Renewable Natural Gas Isn't a Green Solution for Climate Change
By Emily Grubert
Natural gas is a versatile fossil fuel that accounts for about a third of U.S. energy use. Although it produces fewer greenhouse gas emissions and other pollutants than coal or oil, natural gas is a major contributor to climate change, an urgent global problem. Reducing emissions from the natural gas system is especially challenging because natural gas is used roughly equally for electricity, heating, and industrial applications.
There's an emerging argument that maybe there could be a direct substitute for fossil natural gas in the form of renewable natural gas (RNG) – a renewable fuel designed to be nearly indistinguishable from fossil natural gas. RNG could be made from biomass or from captured carbon dioxide and electricity.
Based on what's known about these systems, however, I believe climate benefits might not be as large as advocates claim. This matters because RNG isn't widely used yet, and decisions about whether to invest in it are being made now, in places like California, Oregon, Washington, Michigan, Georgia and New York.
As someone who studies sustainability, I research how decisions made now might influence the environment and society in the future. I'm particularly interested in how energy systems contribute to climate change.
Right now, energy is responsible for most of the pollution worldwide that causes climate change. Since energy infrastructure, like power plants and pipelines, lasts a long time, it's important to consider the climate change emissions that society is committing to with new investments in these systems. At the moment, renewable natural gas is more a proposal than reality, which makes this a great time to ask: What would investing in RNG mean for climate change?
What RNG Is and Why it Matters
Most equipment that uses energy can only use a single kind of fuel, but the fuel might come from different resources. For example, you can't charge your computer with gasoline, but it can run on electricity generated from coal, natural gas or solar power.
Two main methane sources could be used to make RNG. First is biogenic methane, produced by bacteria that digest organic materials in manure, landfills and wastewater. Wastewater treatment plants, landfills and dairy farms have captured and used biogenic methane as an energy resource for decades, in a form usually called biogas.
Some biogenic methane is generated naturally when organic materials break down without oxygen. Burning it for energy can be beneficial for the climate if doing so prevents methane from escaping to the atmosphere.
In theory, there's enough of this climate-friendly methane available to replace about 1% of the energy that the current natural gas system provides. The largest share is found at landfills.
The other source for RNG doesn't exist in practice yet, but could theoretically be a much larger resource than biogenic methane. Often called power-to-gas, this methane would be intentionally manufactured from carbon dioxide and hydrogen using electricity. If all the inputs are climate-neutral – meaning, for example, that the electricity used to create the RNG is generated from resources without greenhouse gas emissions – then the combusted RNG would also be climate-neutral.
So far, RNG of either type isn't widely available. Much of the current conversation focuses on whether and how to make it available. For example, SoCalGas in California, CenterPoint Energy in Minnesota and Vermont Gas Systems in Vermont either offer or have proposed offering RNG to consumers, in the same way that many utilities allow customers to opt in to renewable electricity.
Renewable Isn’t Always Sustainable
If RNG could be a renewable replacement for fossil natural gas, why not move ahead? Consumers have shown that they are willing to buy renewable electricity, so we might expect similar enthusiasm for RNG.
The key issue is that methane isn't just a fuel – it's also a potent greenhouse gas that contributes to climate change. Any methane that is manufactured intentionally, whether from biogenic or other sources, will contribute to climate change if it enters the atmosphere.
And releases will happen, from newly built production systems and existing, leaky transportation and user infrastructure. For example, the moment you smell gas before the pilot light on a stove lights the ring? That's methane leakage, and it contributes to climate change.
To be clear, RNG is almost certainly better for the climate than fossil natural gas because byproducts of burning RNG won't contribute to climate change. But doing somewhat better than existing systems is no longer enough to respond to the urgency of climate change. The world's primary international body on climate change suggests we need to decarbonize by 2030 to mitigate the worst effects of climate change.
Scant Climate Benefits
My recent research suggests that for a system large enough to displace a lot of fossil natural gas, RNG is probably not as good for the climate as is publicly claimed. Although RNG has lower climate impact than its fossil counterpart, likely high demand and methane leakage mean that it probably will contribute to climate change. In contrast, renewable sources such as wind and solar energy do not emit climate pollution directly.
What's more, creating a large RNG system would require building mostly new production infrastructure, since RNG comes from different sources than fossil natural gas. Such investments are both long-term commitments and opportunity costs. They would devote money, political will and infrastructure investments to RNG instead of alternatives that could achieve a zero greenhouse gas emission goal.
When climate change first broke into the political conversation in the late 1980s, investing in long-lived systems with low but non-zero greenhouse gas emissions was still compatible with aggressive climate goals. Now, zero greenhouse gas emissions is the target, and my research suggests that large deployments of RNG likely won't meet that goal.
Emily Grubert is an Assistant Professor of Civil and Environmental Engineering, Georgia Institute of Technology.
Disclosure statement: Emily Grubert does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Reposted with permission from The Conversation.
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By Tara Lohan
Warming temperatures on land and in the water are already forcing many species to seek out more hospitable environments. Atlantic mackerel are swimming farther north; mountain-dwelling pikas are moving upslope; some migratory birds are altering the timing of their flights.
Numerous studies have tracked these shifting ranges, looked at the importance of wildlife corridors to protect these migrations, and identified climate refugia where some species may find a safer climatic haven.
"There's a huge amount of scientific literature about where species will have to move as the climate warms," says U.C. Berkeley biogeographer Matthew Kling. "But there hasn't been much work in terms of actually thinking about how they're going to get there — at least not when it comes to wind-dispersed plants."
Kling and David Ackerly, professor and dean of the College of Natural Resources at U.C. Berkeley, have taken a stab at filling this knowledge gap. Their recent study, published in Nature Climate Change, looks at the vulnerability of wind-dispersed species to climate change.
It's an important field of research, because while a fish can more easily swim toward colder waters, a tree may find its wind-blown seeds landing in places and conditions where they're not adapted to grow.
Kling is careful to point out that the researchers weren't asking how climate change was going to change wind; other research suggests there likely won't be big shifts in global wind patterns.
Instead the study involved exploring those wind patterns — including direction, speed and variability — across the globe. The wind data was then integrated with data on climate variation to build models trying to predict vulnerability patterns showing where wind may either help or hinder biodiversity from responding to climate change.
One of the study's findings was that wind-dispersed or wind-pollinated trees in the tropics and on the windward sides of mountain ranges are more likely to be vulnerable, since the wind isn't likely to move those dispersers in the right direction for a climate-friendly environment.
The researchers also looked specifically at lodgepole pines, a species that's both wind-dispersed and wind-pollinated.
They found that populations of lodgepole pines that already grow along the warmer and drier edges of the species' current range could very well be under threat due to rising temperatures and related climate alterations.
"As temperature increases, we need to think about how the genes that are evolved to tolerate drought and heat are going to get to the portions of the species' range that are going to be getting drier and hotter," says Kling. "So that's what we were able to take a stab at predicting and estimating with these wind models — which populations are mostly likely to receive those beneficial genes in the future."
That's important, he says, because wind-dispersed species like pines, willows and poplars are often keystone species whole ecosystems depend upon — especially in temperate and boreal forests.
And there are even more plants that rely on pollen dispersal by wind.
"That's going to be important for moving genes from the warmer parts of a species' range to the cooler parts of the species' range," he says. "This is not just about species' ranges shifting, but also genetic changes within species."
Kling says this line of research is just beginning, and much more needs to be done to test these models in the field. But there could be important conservation-related benefits to that work.
"All these species and genes need to migrate long distances and we can be thinking more about habitat connectivity and the vulnerability of these systems," he says.
The more we learn, the more we may be able to do to help species adapt.
"The idea is that there will be some landscapes where the wind is likely to help these systems naturally adapt to climate change without much intervention, and other places where land managers might really need to intervene," he says. "That could involve using assisted migration or assisted gene flow to actually get in there, moving seeds or planting trees to help them keep up with rapid climate change."
Tara Lohan is deputy editor of The Revelator and has worked for more than a decade as a digital editor and environmental journalist focused on the intersections of energy, water and climate. Her work has been published by The Nation, American Prospect, High Country News, Grist, Pacific Standard and others. She is the editor of two books on the global water crisis. http://twitter.com/TaraLohan
Reposted with permission from The Revelator.
The last Ice Age eliminated some giant mammals, like the woolly rhino. Conventional thinking initially attributed their extinction to hunting. While overhunting may have contributed, a new study pinpointed a different reason for the woolly rhinos' extinction: climate change.
The last of the woolly rhinos went extinct in Siberia nearly 14,000 years ago, just when the Earth's climate began changing from its frozen conditions to something warmer, wetter and less favorable to the large land mammal. DNA tests conducted by scientists on 14 well-preserved rhinos point to rapid warming as the culprit, CNN reported.
"Humans are well known to alter their environment and so the assumption is that if it was a large animal it would have been useful to people as food and that must have caused its demise," says Edana Lord, a graduate student at the Center for Paleogenetics in Stockholm, Sweden, and co-first author of the paper, Smithsonian Magazine reported. "But our findings highlight the role of rapid climate change in the woolly rhino's extinction."
The study, published in Current Biology, notes that the rhino population stayed fairly consistent for tens of thousands of years until 18,500 years ago. That means that people and rhinos lived together in Northern Siberia for roughly 13,000 years before rhinos went extinct, Science News reported.
The findings are an ominous harbinger for large species during the current climate crisis. As EcoWatch reported, nearly 1,000 species are expected to go extinct within the next 100 years due to their inability to adapt to a rapidly changing climate. Tigers, eagles and rhinos are especially vulnerable.
The difference between now and the phenomenon 14,000 years ago is that human activity is directly responsible for the current climate crisis.
To figure out the cause of the woolly rhinos' extinction, scientists examined DNA from different rhinos across Siberia. The tissue, bone and hair samples allowed them to deduce the population size and diversity for tens of thousands of years prior to extinction, CNN reported.
Researchers spent years exploring the Siberian permafrost to find enough samples. Then they had to look for pristine genetic material, Smithsonian Magazine reported.
It turns out the wooly rhinos actually thrived as they lived alongside humans.
"It was initially thought that humans appeared in northeastern Siberia fourteen or fifteen thousand years ago, around when the woolly rhinoceros went extinct. But recently, there have been several discoveries of much older human occupation sites, the most famous of which is around thirty thousand years old," senior author Love Dalén, a professor of evolutionary genetics at the Center for Paleogenetics, said in a press release.
"This paper shows that woolly rhino coexisted with people for millennia without any significant impact on their population," Grant Zazula, a paleontologist for Canada's Yukon territory and Simon Fraser University who was not involved in the research, told Smithsonian Magazine. "Then all of a sudden the climate changed and they went extinct."
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Transitioning to renewable energy can help reduce global warming, and Jennie Stephens of Northeastern University says it can also drive social change.
For example, she says that locally owned businesses can lead the local clean energy economy and create new jobs in underserved communities.
"We really need to think about … connecting climate and energy with other issues that people wake up every day really worried about," she says, "whether it be jobs, housing, transportation, health and well-being."
To maximize that potential, she says the energy sector must have more women and people of color in positions of influence. Research shows that leadership in the solar industry, for example, is currently dominated by white men.
"I think that a more inclusive, diverse leadership is essential to be able to effectively make these connections," Stephens says. "Diversity is not just about who people are and their identity, but the ideas and the priorities and the approaches and the lens that they bring to the world."
So she says by elevating diverse voices, organizations can better connect the climate benefits of clean energy with social and economic transformation.
Reposted with permission from Yale Climate Connections.