In a quest to reduce dependence on foreign oil, the United States government is increasing its mandatory minimum levels of renewable biofuel production each year. Because the US’s first large-scale foray into biofuels—corn for ethanol—was heavily criticized, many non-food plant species are now under consideration for biofuel production. However, this search for non-food biofuels has another, currently underappreciated, impact: The introduction and spread of invasive plant species across the US.
The problem with using nonnative plants for biofuel is that successful biofuel crop traits —short generation time, pest resistance, high growth rates, high water-use efficiency—are the same traits of many invasive plants.
Nonnative plants are those humans introduce into an area from far-off geographic regions. If these plants spread far beyond the place where they were originally planted, they are considered invasive. Not all nonnative plants turn invasive, but recent research indicates that the species the US government is considering for biofuels are three times more likely to be invasive than a random sampling of nonnative species. For more on the plants currently under consideration, see the sidebar Potential Invasives Awiting Approval below.
To address this, the National Environmental Coalition on Invasive Species brought invasive plant experts from around the nation to the Washington, DC last week to meet with members of Congress, congressional staff, and federal agencies The goal of the meetings was to dissuade policymakers from providing federal support for the use of nonnative, invasive plants as biofuel feedstock.
The Environmental Protection Agency gave the green-light nearly a year ago to businesses wishing to grow two well-known invasive grasses: giant reed (Arundo donax) and napiergrass (Pennisetum purpureum). Ironically, the EPA is not the only governmental agency thinking about these species. Giant reed, an aptly named grass that can easily grow stalks over 30 feet in height, is growing unabated along the US-Mexico border. This weed presents such a problem for border patrol agents with the Department of Homeland Security that DHS has commissioned the US Department of Agriculture’s help in coming up with a method to reduce the giant reed populations in Texas.
So why would the EPA approve the wide-spread planting of invasive species? It comes down to strict and literal adherence to laws passed by Congress a few years back. Currently, the EPA reviews potential biofuel feedstocks as part of the Renewable Fuel Standards (RFS) Program, created under the Energy Policy Act of 2005 and revised in the Energy Independence and Security Act of 2007. These laws, in short, demand that the transportation fuel must be a blend of traditional carbon-intensive oil as well as renewable fuels with lower carbon emissions.
EPA conducts a greenhouse gas (GHG) lifecycle analysis on potential biofuel feedstocks to determine if they have lower carbon emissions than traditional fuels. Biofuel producers and purchasers can (and must) petition the EPA to consider their specific biofuel “pathway” to see if it is eligible for renewable fuel standard credits. Because the only explicit requirement in the Energy Independence and Security Act is for EPA to perform GHG analysis, the EPA is sticking to this bare minimum in its environmental review, and has chosen to ignore other existing mandates, such as a presidential Executive Order requiring federal agencies to prevent the introduction and spread of invasive species.
Although EPA doesn’t explicitly consider the potential invasiveness of a plant species under the RFS program, the agency did respond to the unanimous outcry from scientists in 2012 when it first approved giant reed and napiergrass as RFS compliant. However, EPA’s concession did not signal a commitment to consider the ecological impacts of potential feedstocks. Instead, EPA determined that if these invasive plants spread beyond the original planting, necessary control and management efforts would increase their “carbon-costs.” In other words, EPA determined that in some cases, invasion may have climate implications.
EPA ended up withdrawing the original 2012 ruling, and replacing it in 2013 with a supplemental ruling that required producers to submit a “Risk Mitigation Plan” that lays out a plan for keeping these species from spreading beyond the biofuel plantations. So far, no company has submitted a plan. And the scientific community is skeptical about the effectiveness of any self-enforced plan.
For those of us who think using invasive plants for biofuels is a bad idea, the ultimate frustration is that many other plants could make excellent feedstock. There does not have to be a “business vs. environment” trade-off when choosing renewable biofuel plants. Although the traits of biofuels and invasive plants strongly overlap, scientists have a resoundingly solid track record of predicting what species are at “high risk” of becoming invasive, and they’ve developed many practical and useful Weed Risk Assessment tools that allow users to evaluate the potential invasiveness of a species. These tools are so accurate that some governments, including Australia and New Zealand, require that all plant species pass an assessment before introduction into the country.
The scientific recommendation is that Weed Risk Assessments are made a fundamental component of any federal decision on biofuel production. Plants that are considered “low-risk” should be prioritized and incentivized over those that are “high-risk” for invasive potential. Last week, there was some indication that this could be a possibility. Scientists with the National Environmental Coalition on Invasive Species had positive reception from some agency staff, namely the Department of Energy’s Bioenergy Technologies Office that provided R&D funding for many potential biofuel feedstocks. These staffers were already aware of the invasive potential of some biofuel feedstocks, and seemed receptive to using more formalized assessment tools in their own internal decisions on what species should receive federal funding.
However, it appears that under the current status quo, ecological invasions are likely to increase. The passing of the Energy Independence and Security Act increased EPA’s workload without increasing staffing to complete the task. This has, in part, probably led to EPA’s decision to stick with only the limited consideration of lifecycle GHG emission. And, in another round of agency irony, the Department of Agriculture is touting the transformation of field pennycress (Thlaspi arvense) from “nuisance weed to biofuel” as if the new use will change its ecological properties or limit its invasion.
USDA has a long history of importing invasive plants into the United States. Through the Department of Agriculture Soil Conservation program, many nonnative species were promoted for preventing soil erosion and improving wildlife habitat. The most infamous of these species is kudzu (Pueria lobelata) “the vine that ate the south,” but also includes the highly invasive bush honeysuckle (Lonicera maackii), autumn olive (Elaeagnus umbellata) and Russian olive (Elaeagnus angustifolia).
Would it really be too much to ask for our federal agencies to learn from their past mistakes and avoid promoting kudzu’s successor?
Want to know more about invasive species and US biofuel policies? Check out these good reads:
Lewis KC and RD Porter (2014.) Global approaches to addressing biofuel-related invasive species risks and incorporation into U.S. laws and policies. Ecological Monographs 171. http://dx.doi.org/10.1890/13-1625.1
Quinn LD, Gordon D, Glaser A, Lieurance D, and SL Flory. (accepted, in press) Bioenergy feedstocks at low risk for invasion in the US: A white-list approach. Bioenergy Research.
Potential Invasives Awiting Approval
While it seems highly unlikely that the EPA will revise its final ruling on giant reed and napiergrass, more potential invasive plants are sitting in the EPA’s docket. Most of these petition listings are so vague that it is impossible to evaluate the invasiveness potential without further clarification of the exact species under consideration. Currently, the EPA has four different petitions for “grain sorghum,” one for “biomass sorghum,” one for “jatropha,” and one for “pennycresss.” Although scientists and taxonomists purposely use a consistent and widespread convention for naming plants and animals so that they can avoid confusion between different languages or even different regional slang, these petitions are most likely intentionally vague to protect proprietary information about the exact variety of the plant under consideration.
For example—and using the proper conventional nomenclature—the plant genera Sorghum contains a few highly invasive plants species: Sorghum bicolor (which has a slew of common names including shattergrass, Sudangrass, and, sometimes, grain sorghum) is listed as a noxious weed in six states, and its close relative Sorghum halepense (Johnsongrass) is listed in a 19 states. Likewise, the genera Jatropha contains two members of the IUCN’s infamous “100 of the World’s Worst Invasive Alien Species.” Some proactive researchers have already red-flagged these species because of Weed Risk Assessment results: Jatropha curcas was resoundingly rejected by three different assessments, Sorghum halepense and Thlaspi arvense (field pennycress) by one, and Sorghum bicolor was recommended for further evaluation three times.