Energy: Wastewater Used To Produce Electricity
San Diego’s new method to create energy may not be the most pleasant of processes, but according to Mayor Dick Murphy, it works.
The city recently dedicated a new hydroelectric turbine at the Point Loma Wastewater Treatment Plant. It can produce 1.35 megawatts of electricity , enough to power about 1,350 homes. The energy will be sold to the local electric grid.
Murphy said the recent electricity crisis has forced the city to be creative in its efforts to conserve energy. He has referred to this plan as “turning waste to watts,” or “poop to power.” Although Murphy knows it’s not the entire answer to the energy crisis, it helps.
“Every little bit we do is certainly cutting the cost to taxpayers during this energy crisis,” Murphy said. “I think the energy crisis has encouraged creativity. The city looked for less-expensive ways to acquire electricity.”
State Grant
The $1.2 million product includes a $360,000 grant from the California Energy Commission and $420,000 in renewable energy incentives from the state over the next five years.
Using the wastewater facility to generate energy is not a new idea at City Hall. Murphy said the plan was proposed more than a year, but the current council encouraged the city’s staff to accelerate, he said.
“This is just one more example of how the city is working to meet our goal of becoming energy independent,” Murphy said. “The cumulative effect of initiatives such as this hydroelectric plant, along with continuing improvements in conservation, will make a big difference in San Diego’s energy future.”
The turbine has been at the Point Loma plant since the mid-1980s, but it wasn’t capable of doing the job. Modification of the plant’s piping system and the recent rehabilitation project have made operation of the generator technically feasible.
The turbine is powered by treated wastewater from more than 2 million people in the city that drops 90 feet from the cliffside plant into a 4.5-mile-long ocean outfall. The power produced is said to be enough to supply electricity to more than 10,000 homes.
Renewable Resources
Scott Tulloch, director of Metro Wastewater, said using the byproducts of wastewater treatment makes perfect sense.
“Waste power and methane are not only renewable, but they cost the ratepayers nothing,” Tulloch said. “All monies made from the sale of excess energy produced are used to help defray the energy costs of other Metro facilities that do not have their own power generation capabilities.”
Bringing the hydroelectric plant online is just one of the city’s energy initiatives.
According to city staff members, the Wastewater Department already produces more than 16 megawatts of power, with nearly half of that going to the power grid. The Point Loma plant, which is energy self-sufficient, uses methane gas to run two turbines that produce the 4.5 megawatts of power. On average, the Point Loma plant uses only 45 percent of that energy.
Other green power initiatives in place by the Wastewater Department include the methane cogeneration facilities at the North City Water Reclamation Plant and the Metro Biosolids Center that make both energy self-sufficient. Combined, the two facilities produce 10.2 megawatts of power.
