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Picmcntcl/Problcmy Ekorozwoju/Problcms of Sustainablc Deyelopment 2/2012,15-22

Argumenty przedstawione przez profesora D. Pimentela podważają tezę głoszącą, że paliwa ciekłe produkowane z biomasy stanowią alternatywę dla paliw uzyskiwanych z ropy naftowej. Co więcej, przeprowadzona analiza wykazuje, że wprowadzanie ciekłych paliw produkowanych z biomas}' jest sprzeczne z ideą zrównoważonego rozwoju._

Introduction

Each year. the U.S. and other nations import morę than 60% of their oil at a tremendous cost to them-selves (USCB, 2009). In the U.S. alone, oil repre-sents nearly 40% of the U.S.’s energy consumptioa leading the International Energy Administration (2008) and other organizations to estimate that cheap world oil supplies will be depleted by 2040 (Murray. 2004; Green et al.. 2006; Hodge. 2008; W. Youngquist, Personal communication, Decem-ber 8, 2009). Such a forecast has created an urgent necd for an altematc liquid fucl and has stimulatcd many nations to seek diverse ways to produce liq-uid fuels. As a consequenee. maize ethanol produc-tion has become a popular feedstock for ethanol production. Unfortunately the production of ethanol from maize grain has proven to be energetically and environmentally costly in terms of the subsidies which no w total $12 billion per year (Koplow and Steenblik, 2008). In addition. comerting com into ethanol has inereased U.S. food prices (Piinentel et al.,2009). Clearly, using food as a source of ethanol presents important ethical problems.

Increasing food costs and reduccd food supplies worldwide has both the Director General of the United Nations and President of the World Bank waming that using grains and other human foods to produce fuel is leading to increasing malnutrition and stanation worldwide (Spillius, A. 2008). A total of 2.3 billion tons of grains are produced an-nually in the world and about 20% of this total is used for ethanol production. Another important food product. \egetable oils. are being used for biofuel. tliesc oils include soybean, canola. and palm oil. Currently in Europę 60% of the rapeseed oil is being used for biodiesel or about 1.5 billion gallons (6 billion liters) (FAO, 2009).

Using food products in the production of biofuels is particularly troublesome because of the limited supply of biofuel energy that can be produced from foods. For example. the U.S. currently produces 34 billion liters of ethanol, consuining 33% of all U.S. maize production now . but only provides 1.7% of total oil consumption in the U.S. assuming no fossil energ}' inputs (USCB, 2009). In fact. if 100% of U.S. maize were comerted into etlianol it would provide the U.S. with only 5% of its needed oil fuel. assuming again zero fossil energy inputs.

Other countries like Brazil. are producing about 27 million liters of ethanol but their source of ethanol is from sugarcane (Ministiy of Brazilian Agricul-ture 2009). However. even the 27 million liters of ethanol are not enough to meet their consumption needs as Brazil s oil consumption during the past 10 years has inereased 42% (Ministry of Brazilian Agriculture 2009). Additional costs to consumers in Brazil include the subsidies that total several billion dollars per year just for ethanol (Murray. 2004; Coelho. 2005; Green et al., 2006; Hodge. 2008;Berg, 2004; FEE, 2009; Schmitz et al.. 2009). Others report that there are no subsidies for Brazilian etlianol (Union of Sugarcane Industry Associa-tion. 2009; Walter, 2009). However. the subsidies for ethanol are contributing to deforestation and other emironmental problems in Brazil (Pacific Ecologist, 2009).

In addition to the subsidies in the U.S. and Brazil, there is the question whether green plants. such as maize. switchgrass. willow. and all other kinds of biomass can provide suitable sources of liquid fuels. Unfortunately. these green plants in the U.S. coiwert only about 0.1% solar energy into plant materiał (Table 1; Pimentel et al., 2009). The use of grain and other biomass for liquid fuels, also contribute C0₂ emission to the atmosphere (Pimentel et al., 2009). In contrast. photovoltaic cells collect morę than 150 times the solar energy that green plants collect and add relatively little C0₂ to the atmosphere (Pimentel, 2008; Pimentel and Patzek. 2008).

In this article, we examine the potential for improi-ing the efficiency of converting com grain and cellulosic biomass into etlianol. Also we examine the production of biodiesel using algae. In sum-maiy, we attempt to define the impact of biofuel production on greenhouse gas einissions and the prevention of malnutrition and hunger.

Energy Inputs in Com Ethanol Production

In this analysis, the most recent scientific data for maize fermentation/distillation were used. All cur-rent fossil energy inputs were also used in maize production and for the fermentation and distillation and were included to determine the entire energ}' cost of etlianol production. Additional costs to consumers include federal and State subsidies (Koplow and Steenblik, 2008). plus costs associated with emironmental pollution and/or degradation that occur during the entire production process.

In a large etlianol comersion plant, the ethanol yield from 2.69 kg of maize grain produces 1 liter of ethanol (approximatcly 9.5 liters pure ethanol per bushel of com). The production of maize in the United States requires a significant energ}' and monetary iiwestment for an ai erage of 14 inputs, including labor. farm machinery. fertilizers, irriga-tion. pesticides. and electricity (Table 2). As listed in table 2. the production of an average maize yield

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