Thanks to proven reliability and the decreasing costs of solar panels, solar energy is proving a viable ticket to energy efficiency at wastewater treatment plants (WWTPs). WWD Managing Editor Elizabeth Lisican recently spoke with SPG Solar Director of Project Development Dylan Dupre about solar’s increasing influence.
Lisican: Municipalities across the country often are faced with this pressing question for their wastewater treat- ment facilities: What kind of alternative energy strategies not only will save a significant amount of money, but also have minimal environmental impact?
Dupre: With electricity costs as the largest portion of the annual operating budget for water and wastewater treatment facilities, solutions to control and lower costs while creating clean energy are key. Solar energy taps into the largest resource available—the sun. In fact, every hour, the sun radiates more energy onto the earth than the entire human population uses in one whole year. Solar makes sense for wastewater treatment plants. A compelling feature of solar is that it can help manage peak electricity demand. Solar power systems generate the most electricity midday. This coincides with when utility rates are most expensive, so solar provides a mechanism for peak saving and immediate savings.
Lisican: What are some of the biggest trends you are seeing right now in terms of energy savings at WWTPs?
Dupre: Wastewater treatment plants are looking at demand-response to shift operating and pumping hours to off-peak hours. Also, wastewater treatment plants nationwide are realizing the business case for solar. A key vehicle for adoption has been the Power Purchase Agreement, which allows townships to access tax credits through private investors. There is no need for a capital outlay and the risk around the installation and maintenance is removed from the wastewater treatment plants. The outcome of a solar installation is a hedge against rising utility rates and long-term predictability.
Lisican: How can solar energy be harnessed to solve WWTPs’ energy efficiency issues?
Dupre: Solar is a longer-term energy solution for wastewater treatment plants and makes sense. With the costs of solar panels coming down 44% in 2011 and an operating life of 20 to 35 years, solar power is reliable. Additionally, solar has a great application value, providing flexibility. You can install it on a rooftop, car- port, the ground or even on water.
Lisican: What future developments do you foresee regarding solar energy’s role in wastewater treatment?
Dupre: We see a hybrid solution available for wastewater treatment plants. In addition to solar on land, solar can also float on water. This provides a solution if land is too costly, since float- ing solar converts an available holding pond into a renewable energy production platform. SPG Solar installed the first commercial floating solar power system in 2007. It not only produces clean electricity, but it also helps reduce water evaporation by up to 70% and improves water quality by reducing algae growth. Additionally, the solar panels not only cool the water, but the panels work more efficiently since they, too, are cooled.
Lisican: Please discuss a few examples of projects in which solar has been implemented at a WWTP.
Dupre: SPG Solar designed and installed an innovative 2.3-MW DC system at the Neely Waste Water and Reclamation Facility in Gilbert, Ariz. [Because] space was limited, we engi- neered one of the first ground-mounted tracking systems built directly in five operating recharge basins. With no upfront capital costs to the municipality, since SPG Solar provided a Power Purchase Agreement, the system will provide a savings of up to $2 million over the next 20 years and provide the equiva- lent of approximately 40% of the electricity used at the reclamation facility.
Dylan Dupre is director of project development for SPG Solar. Dupre can be firstname.lastname@example.org  or 415.382.2172.
Solar power gains ground in wastewater treatment