Updated

Editor's Note: This article was corrected on Nov. 23. An explanation appears at the bottom.

If Willie Nelson supports it, it must be green, right? Not so fast.

Amid rising concern over U.S. dependence on fossil fuels, many hope that running our cars on so-called "biofuels," which are grown rather than processed, could solve our sustainability woes. But a new report argues that these renewable resources may not be as green as they seem.

The ETC Group, an international organization supporting sustainability and conservation, has just published its newest report, an 84-page document that presents a lengthy criticism of "the new bioeconomy." In it, principal author Jim Thomas argues that using biofuels for energy and resources isn't green -- in fact, he says, in certain ways they can be more harmful to the environment than coal.

"What's being presented by the government as 'the green way forward,' is this idea that we can use plant matter from crops, trees, or algae and convert it into fuel, plastics or chemicals," Thomas told FoxNews.com. "And it's just assumed that it's carbon neutral. But when you burn something like a tree, you release as much, if not more, carbon dioxide than when you burn something like coal."

Biofuels are fuels derived from living organisms, such as trees, algae plankton and more; they're collectively called biomass.Thomas' report -- "The New Biomassters: Synthetic Biology and the Next Assault on Biodiversity and Livelihoods" -- acts as a comprehensive critique of the entirety of the biofuel industry, summarizing all the different criticisms and compiling them into a single essay.

He says he hopes that his research will be able to educate others on what he feels is a scary and careless venture.

"The essential tool the industry is using is called synthetic biology, designing new organisms that have never existed in nature," Thomas told FoxNews.com. "This is a very risky venture, and there's no regulation surrounding it. And that's one of the findings in this study, that this is growing very fast without regulation or oversight."

Early biofuels came about from fermenting sugars from foods such as corn and wheat. But the movement came under scrutiny after it led to crop shortages in developing countries and sharp increases in food prices. At issue was whether thos crops should be used to feed humans or power cars.

But other scientists say the biofuel economy is complex, and they note that it's hard to lump absolutely everything labeled biomass together.

"One needs to recognize that all biofuels are not the same. The current generation is based on corn in the U.S., based on wheat and rapeseed in Europe," Dr. Madhu Khanna, a professor of agriculture at the University of Illinois, told FoxNews.com.

"But even among the first generation, there is also sugarcane, which is a much cleaner fuel, and Brazil has a lot of available land for sugarcane production. You're able to expand without coming into conflict with food production. So you don't hear the same criticism necessarily about sugarcane."

There are up to four "generations" within the biofuel movement, starting with its origin in corn. Second-generation biofuels arose to combat the problems of the first, by using parts of crops that were not consumed, such as corn stalks rather than the corn itself, or non-food crops such as rapeseed. Third and fourth generations move into other areas, such as algae. Thomas claims that this just raises more issues.

"If you start using the stalk of a corn, you have to put more fertilizer in the soil," Thomas said. "Fertilizer production is very energy intensive. It produces large amounts of nitrous oxide, which is 300 times stronger than carbon dioxide. So if you're moving over to these fuels that use the corn stalk supposedly to cut back your greenhouse emission, then it's very counterproductive."

The report also claims that this transition doesn't solve the food shortages in third-world nations.

"The U.S. government says there's a billion tons of fair biomass that they can turn into fuels and chemicals and burn for electricity," Thomas said. "When I began to look at the billion-ton study, it doesn't exist. In fact, it doesn't make any sense to source biomass in the U.S. because there's much more biomass coming from Sub Sahara Africa and Brazil."

Thomas is adamant that land use will become a massive issue for the biomass industry. "This isn't a switch, it's a massive grab on land," he said. "This movement to a plant-based, or so-called green economy, will throw a lot of people off their land in the developing world."

But Khanna cites recent studies that have shown a decrease in deforestation in Brazil due to recent regulations. She attributes the difference in opinions like this to the intricacy of such an ambitious movement. Both Khanna and Thomas  agree that a proper combination of well-developed technology and public policy are the keys to solving the fossil-fuel issue.

"The government, instead of putting money into these quick technological fixes, need to invest into more long term fixes," Thomas said. "It's economical and social fixes rather than technological fixes that will help us through. It's about the government giving support for both kinds of choices."

Correction: An earlier version of this story incorrectly stated that the report's principal author, Jim Thomas, claimed that using biofuels for energy is more harmful to the environment than coal. In fact, he was talking only about carbon dioxide emissions; coal has several other harmful effects on the environment. This story was updated on Nov. 23 to reflect the correction.