Back in 2007 the city of San Jose set out to achieve a 100% landfill diversion rate by the middle part of the century. The plan, dubbed Green Vision, requires the expansion of recycling and composting services, as well as increased investments in waste-to-energy technology. Six years later, the city of San Jose is on the verge of flipping the switch on its first commercial-scale anaerobic digestion plant.
The new facility houses 16 digestion tanks that can hold 350 tons of waste each. By the end of this month, the facility will begin accepting food scraps and organic waste from the city’s hundreds of restaurants and commercial businesses. The facility’s relatively large capacity will allow the city to divert the majority of its food waste from local landfills. And the plant’s owner, Zero Waste Energy, has planned out three additional phases of development for the site. Each new phase will allow the facility to expand its capacity to handle 90,000 tons of organic waste each year.
Diverting organics prevents the buildup of methane inside landfills, where it can easily escape into the atmosphere. Methane originating from municipal solid waste landfills is one of the largest sources of human-generated methane in the world. And even though a significant portion of modern landfills utilize bio-gas capture systems, they are largely inefficient and prone to developing leaks. Using digesters significantly reduces the chances of gas leaking out into the air, while also maximizing the efficiency of the energy conversion process.
San Jose’s investment in sustainable energy has largely been self-motivated, though the state of California has played a role by legislating expanded use of renewables. The state’s “Renewable Portfolio Standard” requires all utility companies currently operating in California to expand their renewable energy use to 33% by 2020. San Jose’s new anaerobic digestion plant counts towards the state’s standards, creating an example for other cities to follow as the mandate deadline approaches.