The biomass energy industry is largely fueled by lignocellulosic biomass – or, biomass that comes from plant dry matter. When most people think of biomass, they think of this type, which includes fuel from trees, switch grass, and agricultural waste from sugarcane and corn production.
There’s another type, though, that is rising in popularity and could be the future of energy production from organic material. Everyone living in America encounters this potential fuel source at least three times a day.
It’s food – or, more accurately, the 70 billion pounds of food Americans waste each year.
How Energy Comes from Food Waste
Biogas, simply defined, is gas that is formed from organic matter without oxygen. This gas can be burned for energy because it is comprised of mostly methane and carbon dioxide, along with a smattering of other gases.
There are several potential sources of biogas, but the one that potentially has the most promise is food waste. As mentioned, Americans waste 70 billion pounds of food each year, from the kitchen table to grocery stores and restaurants that throw out what they don’t use.
Instead of being thrown into a landfill or repository, this waste can be recycled and placed into what is called an anaerobic digester. This device breaks down the waste in an oxygen-less environment, producing methane and other gases that can be burned to generate biomass energy in the form of electricity or heat.
Most of the biogas generated in the United States over the past half-century came from landfills, which produced “landfill gas” that was most often burned off as a waste by-product. In 2003, approximately 147 trillion BTU of landfill gas was consumed. Landfill gas wasn’t always economically viable, so producers turned to cow manure as a feedstock.
Now, though, food waste is being developed as a feedstock that is far more plentiful than cow manure and landfill gas – and is more economically viable to boot.
Exploring the Potential of Food Waste Biogas
Given just how much food waste is generated each year (70 billion pounds a year works out to a staggering 191 million pounds of waste per day), the potential for biogas is enormous.
Already, various organizations and agencies across the nation have experimented with biogas from food waste. As many as 15 wastewater facilities throughout the country use a mixture of food waste and human waste to produce biogas that is in turn used for energy production.
Another 860 sewage treatment plants use anaerobic digestion to produce biogas that helps to power the plants themselves. Some of these plants – like some in Nevada, Indiana, and Iowa – have begun incorporating food waste into this plan. The East Bay Municipal Utility District in the Oakland-Berkeley area in California was actually the nation’s first such plant to use food waste as a source of biogas, back in 2002. Last year, it sold surplus power to Oakland and pocketed $1 million after the biogas program produced more than enough energy to power the plant.
The latest development is a fully-automated biogas plant that’s capable of producing 1.2 MW of power from 40,000 tons of food waste each year, set for completion and operation by the end of 2016. This plant, produced by Quantum Energy, is Connecticut’s first biogas plant to use food waste as a feedstock.
Slowly but surely, the use of food waste in biomass energy production is growing. Biogas is carbon neutral, doesn’t involve incineration, can be used right now in natural gas production facilities as a substitute – and, with modifications, in existing conventional energy facilities.
Of course, there remains an obstacle: economic viability. A study conducted by the EPA and the National Renewable Energy Laboratory in 2013 of potential for anaerobic digestion of food waste in St. Bernard Parish in Louisiana concluded that the net present value of the project was -$6.7 million. Furthermore, the study stated that “revenues from the plant…are not anticipated to be sufficient to overcome costs.” Much of the negative net present value came from the high installation and startup costs of creating a commercial-grade biogas plant featuring anaerobic digestion.
While the aforementioned study was narrowly focused on one particular project in one part of the country – the study admitted that much of the negative value stemmed from low landfill and energy prices in Louisiana, which would vary by state and region – there has to be sufficient evidence of viability before a private actor would agree to invest in a venture.
Biogas could be a prime source of biomass energy in the future. As it stands now, it’s a developing technology with a lot of promise, but little realization.