Note to U.N. Climate Delegates: Don't Forget Renewable Natural Gas

By Joanna D. Underwood

Amid clamor for bolder action on climate change, there’s dispute over the U.S. strategy of boosting production and dependence on natural gas as a bridge to a low-carbon future.

2013 was a record year for global CO2 emissions, and included a 2.9 percent rise in U.S. CO2 emissions after several years of decline. Burning natural gas to generate power releases only half the CO2 of burning coal, and when it is used as a vehicle fuel, it’s 20 to 25 percent better in terms of overall greenhouse gas emissions than gasoline or diesel.

But it is, after all, still a fossil fuel. It consists mostly of methane, an unregulated heat-trapping gas 25 times more powerful than carbon dioxide. Methane leakage from well sites and pipelines has become a hot topic. U.S. environmental groups are demanding the EPA regulate it, and it’s an issue at the United Nations Climate Summit taking place in New York this week.

Renewable energy advocates point out that the money spent on natural gas development preempts renewables spending, and there’s a limit to how much methane leakage and emissions regulation can be controlled and how much natural gas emissions can be improved. It’s understandable why, for many, swapping natural gas for oil and mitigating carbon dioxide emissions with methane seems like incremental punting -- not a robust solution to climate change.

But natural gas critics and boosters alike are missing something important: the advent of a fuel called renewable natural gas (RNG), which is chemically similar to fossil natural gas, but better. It is produced not by drilling or hydrofracking fossilized deposits, but by capturing biogases wherever organic wastes decompose: in landfills, wastewater treatment plants, etc. The stream of organic waste is massive, but until recently, we’ve largely ignored it as a source of energy and emissions savings.

Over its lifecycle, burning RNG as a vehicle fuel lowers greenhouse gas emissions by 88 percent or even more. In fact, GHG emissions from RNG can be net zero, or even net negative, meaning that producing and burning the fuel actually prevents more greenhouse gasses from entering the atmosphere than it emits. Here’s why:

If we leave fossil fuel deposits in the ground, their hydrocarbons stay in the ground. But if we leave our organic wastes alone and don’t refine them into fuel, they release their hydrocarbons into the atmosphere anyway as they break down. Every day, in urban and rural landscapes across the U.S., over 78 million tons of food and yard wastes are thrown out by homes and businesses, plus much more organic waste from food processing plants, supermarkets, farms, sewage, etc., are decomposing and emitting GHG without producing usable energy.

If we turn their biogases into fuel, and use it to offset emissions from fossil fuels, the overall impact on GHG isn’t incremental; it’s dramatic -- vastly greater than an equivalent amount of fossil natural gas.

RNG now powers hundreds of buses and trucks in Sweden, Spain, France, Germany, the Netherlands and Norway. In recent years a dozen waste-to-fuel initiatives have been launched in the U.S., and RNG is powering trucks and busses in six states, a harbinger of much bigger impacts to come.

America’s fleet of 10 million trucks and buses are our economic lifeblood, supplying our cities with transit and waste and recycling services and transporting materials and goods nationwide worth 70 percent of GDP. They also consume nearly a quarter of the nation’s vehicle fuel and emit nearly a quarter of the transportation sector’s GHGs.

Every fleet converted from diesel to RNG would cut its GHG emissions by 88 percent or higher. This exceeds U.S. goals of a 20 percent reduction by 2020 and and 80 percent reduction by 2050, as well as even tougher goals recommended by the Intergovernmental Panel on Climate Change (IPCC). RNG would cost about a third of diesel, and create tens of thousands of sustainable, place-based, unexportable jobs.

RNG qualifies as an advanced biofuel under EPA’s Renewable Fuel Standard, which helps incentivize low-carbon non-petroleum fuels. But it’s in our environmental and economic interests to develop RNG rapidly. So, mayors and governors contending with costly waste streams and emissions regulation compliance, federal officials and U.N. Climate Summit delegates wrestling with hydrofracking and methane regulation, and renewables advocates and concerned citizens demanding robust climate action should take note: A significant part of the solution is languishing -- literally -- in our own backyards.

Image courtesy of the author

Joanna D. Underwood is president of Energy Vision, whose mission is to analyze and promote ways to make a swift transition to pollution-free renewable energy sources and to the clean, petroleum-free transportation fuels of the future.