Discussion paper: Biomass not a viable energy source for modern economies

12 March 2013

The United States cannot achieve energy security through biofuels, and even the attempt is ironically achieving effects contrary to “clean” and “green” environmental goals and actively threatening global security, concludes a US Navy analyst, Captain T.A. Kiefer, in a discussion paper published by the Waterloo Institute for Complexity and Innovation (WICI) [3572]. The paper is an expanded version of an article in Strategic Studies Quarterly (SSQ) [3571], a journal published by the US Air Force Research Institute.

The paper—while not representative of the official position on biofuels by the US Army—reflects the concerns among US military experts and their experience from the numerous biofuel programs that were conducted by various branches of the US Department of Defense. The paper is based on the same stream of new, interdisciplinary scientific research that was underlying the recent European proposal to reverse the EU biofuel policy and to cap the usage of crop-based biofuels at the current level.

Biofuel science from the 1980s and 1990s viewed biomass-derived liquid fuels as a prospective replacement for petroleum-based transportation fuels. However, most of the early biofuel studies were overly focused on the conversion of solar energy and ambient CO₂ into biomass during plant growth, while overlooking a number of important lifecycle, or “well-to-wheel”, effects. In many media reports, crop-based biofuels such as ethanol or biodiesel are still seen as being able to increase domestic fuel supply and improve energy security, while reducing greenhouse gas (GHG) emissions and stimulating the economy. These arguments all fall apart under scrutiny, states the paper. Uncultivated biofuel yields are far too small and diffuse to displace any meaningful fraction of US primary energy needs, and boosting yields through cultivation consumes more energy than it adds to the biomass.

Energy return on investment (EROI) is the key metric used in the paper to assess and compare fuels. EROI is defined as the ratio of usable energy in newly produced fuel to the energy consumed in producing the fuel. In a modern civilization, EROI must be significantly greater than unity, as survival and standard of living depend upon the size of this margin. The ancient Roman civilization achieved EROI (calculated as the ratio of their output physical work to the input of crop farming resources and labor necessary to feed them) of between 1.8:1 and 4.2:1. A significant increase of EROI was possible when steam engines were developed that could extract high EROI work from coal. Later, petroleum’s high EROI, combined with high energy density and versatility, enabled the transportation revolution of aircraft and rockets. The magnitude of the energy revolution can be appreciated when one realizes that a car’s tank of gasoline contains approximately two man-years of energy.

In 2010, the overall EROI in the United States was at 12:1. Based on studies of historical economical performance, a modern developed nation must maintain an EROI of at least 6:1 to avoid slipping into recession. When the overall EROI drops below 3:1, energy starvation sets in.

Energy sources with the highest EROI include hydro power, followed by coal, natural gas, oil and nuclear energy. Among newer energy sources, reasonably high EROI levels—matching or exceeding the current US 12:1 average—may be possible with solar, wind, geothermal, as well as wood and waste-derived energy. Tar sand fuels are estimated to have EROI of up to about 10:1.

By comparison, crop-based fuels offer EROI performance at energy starvation levels. Food crop-based ethanol and biodiesel have EROI below 3:1, while hydrotreated and cellulosic crop fuels have EROI of less than 0.7:1. The low EROI of biofuels is caused by high (petroleum) energy consumption in their production. In the case of US-based corn ethanol (EROI ~ 1.25), nitrogen fertilizers represent a very significant input of fossil energy (the fertilizers are based on ammonia which is manufactured from natural gas). Hence, the life cycle of corn-ethanol is described as transformation of high quality fossil fuel into an approximately equivalent amount of lower quality gasoline additive, accompanied by release of CO₂ emissions and consumption of significant quantities of water.

The EROI methodology described in the paper shows that biofuels in the United States are not displacing fossil fuels—they are accelerating their use. The only way to displace imported petroleum and improve national security—points out the paper—is to domestically produce fuels with higher EROI than refined petroleum.

The evidence of the poor EROI of biofuels is their high price—due to the amount of petroleum energy consumed in their production they cannot compete with petroleum-based fuels and can exist in the market place only with the support of government subsidies and mandates. The cheapest price the US Navy has ever paid for any biofuel is $25.73 per gallon ($6.80 per liter), according to the paper. Since 2007, the US military has spent $67.8 million on 1.35 million gallons of biofuel, averaging more than $50 a gallon ($13.20 per liter) and costing $60 million more than if conventional fuel had been purchased.

The paper analyzes a number of other social and environmental costs and impacts of biofuels, including:

• Energy Sprawl—Soy can produce 70 gallons of biodiesel per acre and corn 500 gallons of ethanol per acre, corresponding to a power density of only 0.069 W/m² and 0.315 W/m², respectively. Replacing the 28 exajoules of energy that the US uses every year for transportation with biodiesel would require 3.2 billion acres of soy—one billion more than all US territory including Alaska. Algae biodiesel has the highest potential power density of any biofuel, but its predicted best-case future performance is equivalent to today’s solar panels.
• “Green Grabbing”—Large amounts of cellulosic forest floor debris and cultivated crop residue stalks and leaves that are considered feedstocks for “2^nd generation biofuels” are not truly waste that can be harvested for fuel, but are vital parts of the ecosystem that need to be left in place to conserve soil and water. Whatever fraction of biomass is removed from an ecosystem or farmer’s field instead of being left to compost and recycle is a loss that must eventually be replaced or the soil will be depleted. Another form of “green grabbing” are confiscations of land from poor villagers in Latin America, Africa and Asia to grow biofuel crops.
• GHG Emissions—The low EROI of biofuels also indicates high CO₂ emissions, while the use of nitrogen fertilizers to grow biofuel crops translates to high emissions of N₂O—a GHG much more potent than CO₂. In addition, very significant CO₂ emissions can be released via indirect land use change (ILUC). Indonesia, for instance, became the world’s third CO₂ emitter (after China and the United States) due to the burning of forest and peatland while converting jungle into palm plantations that supply the European biofuel demand.
• Competition of Fuel and Food—By putting an upward pressure on food prices, biofuels are becoming a threat to global food security, and thereby to global stability. For example, one of the underlying reasons of the “Arab Spring” uprisings was outrage at increasing food prices.
• Water Demand—Conventional gasoline has a water footprint of 2.3 to 4.4 liters of water per liter of ethanol equivalent energy (L/L). In contrast, global averages for biofuels range from sugar beet ethanol at 1,388 L/L, through corn ethanol (2,570 L/L), soy biodiesel (13,676 L/L) and rapeseed biodiesel (14,201 L/L) to jatropha biodiesel at 19,924 L/L. This level of water demand is not sustainable in a world that is facing water deficit. Countries that already rely on desalination of seawater—from Saudi Arabia to Spain—are spending one liter of ethanol equivalent energy to produce from 126 to 970 liters of water.

The author concludes that biomass is an inefficient middleman between solar energy and fuel—a better approach would be to bypass the creation of biomass completely and directly synthesize liquid fuel from sunlight. In its concluding remarks, the paper calls on the US government to end subsidies and market-distorting policies that encourage low-EROI biofuels over high-EROI energy sources.

Source: Twenty-First Century Snake Oil (WICI) | Energy Insecurity (SSQ)