Stanford has done it again, this time with a process that is rather unexpected. Their system will alter the wastewater treatment process to create nitrous-oxide (N2O) and methane gas that will then be burned to power the plant.
Historically, rockets have not been considered environmentally friendly, but these thrusters run on N2O and create no emissions. (Well, technically speaking, the emission is oxygen-enriched air, but I don’t think we mind making it a little easier to breathe.) The N2O will come from the wastewater treatment plant, and a rocket the size of a basketball should be all that’s needed to do the job. That rocket produces heat to power the plant, making it both emissions-free and energy-neutral.
Traditional wastewater treatment plants pump air into the wastewater sludge to provide oxygen for aerobic bacteria. This type of bacteria breaks down the organic material in the sludge into nitrogen gas, which is harmless, but also useless. Stanford’s redesign doesn’t need all that extra oxygen, aiming to foster anaerobic bacteria instead. There are two bacteria that live in harmony in Stanford’s system—one of them produces nitrous-oxide while the other produces methane. That methane can then be used as fuel to power other parts of the plant, since it isn’t needed to pump air into the sludge.
The engineers of this system are also looking to expand its applications to other fields (literally) where nitrates contaminate groundwater. If there are other sources of N2O available, their rocket technology could be used to turn that greenhouse gas into energy and a cleaner atmosphere.