The city of Chicago is turning sewage waste into electricity. Engineers at the city’s Metropolitan Water Reclamation District (MWRD) have the goal of cutting the city’s spending on electricity down to zero within the next eight years by making use of this technology. If they are successful, they will become the nation’s largest wastewater treatment authority to achieve this feat.
Project manager for the Water Environment Research Foundation Paul Kohl said, “There’s more energy in the sewage that comes into a wastewater treatment plant than is required to treat it. We think we ought to be able to go ahead and get that back out.”
According to some estimates, there is anywhere between two to ten times as much energy contained in wastewater than the amount of energy that a water treatment agency uses in treating the water. In the United States, water treatment accounts for about 3% of total energy usage in the United States.
Achieving energy neutrality would present tremendous savings to the Chicago water treatment company. It would also help to protect them from future increases in the price of energy.
Executive director of MWRD David St. Pierre said, “Some people do it for the environmental benefit, but I was raised as a business person. Having your own energy source, we can convert it to anything we need. So if the market drives costs, we can really kind of control that unforeseen cost of energy in the future.”
Currently, the facility obtains about a third of its energy by harvesting gas that is produced by special bacteria used to break down the toxic components of wastewater. This process is known as anaerobic digestion.
In the future, MWRD is planning to take local waste, convert it into electricity and sell it back to customers. This would be an innovative method of converting outside waste and making good use of it. However, there are still logistical issues that must be worked out before this can happen.
While the treatment facility will have to pay a steep initial cost for this program, it will pay for itself in just a few years thanks to the savings. Indeed, this water treatment facility is doing some pretty nifty things with what most people would consider to be mere garbage.
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