There is a lot of hype right now about the “Bloom Box.” Google installed one, Adobe installed one, and Bloom Energy has an active sales force hitting up the Fortune 500. So what is a Bloom Box and what does it mean for the future of the energy world?
A Bloom Box is a hydrogen fuel cell. The simple picture is that you feed it natural gas and it spits out electricity. How is it different from a regular natural gas power plant? There’s no combustion in a fuel cell, just the silent separation and recombination of protons and electrons.
Fuel cells rely on a catalyst to split hydrogen ions off from natural gas. The hydrogen ions are super positively charged – a hydrogen ion is a single proton – so electrons can be made to do pretty much anything to meet up with them. An electron will flow through your light bulb, or your entire Google office and create power, just to reunite with its long lost proton.
So that’s a Bloom Box. Rip apart some natural gas, separate out the protons, and make electrons do useful work to meet up with them. No combustion, and lots of awesome innovation on the catalyst side of things.
There are two problems though. The first is that there’s carbon in the natural gas, so when you rip the hydrogen atoms away from it, that carbon gets emitted and becomes carbon dioxide (CO2). Bloom Boxes are pretty good, but they are not a carbon free source of electricity like solar or wind. Specifically, a Bloom Box emits 773 lbs of CO2 per megawatt-hour (MWh) it generates. This is quite a bit better than grid power in most states, but not all. Check here for a list of states and their emissions factors.
A Bloom Box, or any hydrogen fuel cell, could be carbon free if you fed it pure hydrogen (or renewable biogas), instead of natural gas. The problem then is where you source the hydrogen. Ultimately, we could get hydrogen by using solar power to split water molecules apart, which would result in zero carbon emissions and result in a really cool way of storing the energy produced by the sun: we could generate hydrogen during the day from the sun, and then use the hydrogen at night to generate clean electricity. This would be an amazing way to store solar energy, and this was in fact the dream of many hydrogen buffs back in 2000. Unfortunately, it is still outrageously expensive. Which brings us to our next problem.
Economics. Federal incentives will currently (2011) pay for 65% of the Bloom Box, and State and utility incentives will often pay for up to another 20% of the total costs depending on your State. That can make a Bloom Box investment very, very good. But what about without incentives? Without incentives, the economics don’t work out favorably for the Bloom Box. And since the Bloom Box is pretty much the best hydrogen fuel cell right now, it means economics aren’t great for any fuel cells. The Bloom Box is about 50% efficient, which is pretty good, but still less efficient than a new central station natural gas plant. Side note: there aren’t electric transmission losses when you generate electricity on site, but there are transmission losses in our natural gas distribution infrastructure on the order of a couple percent, and since methane (which makes up greater than 90% of natural gas) is 20-25 times worse than carbon dioxide in terms of global warming, the transmission losses for a Bloom Box do not work out favorably.
Back to economics. The best info on price we could find for the Bloom Box was between $10,000 and $12,500 per kilowatt (kW), and Bloom Boxes sell in increments of 100 kW. Depending on what state you’re in, and if you sneak in a purchase before bonus depreciation disappears, then you should get about 65-90% of the total cost back, so we’re guessing a 100 kW Bloom Box installation costs about $200,000 after rebates. If you take out a loan at 4%, assume maintenance is a few percent, and you buy gas at $0.90 a therm, then the device will give you power at around $0.10/kilowatt-hour (kWh). That’s not great. The US average is about exactly that. Don’t like our assumptions? No problem. We made a spreadsheet for you to put in all your own assumptions and see the calculations exactly, and you can download it here. Have fun!
So what’s the point of all of this? The Bloom Box is a cool technology that is still expensive and doesn’t get companies to carbon free. If we ignore rebates (which we should if want a sustainable future that can be exported to India and China), then the Bloom Box is still about 8 times more expensive than coal, and more than twice as expensive as solar. Unlike solar the Bloom Box generates carbon emissions, but also unlike solar, the Bloom Box can generate electricity at night. I wouldn’t put my money on fuel cells powering the future any time soon, but I am excited by all the exciting engineering progress that has been made so far, and for another eventual arrow in the quiver against climate change.