Chapter 3: Key Environmental Concerns for Biofuels

Biofuels are only as sustainable as the agricultural and industrial processes that produce them. Biofuels can clearly provide positive environmental benefits if the environmental consequences of feedstock production and fuel processing are carefully considered and care is taken to mitigate any negative impacts. This section examines a range of environmental concerns – including net energy, greenhouse gas emissions, air quality, water quality, soil erosion, forest health, and biodiversity – and suggests ways to maximize environmental protection.

3.1  Net Energy

One of the more controversial debates surrounding biofuels is the question of net energy: simply put, whether biofuels require more energy to produce than they take to make. On the surface, this seems an obvious consideration. What good is it producing a fuel that requires more energy to make than it produces? Actually, the question of net energy is far more complex than it appears. For example, a USDOE report notes that producing “1 MJ of biodiesel requires an input of 1.24 MJ of primary energy,”¹³ which seems to make biodiesel a net loser. However, the term “primary energy” includes the solar energy that is “lost” during plant photosynthesis. What we are actually concerned with is the energy of the fossil fuels that go into producing biofuels. Thus the measurement of how much fossil fuel energy is needed to produce a biofuel is usually what people are usually referring to when they talk about net energy.^G

Even the production of fossil fuels requires the use of fossil fuel energy. For example, to produce a million BTUs of gasoline, you have to use 1.23 million BTUs of fossil fuel energy, mainly natural gas and coal. This applies not only to fuels, but also to electricity. To produce 1 million BTUs of electricity, you need to use 2.34 million BTUs of energy, which usually comes from fossil fuel.

The vast majority of studies released have stated that the net energy of biofuels is positive, and the few that do not have been controversial. More important than worrying about what any particular study says is to understand the factors that go into determining what the net energy is, in order to appreciate how to maximize energy gains. A major part of what makes the net energy balance of biofuels positive is the energy credit given for co-products. With all biofuels, including cellulosic technologies, a large portion of the biomass is not converted into fuel but can be converted into other useful co-products, such as distiller’s grains, a valuable animal feed. How you measure the value of these co-products and what you do with them have a significant impact on how much fossil fuel you are saving. If you burn the co-products to produce heat or electricity, it is relatively clear what their energy value is; but if you use the co-product as animal feed, it is less clear what the energy credit should be. Do you consider the protein content of the feed, the nutritional qualities, the market value, or the energy it would have taken to produce a similar quantity of feed? While it is clear that if we use them efficiently, we are gaining substantial amounts of energy from the co-products, translating that into a single fossil-fuel equivalent number is challenging.

To show how this breaks down, it is worth examining a 2004 study of wheat ethanol.¹⁴ Wheat ethanol produced in a plant using a natural gas boiler and grid electricity has a net energy of 1.1 GJ/f/GJ EtOH, meaning you are in fact using slightly more fossil fuel energy than you are getting from the ethanol. However, this does not include the possible uses of the distiller’s grains that are left after you have produced the ethanol. If you dry the distiller’s grains and use them as animal feed, the study includes an energy credit that improves the net-energy balance to .9, meaning a slight gain. If you don’t have to dry the grains (an energy-intensive process) and can feed wet distiller’s grains to livestock right near the plant, you can save even more energy. The other possibility is to burn the distiller’s grains in the ethanol plant to provide heat and power. If you burn the same distiller’s dry grains for power, the net energy gain improves radically to .24, although you have now lost any food value from the wheat. In other words, different uses of the co-products can have a dramatic effect on the overall net energy of the ethanol, although with different trade offs. For example you need to consider whether the distiller’s grains are more valuable to society as feed or as energy. While distiller’s grains are the main co-product of ethanol production, wheat (or corn) production has another important co-product: wheat straw (or corn stover). Just like with the distiller’s grains, processing plants can be set up so that they can burn wheat straw to help produce electricity and power for the process. According to the study, if you use wheat straw to generate power in a more efficient plant, you can achieve a net energy gain of .45. In the best case scenario you can not only generate the electricity for the plant but also sell the excess electricity generated back to the grid. In that case, you can not only eliminate fossil fuel use but even displace fossil fuel use elsewhere. These numbers are similar to those the US Department of Agriculture (USDA) has suggested for conventional corn ethanol production.

While advanced biofuels are capable of attaining even more impressive net energy gains, it is probably also possible to produce them at a loss. What is important in determining net energy is not simply the type of fuel and the feedstock (i.e., corn ethanol), but the entire bioenergy system, a point that is particularly true when analyzing greenhouse gas emissions. Therefore, to maximize energy savings and reduce greenhouse gas emissions it is necessary to use co-products in the most efficient way possible, use other renewable energy sources to power the process, and improve the efficiency of agricultural and distribution systems.

3.2  Greenhouse Gas Emissions

The need to reduce our greenhouse gas (GHG) emissions is a major driver of interest in biofuels, and biofuels have been identified as a key part of Oregon’s global warming reduction strategy in its Oregon Strategy for Greenhouse Gas Reductions.¹⁵

Biofuels are often referred to as “carbon-neutral” fuels, because the carbon and other GHGs released when they are burned are recaptured when the plant is re-grown. Of course this assumes that the plant is re-grown, and to the same size and depth that it was before harvesting. The carbon-neutral statement also ignores the potential loss of carbon from the soil, the fossil-fuel-derived fertilizers and other inputs into growing the plant, and the fuel used in planting, harvesting, transporting and processing. When all of these are added up, biofuels can range from being carbon-negative (in that they are actually sequestering GHGs) to releasing more carbon than fossil fuels.

To accurately calculate biofuels’ greenhouse gas emissions, one must use a life-cycle analysis methodology that captures emissions at all stages of production and use. The largest percentage of GHG emissions in the production of biofuels comes from the agricultural production of the feedstock.18 Unfortunately, agricultural emissions also pose the greatest challenges for accurate accounting due to the range of emission types and the sensitivity to local conditions. While certain emissions from agriculture, like the use of fossil fuels in farm equipment, are easy to understand and quantify, others are not as straightforward. N₂O, which is 296 times as potent a greenhouse gas as CO₂¹⁹, is released from soil as a result of microbial activity and is increased by the application of nitrogen fertilizer. These emissions could account for around 40% of total agricultural emissions,²⁰ but getting accurate measurements is difficult because “actual emissions…depend on several site-specific factors including agronomic practices, temperature, and moisture.”²¹

Carbon sequestration in the soil is also heavily dependent on both the kind of tillage (conventional, conservation or no-till), the soil type, the type of crop, the rotation and use of fallow and a range of other factors.²² While exact figures for these types of emissions are hard to produce, it is possible to create sufficiently detailed approximations based on readily available data. The upshot of this is that improving agricultural practices will be a key part of ensuring that the climate benefits from biofuels are fully realized.

The next largest percentage of GHG emissions comes from the production of the fuel itself. It depends on the type of fuel that the plant uses and how the plant is designed, for example whether it uses combined heat and power (CHP or cogeneration). While emissions associated with distribution and infrastructure are substantial, both fossil fuels and biofuels have similar requirements, so these factors have relatively little impact when you are comparing biofuels against fossil fuels.²³ However, because biofuels – particularly those derived from bulky cellulosic feedstocks – are likely to be produced in relatively isolated areas, developing an efficient transportation system will be a key aspect of their sustainability.

Changes in land use, particularly conversion of native ecosystems like forests or grasslands to agricultural production, also have serious negative implications for GHG emissions. This is because all of the sequestered carbon, both in the biomass and in the soil, is rapidly released when land is converted, which will overcome any GHG benefits for years to come.

The US Environmental Protection Agency has suggested that biofuels produced from energy crops, including short-rotation woody crops like hybrid poplar, can save 4.8-5.5 tonnes of CO₂ per acre per year by substituting for fossil fuels. On the other hand, deforestation can release 83.7-172.1 tonnes of CO₂ per acre immediately. This means that in the best case scenario it would take 16-35 years before biofuels produced from that land would offset the carbon released.²⁴ Conversion of wetlands, grasslands, forests, and other carbon sinks would also have a similarly dramatic impact. This also means that because conventional agriculture often produces, rather than sequesters, GHGs, first-generation biofuels could take hundreds of years to offset the GHGs produced by land conversion.

Accurately assessing the climate change impact requires consideration of the entire production process of the biofuel. GHG reductions are not intrinsic to any one product or process but the result of environmentally sound choices being made consistently along the entire value chain. If old-growth forests are clear-cut to plant hybrid poplar and the poplar is grown with excessive chemical inputs then processed into ethanol in a coal-fired plant, there could be little or no improvement in emissions over conventional fuels.

If on the other hand, degraded farmland is converted to perennial energy crops grown with no or minimal chemical inputs then processed into ethanol in a plant powered by natural gas or renewables, GHG benefits will most certainly be positive.

Impacts of Global Warming in Oregon

The 2004 “Scientific Consensus Statement on the Likely Impacts of Climate Change on the Pacific Northwest”¹⁶ concluded that our region is warming, average annual precipitation has increased, land on the central and northern Oregon coast is being submerged by rising sea level, and the region’s snow-pack has declined precipitously. These trends are expected to continue.

Global warming comes with a big price tag. Climate change will impact farm and fisheries productivity and hydroelectric energy production. Drier summers will lead to drought stress and vulnerability of forests to fire, disease, and insects.

Global warming will also impact human health.¹⁷ Among the most serious health impacts, Oregon is likely to see an increase in unhealthy air days as hotter summertime temperatures generate more smog; a longer pollen season will make life more uncomfortable for people with asthma and allergies; and such insect-borne diseases as malaria are expected to reappear.

3.3  Air Quality

The original idea of blending ethanol with gasoline was to reduce reduce air pollution, in particular carbon monoxide. However the long-term impact, particularly of ethanol, on air quality is not yet entirely clear. Biofuels reduce emissions of some pollutants, like carbon monoxide, particulate matter and benzene, but may increase emissions of others, like acetaldehyde and nitrogen oxides. Regular monitoring of changes in air quality as increased quantities of biofuels are used in Oregon will be necessary to ensure that there are no unforeseen effects from changes in the fuel mix.

3.3.1 Tailpipe Emissions

Concern for reducing pollution from cars directly led to the first national Renewable Fuel Standard under the Clean Air Act. Much of the incredible growth that has been seen in the ethanol industry has been driven by phasing out MTBE, an oxygenate additive that was found to contaminate groundwater, and replacing it with ethanol. The high level of oxygen in ethanol helps reduce the amount of carbon monoxide produced. Despite this and the other clear advantages that biofuels have over traditional fossil fuels, such as being biodegradable and non-toxic in marine environments, biofuels do not provide air quality benefits across the board. As detailed below, the use of biodiesel results in much lower emissions of almost every pollutant, with the possible exception of nitrogen oxides. The use of ethanol also results in lower emissions of most pollutants, but ethanol can increase emissions of nitrogen oxides, volatile organic compounds – especially at low blends – and can also increase acetaldehyde emissions.

Air Quality in Oregon

While Oregon’s and the nation’s air is generally cleaner than it has been in the past, air pollution continues to negatively impact people’s health and the environment. In Oregon, air pollutants of par-
ticular concern include air toxics, fine particulate matter, and ground-level ozone (also known as smog).

Most Oregon communities consistently meet the current federal standards for ozone and particulate matter set by the US Environmental Protection Agency. This means that levels of these pollutants in Oregon’s air are considered low enough to not pose a risk to human health. However, there is still reason to be concerned:

• Klamath Falls and Oakridge occasionally experience dangerous levels of fine particulate matter and are unlikely to meet the federal standards that were revised in 2006.²⁵
• Scientific evidence indicates that exposure to smog at levels below the current standards is causing adverse public health effects, particularly in those with respiratory illness.26
  

In addition, it is estimated that there are 16 air toxics in Oregon’s air at levels more than 10 times the federally determined safe level, including several associated with vehicle exhaust: diesel, benzene, acetaldehyde, acrolein, formaldehyde, polycyclic organic matter, and 1,3-butadiene. Air toxics are pollutants in the air that are known or strongly suspected to cause serious health problems, including cancer. Diesel emissions alone are known to contain more than 40 air toxics.²⁷

Biodiesel

While tailpipe emissions from biodiesel depend on the blend used, the type of biodiesel (since different feedstocks have different properties), and the type of engine, there are some general statements that can be made with certainty. Biodiesel has fewer emissions compared to petroleum diesel of particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC). The US Environmental Protection Agency estimated that for a soybean-derived B20 blend these could be as much as -10.1% for PM, -21.1% for HC and -11.0% for CO.28 Higher blends provide greater benefits. Research has also shown that biodiesel reduces emissions of such air toxics as benzene, 1-3 butadiene, acetaldehyde, and formaldehyde.²⁹

There has been some disagreement on nitrogen oxide (NOx) emissions from biodiesel with the US EPA study referenced above suggesting that B20 may increase emissions by 2%. However, a 2006 National Renewable Energy Laboratory study concluded that B20 had no net impact on NOx emissions.³⁰ Recently, the Texas Commission on Environmental Quality delayed implementing a decision to ban the use of B20 (due to concerns over increased NOx emissions) pending the results of further testing.³¹ If the NOx issue is resolved through further testing or processing refinements, it is likely that biodiesel can provide major improvements in air quality for all major pollutants. In any case, it is a clear improvement over petroleum diesel.

Ethanol

Unlike biodiesel, ethanol tailpipe emissions do not vary based on the feedstock used to produce the ethanol because the end product is the same chemical compound – C₂H₅OH.

The results of studies of ethanol tailpipe emissions have been mixed, and there are continuing debates on what the long-term impacts are. The Renewable Fuels Association states that “ethanol reduces tailpipe carbon monoxide emissions by as much as 30%, toxics content by 13% (mass) and 21% (potency), and tailpipe fine particulate matter emissions by 50%” and reduces smog formation. Although the US EPA has stressed the air quality benefits from ethanol, particularly in reducing carbon monoxide and smog, their own analysis and literature review shows a more complicated picture than for biodiesel. While different studies show a range of a results, the US EPA model of E10 estimates in some cases a 7.4% reduction in volatile organic compounds (VOCs) and a 11-19% reduction in carbon monoxide (CO), but a 7.7% increase in NOx.³² Also due to the higher volatility of E10, more evaporation occurs, which results in the release of more VOCs than from the tailpipe alone. The use of ethanol likely also increases acetaldehyde emissions.³³  Research indicates that NOx emissions may be improved by the use of E85 or other higher ethanol blends,³⁴ and that E85 may also reduce evaporative emissions compared to low blends.35 However, a controversial study by an atmospheric chemist at Stanford University has suggested that the increased use of E85 “may increase ozone-related mortality, hospitalization, and asthma,”³⁶ although he notes that “because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles.” While this report has been widely questioned,³⁷ what is clear is that ethanol raises more air quality concerns than biodiesel, and that the increased use of ethanol may result in tradeoffs between different pollutants rather than across the board benefits.

3.3.2 Biofuel Refinery Emissions

While air quality concerns stem primarily from the tailpipe emissions from burning biofuels, increased emissions from production facilities are also an issue, particularly for those that use coal. As biofuel production is theoretically displacing oil production, the effect may be negligible or even positive, but localized impacts are important to consider.

3.4 Water Quality

One of the great advantages of biofuels is that they are biodegradable and pose little risk of directly contaminating water supplies. For example, biodiesel degrades two to three times as fast in water as petroleum diesel and is less toxic.³⁹ Ethanol also readily degrades and is unlikely to contaminate groundwater sources. Biofuel production, however, can have major impacts on water quality. The two areas that are of greatest concern are impacts from intensified agricultural production and wastewater discharges from production facilities.

3.4.1  Agricultural impacts on water quality

Several water quality concerns relate to agricultural production: nutrient loading from fertilizer runoff, contamination from certain fertilizers and pesticides, and silting and other issues from eroded soil.⁴¹ None of these are unique to growing feedstocks for biofuels, but to the extent that biofuels are based on an expansion of conventional agriculture these water quality impacts pose one of the greatest environmental challenges to sustainable bioenergy.

Agricultural runoff of fertilizers produces blooms of algae that drain all of the oxygen out of large areas of water producing eutrophication and hypoxic zones, including the “dead zone” in the Gulf of Mexico, which is rendered incapable of supporting life for long stretches of the year.⁴² Because corn is grown over so much of the area that drains into the Mississippi river and uses so much nitrogen fertilizer, corn production is closely linked with the dead zone. Experts are suggesting that the dead zone may be the biggest ever this year and could reach 8,500 sq miles, which is almost double the average since 1990.⁴³ While increased rains and other factors may have as much of an impact as increased corn production in the size of the dead zone, agricultural runoff in general is clearly a root cause.⁴⁴

Soil erosion into streams can also have a profound impact on overall water quality. Fine sediment has been identified as a source of stream impairment in much of Western Oregon’s stream basins.⁴⁵ Finally, certain herbicides and pesticides can pose a direct threat to the health of both people and wildlife.

Fortunately, all of these problems can be addressed by the adoption of best management practices. The use of conservation tillage, cover crops or better rotations can help cut down on soil erosion and runoff, as can planting buffers of trees or native vegetation along streams. Nutrient management planning, where care is taken not to apply more fertilizer than the plants can take up, or building healthy soil through compost or cover crops to reduce or eliminate the need for chemical fertilizers, can substantially reduce nitrogen runoff. Finally, the use of integrated pest management and other techniques can reduce or eliminate the amount of chemical inputs that are required. Many of these techniques will also reduce the net GHG emissions and improve the energy balance of biofuels as well. These best management practices are applicable to all agricultural crop production, not just the growing of feedstocks for biofuels.

3.5 Water Use

Biofuel production is generally very water intensive. In addition to the irrigation requirements of most current biofuel feedstocks, biofuel plants currently use several gallons of water for every gallon of fuel produced. Because plants are usually placed close to where the feedstock is produced to minimize transportation costs, local water supplies may need to bear the brunt of both increased irrigation and production demands. This is of particular concern when the water is being drawn from sources that are already being depleted and for more arid areas, including much of Eastern Oregon. While oil refineries are probably less water intensive per BTU of energy produced, they do use substantial amounts of water and certainly the extraction and processing of petroleum poses a higher risk of contaminating water supplies.^H Regardless, the full water-use implications of biofuel production for each watershed region need to be carefully considered to ensure that water use is sustainable over the long-term. This is particularly true as global warming is likely decrease snow pack runoff and otherwise affect water tables and precipitation levels in many areas.⁴⁶

3.5.1  Ethanol refinery water use

Ethanol plants use large quantities of water for cooling and wastewater discharge, and although plants recycle water, substantial quantities are lost to evaporation. Improved plant design has resulted in substantial improvements in water needed per gallon of ethanol, from 5.8 gallons of water to produce 1 gallon of ethanol in 1998 to 4.2:1 in 2005, and the current average is probably between three to four gallons per gallon for new plants.⁴⁷ That means that a 100 million gallon plant might use 400 million gallons of water per year, which is the same as a town of 10,000 people.⁴⁸

3.5.2 Biodiesel refinery water use

Biodiesel production uses far less water than ethanol, but still about two gallons of water per gallon of biodiesel produced.⁴⁹

3.6 Soil Erosion

Intensified agriculture, particularly using conventional tillage, can result in increased soil erosion and loss of soil fertility. On the other hand, the conversion of agricultural land in annual crops to perennial grasses or trees can stop or even reverse erosion. One of the most promising sources for cellulosic biomass in Oregon is agricultural residues, particularly wheat straw. However, residues left on the field help prevent soil erosion and water loss and maintain soil fertility. Sustainable residue removal rates vary depending on management practices (such as no-till or conservation tillage), soil type and climate. Developing clear guidelines specific to Oregon agriculture for how much residue can be removed without increasing erosion will be a key part of ensuring the sustainable use of this resource. This is discussed in more detail in the section on agricultural residues (6.3.2).

3.7 Forest Health

The use of forest thinnings and other non-merchantable material has been identified as one of the most promising sources of biomass for cellulosic ethanol in Oregon.⁵⁰ Particularly in cases where forests are overloaded due to years of fire suppression, thinning can improve forest health; but there are also serious concerns. Woody biomass provides vital habitat for plants and animals and is a critical part of natural forest health. In cases where biomass removal is being added on to clear-cut logging and other more intensive practices there are even greater concerns. These concerns and a policy recommendation are discussed in more detail in the section on woody biomass (section 6.3.3).

3.8 Biodiversity and Ecosystem Conversion

While there has been some research on the use of native grass poly-cultures as feedstocks for biofuels,⁵¹ the vast majority of energy crops – from oilseeds to trees – are likely to be grown as intensely cultivated monocultures. Monocultures are unable to support the biodiversity of natural ecosystems, with major environmental and social implications.

An excellent example of this trade-off is the current debate over the federal Conservation Reserve Program (CRP) and the Oregon Conservation Reserve Enhancement Program (CREP). CRP and CREP, which combined have approximately 541,000 acres enrolled in Oregon, pay farmers to convert highly erodible cropland or other environmentally sensitive acreage to vegetative cover, such as native grasses, wildlife plantings, trees, or riparian buffers. Farmers receive an annual rental payment for the term of a multi-year contract which is usually 10-15 years for CRP, and 15 or 30 years for CREP. Cost sharing is provided to establish the vegetative cover practices. CRP supports huge amounts of wildlife and plant species, including millions of birds. There has been some discussion of opening up CRP or other conservation programs to biomass production, but this is likely to have negative implications for biodiversity. The millions of birds and other wildlife that are dependent on CRP grasslands and wetlands or CREP riparian buffers need habitats that are left fallow for five years or more, and will not fare well under a regularly harvested system. Most CRP and CREP lands are small and scattered across the landscape in nowhere near the concentration that would be needed to supply the feedstock for a biofuel plant. Those blocks that are large enough to supply a plant are also disproportionately important to wildlife, particularly migratory waterfowl.⁵² While in some cases biomass production from perennial crops can offer improvements in wildlife habitat over annual crops, it is no substitute for areas that are never harvested.

Next: Chapter 4 - Social Sustainability

<sup>F The DOE-funded projects will be completed between 2009 and 2011 and will likely need to run a few years before investors will be willing to put down money for a commercial-scale plant. The plants are Abengoa Bioenergy Biomass in Kansas; ALICO, Inc. in Florida; BlueFire Ethanol, Inc. in Southern California; Broin Companies in
Emmetsburg, Iowa; Iogen Biorefinery Partners in Shelley, Idaho; and Range Fuels in Soperton, Georgia.

G The net energy measurement does not capture such qualities as how easily the fuel can be transported or converted into other forms. Both gasoline and electricity are higher quality fuels that can be cheaply transported and stored and used for a variety of applications.</sup>

^{H For comparison purposes several sources have suggested that oil refineries use about .5 gallons of water for every gallon of crude oil refined into gasoline, diesel, kerosene and a range of other fuels, and one technical report suggested that New Mexico refineries used between .25 and 1 gallons of water for every gallon of crude. Ethanol also only contains approximately two-thirds the energy of gasoline, so more needs to be produced to generate the same amount of energy. Sources: Water use, conservation and wastewater treatment alternatives for oil refineries in New Mexico, 1985
(www.osti.gov/energycitations/product.biblio.jsp?osti_id=5808988);
Water Use in Oil Refineries (http://i-r-squared.blogspot.com/2007/03/water-usage-in-oil-refinery.html); and
Ethanol faces big hurdle: water use, St. Petersburgh Times, May 28, 2007 (http://www.sptimes.com/2007/05/28/Hillsborough/Ethanol_faces_big_hur.shtml)}