UP FUTURE CREEK WITH A SHIT PADDLE
Renton, WA is home to the largest sewage -> hydrogen power generation project in the world (via World Changing, who had the good taste not to mention MSNBC's "Poop Power?" headline):
Day in and day out, some 700,000 people send 86 million gallons of sewage, mostly toilet and kitchen waste, to the King County treatment plant in Renton, a Seattle suburb.
Little do they know that 30 million of those gallons are producing enough methane gas to run the 1 megawatt, fuel-cell power plant that was built here this year. The system can power 1,000 homes, but in this case all the electricity is going to help run the treatment plant, which needs about 7.5 MW per hour a day on average.
The largest project of its type in the world, the process goes like this: Biodegradable solid waste is sent to large tanks, called digesters, that provide a home for three to four weeks. There bacteria eat away at the waste, releasing methane gas and further reducing the amount of solid waste.
Most treatment plants flare off the methane, and a few burn it to get electricity for their sites. But the Renton plant captures the gas and sends it to a fuel cell system, where the methane is broken down into hydrogen and carbon dioxide. The carbon dioxide is recirculated to produce carbonate. The carbonate then combines with the hydrogen to produce electricity, water, carbon dioxide and heat.
Fuel cells operate like a battery, and methane or any other fuel containing hydrogen can be used to power the process. A key advantage to fuel cells is that they are much more efficient at generating electricity than the combustion process found in today's cars and power plants.
The plant doesn't produce a whole lot of power and is completely expensive, at a cool $22 million ($20 million of which was provided by the EPA, which made the project feasible), but if successful it should provide a duplicable model for use in sewage treatment plants across the country - nay, the world! A spokesperson for the company that built the plant says that "we're able to lower the cost by 25-35 percent" with each new prototype they've built - a few more 25-35%s and we're in the ballpark! Cost aside, the plant will yield important reductions in methane, an oft-overlooked greenhouse gas that is four times as potent as CO2, as well as reducing CO2 emissions by 50% and nearly eliminating NOx emissions (one of the main components of smog).
FYI, FuelCell Energy, the company that built this plant, is also providing power for next week's Democratic National Convention in Boston with a temporary distributed electricity microgrid with a 250 kW hydrogen fuel cell power plant at its center. The plant internally reforms natural gas to produce hydrogen, which in turn powers the fuel cell - a process that is approximately twice as efficient as conventional power plants, while reducing CO2 emissions by 60% and NOx by 99%. The greenest convention ever, they say, meaning 'the greenest convention in the modern era' I guess. Kudos!