Climate change is a pillar of the presidential campaigns of both Sen. Bernie Sanders and Hillary Clinton, who have both made proposals to offer tax subsidies and other financial incentives to generate more energy alternatives to fossil fuels.
The number one form of "renewable" energy in the United States is bioenergy, an energy source derived from burning trees, crops, manure, trash or waste for electricity and/or heat, or converting transportation fuels. According to the Energy Information Administration, 49.6 percent of renewable energy in the US in 2014 came from bioenergy; 18 percent, from wind; and 4.4 percent, from solar photovoltaics.
With 82 percent of US energy generated from fossil fuels, barring a reduction in energy consumption, policies facilitating the transition away from oil, gas and coal will likely continue to rely, in large part, on bioenergy.
Bioenergy poses risks because of its carbon emissions, contributions to air pollution and freshwater demand.
Bioenergy's main selling point is that, unlike foreign oil, it's a locally sourced feedstock, which means more money stays in local economies. Industry and supporters say bioenergy is a clean, low-carbon, baseload source of energy that should be further expanded.
But bioenergy also poses risks because of its carbon emissions, contributions to air pollution, freshwater demand and land impacts. Opponents -- including medical professionals, climate and forest advocates, environmental justice activists and scientists -- say bioenergy may actually do more harm than good.
So where do the Democratic presidential candidates stand on bioenergy?
Renewable Energy Policy
Clinton wants renewables to "power every home in America," according to the climate section of her website. In July 2015, The New York Times reported that she aims to generate 33 percent of US electricity from renewables by 2027, up from 10 percent in 2014.
While Sanders hasn't committed to a specific target, his "Economic Agenda for America" declares, "We must transform our energy system away from fossil fuels and into energy efficiency and sustainable energies."
Sanders has sponsored or co-sponsored several bills that include tax or other financial incentives for biomass energy from trees, trash and manure incineration, and liquid biofuels, including the American Clean Energy Investment Act of 2015, the Climate Protection Act of 2013 and the Clean Energy Standard Act of 2012.
In 2010, as US secretary of state, Clinton helped launch the Energy and Climate Partnership of the Americas, an effort to unite Western governments on energy and climate issues, which involves several bioenergy initiatives, including turning coffee "waste" into ethanol.
In 2007, Clinton (as a US senator from New York) and Sanders co-wrote the Green Jobs Act, which funded research and job training for the biofuels industry, and passed as part of a larger energy bill.
Clinton was one of 22 co-sponsors of the Clean Power Act of 2002, which would've provided incentives for the use of alternative energy sources, including bioenergy.
Biomass Electricity and Heat
Commercial, industrial and residential biomass heating made up 62 percent of total bioenergy in the United States in 2014, with another 11 percent coming from biomass electricity (the remainder came from liquid biofuels).
In a May 2015 guest column in the Cedar Rapids Gazette, titled "Invest in Rural Clean Energy," Clinton wrote that she seeks to "significantly expand clean energy production on public lands." Trees and logging residue from national forests are increasingly being used to fuel biomass energy facilities.
Clinton aims to reduce US oil consumption by one-third through "cleaner fuels and more efficient ... boilers." Biomass energy is the only alternative energy technology that utilizes boilers.
In her fact sheet on "Advanced Buildings," Clinton describes her plan to switch out residential and commercial boilers with "cleaner alternatives," citing New York City's PlaNYC, which favors burning "municipal waste biomass" and "biomass to liquids" for energy.
Sanders includes biomass energy among the "sustainable" energy technologies he promotes. On his website, he celebrates his past support for biomass energy, and how he has "successfully fought for innovative rural economic development initiatives, including ... large scale bio-mass fired electric plants."
In a public forum in Burlington, Vermont, in May 2015, when criticized by an audience member for his stance on bioenergy, Sanders responded, "What's the danger of biomass? The danger is you don't want to do deforestation ... You have to do the harvesting in a technically intelligent way, otherwise you're going to have a serious problem."
In an opening statement for a green jobs subcommittee field hearing at the Vermont Statehouse in 2009, Sanders praised Middlebury College's combined heat and power biomass facility as an "energy innovation," and touted Burlington's McNeil Generating Station, a 50-megawatt biomass power facility that was built when Sanders was mayor of Burlington in 1986. He also spoke of his role in securing funding for biomass energy and solar power at the Vermont National Guard.
Likewise, he promoted efforts to expand biomass heating, saying Vermont has "substantial biomass resources here which could provide heating for our homes and schools and keep that money in our economy."
On his website, Sanders says biofuels such as corn ethanol have been an "economic lifeline" to rural and farm communities in the Midwest.
On an Iowa Public Television appearance in December 2014, Sanders cautioned that corn ethanol "drives up food price[s]," but called it "proper for government to be subsidizing sustainable energies." In 2011, the senator voted against a subsidy for corn ethanol, citing higher food prices
Sanders has expressed stronger support for "advanced" biofuels, which include more experimental cellulosic ethanol from trees, grasses and algae. His website says they have "enormous potential to deliver dramatic reductions in carbon pollution and strengthen rural economies."
During a 2015 interview on "Roske on Politics," he spoke in favor of the Renewable Fuel Standard, which requires blending ethanol into gasoline, but said he wanted to see "more emphasis" on cellulosic ethanol.
Clinton, too, spoke favorably of corn ethanol in her Gazette piece, saying the Renewable Fuel Standard, which she supports, has been "a success for Iowa and much of rural America." Also, like Sanders, she prefers advanced biofuels.
In 2007, when running against Barack Obama for the Democratic nomination for president, Clinton said in a speech that she would "increase the goal for biofuels to 60 billion gallons by 2030, with almost half of that coming from advanced biofuels like cellulosic ethanol." In 2015, only 2.2 million gallons of cellulosic ethanol were produced.
She also has promised to help farmers by expanding US Department of Agriculture programs, including "doubling loan guarantees that support the bio-based economy's dynamic growth." She not only supports biofuels in cars, but also ships and airplanes.
Waste Technologies Industries Incinerator
Waste Technologies Industries (WTI), a hazardous waste incinerator in East Liverpool, Ohio, has long been opposed by members of the local community concerned about air pollution.
In the 1980s, Clinton was a partner in the Rose Law Firm (of Whitewater fame), which represented WTI.
Alonzo Spencer, president of Save Our County, a grassroots organization that has fought the East Liverpool incinerator, recalls that the facility was originally proposed as a power plant, though the electricity generation component was later scrapped.
In 1993, WTI East Liverpool failed its test burn by emitting high levels of carbon tetrachloride, a carcinogen, and "emitting three times as much mercury as allowable," according to Rachel's Hazardous Waste News.
In 1993, a federal judge, Ann Aldrich, wrote in her opinion that the facility "may cause imminent and substantial endangerment to health and the environment."
In 2011, the Environmental Protection Agency (EPA) fined WTI (now Heritage) $50,000 for violating the Clean Air Act, and the facility has also been fined for ash violations. Overall, at least 200 toxic incidents have occurred at WTI, according to a May 2015 news report by WKBN.
The Ohio Citizen reported that a state health study found that local elementary schoolchildren had increased levels of mercury in their urine compared to levels measured before the facility's operation.
The WTI incinerator sits roughly 800 feet behind the house of Sandy Estelle, a "very strong" Democrat who has traveled to Washington, DC, to protest the facility many times over the years, on behalf of Save Our County.
"[Clinton] was involved with this," Estelle said. "Her law firm helped put this company here."
It would benefit Clinton's campaign, Estelle added, if the candidate would "at least make the effort to say that we understand your concerns, and will look into this, and see what we can do."
Lafarge Cement Kilns
From 1985 until 1992, Clinton made $31,000 per year as a board member of Lafarge Corporation, a cement company operating kilns across the United States -- including in Alpena, Michigan, and Paulding, Ohio -- which also burns hazardous waste.
Thirteen million gallons of Systech's (a subsidiary of Lafarge) hazardous waste was burned in the Alpena, Michigan, Lafarge facility in 1993, according to The New York Times. Since 1979, Lafarge has incinerated over 400 million gallons of toxic waste, Forbes reports.
Bill Freese, an Alpena resident and director of the Huron Environmental Activist League, doesn't believe it's a coincidence that the University of Michigan has its own cancer clinic. He also warns of hazardous waste ash that Lafarge is storing in a lakeshore dump and an old quarry that he says is running into Lake Huron with "high contents of mercury pollution."
Jim Travers of Coeymans, New York, has long opposed Lafarge's planned expansion of its existing Ravena, New York, cement kiln. Travers, a board member of the Citizens' Environmental Coalition and Selkirk Coeymans Ravena Against Pollution, says Clinton's past relationship with Lafarge is significant.
"Those ties don't go away," Travers said. "She needs to wear her own laundry and she needs to wear it well."
The McNeil Generating Station
In the 1980s, when Bernie Sanders was mayor of Burlington, Vermont, he played a key role in the construction of the McNeil Generating Station, a 50-megawatt biomass facility that burns trees and logging byproducts from northeastern forests, along with a varying percentage of natural gas.
McNeil has been labeled Vermont's biggest polluter by VT Digger, with the EPA calculating 444,646 tons of carbon dioxide emitted in 2010, as well as air pollutants such as particulate matter, which the EPA says can harm lungs, and volatile organic compounds, which the agency considers carcinogenic.
Brian Tokar, a resident of East Montpelier and lecturer at the University of Vermont, was living in Burlington in 1981, during which time the Sanders administration made proposals to build both McNeil and a trash incinerator. Concerned about the pollution risks, Tokar, in conjunction with the Institute for Social Ecology, joined other Vermonters to oppose the facilities.
After the McNeil proposal quickly passed, Tokar and other locals focused their efforts to oppose the trash incinerator. After the Burlington city treasurer declared the idea a financial risk, Tokar said Sanders "changed his position on the incinerator, but continued to advocate for the woodchip plant."
Sanders was still mayor when McNeil came online in 1986. According to Tokar, the generating station is "a serious source of air pollution both in the neighborhood and the region as a whole."
While Burlington has been celebrated recently in the media as the nation's first city to reach 100 percent renewable energy, Tokar says there are "serious problems" with the city's reliance on electricity from McNeil biomass and large hydroelectric dams in Canada.
In 2014, when McNeil's $8 million annual bond was paid off, Sanders boasted of the facility as "the largest biomass plant of its kind in all of New England."
"Looking back, we were very much ahead of our time," Sanders said of his role in McNeil's construction, "and I'm very proud of that."
Chris Matera, director of Massachusetts Forest Watch, an advocacy group based in Northampton, spends his summers around Lake Champlain, and recreates regularly in Vermont. Matera has contacted the senator many times about his concerns regarding the climate, air and forest impacts of biomass energy.
Matera said he voted for Sanders in the Massachusetts primary because he supports the senator's "sense of ethics." However, when it comes to biomass energy, he says Sanders is "acting just as hypocritical as the other candidates" by simultaneously calling for a reduction in carbon emissions and advocating for burning more wood, which scientists have cautioned emits higher levels of carbon dioxide per unit of energy than coal.
Judging by their statements and actions, both Sanders and Clinton have shown considerable support for bioenergy over their careers. Based on the evidence, it's safe to predict that if a Democrat makes it to the White House in 2016, he or she will work to promote economic incentives for the production of advanced liquid biofuels from trees, grasses and algae, and the generation of heat and electricity from forests.
In fact, all elected officials advocating for a transition from fossil fuels to renewable energy without a significant reduction in overall energy consumption will likely support bioenergy -- the low-hanging fruit of alternative energy -- to meet their goals.