Congratulations to New York City. WE&T April featured an article on the applied research at New York City’s Rockaway Wastewater Treatment Plant, where the first liter of butanol from algae was produced in their test reactor.
New York City always has been a leader of testing improvements in wastewater treatment. When I was in graduate school, some 50 years ago, every activated sludge plant there had capabilities to convert its aerators from natural gas to digester gas. This environmentally sound process faded out, probably because of the low cost of natural gas. Other New York studies experimented with optimizing feeding of digesters.
Now they are studying energy from algae. There are numerous ways of obtaining the energy from algae. One of them, as in this New York City study, is using a biological system to convert sugars in the algae mass to butanol. Another way comes from the oils many algae store for energy for use when they are stressed. This oil can be separated easily and refined to gasoline. The residual biomass can still be used to produce butanol or can be used directly as a fuel or as a fertilizer.
As pointed out in the article, the area needed to produce ethanol from corn is at least five times greater than the area needed to produce an equivalent amount of energy as butanol from algae. In addition, algae can grow on the nutrients in wastewater, and, in some cases, remove certain trace constituents.
Instead of collecting carbon dioxide and injecting it into the ground for our grandchildren to worry about, these researchers are letting the algae use the carbon dioxide to produce oxygen and biomass. And, if there is a nearby source of waste heat, algae can be grown year-round in northern climates, thereby reducing global warming.
Why haven’t we done more to recover the energy from algae? Probably it is the result of the oil and coal lobbies that want to recover their investment in infrastructure and the farmers who can get a higher price for their corn at the expense of our corn flakes.
New York City has the right idea in studying methods to recover energy from algae, the most efficient method of recovering solar energy. We have to start sometime; why not now before we use up all our polluting fossil fuels?
Donald B. Aulenbach
Clifton Park, N.Y.
©2011 Water Environment Federation. All rights reserved.