Researchers at Dartmouth College have published a new analysis on how current and future uses of plant-based energy could be a key solution to climate change.
The study looks at bioenergy and biofuels, which can come from all kinds of plants, including grass, trees, corn or algae.
Biofuels are generally thought of as renewable, because plants can regrow. They’re considered more climate-friendly than fossil fuels, because the carbon they emit was stored only recently instead of many millions of years ago.
They’re considered especially useful for transportation – a sector that has had more trouble decreasing emissions than the energy sector has had, in New Hampshire and worldwide.
Still, there’s long-running debate about exactly if and how bioenergy can be truly carbon-neutral. That's one reason that wood biomass energy, which generates electricity from burning trees, has been particularly contentious in Northern New England.
The paper, co-authored by Dartmouth professor Lee Lynd and others at Colorado and Penn State Universities, seeks to address this kind of criticism of bioenergy with modeling and data.
“Our results—particularly those for future biofuel technology scenarios—stand in sharp contrast to recent critiques that advocate eliminating policy support for bioenergy technology research and deployment,” the study says.
In an interview, Lynd says this is important new information for climate policymakers – but they’ll need to be deliberate in how they apply it.
“We can get mitigation with biofuels, but we need to pay attention,” Lynd says. “Don’t count on that being guaranteed; don’t count on that happening by accident.”
Current critiques of bioenergy, according to the study, “focus on whether feedstock crops can be sustainably sourced without causing self-defeating reductions in ecosystem carbon storage.”
For instance, Lynd says, critics argue that land used for bioenergy might have a greater benefit if left alone, or might displace food production and cause emissions to rise elsewhere.
“The blessing and the curse of bioenergy is that it’s kind of connected to everything,” Lynd says. “It’s connected to environment, to energy, to agriculture, to habitat, to carbon storage, to economic development, et cetera.
“Advocates look at that and they go ‘Gee, we’re not just going to produce energy – think of all the other benefits we can get,’” he says. “Critics say, ‘Oh my god, in the course of producing energy, think of all the other things I care about that you’re going to sacrifice.’”
This study analyzes ways to avoid these trade-offs and increase the amount of carbon stored in the earth.
Lynd says their most promising scenario involves growing and refining switchgrass into a fuel called cellulosic ethanol -- a process they found has comparable benefits to reforestation.
The study says this becomes four times as useful as reforestation when paired with carbon capture and hypothetical future advances in crop yields and refining processes.
With or without those changes in the future, the study’s authors find growing switchgrass for biofuel to be a far better use of current agricultural areas than restoring them into grasslands.
The findings are less positive on using forests for bioenergy, which the study says “results in ecosystem carbon debts requiring several years to several decades or more to overcome, depending on conversion technology and whether [carbon capture and storage] is deployed.”
New Hampshire's timber industry has long argued, largely unsuccessfully, that they need incentives to harvest lower-value wood for energy, as a means of keeping forests maintained, intact and contributing to carbon storage and local economies.
In looking at the benefits and drawbacks of many kinds of biofuel, Lynd concludes that it should only be one part of the world's solutions to climate change.
But he says he hopes his paper will encourage climate policy-makers to think beyond energy changes, and to broaden their focus to how we use land -- including for food production, which is a huge contributor to global emissions.
“If we don’t get managing the world’s land right, we can do all we want on energy and we’ll still blow it," Lynd says. "If we factor climate into land decisions, then I think making room for bioenergy is relatively easy.”
To explore more holistic combinations of climate solutions, Lynd recommends using the Global Calculator developed by the British government and others in 2015.