company in it will pop right up. Seem like a lot of work to call people in a bunch of States to get a list of companies? No problem, CASE just publishes a list of their member companies. There’s even an industry group that publishes a list of solar industry groups for you. Solar not your thing? There’s AWEA for wind, there’s the DRCC for Demand Response, there’s Efficiency First for energy efficiency, etc. Choose your topic area, google “My Area of Interest” Industry Group, and you’ll be on your way.

3. Another easy place to develop a national list of companies is through Pacific Gas and Electric, the largest utility in California. PG&E maintains a list of “3rd Party Program Providers”. These are private companies, many of them national is scope, that run incentive programs to promote energy efficiency. You can develop a list of them here.

Go to the bottom and click on the industries you’re interested in. A list of companies providing energy efficiency services for each will be provided. Using this list, you can develop a list of 25 target companies in ten minutes.

There are similar sources of companies in states not serviced by Pacific Gas & Electric. Massachusetts, for example, has the Massachusetts Technology Collaborative. New York State has NYSERDA. California has the California Energy Commission, and, luckily for you, every single State has a Public Utilities Commission (PUC). The PUC may be called something different (in New York it’s the Public Service Commission or PSC), but they are all there to regulate utilities and are required to disclose who wins contracts for efficiency work. If the utilities in your State run energy efficiency programs, they need to disclose who wins contracts as well.

How do you talk to these giant organizations? You need to reach people called “Project Managers,” “Account Executives,” or “Account Managers.” These are the people who are customer facing. Customer facing is good. It means they are in the service business and are more likely to be friendly and inclined to help you. It also means they know who the companies are that are working with customers. Working with customers is good because it means revenue, and hence the potential to hire you.

One note on this sourcing method: persistence is key. Not every government or regulated monopoly employee will be incredibly helpful to you immediately. You can always politely ask to be transferred to someone who runs a different program or interacts with a different set of customers. You may get bounced around a lot, but you should eventually be able to get to someone helpful.

4. Don’t forget, PUCs and utilities need employees too, and those can be interesting and stable jobs that provide good perspective on the cleantech industry. Cleantech companies find it as difficult to get good talent as you find it to difficult to find them (the two are related), so working for government or a utility can be a great stepping stone; cleantech firms often try to woo away public employees.

5. Another place for potential jobs is oil companies. That’s correct. Chevron Energy Solutions, for example, is one of the largest players in the solar market. Shell has a large biofuels unit. So does BP. Are they oil companies? Yes. Are those divisions still full of people trying to build a sustainable planet? Yes.

6. Getting tired of doing research on companies to talk to? No problem, have someone else do it for you. Headhunters make a living by helping people like you get jobs. You don’t even need to pay them; the company that ends up hiring you will do that for you. Don’t know headhunters? No problem: Hobbs and Towne, ON Search Partners, Heidrick & Struggles, Clarey/Napier International, Bright Green Talent, Zander Green, Think Resources, and Whitham Group all have cleantech recruiters. There are many more firms as well that a quick web search will reveal.

7. Need yet more sources? Lots of green companies are public, which means Google or Yahoo Finance are your new best friends. Go to the website, and enter any public company in an industry you’re interested in. For example, if solar is your thing, enter Trina Solar and then scroll down. A list of their competitors, e.g. other companies you can apply to work at, will pop up.

8. Venture Capital firms are also helpful here. They publish some of their portfolio companies. If you are any type of engineer, scientist, mathematician, or just generally someone who gets a warm fuzzy feeling when you hear the phrase “we got an adjusted R-Square of 0.94”, this conversation is very easy: “Hi, I’m an engineer interested in working for X, could you please put me in touch with the hiring manager?” VCs love introducing engineers to their portfolio companies, and the portfolio company will always take the call after an intro from their VC because they feel beholden. You don’t get a warm fuzzy feeling from regressions? No problem, try anyway. You’ll learn in a few phone calls whether or not this strategy will work for you. VC firms do hire themselves, but you usually need an intro for that.

9. Are you a former banker? Great, there are now at least a dozen energy efficiency finance firms. Transcend, Metrus, Cedargate Capital, Green City Finance, Pinnacle Capital, Green Campus Partners, Serious Capital, and Groom Energy are just a few. Groom and Serious do a lot more than just finance as well. Call ‘em up.

Like the finance idea? There’s a lot more opportunity. There are (finally) starting to be “PACE” regions throughout the country. PACE is Property Assessed Clean Energy. It’s a clever way to pay for energy efficiency and renewable energy projects. We could probably write a whole series of posts just on PACE alone, but the quick version is that municipalities issue bonds, use the money to pay for clean energy projects in buildings, and then recoup their money through increased property taxes on whatever buildings took advantage of the free money. The idea is that the increase in property taxes is less than the energy savings, so building owners save money from day one and cities get more efficiency projects. It’s a clever redistribution of money from power plants to municipalities, with banks getting a fee, but no one talks about that and we’ll let that go for now. Why do we mention PACE? PACE regions hire people to manage PACE. Whole companies have sprung up to service PACE regions.

10. Fortune 2000 companies have sustainability teams now too. They’re small, but they’re there. Most receptionists will just transfer you directly to someone in HR, and you can ask them who’s on the sustainability team and what their extension is.

11. ESCOs are Energy Service Companies. There are lots of them. Trane, Johnson Controls, Seimens, Ameresco, Carrier. The list goes on. Many of them are profitable. Some of them are hiring. There are new ESCOs everyday.

12. There are all sorts of niche parts of the green jobs market. Don’t be afraid to do a narrow web search and see what comes up. There are companies that make Smart Meters (SilverSpring Networks, Itron), there are companies that finance solar installations (SunRun, SolarCity, Sungevity), there are energy storage companies, electric and other car companies (Tesla, Mission Motors, Nissan, GM, Toyota), there are green consulting companies (Green Order, Blu Skye, E Three), and there are tons of great not-for-profits as well like the Natural Resources Defense Council and Environmental Defense Fund. Many of them are hiring. Solar City, for example, hired 800+ people last year alone and as of the writing of this post is continuing to hire like gangbusters.

13. People. In the end, people are the fastest route to job opportunities, since few if any hiring processes don’t involve people at some point. If you’ve been looking for work for many months, you’re likely tired of hearing the importance of networking. Rather than state its importance, we’ll list some good general green networking resources. If you go in with an open mind and positive attitude, you are almost guaranteed to come away feeling good from events like: Green Drinks, Eco-Tuesday, US Green Building Council events, and LinkedIn green group events. Be selective with the last one as there are hundreds of green-related groups and there is a variance in quality. For those who are young or young at heart, Young Professionals in Energy (YPE) has very interesting speakers and networking events. Conferences like Green Build and others provide informal ways to meet green business people. Even if many of the people you meet are looking for green jobs like you, odds are they’re seeking a different kind of job, and they can be a resource for you in your search.

There is no shortage of cleantech firms, and even though most of them don’t recruit at career fairs, hopefully the systems outlined in this post will help you find them.

Still reading and not bored to tears yet? Great! Leave a comment with your thoughts or even just letting us know if this was helpful or not. The more comments, the easier this post is to find for everyone, and the more people join the clean energy fight!

If at the end of all your research, you still can’t find a team of passionate people that is creating something you’re so excited about you can’t sleep, then start your own. There are tons of green business opportunities and tons of resources out there for entrepreneurs trying to solve issues in the green space. Those, however, are topics for another post.

Turbines are responsible for almost all electricity on the planet. Solar photovoltaic panels are one of the only sources of electricity that do not involve turbines. In addition to wind energy, turbines transform coal, gas, oil, hydro, tidal, and nuclear energy into the electricity that powers your and your neighbors’ homes. Turbines are a major part of the modern energy landscape.

But you probably have not seen a microturbine before. You might soon, and this post is designed to help make sense of them. The last fifteen years has seen the commercialization of microturbines, an electricity generating workhorse designed to power only a single building. Microturbines are installed on site, where the power is needed, rather than at a centrally generating power plant that distributes the energy long distances over power lines. (Microturbines are also feasible in cars, and some versions are small enough for homes though their efficiencies remain low).

The physics of turbines are complex, and there are many varieties of turbines, of which microturbines for commercial buildings and small industrial plants are just one. The short version is that microturbines are powered by the combustion of compressed natural gas or other fuels. This combustion produces high temperature and pressure gases that flow into turbine blades, spinning them. As the blades spin, they turn a rotor and generate electricity.

Microturbines are more expensive than traditional generators like reciprocating engines (more on cost below), but they have several advantages. Most noteworthy are lower emissions and higher temperature waste heat. High temperature waste heat is easy to turn into useful energy that can power an absorption chiller or provide heating to a building. This heat capture process, more commonly done at a centralized power plant, is known by many names including cogeneration or combined heat and power. When used for electricity generation alone, however, microturbines only have efficiencies of 25-35%, well below modern combined cycle natural gas turbine plants which achieve efficiencies of 60% (though central plants lose some energy in transmission).

Costs

When you include capital costs as well as the ongoing cost of fuel and maintenance, microturbines produce electricity for anywhere between $0.09-$0.14/kWh. The cost of the turbines themselves is between $1.20-$1.60/Watt, and installation, commissioning, permitting and development runs an additional ~$2/Watt. This depends heavily on how large a system is being installed.

As solar panel costs have dropped dramatically in the past few years, it’s worth comparing solar costs to microturbine costs. A solar array of comparable size to a typical microturbine project, say 1 MW, would cost on the order of $4/Watt installed, only 10-15% more than a microturbine. Solar panels themselves actually cost less than microturbines, at only $1/Watt.

The drawback for solar is therefore not one of cost. This is an important point in and of itself.

The real issues are space requirements and intermittency. One MW of microturbines needs a footprint of a 500 square feet for a concrete pad. One MW of solar needs roughly 100,000 square feet. Additionally, microturbines can be turned on and off at will (as long as there is fuel available) whereas solar energy production fluctuates with cloud cover and time of day.

Emissions

When used for electricity generation alone, the carbon dioxide emissions of microturbines burning natural gas will be worse or better than those of the existing utility grid depending upon location. At an efficiency of 31%, microturbines produce approximately 1.29 lbs CO₂/kWh. California’s electricity grid (ignoring imported power) is much cleaner, with emissions of 0.49 lbs CO₂/kWh, though some states are much higher. Fuel cells, a technological competitor to microturbines, generate electricity more efficiently; when burning natural gas, they have emissions ~0.75-1.00 lbs CO₂/kWh and can be as high as 50% efficient.

Microturbine emissions for non-CO₂ sources are actually better than the grid’s. According to the EPA, Capstone microturbines’ NOx emission are 0.00015 lbs/kWh and their CO emissions are 0.00010 lbs/kWh. Emissions from the grid (even in relatively clean California) are 0.00062 NOx lbs/kWh.

Reliability

Since they became commercially available, microturbines have gained in popularity and have therefore been subject to review. The Environmental Protection Agency’s Environmental Technology Verification Program (sponsored by the Federal Department of Organization’s Unnecessarily Cumbersome Nomenclature Initiative) measured and signed off on microturbine output frequency, voltage, power factor, harmonic distortions, and other factors. The data is a good starting point though limited in the number of cases reviewed. Sample reports can be reviewed here. At Fort Drum, the US Army conducted its own review of microturbines and found they did not degrade electrical power to their facility. A University of Colorado study found that microturbines efficiencies matched those predicted by the manufacturer.

Several issues have cropped up regarding microturbines, though most problem areas involve auxiliary equipment not related to the reliability of the turbines themselves:

• Noise. High-pitched squeals, albeit at a low volume. Exhaust silencers may be installed.
• Air filters. Need to be kept clear and may not last as long as suggested.
• Fuel compressors. The US Army could not maintain the 55 psi gas they needed.
• Heat exchangers. Problems reported in the heat exchangers used to transfer waste heat.
• Commissioning issues. Bearings, diodes, electrodes, software sequencing, and other pieces of equipment can cause issues during set up (as with any new equipment installation).

Efficiencies

Microturbine efficiency varies with outdoor air temperature. According to EPA, at 80°F outdoor air temperature, the microturbines are about 3% less efficient than at 50°F outdoor air temperature. Using government weather data from a Typical Meteorological Year, one can determine the average temperatures for all 8,760 hours in the year when the turbines will be operating.

Load also impacts efficiency. If a building does not demand much energy and the microturbines need to turn down, the turbine efficiency will drop. Low load efficiencies are 10% or more below those of full load efficiencies. NOx and CO emissions per kWh increase as the load drops.

There is also an output penalty for microturbines: a turbine rated at 200 kW will only produce between 160-190 kW of actual power due to parasitic loads like running the natural gas compressor and other inefficiencies. The output efficacy decreases at higher temperatures.

Manufacturers

In the United States, a single company, Capstone, controls approximately 80% of the domestic market for microturbines. Over the past many years they have, Leviathan-like, swallowed up a host of competitors. Flex Energy is one of Capstone’s only main competitors, having acquired the microturbine technologies of Ingersoll-Rand.

The two products are similar. Each manufacturer makes a range of slightly different sized turbines form the other (e.g. Capstone’s 200 kW unit vs. Flex’s 250 kW unit). Flex’s turbines cost a bit less than Capstone’s but are also less efficient than Capstone’s at higher outside air temperatures.

Conclusions

Microturbines are an interesting if imperfect technology with a lot of potential, especially in locations that can make use of its high temperature waste heat. It will be exciting to watch how microturbine manufacturers and the makers of competing technologies innovate to bring about ever cleaner, cheaper, and more reliable energy solutions.

The mechanisms that reduce the amount of time your battery lasts after a single charge are different than those that cause it to fail entirely, so we will address these mechanisms separately.  Furthermore, the length of any given discharge depends in part on how you use the battery. Laptop users may notice that their batteries drain quickly if they run many programs simultaneously, or if their screen is set to full brightness.  In these cases, the computer is using a lot of power, so it is draining energy from the battery at a high rate.

Reducing screen brightness and closing background programs will make the computer last longer. Similarly, scanning through photos on a camera, or using apps on your phone, will run down a battery faster than if it is in standby.  The fewer programs you can use on any device, the longer it will last on an individual charge.

Batteries also never seem to last as long when it is cold out.  You may have pulled your camera out to snap a picture on a ski trip to see that the battery light is flashing red, even though it seemed just fine in the lodge that morning.

Two factors are at work here. The first is that when it is cold, the chemical reactions that govern energy storage in a battery require more energy.  When it is hot out, it takes less additional energy for these reactions to take place, so the battery lasts for longer.  (Note: being hot isn’t actually good for a battery. We’ll get to this later.)  The other problem is that your camera estimates how much charge is left in a battery based on the voltage of the cell. When it’s cold, the battery voltage drops and your camera thinks that it has discharged more than it actually has.   Next time you find yourself in cold weather with an unexpectedly discharged battery, try taking it out of your camera and heating it in your hand.  When you put it back in, it may have recovered somewhat.

No matter how carefully you use your laptop or camera, however, you will eventually notice that the battery doesn’t last as long as when you first bought it.  This phenomena is called “capacity fade.”

The actual mechanisms that cause your battery to degrade depend both on the battery chemistry and how it is used.  A lot of capacity fade is the result of the fact that the “reversible” chemical reactions in the battery are not always completely reversible. Irreversible side reactions build up over time.  These reactions reduce the surface area of the electrode, so the amount of electrode material available to store energy decreases with each cycle.

In the lead-acid batteries used to start most cars, for example, lead sulfate builds up on discharge and is typically broken down during charge.  Over time, however, the lead sulfate can form crystals that are hard to break down and block the surface of the electrode, reducing the active area; this “sulfation” is even worse if the battery is not fully charged on a regular basis.

Nickel-cadmium batteries, found in some portable electronics, also can suffer from a buildup crystals if they are not fully discharged on a regular basis. The lithium-ion batteries in your laptop or iPhone can suffer from side reactions, corrosion, electrolyte degradation, and other chemical and mechanical aging mechanisms common

Complete battery failure is usually a result of either battery mismanagement (i.e. running your battery down too low) or mechanical failure.  During charge and discharge, the movement of ions in and out of the electrodes increases the stress in the battery and can lead to mechanical failure.  This stress is greatest when the battery is fully charged, so most battery types should not be stored at full charge (the exception being lead-acid, which suffer from sulfation if it is left undercharged).

In other cases, the crystal growth mentioned above can build up into branch-like structures called dendrites.  A polymer separator typically keeps the electrodes in the battery from touching, but the dendrites are sharp and can pierce through this separator, connecting the electrodes and creating a short, rendering the battery useless.

While capacity fade in a battery is inevitable, you can reduce the speed at which it occurs by following a few of the following guidelines:

• Don’t keep your battery at high temperature.  Avoid heaters and hot cars.  High temperatures speed up the side reactions that damage the battery.

• If you leave a lithium-ion battery unused for a long period of time (say, a month), leave it only partially charged. Battery electrodes experience the most mechanical stress when the cell is fully charged, leading to failure. Furthermore, unwanted side reactions are more likely to occur near the battery’s maximum voltage, and can be slowed by maintaining the battery in a lower state of charge.  It is not good to leave the battery fully discharged either.

• Don’t fully discharge your battery on a regular basis. This guideline is a funny one.  First of all, most laptops and cameras will go into standby rather than let you discharge your battery entirely.  Also, it is important to occasionally discharge your laptop battery so that the laptop’s control system can recalibrate and improve its estimate of the battery’s state of charge.  Some types of batteries can also withstand “deep discharge” better than others.  Lithium-ion batteries, for example, are designed to be deep-discharged regularly, whereas many types of lead-acid batteries degrade very quickly when discharged all the way.  As a rule of thumb, however, the more often you run your battery down very low, the faster it will degrade.

• Do not overcharge or overdischarge your battery.  Your battery is designed to operate within a certain voltage range where desirable reactions are favored and undesirable reactions (like hydrogen evolution in an aqueous electrolyte) are minimized.  Overcharging and overdischarging your battery can increase the rate of irreversible side reactions. Most chargers protect against overcharge and overdischarge.  (Note: Some chargers for nickel-based batteries, rely only on the charging time to determine when the battery is fully charged, so they may overcharge the battery if it is not fully discharged first.  The reason for this charging technique is that unlike other battery chemistries, nickel-based batteries do not always reach the same voltage when they are fully charged.  If the charger cannot detect the subtle changes that indicate full charge, like the small dip in a voltage seen when the battery is finished charging, it may rely on charging time to determine its cut-off.  If the battery is not fully discharged and is placed on such a charger, it will overcharge the battery).

•  Charge and discharge your battery slowly when possible. If you’re running an energy-intensive computer program, it’s probably a good idea to run the computer from an outlet if you can. This is because demanding lots of power from a battery degrades it faster. If your battery has a “fast-charge” option, only use it when you really need to, and the rest of the time let it charge slowly.

• Don’t cycle your battery unnecessarily. The life of your battery is cycle dependent.  The more you cycle your battery, the sooner it will die. If you can plug your laptop into the wall while using it, do so, although never cycling the battery isn’t good for it either.  As for the oft-asked question of whether you should leave your computer or phone plugged in when you’re not using it: the answer depends on the type of control system governing the battery charger.  Sorry we can’t just give you the answer. Batteries are complicated.

Figure 1: Whole Foods market outreach to promote sustainable seafood choices. (4)

We will explain the general Life Cycle Assessment theory now, and then use a simplified LCA to quantitatively compare the true benefits and costs of incandescent versus compact fluorescent (CFL) bulbs. There is a three step process to a Life Cycle Assessment. First, researchers outline the goal and scope of the assessment. This tailors the system boundaries and centralizes the analysis around a specific sector or product. For example; do we care only about the direct emissions from our building, or are we interested in the emissions behind the meter? Second, researchers use one of several quantitative methods to build an inventory of the inputs and outputs for a given product system throughout its entire life cycle or supply chain, capturing the total material, emission, and energy flows within the system boundaries. Third, researchers conduct an impact assessment based on the inventory analysis. These impacts broadly fall into categories such as ozone depletion, human toxicity, or global climate change. Taken together, a thorough LCA provides the quantitative measures to draw conclusions and iterate a service or product.

Generally, there are two methods to conduct a life cycle assessment. An Economic Input-Output (EIO-LCA) approach quantifies the material, energy, and financial flows resulting from economic activities within different sectors. This was developed principally by Wassily Leontif in the 1970’s and brought into mainstream use by Carnegie Melon University[5]. A Conventional (or Process-Based) Life Cycle Assessment approach focuses on a specific product or service rather than a sector, typically defined by a function and normalized with a functional unit. For example, the purpose of a PV plant is to supply electricity (function), and the basis for the LCA could be a kWh of electricity (functional unit). The major advantage of this method is the ability to differentiate two products or services that have the same function.

To put this theory to practice, let’s consider the decision to replace a light bulb with either a CFL or incandescent bulb using a Process-Based LCA. Since we’re concerned about both our pocketbook and the environment, let’s use our LCA to quantify both the financial aspect and two emission streams (mercury and CO2 emissions), and limit the scope to lighting and disposal.

Using a simple LCA to determine the most 'sustainble' lighting choice (6).

The function of the light bulb is to provide lighting for 6 years (6 hours / day), with a required functional unit of approximately 700 lumens of lighting (fairly standard bulb). A quick Home Depot search turns up two bulbs capable of providing the necessary illumination: an incandescent bulb ($1.30, 60W, 986 hr lifetime) and a CFL bulb ($6.50, 13W, 9855 hr lifetime). A deeper look reveals that the CFL has up to 0.03% mercury content, a concern amongst some homeowners. At first glance, it may be enticing to go with the incandescent; the low cost and lack of mercury may seem like an easy decision. But let’s expand the analysis.

The six year lighting scope translates to 13,140 hours of illumination. This means we need to purchase 2 CFL’s and 14 incandescent bulbs, based on our manufacturer lifetime guarantees. When we account for the electricity consumption, this translates to ~171 kWh for the CFL, and ~788 kWh for the Incandescent. Using a price of $0.12/kWh for electricity, this becomes ~$20.50 for the CFL and ~$94.60 for thei. Suddenly the financial picture shifts; the total cost for the CFL bulb becomes ~$33.50, and the Incandescent bulb ~$113.30, a difference of nearly $80 in favor of the CFL.

The environmental picture is a bit more complicated. The US grid emits ~0.012 mg of mercury and 0.66 kg of CO2 per kWh of electricity. If we assume all of the mercury already in the bulb ends up in the landfill, the CFL releases a total of 9.2 mg of mercury and 113 kg of CO2. The incandescent bulb releases 9.4 mg of mercury and 520 kg of CO2. Essentially, the increased energy consumption penalizes the incandescent’s CO2 emissions inventory.

Life cycle inventory of cost, mercury, and CO2 emissions.

This simple Life Cycle Assessment exercise highlights the importance of thinking holistically, giving us the measurements to make a ‘sustainable’ choice. From a financial perspective, the CFL is the clear winner. From an ecological perspective, the CFL has a much better CO2 emissions profile, and both bulbs perform equally with respect to mercury emissions.

Today, various organizations have begun to promote sustainability through more rigorous quantitative frameworks. The Global Reporting Initiative[7], a non-profit organization, is striving to make sustainability reporting a standard industry practice. The International Standards Organization[8] currently has voluntary Life Cycle Assessment standards as part of its 14000 Environmental Management Series, with the intention to indentify, improve, and monitor the environmental impact of activities. The Earth Day Network[9] provides a simple tool to calculate the ecological footprint of a lifestyle, using earth’s global hectares instead of materials or dollar indicators. High end LCA software such as SimaPro[10] gives the ability to create very detailed inventories for unique systems.

Some products that claim to deliver energy efficiency are actually just energy reductions without the efficiency. Doing the same thing more efficiently does not sacrifice an end product (light levels stay the same, the amount of cooling your AC provides remains the same, etc.), energy reductions not gained through energy efficiency might sacrifice operations or comfort. Energy reductions are fine where appropriate – many commercial office spaces in the U.S. have lighting levels well in excess of modern recommended amounts and are therefore excellent candidates for removing 10-40% of the lamps – but if light levels are already appropriate, reducing the number of lightbulbs may not be a good idea.

Fundamentally, life cycle assessments attempt to measure sustainability to aid decision making. Much work remains to standardize the framework and better interpret the impact assessment, but it’s exciting that Life Cycle Assessment application has moved into mainstream discussions. In the meantime, give your personal life an ecological score with Earth Day’s nifty calculator found here.

Sources
[1] http://www.wholefoodsmarket.com/values/seafood.php
[2] http://www.amourvert.com/green/
[3] http://www.un.org/documents/ga/res/42/ares42-187.htm
[4] http://www.wholefoodsmarket.com/seafood-ratings/
[5] http://www.eiolca.net/
[6] sophia.smith.edu
[7] https://www.globalreporting.org
[8] http://www.iso.org/iso/iso_14000_essentials
[9] http://www.earthday.org/footprint-calculator
[10] http://www.simapro.co.uk/

Part of what makes von Neumann so remarkable is he didn’t just contribute to these fields, in many cases he fathered them. He developed the mathematical underpinning of quantum mechanics by showing the physics’ interchangeability with Hermitian operators in Hilbert spaces. In Game Theory, forget John Nash: students of economics know well the Von Neumann-Morgenstern utility theorem; von Neumann was a major pioneer. He is also the father of the modern computer, developing the first single memory, stored program architecture. In other words, he is awesome. And that’s only a partial list, too.

In tackling the challenge of building a sustainable planet, we draw inspiration from the great scientists and engineers who solved countless problems and opened up entire fields. Our modern problems will be solved. At Carbon Lighthouse, making buildings 100% carbon-free profitably is our first iteration of a solution. We will keep iterating, too, deploying improved technologies and business models. We are excited to work with others who want to think our way to a cleaner planet – through innovative engineering, innovative project finance, and innovative ideas that haven’t yet been thought up.

And now, our favorite von Neumann story. Severe nerd warning!

At a Princeton cocktail party a Chemistry Professor saunters up to von Neumann and says, “I have a puzzle for you.”

Von Neumann smiles, his cheeks buzzing with excitement, “Proceed professor.”

The Chemistry Professor says, “Here it is. There are two trains. They’re on the same track heading towards each other. They start forty miles apart. They travel twenty miles per hour. There’s a bumble bee, traveling sixty miles per hour, that starts on one train, flies to the other, then back to the first train and so on and so forth, zigzagging. The question is: When the trains crash and smush the bee into oblivion, how far has the bee traveled?”

The Chemistry Professor is feeling very good about this question. Because he knows there are two ways to solve the puzzle. One is the engineer’s way, which is to reason that if the trains are forty miles apart, they’ll collide at the midpoint: twenty miles. Since the trains go twenty miles per hour, this means they’ll have traveled for one hour. The bee meanwhile, travels sixty miles per hour, and if he has one hour until the trains crash then he will have gone sixty miles. Problem solved. Takes five seconds. This is the clever solution, and if Von Neumann got it this way, the professor could write if off as von Neumann’s having heard the puzzle before. The hard way to solve the problem is to treat it as a mathematician would, which is as an infinite series. You have to calculate the distance the bee covers every leg of the trip, back and forth between the trains until they crash. And then you add up all of those trips in an infinite series. If von Neumann did it this way, it would take even the great John von Neumann some time and the Chemistry Professor could take pride in having given a tough problem to the famous Hungarian-American mathematician.

But not three seconds elapsed from when the question was posed until von Neumann spoke up, “The bee traveled sixty miles.”

The Chemistry Professor nods, “Yes, that’s correct. So you knew the trick?”

Von Neumann looks puzzled, “The trick?”

“Yes. You know, because the trains crash after an hour and the bee travels sixty miles per hour?”

Von Neumann looks up then smiles, “Oh, yes, that’s very nice.”

The Chemistry Professor says, “You mean you didn’t know the trick?”

Von Neumann shakes his head, “No. I just summed the infinite series.”

In theory, when we add a solar array to a building we should reduce these demand charges since most buildings use the most energy in the afternoons when it is hot outside and the sun is shining. Incidentally, when the sun is shining is also when a solar array generates the greatest amount of electricity.

Solar companies have a range of methods for calculating energy savings. Some are formal analyses, some are simple rules of thumb. One rule of thumb from our own experience is indicative: for a typical commercial building, with a solar array that meets 50% or more of the building’s peak energy needs, demand charge savings will be no more than 7%.

Seem small? What follows is a discussion of some of the factors that are critical to understanding the impact of the energy generated by a solar array on demand charges.

The Problem of Variability

Demand charge savings and solar are notoriously difficult to model because of the intersection of two unpredictable and partly independent factors: solar output and facility energy demand. The sun shines when it is hot, but may hide behind clouds at any moment for 15 minutes or more during which time facility energy needs will not change much. Buildings also need more energy when it is hot out, but sometimes require lots of energy at night as well. Energy demand differs by building: a university will have a different energy usage profile from a refrigerated warehouse which will have a different usage profile from an office building.

The demand charges will also differ based on the details of the utility’s rate structure. Some utilities have a single demand charge. Others have one demand charge for weekday peak energy demand between 11 am – 6 pm, another demand charge for weekday peak usage between 6 pm – 9 pm, and a third for peak usage on the weekend and between 9 pm and 11 am. There are many other variations. Peak demand rates can vary from winter to summer (e.g. $6/kW in the winter months and $15/kW in the summer months). Most rates are based on 15-minute demand intervals, but some use 10 minutes and others 30.

Resolving these issues requires the careful of collection of data about utility rate structures and facility energy demand.

The Problem of Average Solar Production

Using the National Renewable Energy Laboratory’s PV Watts tool, anyone can obtain hourly solar production data from key locations across the United States. PV Watts uses 40 years of historical data to model expected solar output.

What’s great about this hourly data for solar production is that if you also have hourly data for the energy demand of your building, you can deal with issues like the one we encountered at the end of the last post. As you may recall, we imagined having 500 kW building demand and 250 kW solar output at 1 pm and 475 kW demand and 0 kW solar output at 7 pm. It’s easy to use the hourly solar and demand data to calculate that in such a case, your demand charge would only be reduced from the previous maximum (500, which fell to 250 because of the solar) to the new highest amount (475 which does not fall at all because there is no solar). Calculating the corresponding changes in demand charges is just a matter of multiplying the kW savings (25) by the $/kW rate.

Problems emerge, however, with this hourly model when we model demand charges using the average solar hourly output from PV Watts.

For example, if the amount of solar energy produced by a solar array between 9 am and 10 am on:

• January 1^st was: 13 kWh = 13 kW (because it’s over one hour exactly)
• January 2^nd was: 11 kWh = 11 kW
• …
• January 31st was: 10 kWh = 10 kW

And you took the average of all the solar energy produced between 9 am and 10 am in the month of January to obtain say, 14 kW of power, that would give you the average solar power production at that hour. If you did it for every hour of every month, you would get a chart like this one (color added for clarity):

And if you knew the average facility demand between 9 am and 10 am across the month of January were 30 kW, then the average new facility demand would be:

• 30 kW – 14 kW = 16 kW

Then you could subtract the hourly solar production data from hourly building demand data for every hour of the year and multiply by the demand charge rates. The difference between that cost and the demand charges when there was no solar array is the demand charge savings.

While this is a good model, it has the following key shortcoming: the peak demand charges could very well occur when solar production is at its lowest not its average.

Energy consumption scales with temperature, which is correlated with solar irradiance, but a facility’s peak demand could overlap with minimal solar production. A temporary change in weather (cloud cover, brief storm) can cause a substantial drop in solar production with minimal change facility demand in a 15 minute period. Any drop in solar production for 15 minutes could throw off the demand savings for the entire month since demand savings are usually set by the highest facility demand during the entire month.

There is, fortunately, an easy way to make the hourly model of demand charge savings more accurate: select the minimum solar production for the month from the PV Watts data, rather than the average solar production. For example, if the amount of solar energy produced by a solar array between 9 am and 10 am on:

• January 1^st was: 13 kWh
• January 2^nd was: 11 kWh
• ….
• January 31st was: 10 kWh

And you searched the month and took the minimum of the solar energy produced between 9 am and 10 am to obtain say, 6 kW of power, that would give you the minimum solar power production at that hour. And if you knew the average facility demand between 9 am and 10 am across the month of January were 30 kW, then the new net facility demand for that hour factoring in the solar array would be:

• 30 kW – 6 kW = 24 kW

You could then make a new chart of minimum hourly solar production and subtract off every hour from the facility demand as we did before. This would create a more conservative estimate of hourly solar production. You would be using the PV Watts historical solar irradiance (and hence weather-impacted) data to account for changes in weather. That would be preferable to using average hourly data.

The Problem with Hourly Data

Which brings us to an additional problem: we’re looking at hourly intervals but the utility invoices the building based on 15-minute demand intervals. Let’s say the hourly data show that the building’s peak hourly demand for the month of March happened at 3 pm and was 40 kW. Then we look at the 15-minute data and we see that between 3:15 and 3:30 the building really used 70 kW, it just happened to use 30 kW between 3 and 3:15, and 3:30 – 4 pm, so that the total averaged to 40 kW over the hour. That’s a real problem, and a likely one. The utility is going to bill the building based on having used 70 kW, but looking at the hourly data you would think you’re only being billed based on 40 kW of demand.

Hourly demand forecasts are a good proxy for how demand charges are calculated, but because they were calculated on the hour and not every 15 minutes, they are likely to be below actual peak demand given the 15-minute fluctuations within the data.

One thing you can do is compare the maximum 15-minute interval in every hour-long interval to the average hourly demand, and then analyze the differences across every hour of every month. Variation may exceed 100% within an hour (e.g. between 4-5 pm the facility needed an average of 100 kW, but at 4:45-5:00 it needed 200 kW). You could end up with a chart showing the percent greater that the max demand in the 15 minute intervals is compared to the average hourly demand:

You may note all the red around the hours of noon. That’s because this particular data is adapted from a facility that had a solar array. The solar production fluctuated from cloud cover and other weather-related changes causing substantial swings in the net energy demand of the facility within a given hour

A reasonable correction for this hourly/15-minute problem is to take the maximum of the 15 minute demands in every increment and update your hourly and monthly chart accordingly. Alternatively, one could come up with an hourly multiplication factor of say, 1.4, in which you assume that there will be 40% greater demand within a given hour than the hourly average. Then multiply all the hourly demand numbers by 40%. Both these solutions allow for more accurate modeling of the actual, 15-minute demand charges.

Final Improvements

It is certainly possible to conduct an even more comprehensive analysis of solar and demand charges than what we discussed above. One further step is to run a Monte Carlo simulation. You vary solar production based on weather data and vary facility energy demand based on historical energy demand data as well as weather data. Running this simulation a thousand or a hundred thousand times generates a range of likely savings – because of the range of overlaps of solar production and facility energy demand. Taking averages and ranges would give you an even better model of likely demand charge savings from solar.

But a model it remains. Because unless you can predict when the sun will shine, as well as when a building will use the most energy, in 15-minute intervals, exactly, for the next twenty years, without fail, then you cannot have certainty in demand charge savings.

We can do some very powerful modeling that approximates reality pretty closely. And now you know some of the complications that go into it.

Residential electric bills usually only charge you for energy supply. These charges are based on the total units of energy (kilowatt-hours, kWh) you use. If you use 500 kWh per month, and the supply charge is $0.10 per kWh, your total cost for the month will be $50. (Note that you probably pay a handful of other charges for distribution, societal benefits, etc. These are also all assessed on a per kWh or flat fee per month basis).

Residential customers rarely pay what are called demand charges, but commercial and industrial facilities usually do. These facilities also pay supply charges on a per kWh basis, though their rates are often lower. Demand charges, however, do not work on a per kWh basis. They are charged on a per kW (kilowatt) basis. What’s the difference? As you may recall, kWh is a unit of energy, while kW is a unit of power (energy per second). Demand charges are levied on customers based on the peak power demand (kW) of the building. Thus the name, demand charges.

When a utility levies demand charges in addition to energy charges, it is similar to if your gas station charged you for your top speed as well as the number of gallons you used the past month. Your utility records the power draw of a commercial building continuously, breaking the building’s energy demand into 15 minute intervals. At the end of the month, the utility looks across every interval to see when the facility had the highest energy consumption. Then they charge the building based on that demand. So if, for example, over the course of December, a building’s maximum energy use in a 15 minute interval were 100 kWh, and the demand charge rate were $7 per kW, then the building would be charged $2,800 that month for demand charges. Where do these numbers come from?

• 100 kWh were used in 15 minutes
• This means that over the course of the hour (60 minutes) the building was on pace to use 100 kWh * (60 minutes/hour) / (15 minutes) = 400 kWh/hour = 400 kW.
• 400 kWh used over one hour is a peak demand of 400 kW.
• 400 kW * $7/kW = $2,800.

Demand charges are frequently 25% to 50% of a customer’s utility bill.

Part of the reason demand charges exist is because it is dramatically more expensive for the utility to produce energy at peak times than it is at off peak times. Part of the solution to this challenge is demand response, a payment buildings receive for reducing peak load on days when the grid is at risk of blackouts. This is an important carrot used to reduce peak energy use. The flip side of that solution is the stick of demand charges, which penalize customers for using too much energy at any one time. Peak demand charges, however, are not as precise as demand response: demand response events happen only the 10 times a year the grid really needs it. Most demand charges are applied monthly, so even if the month was uneventful from a grid perspective, a large customer could still pay a hefty demand charge. Some demand charges are “ratcheted,” meaning whatever your highest peak demand was sets your demand charge for the next twelve months.

This is all particularly relevant when a solar array is installed on a roof or nearby grounds. That solar array typically produces peak-loaded power, which is a formal way of saying it generates energy when the grid most needs it – on hot, sunny, summer days in the afternoon when buildings are running air conditioning at full blast and putting stress on the grid. Solar arrays produce energy when it is most needed and when, for most buildings, their demand will be greatest. Then great, solar reduces demand charges.

If only it were that simple. What if, for example, the building had a peak demand of 500 kW of energy at 1 pm and had a solar array that produced 250 kW of power; would the demand charges be cut in half? Almost certainly not. Because that same day the building could need 475 kW of energy at 7 pm, when the solar array produces 0 kW. So your peak demand only fell by 25 kW, from 500 to 475. As you can see from this one example, accurate modeling of solar demand charge savings is a notoriously difficult endeavor. In the next installment, we will explore some strategies to tackle it.

Or maybe not. Since it is, in fact, a relatively obscure energy modulating solution. And though it has recently begun being marketed as an energy efficiency panacea, odds are you have probably not heard of it—yet.

Voltage optimization is the process by which the voltage entering a piece of equipment is fine-tuned (usually reduced). A number of technologies of varying degrees of sophistication deliver voltage optimization: many are simply adjustable transformers that step down the voltage, just as your utility reduces your voltage on your nearby poles. In theory, voltage optimization lowers energy use, because of the equation:

• P = I * V   where

• P = Real power used by a device measured in Watts
• I = Current used by a device measured in Amps
• V = Voltage used by a device measured in Volts

If we make V lower, P decreases as well. Saving Watts. Saving Power.

Sounds great. Of course, so do the best synthesized bird calls. That doesn’t make them real.

While voltage optimization solutions can deliver energy savings, principally for certain kinds of motors, in many cases their value has been grossly inflated by marketing efforts. Voltage optimization advertisements saying you’ll reduce carbon emissions in your home by 10% are in most cases simply greenwashing.

What is greenwashing? It is the practice of marketing processes or technologies as environmentally-beneficial when in fact their benefits are negligible or non-existent. The Greenwashing Index through the University of Oregon tracks some corporate products and advertising that are suspected of greenwashing.

But general consumer goods companies are not the only ones that greenwash their products. Much greenwashing relates to energy efficiency. How to properly verify energy efficiency efficacy is well-established but that doesn’t mean consumers can do it or that they know to ask for it.

Some products that claim to deliver energy efficiency are actually just energy reductions without the efficiency. Doing the same thing more efficiently does not sacrifice an end product (light levels stay the same, the amount of cooling your AC provides remains the same, etc.), energy reductions not gained through energy efficiency might sacrifice operations or comfort. Energy reductions are fine where appropriate – many commercial office spaces in the U.S. have lighting levels well in excess of modern recommended amounts and are therefore excellent candidates for removing 10-40% of the lamps – but if light levels are already appropriate, reducing the number of lightbulbs may not be a good idea.

If I reduce the voltage going to your light bulb, it receives less power. But if it receives less power, it produces less light. If you do not mind lower levels of light, no problem. But then you could have just bought a lower wattage light bulb instead. Voltage optimization is usually no more than a simple energy reduction. By contrast, you could buy a 20-Watt incandescent light, but it would produce about 25% of the light as a 20-Watt compact fluorescent light. Same power, greater usefulness: that is energy efficiency.

In many cases, voltage optimization delivers temporary power reductions. But in many of these cases, these power reductions do not actually provide overall energy savings because of the nature of the energy consumption. Some specific cases will help illustrate this point:

• If you reduce the voltage to a 2000 W space heater by 10%, so that it now only uses 1800 W, it will also produce less heat. You will need to run it longer to give you the desired effect though, so there are no real energy savings.
  
• If you reduce the voltage to your hot water kettle, it will take longer to boil. There are no shortcuts to the specific heat of water: it needs 1 BTU of energy to increase its temperature by 1 degree Fahrenheit. Reducing the voltage just means the kettle will need to draw less current for a longer time.
• If you reduce the voltage to your refrigerator, it will run the compressor for longer. You will not save energy, because your refrigerator has to produce a set point temperature. There are no shortcuts to thermodynamics.
• If you reduce the voltage to a motor outside its recommended 10% tolerance you will degrade the motor’s operation. The U.S. Department of Energy has helpful papers on this topic. If the motor is fully loaded, then even on a small voltage drop the motor will draw more current to meet the load. This will cause it to run hotter, shortening its life. A voltage drop will also reduce torque and motor efficiency (see p. 385 in this IEEE article for a more thorough treaterment). Not good at all. If you reduce voltage for a motor serving a variable load, there will be some energy savings (this happens because of the relationships between slip, load, efficiency, and voltage and the fact that magnetizing losses are lower at decreased voltage; the short explanation here is the slip at a lower load is less, which actually is more efficiently served by a lower voltage, so in this regime a lower voltage will still meet the load requirements while reducing magnetization losses. Therefore, the optimal voltage decreases as load decreases). Nonetheless, a Variable Speed Drive is still widely considered a more robust and more cost-effective solution for variable loads.

As you can see, the devil haunts the details of each application. The above is only a summary. The United Kingdom’s Ministry of Defense (MoD) conducted a wide-scale review of the energy savings opportunities resulting from Voltage Optimization. Their conclusions broadly match with those of our team.

Voltage optimization has been a major topic in the United Kingdom in particular because of reports of systemic overvoltage. This results partially from 1995 EU regulations that required voltages to come down to 230 Volts. In many areas of the UK, this did not occur. As a result, reducing the voltage that enters homes and offices offers some savings opportunities for consumers. But because transformer losses in voltage optimization equipment are still a few percent, a better solution would be to reduce voltage levels fed into the grid and, especially, to adjust the step-down equipment along the grid so that it produces the targeted 230 Volts. Skeptics of voltage optimization in the UK abound.

In a normal grid, proponents of voltage optimization argue it can reduce energy consumption by as much as 10%. It can. In select circumstances: mostly in industrial concerns, sometimes in commercial concerns, and almost never in homes. The main advantage of voltage reductions on the grid are temporary power reductions when the grid is stressed, not overall energy savings.

At Carbon Lighthouse, our excitement for technologies like voltage optimization is muted partly because too often voltage reducers are simply a greenwashed product. More importantly, voltage optimization, while it has its limited place, does not bring us closer to a more sustainable planet. Compact fluorescent lights cut the lighting energy needed in a home by 75% but still deliver the light we need. High efficiency washing machines use less energy and less water while providing the same clean clothes. Variable speed drives cut motor energy by 20-80% and deliver the power we need to pump chilled water and ventilate our buildings. Drawing window blinds on a hot day reduces heat load on our buildings. These are the kinds of changes that bring us closer to where our planet needs to be.

Not all that glistens is green.

End Note

Voltage imbalance in a motor can be a serious problem, causing substantive reductions in energy performance. For such motors it would be beneficial to undertake voltage correction (which frequently can only be solved not with a silver bullet “voltage optimizer” but rather with a comprehensive analysis of the building’s electrical one-line diagram, ground faults, 120 Hz vibration issues, and faulty power factor correction equipment).