Many human activities result in the release of carbon into the atmosphere. In the past year, the carbon emissions of different fuels have come under intense scrutiny, with the Energy Independence and Security Act of 2007 requiring the evaluation of “ baseline lifecycle greenhouse gas emissions.”

Two studies released in 2009 depict the stark contrast between the trend in biofuels and the trend in petroleum fuels. Ethanol is incrementally reducing its carbon footprint, while oil production increases emissions as it uses more and more energy to seek out what remains of a dwindling supply of fossil fuels.

Ethanol production results in 51 percent fewer greenhouse gas emissions compared to average gasoline production, according the report “ Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol.” Dr. Ken Cassman, Director of the Nebraska Energy Sciences Center at University of Nebraska-Lincoln, who wrote the report along with an interdisciplinary team of researchers, published this information in January. The group conducted an analysis of dry grind ethanol plants powered with natural gas, the type representing approximately 90 percent of current U.S. ethanol production.

In March, the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) in Pittsburgh published “ An Evaluation of the Extraction, Transport and Refining of Imported Crude Oils and the Impact on Life Cycle Greenhouse Gas Emissions,” written by Kristin J. Gerdes and Timothy J. Skone.

The NETL study found that Canadian tar sands have almost double the carbon intensity of the average carbon intensity of all petroleum processed in the U.S. in 2005. To take the tar sands from the ground, process it, and refine it into gasoline emits 34 kilograms of carbon dioxide per million British Thermal Units (mmBTUs). This compares to a weighted average of 18.4 kilograms per mmBTU for other gasoline.

While oil from tar sands currently contribute only about three percent of the gasoline supply, this could rise to as much as one-fifth of the total gasoline supply by 2030, according to a University of Nebraska study of land use impacts on GHGs, published in February by professors Adam Liska and Richard Perrin.

The average GHG-intensity of the global petroleum supply is also becoming more intense due to depletion of easily accessible deposits, according to the report, called “Indirect Land Use Emissions in the Life Cycle of Biofuels: Regulations vs. Science. “Global conventional crude oil production is projected to remain relatively constant over 2007–2030, as increases in new capacity are off set by declines from existing fields. The bulk of the increase in global oil production will come from natural gas liquids (e.g. propane) and unconventional resources and technologies, primarily tar sands.”

Global conventional oil reserves are estimated at 1.34 trillion barrels, while global economically recoverable tar sands reserves are estimated at up to 2 trillion barrels.

According to the report, 17.3 percent of current global petroleum reserves are in tar sands found in Canada (175 billion barrels, or 13 percent) and in Venezuela (58 bbl, or 4.3 percent). This total of 223 billion barrels compares to 264 billion barrels in Saudi Arabia, which comprises 20 percent of reserves and is the largest reserve globally. Tar sands oil reserves that are economically recoverable from Canada and Venezuela are estimated to be roughly 315 and 250 billion barrels, respectively.

“These two countries are also the first and fourth largest exporters of petroleum to the United States, and if this dependence continues, tar sands will likely be an increasing fraction in gasoline, which could rise to nearly a fifth of supply in the next 11 years,” the report states.

Liska and Perrin do not dismiss the use of Indirect Land Use Change (ILUC) in the calculation of greenhouse gas benefits, but they, like Cassman, believe that the science of measuring ILUC is in its infancy.

Cassman points out that singling out biofuels alone for ILUC calculations will not achieve the important goal of preserving the world’s precious natural resources such as the rainforests. Instead, ILUC, when it has been fully developed and can provide a much more complete set of data and models, should be applied fairly to the whole spectrum of industry and land uses, going beyond agriculture to construction and recreational uses also.

Casssman’s group developed the Biofuel Energy Systems Simulator ( BESS) to make their calculations and utilized the lifecycle analysis model, known as GREET, developed by Dr. Michael Wang at the DOE’s Argonne National Laboratory.

“In January we noted that the number has to change, because the gasoline that’s coming out of the pump is increasingly coming from more carbon intense sources, like tar sands and deep water,” Cassman said. “It’s simple – these forms of crude take more energy to extract them, particularly tar sand, and that means more carbon emissions.”

BESS can calculate a whole gamut of metrics which ethanol companies make use of: energy yield and efficiency, greenhouse gas emissions, and resource requirements for individual plants.

“In general, there is an air of excitement in the biofuels industry and among biofuels researchers about how to gain a better carbon footprint, and reduce dependence on fossil fuels such as natural gas and coal,” said Chris Zygarlicke, Deputy Associate Director for Research at the Energy and Environmental Research Center (EERC), University of North Dakota.

“The trend in biofuels will be ongoing incremental change – I don’t see outlandish changes,” he continued. “Ethanol plants continue to become greener overall. Ethanol companies are beginning to recognize the public relations dimension to having a lower carbon footprint. The second thing driving this change is legislation about capping or trading carbons. If you can start down that road, to reduce or eliminate the carbon footprint, you will be ahead of the game.”

The U.S. House of Representatives passed a carbon emissions cap and trade bill in early July, and the U.S. Senate will take up the issue in the next few months. Internationally, the next Global Climate Change summit has been scheduled to take place this December in Copenhagen.

The UNL team calls its BESS software suite a "seed-to-fuel" tool. Anticipating the regulatory requirements and potential credit benefits to a biofuel production facility, BESS quantifies lifecycle carbon savings and various environmental impacts for an individual biofuel plant. It takes into account the energy used for the whole process, the greenhouse gases generated to raise the feedstock crop, credits for co-product usage, and finally the amount of energy it takes to get the ethanol to the fuel terminal.

Zygarlicke believes more and more ethanol plants will have a direct interest in calculating their carbon footprint. He takes Chippewa Valley Ethanol Company (CVEC) of Benson, Minnesota as a case in point. The biomass gasifier it has developed, which runs on wood chips and corn cobs, already replaces a good portion of the natural gas the plant previously required.

“An ethanol plant that replaces a significant portion of its natural gas from biomass gasification, not only do they improve their carbon footprint, but they may have credits to trade and an economic benefit to realize,” he noted.

CVEC installed its biomass gasifier in mid-2008 and in those 15 months has replaced, on average, a quarter of its natural gas-derived power with power from its biomass gasifier.

“The next phase will take us to a higher level of natural gas replacement,” said Bill Lee, CVEC General Manager. “With this technology we can repower a whole spectrum of industries to a renewable base. Right now the incentives many states are creating focus much more on renewable sources for electric and stationary power generation, even more so than renewable transportation fuels.”

Ultimately, CVEC envisions replacing 90 percent of its natural gas usage with the power derived by gasifying 300 tons of biomass per day. Corn cobs and stalks, wood chips, saw dust, grain hulls, wheat straw, and other ag waste products – and possibly energy crops like switchgrass, if that becomes available – could power its two steam boilers and two grain dryers.

Lee and CVEC see a major business opportunity in the repowering of existing industry with renewable energy. When CVEC began working with Frontline Bioenergy – an Ames, Iowa-based venture created to offer biomass gasifier technology as a renewable power solution – CVEC took a minority ownership position in the company, to help it develop. In June, CVEC took a majority stake in the company, and by the end of the year, Lee will take over as its CEO. Frontline’s “Cleangas” technology can provide up to 160 gigawatts of power.

According to Lee, biofuels producers can vastly reduce their carbon footprint through this technology. And as petrofuels get dirtier, this gulf will become enormous.

Cassman believes the biofuels industry could realize major carbon savings, while petroleum has no real prospect for improvement. “With petroleum you get what you see – and it’s only going to get worse,” he said.

He doesn’t let the ethanol industry off easily, though, noting that a concerted effort will be needed to bring biofuels to where it could and should be. The key, he believes, will be publicly funded research whose findings can be implemented across agriculture and biofuels production.

“Further reducing biofuels’ carbon footprint all depends on how well the feedstock is produced, how well the refinery works, how efficient the use of co-products is, and then this broader issue of indirect land use change,” Cassman said. “You could say with appropriate attention to improving things – if the corn industry was committed to obtaining funding from the federal government for public sector research into how to make lower greenhouse gas emissions per unit of corn produced, and likewise efforts by plants to minimize water use, further limit emission of volatiles, take advantage of the efficiencies of co-locating next to livestock production. Then there no question that biofuels could be much better than any other transportation fuel out there.”

Lee feels that ultimately, biofuels’ potential as a leader in low carbon transportation fuels will carry the day.

“Biofuels will become feedstock neutral with the focus on carbon intensity,” Lee said. “Whatever the feedstock the next generation of biofuels plants uses, whether it’s corn or any other form of biomass, it will be grown and harvested by means that have been specifically designed to minimize carbon intensity and bring it within acceptable thresholds for use in energy production.”