US cities could churn out renewable hydrogen from wastewater

We’ve been giving hydrogen fuel cells the sustainability stinkeye because of the huge amount of energy needed to manufacture hydrogen, which typically involves natural gas, which brings us around to the impacts of fracking including water contamination, fugitive greenhouse gas emissions and even earthquakes. However, a new fuel cell demonstration project from Lawrence Livermore National Laboratory might be enough to shut us up. The $1.75 million project, in partnership with the Florida company Chemergy Inc., aims to reclaim hydrogen from municipal wastewater, aka sewage.

Renewable Hydrogen From Wastewater

The renewable hydrogen fuel cell project is partly funded by the California Energy Commission as well as Chemergy. It also partners the US Department of Energy, the Department of Defense Construction Engineering Research Laboratory (didn’t know we had one of those, did you?), and the Bay Area Biosolids to Energy Coalition, which includes 19 municipal wastewater authorities in the San Francisco Bay area. A wastewater treatment plant operated by a coalition member, the Delta Diablo Sanitation District in Antioch, was selected to be the testbed.

Raw wastewater is typically more than 99 percent water, so the two-step system developed by Chemergy comes in after the treatment process has reduced wastewater to wet biosolids.

Using a low temperature thermochemical process, a hydrogen compound is extracted from the biosolids along with reclaimed heat and carbon dioxide. The compound is then decomposed to form hydrogen.

The renewable hydrogen will go to fuel cells developed by DOE and the Defense Department. The expectation is that within a year, the fuel cell system will process about one ton of wet biosolids daily and reach a capacity of up to 30 kilowatts. The electricity will be used to power some of the treatment plant’s operations.

Based on Livermore’s energy equivalency calculation of one kilogram of hydrogen per gallon of gasoline, the system is expected to produce hydrogen at a competitive price of $2.00 per kilogram.

As for the multiplicity of partners involved in this relatively modest project ($1.75 million doesn’t buy much these days), Chemergy’s expertise is in the chemical conversion of wastewater to hydrogen, but in order for the system to function efficiently from soup to nuts you also have to factor in the durability and safety issues involved in hydrogen storage and use, which is where the experts at Livermore come in. The lab has been partnering closely with the departments of Energy and Defense on advanced fuel cell technology.

Meet Your Friendly Neighborhood Sewage Treatment Plant

Aside from recovering a clean, renewable fuel from wastewater, the fuel cell system also cuts down on the amount of wastewater byproducts that need to be transported off site for disposal. In addition to saving money, that cuts down on greenhouse gas emissions related to transportation and disposal.

That’s just the tip of the iceberg as far as resource recovery from wastewater treatment plants goes. Other examples that are already becoming commonplace are renewable methane gas recovery (both for stationary use and as a vehicle fuel) as well as natural soil enhancer from dewatered biosolids.

Also in the works are bioplastics and liquid biofuel from reclaimed grease.

With their huge, sprawling infrastructure, municipal wastewater treatment facilities also have potential for hosting other forms of renewable energy including photovoltaic installations and hydrokinetic turbines.

http://cleantechnica.com/2013/09/13/us-cities-could-churn-out-renewable-hydrogen-from-wastewater/