Wastewater treatment plants are vast expanses of bubbling tanks that sprawl around the outskirts (and sometimes the inskirts) of cities and towns. All that acreage can be put to another use and one solar energy company, SunPower Corp. is pointing the way. The company recently completed work on a one-megawatt solar power system at the West Riverside Wastewater Treatment Plant in Corona, California.
The new solar power system will generate about 25 percent of the plant’s energy needs, and that’s significant in terms of a more energy efficient and sustainable future. Wastewater treatment plants are packed with industrial-sized aerators, pumps, and other energy-gobbling machines, so getting them off the conventional energy grid would be a major step forward.
Bigger and Better Sewage Treatment Plants: the Solar Connection
SunPower’s high efficiency panels are mounted on the company’s SunPower T20 Tracker system, which needs less land to install but follows the sun to capture up to 30% more light. That puts a good chunk of solar energy within reach of modestly sized treatment plants as well as the big ones. SunPower has a growing number of large scale installations in California, Florida, and worldwide, totaling hundreds of megawatts. The Western Riverside project pales by comparison at only 1 MW, but that could change. The treatment plant can handle up to 8 million gallons per day currently, but it is capable of expanding to 32 mgd – and consequently it will require more energy to run. Aside from the impact of population growth on the energy requirements of sewage treatment, it is likely that federal sewage treatment standards will continue to become more exacting, which may also require more energy to run new equipment. Solar, wind and other on-site sustainable energy will become more important as these two trends develop.
Sewage as a Sustainable Resource
The sewage treatment plant of the future is going to be an all-around, self sustaining resource recovery facility. Solar-powered equipment is already available for some plant operations, and companies are developing more energy efficient processes including a “sewage mole” that helps aerate and dry biosolids – which can then be used as a soil enhancer. Methane gas is another resource that more sewage treatment plants are beginning to recover, and water expert Bluewater Bio is one company that is working on recovering more usable water instead of shunting it into the nearest river. There is even a move afoot to use sewage biosolids for manufacturing bioplastic.
Image: Sewage treatment plant by user Xofc on wikimedia commons.