Biofuels, Solar and Wind as Renewable Energy Systems: Benefits and Risks pptx

This book examines various renewable energy technologies and reports on theirpotential to supply the United States and other nations with needed energy.. His research in LCA covers renew

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The petroleum age began about 150 years ago Easily available energy has ported major advances in agriculture, industry, transportation, and indeed manydiverse activities valued by humans Now world petroleum and natural gas sup-plies have peaked and their supplies will slowly decline over the next 40–50 yearsuntil depleted Although small amounts of petroleum and natural gas will remainunderground, it will be energetically and economically impossible to extract In theUnited States, coal supplies could be available for as long as 40–50 years, depending

sup-on how rapidly coal is utilized as a replacement for petroleum and natural gas.Having been comfortable with the security provided by fossil energy, especiallypetroleum and natural gas, we appear to be slow to recognize the energy crisis in theU.S and world Serious energy conservation and research on viable renewable en-ergy technologies are needed Several renewable energy technologies already exist,but sound research is needed to improve their effectiveness and economics Most ofthe renewable energy technologies are influenced by geographic location and faceproblems of intermittent energy supply and storage Most renewable technologiesrequire extensive land; a few researchers have even suggested that one-half of allland biomass could be harvested in order to supply the U.S with 30% of its liquidfuel!

Some optimistic investigations of renewable energy have failed to recognize thatonly 0.1% of the solar energy is captured annually in the U.S by all the green plants,including agriculture, forestry, and grasslands Photovoltaics can collect about 200times more solar energy per year than green plants The green plants took more than

700 million years to collect and then be stored as the concentrated energy found inpetroleum, natural gas, and coal supplies

This book examines various renewable energy technologies and reports on theirpotential to supply the United States and other nations with needed energy Somechapters examine several renewable energy technologies and their potential to re-place fossil fuel, while others focus on one specific technology and its potential, aswell as its limitations In this volume, the aim of the contributors is to share theiranalyses as a basis for more research in renewable energy technologies Basic to allthe renewable energy technologies is that they attempt to minimize damage to theenvironment that supports all life

v

Several of the chapters reflect the current lack of agreement in the field, as sure mounts to explore and develop potential energy alternatives The reader willnotice considerable variability in the energy inputs and potential energy outputs

pres-in some of the studies This is evidence of the complexity of assesspres-ing the largenumber of energy inputs that go into production of a biofuel crop and the extraction

of its useful energy As research continues, we will discover if current analyses

of renewable energy technologies have adequately estimated energy requirements,outputs and environmental consequences Hopefully, this research will help guideenergy policy makers toward the most viable choices and away from energy costlymissteps, as we collectively encounter energy descent

The authors of each of these chapters have done a superb job in presenting themost up to date perspective of various renewable energy technologies in a highlyreadable fashion

I wish to express my sincere gratitude to the Cornell Association of ProfessorsEmeriti for the partial support of our research through the Albert Podell GrantProgram In addition, I wish to thank Anne Wilson for her valuable assistance inthe preparation of our book.

vii

1 Renewable and Solar Energy Technologies: Energy and

Environmental Issues 1David Pimentel

2 Can the Earth Deliver the Biomass-for-Fuel we Demand? 19

Tad W Patzek

3 A Review of the Economic Rewards and Risks of Ethanol Production 57David Swenson

4 Subsidies to Ethanol in the United States 79

Doug Koplow and Ronald Steenblik

5 Peak Oil, EROI, Investments and the Economy in an Uncertain

Future 109

Charles A S Hall, Robert Powers and William Schoenberg

6 Wind Power: Benefits and Limitations 133

Andrew R.B Ferguson

7 Renewable Diesel 153

Robert Rapier

8 Complex Systems Thinking and Renewable Energy Systems 173

Mario Giampietro and Kozo Mayumi

9 Sugarcane and Ethanol Production and Carbon Dioxide Balances 215

Marcelo Dias De Oliveira

10 Biomass Fuel Cycle Boundaries and Parameters: Current Practice and Proposed Methodology 231

Tom Gangwer

ix

11 Our Food and Fuel Future 259

Edwin Kessler

12 A Framework for Energy Alternatives: Net Energy, Liebig’s Law

and Multi-criteria Analysis 295

Nathan John Hagens and Kenneth Mulder

13 Bio-Ethanol Production in Brazil 321

Robert M Boddey, Luis Henrique de B Soares, Bruno J.R Alves

and Segundo Urquiaga

14 Ethanol Production: Energy and Economic Issues Related to U.S and Brazilian Sugarcane 357

David Pimentel and Tad W Patzek

15 Ethanol Production Using Corn, Switchgrass and Wood; Biodiesel Production Using Soybean 373

David Pimentel and Tad Patzek

16 Developing Energy Crops for Thermal Applications: Optimizing

Fuel Quality, Energy Security and GHG Mitigation 395

Roger Samson, Claudia Ho Lem, Stephanie Bailey Stamler

and Jeroen Dooper

17 Organic and Sustainable Agriculture and Energy Conservation 425

Tiziano Gomiero and Maurizio G Paoletti

18 Biofuel Production in Italy and Europe: Benefits and Costs, in the Light of the Present European Union Biofuel Policy 465

Sergio Ulgiati, Daniela Russi and Marco Raugei

19 The Power Density of Ethanol from Brazilian Sugarcane 493

Andrew R.B Ferguson

20 A Brief Discussion on Algae for Oil Production: Energy Issues 499

David Pimentel

Index 501

Bruno J R Alves graduated in Agronomy from UFRRJ (Federal University of Rio

de Janeiro) in 1987 He concluded the Master’s Degree (1992) and PhD (1996) inAgronomy at the same University, specializing in techniques for the study of thedynamics of N in the soil and for the quantification of biological N2 fixation inlegume and non-legume species He is a researcher at the Brazilian Corporation

of Agricultural Research (Embrapa) and a teacher-advisor in the post-graduationprogram in Agronomy at UFRRJ His research covers the quantification of soil Csequestration, greenhouse gas emissions, and energy balance for biomass produc-tion

Robert Boddey graduated in 1975 from Leeds University, UK, with a BSc in

Agri-cultural Chemistry He earned a PhD at the University of the West Indies (Trinidad)

in 1980, with a thesis on biological nitrogen fixation (BNF) associated with wetlandrice He then moved to the Soil Microbiology Centre of the Brazilian Corporationfor Agricultural Research (Embrapa Agrobiologia) in Serop´edica, Rio de Janeiro.There he developed various techniques, including those using the stable isotope15N, to quantify inputs of BNF to grasses and cereals His team also works on theimpact of BNF on N dynamics in various agroecosystems Boddey has publishedalmost 100 papers in international journals, and over 60 chapters in books and con-ference proceedings

Marcelo E Dias de Oliveira graduated in 1997 as an Agronomic Engineer at

Uni-versity of S˜ao Paulo-Brazil, working as an undergrad student with GIS and RemoteSensing In 2001 he started his Master’s Degree at Washington State University –Richland - USA, concluding his work in 2004 During this time he did research onhazardous materials at the Hanford site, and developed his thesis on energy balance,carbon dioxide emissions and environmental impacts of ethanol production Cur-rently he works as consultant for an environmental company in Brazil and is about

to start his PhD studies

Jeroen Dooper holds a Bachelor degree in Ecological Material Technology and is

currently completing a Master’s degree in Sustainable Development, Energy and

xi

Resources at Utrecht University in the Netherlands His research is focused on ergy conversion technologies, energy policies, greenhouse gas mitigation and lifecycle assessments In 2007, he began collaboration with REAP-Canada to pursueresearch on various bioenergy conversion technologies and their efficiencies Hisprevious work experience includes environmental education at Econsultancy, andenvironmental consulting, environmental product development, and optimizing pro-cessing efficiency with the Avans University of Professional Education.

en-Andrew Ferguson, after National Service flying training in Canada, joined BEA

(later British Airways) In the 1960s, he tried to see if it was possible to persuadehis flying colleagues that there was an environmental crisis ahead due to growingpopulation Finding that it was impossible to locate even one person to acquiesce inthis proposition, he waited for more propitious times to engage in wider efforts Inthe 1990s, he became a member of the Optimum Population Trust (UK), started

by the late David Willey, and since 2002 has been editor of the biannual OPTJournal

Thomas Edgar Gangwer has a B.S in Chemistry from Lebanon Valley College

and a PhD in Physical Chemistry from the University of Notre Dame His reer spans basic research, applied research, regulatory compliance, and technol-ogy implementation in the chemistry, engineering, licensing, and environmentalarenas His materials processing experience includes chemical, radioactive, haz-ardous, sanitary, and byproduct feed stocks and wastes For both commercial andgovernment (NRC, DOE, DOD) clients, he has performed methodology devel-opment, process modeling, process evaluation, and project/program managementcovering diverse treatment, transport, pollution prevention, and disposal activi-ties In addition to client reports, he has over 40 scientific/technical literaturepublications

ca-Mario Giampietro is an ICREA Research Professor at ICTA – Institute of Science

and Technology for the Environment - Universitat Autonoma Barcelona, SPAIN

He has been visiting scholar at: Cornell University; Wageningen University; ropean Commission Joint Research Center, Ispra; Wisconsin University Madison;Penn State University, Arizona State University His research addresses technicalissues associated with “Science for Governance” such as Multi-Scale IntegratedAnalysis of Societal and Ecosystem Metabolism, Participatory Integrated Assess-ment of Scenarios and Technological Changes He has published more than 150papers and chapters of books and is the author of: ”Multi-Scale Integrated Analysis

Eu-of Agro-ecosystems” 2003 (CRC press), and co-author Eu-of “The Jevons Paradox”

2008 (Earthscan)

Tiziano Gomiero holds a degree in Nature Science from Padua University and

a PhD in Environmental Science from the Universitat Autonoma de Barcelona,Spain His work concerns integrated analysis of farming systems (which takes

into consideration the environmental, social and economic domains) and ruraldevelopment, including theoretical and epistemological issues, modeling, practicalapplications (he worked in Italian and South-East Asia contexts) He is currently aProfessor of Ecology and Agroecology at Padua University.

Nathan John Hagens is currently at the Gund Institute of Ecological Economics

at the University of Vermont studying the impacts that a decline in liquid fuelswill have on planetary ecosystems and society On the supply side, he is explor-ing net-energy comparisons of the primary alternate fuel sources to oil: coal, wind,nuclear and biomass Prior to coming to the Gund Institute, Nate developed tradingalgorithms for commodity systems and was President of Sanctuary Asset Manage-ment, Managing Director of Pension Research Institute, and Vice President at theinvestment firms Salomon Brothers and Lehman Brothers He holds an undergrad-uate degree from the University of Wisconsin and an MBA with honors from theUniversity of Chicago

Charles A Hall is a Systems Ecologist who received his PhD from Howard T.

Odum Dr Hall is the author of seven books and more than 200 scholarly articles

He is best known for his development of the concept of EROI, or energy return

on investment, which is an examination of how organisms, including humans, vest energy into obtaining additional energy to increase biotic or social fitness Hehas applied these approaches to fish migrations, carbon balance, tropical land usechange and petroleum extraction, in both natural and human-dominated ecosystems

in-He is developing a new field, biophysical economics, as a supplement or alternative

to conventional neoclassical economics

Edwin Kessler graduated from Columbia College in 1950 and received the Sc.D.

in Meteorology from MIT in 1957 From 1954-1961 he specialized in radar rology with the Air Force Cambridge Research Laboratories in Massachusetts, andfrom 1961-1964 he was Director of the Atmospheric Physics Division, TravelersResearch Center in Hartford, Connecticut From 1964 until retirement in 1986, hewas Director of the National Oceanic and Atmospheric Administration’s NationalSevere Storms Laboratory in Norman, Oklahoma In 1989, he received the Cleve-land Abbe award of the American Meteorological Society He has been Chair ofCommon Cause Oklahoma and is now Vice-Chair He manages 350 acres of pas-tures with woodlands and stream in central Oklahoma

meteo-Doug Koplow is the founder of Earth Track in Cambridge, MA (www.earthtrack.

net), an organization focused on making the scope and cost of environmentallyharmful subsidies more visible The author of Biofuels - At What Cost? Governmentsupport for ethanol and biodiesel in the United States (Global Subsidies Initiative,Geneva: 2006 and 2007), Doug has worked on natural resource subsidy issues fornearly twenty years He holds an MBA from the Harvard Graduate School of Busi-ness Administration and a BA in economics from Wesleyan University

Claudia Ho Lem is currently a Project Manager for REAP-Canada’s International

Development and Bioenergy Programs A rural development specialist with over

10 years of experience in environmental project management, Ms Ho Lem holds aB.Sc in Environmental Science specializing in Biology and Chemistry from theUniversity of Calgary She has worked on bioenergy, climate change and agro-ecological development in China, the Philippines, Cuba, West Africa and Canada,supporting farming communities in increasing their self-sufficiency through par-ticipatory assessments, training and research Her experience has given her an in-tegrated understanding of the social, economic, biological, ecosystem and healthimpacts of agricultural development

Kozo Mayumi, a former student of Georgescu-Roegen, has been working in the

field of energy analysis, ecological economics and complex hierarchy theory He

is a professor at the University of Tokushima and an editorial board member ofEcological Economics, Organization and Environment, and International Journal

of Transdisciplinary Research He is the author of The Origins of Ecological nomics: The Bioeconomics of Georgescu-Roegen, published by Routledge in 2001,and The Jevons Paradox and The Myth of Resource Efficiency Improvements fromEarthscan in 2008 Together with Dr Mario Giampietro and three other researchers,Mayumi started a biennial international workshop, (“Advances in Energy Studies,”)

Eco-in 1998

Kenneth Mulder obtained his PhD in Ecological Economics from the Gund Institute

for Ecological Economics at the University of Vermont His research is plinary, applying systems modeling and analysis to problems in ecology, economicsand agriculture He is particularly interested in the development of meaningfulindicators for alternative energy technologies Dr Mulder currently manages anintegrated student farm at Green Mountain College and teaches in the EnvironmentalStudies Department there

multidisci-Maurizio G Paoletti is a Professor of Ecology at Padova University, Padova, Italy.

With a background in biology and human ecology, he is an internationally nized researcher in biodiversity, agroecology, entomology and ethnobiology He hasheld visiting professorships in a number of countries (Finland, China, USA andAustralia) He has organised more than ten international conferences on agroecol-ogy, sustainable agriculture, biodiversity, and is very active in public conferences

recog-to inform citizens on sustainability issues Overall, he has completed 260 scientificpapers and 18 edited books

Tad Patzek is a professor of Geoengineering at U.C Berkeley Prior to joining

Berkeley in 1990, he was a scientist at Shell Development, a research companymanaged for 20 years by M King Hubbert Patzek’s current research involves math-ematical modeling of earth systems with emphasis on fluid flow in soils and rocks

He also works on the thermodynamics and ecology of human survival and energy

supply for humanity Currently, he teaches courses in hydrology, ecology and energysupply, computer science, and mathematical modeling of earth systems Patzek is acoauthor of over 200 papers and reports, and is writing five books.

David Pimentel is a professor of ecology and agricultural sciences at Cornell

Uni-versity, Ithaca, NY His PhD is from Cornell University His research spans thefields of energy, biotechnology, sustainable agriculture, and environmental policy.Pimentel has published more than 600 scientific papers and 25 books He has served

on many national and government committees including the National Academy ofSciences; President’s Science Advisory Council; U.S Department of Agriculture andU.S Department of Energy; Office of Technology Assessment of the U.S Congress;and the U.S State Department In 2008 he received an Honorary Doctorate from theUniversity of Massachusetts for his work in recognizing and publicizing criticaltrends in interactions between humans and the environment

Robert Powers is finishing a BS in Environmental Science at the State University

of New York College of Environmental Science & Forestry under Dr Charles Hall

He is interested in the intersection of energy and economic issues, specifically inmodeling problems to find innovative solutions He has also started a Masters inSystem Dynamics at the University of Bergen (Norway) to further develop his mod-eling skills

Marco Raugei obtained a Master’s degree in Chemistry and a PhD in Chemical

Sciences at the University of Siena (Italy), with a thesis on Life Cycle Assessment

He is currently working as a researcher and consultant in Life Cycle Assessmentand Environmental Management, with active collaborations with Ambiente ItaliaResearch Institute (Rome, Italy), University Parthenope (Naples, Italy), BrookhavenNational Laboratory (NY, USA), Columbia University (NY, USA), and Escola Su-perior de Commerc¸ Internacional - Universitat Pompeu Fabra (Barcelona, Spain)

He has published over 35 peer-reviewed papers in various international journals,books and conference proceedings

Robert Rapier has Bachelor’s Degrees in Chemistry and Mathematics, and a

Mas-ter’s Degree in Chemical Engineering from Texas A&M University Passionateabout energy and sustainability issues, his R-Squared Energy Blog is devoted todebate and discussion of those topics Robert has over 15 years of experience in thepetrochemicals industry, including experience with cellulosic ethanol, gas-to-liquids(GTL), refining, and butanol production He holds several U.S and internationalpatents, and works for a major oil company Robert is currently based in Scotlandwhere he lives with his wife and three children

Daniela Russi earned a Master’s Degree in Environmental Economics at the

University of Siena (Italy) She did an internship at the Wuppertal Institute forClimate, Environment and Energy, in Wuppertal (Germany) She obtained a PhD in

Environmental Sciences at the Autonomous University of Barcelona (Spain) with athesis on Social Multi-Criteria Evaluation (SMCE) applied to a conflict concerningrural electrification and large-scale biodiesel use in Italy She has published peer-reviewed papers in international journals, and contributed to various books and con-ference proceedings on these topics She is presently working for the environmentalconsultancy Amphos21.

Roger Samson is the Executive Director of Resource Efficient Agricultural

Pro-duction (REAP)-Canada, a charitable organization working to develop and mercialize ecological solutions to energy, fibre and food production Mr Samson

com-is a leading world expert in biomass energy development He has authored over

60 publications on bioenergy, ecological farming, and climate change mitigationand has been working on bioenergy projects in North America, Europe, China, thePhilippines, and West Africa since 1991 His work has pioneered ecological ap-proaches for bioenergy production and thermodynamically efficient bioenergy con-version systems Mr Samson holds a B.Sc (Crop Science) from Guelph Universityand a M.Sc (Plant Science) from McGill University in Montreal

William Schoenberg graduated from the State University of New York College of

Environmental Science & Forestry with a Bachelors Degree in Environmental ies He is very interested in energy issues, especially peak oil and its ramificationsfor society He is continuing his studies at the University of Bergen, Norway in theSystem Dynamics program, where he will be able to more fully explore dynamicmodeling and its ability to help society prepare for the backside of the peak oilcurve

Stud-Luis Henrique de B Soares is an Agronomist who graduated from Federal

Uni-versity of Rio Grande do Sul State (UFRGS, Brazil) He received a Master’s degree

in Environmental Microbiology, and his PhD in Molecular and Cellular Biology(Biotechnology Centre, Federal University fo Rio Grande do Sul, 2003), working

on microbial enzymes for industrial applications Dr Soares is currently a ResearchScientist at Embrapa Agrobiologia, Rio de Janeiro, studying principally agroenergy.The areas of his research include biofuels production and processing, enzymology,and energy balances for the assesmenet of agroecosystem sustainability

Ms Bailey Stamler is the Climate Change Project Manager with REAP-Canada.

She has been working with REAP developing business plans for internationalcarbon trading projects using small scale biomass energy technologies in the Philip-pines, Nigeria and Ethiopia since 2005 Ms Bailey Stamler is experienced in bioen-ergy and bioheat pellet potential in Canada, focusing on the use of energy crops,agriculture and crop milling residues for heating applications She also has expe-rience quantifying GHG emissions, mitigation potential and relative efficiencies ofbiofuels Ms Bailey Stamler holds B.Sc (Environmental Science) from LaurentianUniversity and an M.Sc from McGill University (Natural Resource Sciences)

Ronald Steenblik at the time of writing was Director of Research for the Global

Subsidies Initiative (GSI) of the International Institute for Sustainable Development(IISD) Ronald’s career spans three decades, in industry, academia, the U.S federalgovernment, and intergovernmental organizations, working on policy issues related

to natural resources, the environment, or trade Prior to joining the IISD, he was

a senior trade policy analyst in the Trade Directorate of the Organisation for nomic Co-operation and Development (OECD), where his analyses supported theWTO negotiations on environmental goods and services Ronald holds degrees fromCornell University and the University of Pennsylvania

Eco-David Swenson is an associate scientist in economics at Iowa State University and

a lecturer there in community and regional planning as well as in the graduate gram in urban and regional planning at The University of Iowa His primary area

pro-of research focuses on regional economic changes and their fiscal and demographicimplications for communities He has completed scores of economic impact studies,and written and presented extensively on the uses of impact models for decisionmaking Of late, he has scrutinized the potential community economic outcomesassociated with biofuels development in the Midwest and the Plains

Sergio Ulgiati received an education in Physics and Environmental Chemistry He

is a Professor of Life Cycle Assessment and General Systems Theory at ParthenopeUniversity in Napoli, Italy He has expertise in Energy Analysis, LCA, Environmen-tal Accounting and Emergy Synthesis He has published over 200 papers in nationaland international journals and books His research in LCA covers renewable andnonrenewable energy systems (wind, geothermal, hydro, bioenergy; solar thermaland photovoltaic, hydrogen and fuel cells; thermal fossil-powered power plant, in-cluding cogeneration and NGCC plants), as well as zero emission technologies andstrategies (ZETS) He is the organizer and Chair of the Biennial International Work-shop “Advances in Energy Studies.”

Segundo Urquiaga graduated in Agronomy in 1973 from the Agrarian University

“La Molina”, Lima, Per´u, with BSc, and defended his PhD thesis in 1982 in theAgricultural college “Luiz de Queiroz” of the S˜ao Paulo State University, Piraci-caba, S˜ao Paulo In 1984 he moved to the Brazilian Corporation for AgriculturalResearch (Embrapa Agrobiologia) in Serop´edica, Rio de Janeiro At present he isstudying the influence of biological nitrogen fixation (BNF) on the energy balance

of several renewable energy sources such as sugar cane, soybean and elephant grass.Urquiaga has published over 120 papers in national and international journals, andover 50 chapters in books and conference proceedings

Nathan John Hagens

Gund Institute for Ecological Economics, University of Vermont, 617 Main Street,Burlington, VT 05405, USA, e-mail: Nathan.Hagens@uvm.edu

Charles A S Hall

State University of New York, College of Environmental Science and Forestry,Syracuse, New York, NY 13210, USA, e-mail: chall@esf.edu

xix

Green Mountain College, Poultney VT, USA

Marcelo Dias De Oliveira

Avenida 10, 1260, Rio Claro - SP – Brazil, CEP 13500-450,

email: dias oliveira@msn.com

Luis Henrique de B Soares

Embrapa-Agrobiologia, BR-465, Km 07, Caixa Postal 75.505, Serop´edica,23890-000, Rio de Janeiro, Brazil

Stephanie Bailey Stamler

Resource Efficient Agricultural Production (REAP) – Canada, Box 125 CentennialCentre CCB13, Ste Anne de Bellevue, Quebec, Canada H9X 3V9

Ronald Steenblik

Global Subsidies Initiative of the International Institute for Sustainable

Development, Maison Internationalle de l’Environment 2, 9, chemin de Balexert,

1219 Chˆatelaine Gen`eve, Switzerland, e-mail: ronald.steenblik@gmail.comDavid Swenson

Department of Economics, 177 Heady Hall, Iowa State University, Ames IA 50011,e-mail: dswenson@iastate.edu

Renewable and Solar Energy Technologies:

Energy and Environmental Issues

David Pimentel

Abstract A critical need exists to investigate various renewable and solar energy

technologies and examine the energy and environmental issues associated withthese various technologies The various renewable energy technologies will not

be able to replace all current 102 quads (quad = 1015BTU) of U.S energy sumption (USCB 2007) A gross estimate of land and water resources is needed,

con-as these resources will be required to implement the various renewable energytechnologies

Keywords Biomass energy· conversion systems · ethanol · geothermal systems ·

hydroelectric power· photovoltaic systems · renewable energy · solar · wind power

1.1 Introduction

The world, and the United States in particular, face serious energy shortages andassociated high energy prices during the coming decades Oil, natural gas, coal,and nuclear power provide more than 88% of world energy needs; the other 12%

is provided by various renewable energy sources (Table 1.1) Oil, natural gas, coal,and nuclear provide more than 93% of U.S energy needs; the other 9% consists ofvarious renewable and non-renewable energy sources (Table 1.1)

The U.S., with slightly more than 45% of the world’s population, accounts fornearly 25% of the world’s energy consumption (Table 1.1) On average, each Amer-ican uses nearly 8,000 L of oil equivalents per year for all purposes, including trans-portation, industry, heating and cooling

The United States now imports more than 63% of its oil at an annual cost ofapproximately $200 billion (USCB 2007) Projections are that within 20 years theU.S will be importing more than 90% of its oil The United States has consumedmore than 90% of its proved oil reserves (Pimentel et al 2004a) Because the U.S

Table 1.1 Fossil and solar energy use in the U.S and world (quads= 10 15 BTU) (USCB 2007)

Diverse renewable energy sources currently provide 6.8% of U.S needs andabout 12% of world needs (Table 1.1) In addition to energy conservation, the devel-opment and use of renewable energy is expected to increase as fossil fuel suppliesdecline and become highly expensive Eight different renewable technologies areprojected to provide the U.S with most of its energy in the future: hydropower,biomass, wind power, solar thermal, photovoltaics, passive energy systems, geother-mal, and biogas In this chapter, I assess the potential of these 8 renewable energytechnologies, including their environmental benefits and risks, and their energeticand economic costs

1.2 Hydroelectric Power

Hydropower contributes significantly to world energy, providing 6% of the supply(Table 1.1) In the United States, hydroelectric plants produce approximately 3%

or 3.4 quads of total U.S energy (340 billion kWh) (1 kWh = 860 kilocalories

[kcal]= 3,440 BT = 3.6 megajoules), or 11% of the nation’s electricity, each year

at a cost of $0.02 per kWh (Table 1.2; USCB 2007) Development and rehabilitation

of existing dams in the United States could produce an additional 5 quads per year(Table 1.3)

Hydroelectric plants, however, require considerable land for their water storagereservoirs An average of 75,000 hectares (ha) of reservoir land area and 14 trillion

L of water are required per 1 billion kWh per year produced (Table 1.2, Gleickand Adams 2000) Based on regional estimates of US land use and average annualenergy generation, reservoirs currently cover approximately 26 million ha of thetotal 917 million ha of land area in the United States (Pimentel 2001) To developthe remaining best candidate sites, assuming land requirements similar to those inpast developments, an additional 7 million ha of land would be required for waterstorage (Table 1.3)

Table 1.2 Land resource requirements and total energy inputs for construction of renewable and

other facilities that produce 1 billion kWh/yr of electricity Energy return on investment is listed for each technology (See text for explanations)

Electrical energy

Technology

Land required (ha)

Energy input:output

Cost per kWh ($)

Life in years

f Based on 4,000 ha solar ponds plus an additional 1,200 ha for evaporation ponds.

g (Andrew Ferguson, Optimum Population Trust (UK), personal communication, June 16, 2007).

h (Tyner 2002).

i (Peace Energy 2003).

j Calculated from DOE 2000.

k No data available.

l (B Jewell, Cornell University, Ithaca, NY, personal communication 2001).

Table 1.3 Current and projected US gross annual energy supply from various renewable energy

technologies, based on the thermal equivalent and required land area

b This is the equivalent land area required to produce 3 metric tons per hectare.

c Total area based on an average of 75,000 hectares per reservoir area per 1 billion kilowatt-hours per year produced.

d Pimentel et al (2002).

Despite the benefits of hydroelectric power, the plants cause major tal problems The impounded water frequently covers valuable, agriculturally pro-ductive, alluvial bottomland Sediments build up behind the dams, reducing theireffectiveness and creating another major environmental problem Further, damsalter the existing plants, animals, and microbes in the ecosystem (Nilsson andBerggren 2000) Fish species may significantly decline in river systems because

environmen-of these numerous ecological changes

1.3 Biomass Energy

Most biomass is burned for cooking and heating, however, it can also be convertedinto electricity and liquid fuel Under sustainable forest conditions in both temperateand tropical ecosystems, approximately 3 dry metric tons (t/ha) per year of woodybiomass can be harvested sustainably (Birdsey 1992, Repetto 1992, Trainer 1995,Ferguson 2003) Although this amount of woody biomass has a gross energy yield of13.5 million kcal/ha, it requires an energy expense of approximately 33 L of dieselfuel per ha, plus the embodied energy for cutting and collecting wood for transport to

an electric power plant Thus, the energy input per output ratio for a woody biomasssystem is calculated to be 1:22

The cost of producing 1 kWh of electricity from woody biomass is about $0.06,which is competitive with other electricity production systems that average $0.07

in the U.S (Table 1.2) (USCB 2007) Approximately 3 kWh of thermal energy

is expended to produce 1 kWh of electricity, an energy input/output ratio of 1:7(Table 1.2) Per capita consumption of woody biomass for heat in the United Statesamounts to 625 kilograms (kg) per year In developing nations, use of diversebiomass resources (wood, crop residues, and dung) average about 630 kg per capita(Kitani 1999) Developing countries use only about 500 L of oil equivalents of fossilenergy per capita compared with nearly 8,000 L of oil equivalents of fossil energyused per capita in the United States (Table 1.1)

Woody biomass could supply the United States with about 5 quads (1.5 ×

1012kWh thermal) of its total gross energy supply by the year 2050, provided therewas adequate forest land available (Table 1.3) A city of 100,000 people using thebiomass from a sustainable forest (3 t/ha per year) for electricity would requireapproximately 200,000 ha of forest area, based on an average electrical demand

of slightly more than 1 billion kWh (electrical energy [e]) (860 kcal = 1 kWh)

(Table 1.2)

Environmental impacts of burning biomass are less harmful than those associatedwith coal, but more harmful than those associated with natural gas (Pimentel 2001).Biomass combustion releases more than 200 different chemical pollutants, including

14 carcinogens and 4 co-carcinogens, into the atmosphere (Burning Issues 2003).Globally, but especially in developing nations where people cook with fuelwoodover open fires, approximately 4 billion people suffer from continuous exposure

to smoke (Kids for Change 2006) In the United States, wood smoke kills 30,000

people each year (EPA, 2002) However, the pollutants from electric plants that usewood and other biomass can be controlled.

1.4 Wind Power

For many centuries, wind power has provided energy to pump water and to run millsand other machines Today, turbines with a capacity of at least 500 kW produce most

of the commercially wind-generated electricity Operating at an ideal location, one

of these turbines running at 30% efficiency can yield an energy output of 1.3 millionkWh (e) per year (AWEA 2000a) An initial investment of approximately $500,000for a 500 kW capacity turbine operating at 30% efficiency, will yield an input/outputratio of 1:4 over 30 years of operation (Table 1.2) During the 30-year life of thesystem, the annual operating costs amount to about $50,000 The estimated cost ofelectricity generated is $0.07 per kWh (e) (Table 1.2) Some report costs rangingfrom $0.03 to $0.05 per kWh (Sawin 2004) These values are probably located infavorable wind sites

In the United States, 2502 megawatts (MW) of installed wind generators produceabout 6.6 billion kWh of electrical energy per year (Chambers 2000) The AmericanWind Energy Association (AWEA 2000b) estimates that the United States couldsupport a capacity of 30,000 MW by the year 2010, producing 75 billion kWh (e)per year at a capacity of 30%, or approximately 2% of the annual US electricalconsumption If all economically feasible land sites are developed, the full potential

of wind power is estimated to be about 675 billion kWh (e) (AWEA 2000b) shore sites could provide an additional 102 billion kWh (e) (Gaudiosi 1996), makingthe total estimated potential of wind power 777 billion kWh (e), or 23% of currentelectrical use

Off-Widespread development of wind power is limited by the availability of siteswith sufficient wind (at least 20 kilometers per hour [km/h]) and the number ofwind machines that the site can accommodate An average area for one 50 kW tur-bine is 1.3 ha to allow sufficient spacing to produce maximum power (Table 1.2).Based on this figure, approximately 9,500 ha of land are needed to supply 1 billionkWh per year (Table 1.2) Because the turbines themselves only occupy approxi-mately 2% of the area, most of the land can be used for vegetables, nursery stock,and cattle (Natural Resources Canada 2002) However, it may be impractical toproduce corn or other grains because of the heavy equipment used in this type offarming

An investigation of the environmental impacts of wind energy production reveals

a few hazards Locating the wind turbines in or near the flyways of migrating birdsand wildlife refuges may result in birds flying into the supporting towers and rotat-ing blades For this reason, it is suggested that wind farms be located at least 300meters (m) from nature reserves to reduce their risk to birds The estimated 13,000wind turbines installed in the United States kill an estimated 2,600 birds per year(Sinclair 2003) Choosing a proper site and improving repellant technology withstrobe lights or paint patterns might further reduce the number of birds killed

Bat fatalities are another serious concern It is projected that by 2020 annualbat fatalities caused by wind turbines will range from 33,000 to 62,000 individualsannually (Kunz et al 2007) Most bat fatalities are from species that migrate longdistances and are tree roosting Eastern U.S wind turbines installed along forestedridgetops have the highest rate of bat kills, ranging from 15.3 to 41.1 bats per MW

of installed capacity per year (Kunz et al 2007) Monitoring for bat and bird ities and research for the reduction of these should be included in all wind energyplanning

fatal-The rotating magnets in the turbine electrical generator produce a low level

of electromagnetic interference that can affect television and radio signals within2–3 km of large installations (Sagrillo 2006) Fortunately, with the widespread use

of cable networks or line-of-sight microwave satellite transmission, both televisionand radio are unaffected by this interference

The noise caused by rotating blades is another unavoidable side effect of windturbine operation Beyond 2.1 km, however, the largest turbines are inaudible evendownwind At a distance of 400 m, the noise level is estimated to be about 60 deci-bel, corresponding roughly to the noise level of a home air-conditioning unit

1.5 Solar Thermal Conversion Systems

Solar thermal energy systems collect the sun’s radiant energy and convert it intoheat This heat can be used directly for household and industrial purposes or producesteam to drive turbines that produce electricity The complexity of these systemsranges from solar ponds to electricity-generating parabolic troughs In the followinganalyses, I convert thermal energy into electricity to facilitate comparison to theother solar energy technologies

1.5.1 Solar Ponds

Solar ponds are used to capture radiation and store the energy at temperatures ofnearly 100 degrees Celsius (◦C) Constructed ponds can be made into solar ponds bycreating a layered salt concentration gradient The layers prevent natural convection,trapping the heat collected from solar radiation in the bottom layer of brine Thehot brine from the bottom of the pond is piped out to use for heat, for generatingelectricity, or both

For successful operation of a solar pond, the salt concentration gradient and thewater level must be maintained A solar pond covering 4,000 ha loses approximately

3 billion L of water per year (750,000 L/ha per year) under arid conditions (Taborand Doran 1990) Recently, solar ponds in Israel have been closed because of suchdifficulties To counteract the water loss and the upward diffusion of salt in theponds, the dilute salt water at the surface of the ponds has to be replaced with freshwater and salt added to the lower layer (Solar Pond 2007)

The efficiency of solar ponds in converting solar radiation into heat is estimated

to be approximately 1:4, assuming a 30-year life for the solar pond (Table 1.2) A

100 ha (1 km2) solar pond can produce electricity at a rate of approximately $0.30per kWh (Australian Government 2007)

Some hazards are associated with solar ponds, but most can be avoided withcareful management It is essential to use plastic liners to make the ponds leakproofand prevent contamination of the adjacent soil and groundwater with salt

1.5.2 Parabolic Troughs

Another solar thermal technology that concentrates solar radiation for large-scaleenergy production is the parabolic trough A parabolic trough, shaped like the bot-tom half of a large drainpipe, reflects sunlight to a central receiver tube that runsabove it Pressurized water and other fluids are heated in the pipe and used to gen-erate steam that drives turbogenerators for electricity production or provides heatenergy for industry

Parabolic troughs that have entered the commercial market have the potential forefficient electricity production because they can achieve high turbine inlet tempera-ture Assuming peak efficiency and favorable sunlight conditions, the land require-ments for the central receiver technology are approximately 1,100 ha per1 billionkWh per year (Table 1.2) The energy input:output ratio is calculated to be 1:5(Table 1.2) Solar thermal receivers are estimated to produce electricity at approxi-mately $0.07–$0.09 per kWh (DOE/EREN 2001)

The potential environmental impacts of solar thermal receivers include the cidental or emergency release of toxic chemicals used in the heat transfer system.Water availability can also be a problem in arid regions

ac-1.6 Photovoltaic Systems

Photovoltaic cells have the potential to provide a significant portion of future U.S.and world electrical energy (Energy Economics 2007) Photovoltaic cells produceelectricity when sunlight excites electrons in the cells The most promising photo-voltaic cells in terms of cost, mass production, and relatively high efficiency arethose manufactured using silicon Because the size of the unit is flexible and adapt-able, photovoltaic cells can be used in homes, industries, and utilities

However, photovoltaic cells need improvements to make them economicallycompetitive before their use can become widespread Test cells have reached ef-ficiencies of about 25% (American Energy 2007), but the durability of photovoltaiccells must be lengthened and current production costs reduced several times to maketheir use economically feasible

Production of electricity from photovoltaic cells currently costs about $0.25per kWh (DOE 2000) Using mass-produced photovoltaic cells with about 18%

efficiency, 1 billion kWh per year of electricity could be produced on approximately2,800 ha of land, and this is sufficient electrical energy to supply 100,000 people(Table 1.2, DOE 2001) Locating the photovoltaic cells on the roofs of homes,industries, and other buildings would reduce the need for additional land by anestimated 20% and reduce transmission costs However, because storage systemssuch as batteries cannot store energy for extended periods, photovoltaics requireconventional backup systems.

The energy input for making the structural materials of a photovoltaic systemcapable of delivering 1 billion kWh during a life of 30 years is calculated to beapproximately 143 million kWh Thus, the energy input per output ratio for themodules is about 1:7 (Table 1.2, Knapp and Jester 2000)

The major environmental problem associated with photovoltaic systems is theuse of toxic chemicals, such as cadmium sulfide and gallium arsenide, in their man-ufacture Because these chemicals are highly toxic and persist in the environment forcenturies, disposal and recycling of the materials in inoperative cells could become

a major problem

1.7 Geothermal Systems

Geothermal energy uses natural heat present in Earth’s interior Examples aregeysers and hot springs, like those at Yellowstone National Park in the UnitedStates Geothermal energy sources are divided into three categories: hydrothermal,geopressured-geothermal, and hot dry rock The hydrothermal system is the simplestand most commonly used for electricity generation The boiling liquid underground

is produced using wells, high internal pressure drives, or pumps In the UnitedStates, nearly 3,000 MW of installed electric generation comes from hydrothermalresources, and this is projected to increase by 4,500 MW

Most of the geothermal sites for electrical generation are located in California,Nevada, and Utah Electrical generation costs for geothermal plants in the Westrange from $0.06 to $0.30/kWh (Gawlik and Kutscher 2000), suggesting that thistechnology offers potential to produce electricity economically The US Department

of Energy and the Energy Information Administration (DOE/EIA 2001) projectthat geothermal electric generation may grow three- to fourfold during the next20–40 years However, other investigations are not as optimistic and, in fact, sug-gest that geothermal energy systems are not renewable because the sources tend todecline over 40–100 years (Bradley 1997, Youngquist 1997, Cassedy 2000) Exist-ing drilling opportunities for geothermal resources are limited to a few sites in theUnited States and world (Youngquist 1997)

Potential environmental problems of geothermal energy include water shortages,air pollution, waste effluent disposal, subsidence, and noise The wastes produced

in the sludge include toxic metals such as arsenic, boron, lead, mercury, radon, andvanadium Water shortages are an important limitation in some regions Geothermalsystems produce hydrogen sulfide, a potential air pollutant; however, this could be

processed and removed for use in industry Overall, these environmental costs ofgeothermal energy appear to be minimal relative to those of fossil fuel systems.

1.8 Biogas

Wet biomass materials can be converted effectively into usable energy using obic microbes In the United States, livestock dung is normally gravity fed or in-termittently pumped through a plug-flow digester, which is a long, lined, insulatedpit in the earth Bacteria break down volatile solids in the manure and convert theminto methane gas (65%) and CO2(35%) (Pimentel 2001) A flexible liner stretchesover the pit and collects the biogas, inflating like a balloon The biogas may be used

anaer-to heat the digester, anaer-to heat farm buildings, or anaer-to produce electricity A large facilitycapable of processing the dung from 500 cows costs nearly $300,000 (EPA 2000).The Environmental Protection Agency (EPA 2000) estimates that more than 2000digesters could be economically installed in the United States

The amount of biogas produced is determined by the temperature of the tem, the microbes present, the volatile solids content of the feedstock, and theretention time A plug-flow digester with an average manure retention time ofabout 16 days under winter conditions (17.4◦C) produced 452,000 kcal/day and used262,000 kcal/day to heat the digester to 35◦C (Jewell et al 1980) Using the samedigester during summer conditions (25◦C) but reducing the retention time to 10.4days, the yield in biogas was 524,000 kcal/day, and it used 157,000 kcal/day forheating the digester (Jewell et al 1980) The energy input per output ratios for thesewinter and summer conditions for the digester were 1:1.7 and 1:3.3, respectively.The energy output of biogas digesters is similar today (Hartman et al 2000)

sys-In developing countries such as sys-India, biogas digesters typically treat the dungfrom 15 to 30 cattle from a single family or a small village The resulting energyproduced for cooking saves forests and preserves the nutrients in the dung Thecapital cost for an Indian biogas unit ranges from $500 to $900 (Kishore 1993) Theprice value of a kWh biogas in India is about $0.06 (Dutta et al 1997) The total cost

of producing about 10 million kcal of biogas is estimated to be $321, assuming thecost of labor to be $7/h; hence, the biogas has a value of $356 Manure processedfor biogas has fewer odors and retains its fertilizer value (Pimentel 2001)

1.9 Ethanol and Energy Inputs

The average costs in terms of energy and dollars for a large modern corn ethanolplant are listed in Table 1.4 In the fermentation/distillation process, the corn is finelyground and approximately 15 L of water are added per 2.69 kg of ground corn Afterfermentation, to obtain a liter of 95% pure ethanol from the 8% ethanol and 92%water mixture, the 1 L of ethanol must be extracted from the approximately 13 L

of the ethanol/water mixture To be mixed with gasoline, the 95% ethanol must be

Table 1.4 Inputs per 1,000 L of 99.5% ethanol produced from corna

communi-m 20 kg of BOD per 1,000 L of ethanol produced (Kuby et al 1984).

n 4 kWh of energy required to process 1 kg of BOD (Blais et al 1995).

o DOE (2002).

further processed and more water removed, requiring additional fossil energy inputs

to achieve 99.5% pure ethanol (Table 1.4) Thus, a total of about 12 L of wastewatermust be removed per liter of ethanol produced, and this relatively large amount ofsewage effluent has to be disposed of at an energy, economic, and environmentalcost

To produce a liter of 99.5% ethanol uses 43% more fossil energy than the energyproduced as ethanol and costs 44c/ per L ($1.66 per gallon or $2.76 per gallon in-cluding the subsidy) (Table 1.4) The corn feedstock requires more than 33% of thetotal energy input In this analysis the total cost, including the energy inputs for thefermentation/distillation process and the apportioned energy costs of the stainlesssteel tanks and other industrial materials, is $436.92 per 1,000 L of ethanol produced(Table 1.4)

The largest energy inputs in corn-ethanol production are for producing the cornfeedstock, plus the steam energy, and electricity used in the fermentation/distillationprocess The total energy input to produce a liter of ethanol is approximately7,570 kcal (Table 1.4) However, a liter of ethanol has an energy value of only5,130 kcal Based on a net energy loss of 2,440 kcal of ethanol produced, 43% morefossil energy is expended than is produced as ethanol

1.10 Grasslands and Celulosic Ethanol

Tilman’s research (Tillman et al 2006) has merit in the explanation of field iments with various combinations of species of natural vegetation, and the produc-tivity of diverse experimental systems The outstanding, 30-year effort by the LandInstitute in Kansas (Jackson 1980) to develop multi-species perennial ecosystems

exper-that deliver high productivity for long periods has been de facto endorsed by Tillman

et al., albeit without acknowledgement

However, there are concerns about two items First, the statement by Tillman

et al that crop residues, like corn stover, can be harvested and utilized as a fuelsource This would be a disaster for agricultural ecosystems Without the protec-tion of crop residues, soil loss may increase as much as 100-fold (Fryrear andBilbro 1994) Already the U.S crop system is losing soil 10 times faster than sus-tainability (NAS 2003) Soil formation rates are extremely slow or less than 1 t/ha/yr(NAS 2003, Troeh et al 2004) Increased erosion will facilitate soil-C oxidation andcontribute to the greenhouse problem (Lal 2003)

Tillman et al assume about 1,032 L of ethanol can be produced through the version of the 4 t/ha/yr of grasses harvested However, Pimentel and Patzek (2007)reported a negative 50% return in switchgrass conversion Based on the optimisticdata of Tillman et al., and converting all 235 million ha of U.S grassland intoethanol, only 12% of U.S petroleum would be provided (USDA 2004, USCB2004–2005)

con-In addition, to achieve the production of this much ethanol would mean ing about 100 million cattle, 7 million sheep, and 4 million horses now grazing

displac-on 324 millidisplac-on ha of U.S grassland and rangeland (USDA 2004, Mitchell 2000).Already overgrazing is a problem on U.S grasslands and a similar problem existsworldwide (Brown 2001) Thus, the assessment of the quantity of ethanol that can

be produced on U.S and world grasslands by Tillman et al appears to be undulyoptimistic

1.11 Methanol and Vegetable Oils

Methanol can be produced from a gasifier-pyrolysis reactor using biomass as afeedstock (Hos and Groenveld 1987, Jenkins 1999) The yield from 1 ton of drywood is about 370 L of methanol (Ellington et al 1993, Osburn and Osburn 2001).For a plant with economies of scale to operate efficiently, more than 1.5 million

ha of sustainable forest would be required to supply it (Pimentel 2001) Biomass isgenerally not available in such enormous quantities, even from extensive forests, atacceptable prices Most methanol today is produced from natural gas

Processed vegetable oils from soybean, sunflower, rapeseed, and other oil plantscan be used as fuel in diesel engines Unfortunately, producing vegetable oils foruse in diesel engines is costly in terms of economics and energy (Pimentel andPatzek 2005) A slight net return on energy from soybean oil is possible, if thesoybeans are grown without commercial nitrogen fertilizer The soybean under

favorable conditions will produce its own nitrogen Even assuming a slight net ergy return with soy, the total United States would have to be planted to soybeansjust to provide soy oil for U.S trucks!

en-1.12 Transition to Renewable Energy

Despite its environmental and economic benefits, the transition to large-scale use ofrenewable energy presents several difficulties Renewable energy technologies, all

of which require land for collection and production, will compete with agriculture,forestry, and urbanization for land in the United States and world The United States

is at maximum use of its prime cropland for food production per capita today, but theworld has less than half the cropland per capita that it needs for a diverse diet (0.5 ha)and adequate supply of essential nutrients (USDA 2004) In fact, more than 3.7billion people are already malnourished in the world (UN/SCN 2004, Bagla 2003).With the world and US populations expected to double in the next 58 and 70 years,respectively, all the available cropland and forestland will be required to providevital food and forest products (PRB 2006)

As the growing U.S and world populations demand increased electricity andliquid fuels, constraints like land availability and high investment costs will restrictthe potential development of renewable energy technologies Energy use based oncurrent growth is projected to increase from the current U.S consumption of 102quads to approximately 145 quads by 2050 Land availability is also a problem, withthe US population adding about 3.3 million people each year (USCB 2007) Eachperson added requires about 0.4 ha (1 acre) of land for urbanization and highwaysand about 0.5 ha of cropland (Vesterby and Krupa 2001)

Renewable energy systems require more labor than fossil energy systems Forexample, wood-fired steam plants require several times more workers than coal-firedplants (Giampietro et al 1998)

An additional complication in the transition to renewable energies is the tionship between the location of ideal production sites and large population cen-ters Ideal locations for renewable energy technologies are often remote, such asdeserts of the American Southwest or wind farms located kilometers offshore Al-though these sites provide the most efficient generation of energy, delivering thisenergy to consumers presents a logistical problem For instance, networks of dis-tribution cables must be installed, costing about $179,000 per km 115-kV lines(DOE/EIA 2002) A percentage of the power delivered is lost as a function ofelectrical resistance in the distribution cable There are complex alternating cur-rent electrical networks in North America, and 3 of these are tied together by DClines (Nordel 2001) Based on these networks, it is estimated that electricity can betransmitted up to 1500 km

rela-A sixfold increase in installed technologies would provide the United States withapproximately 46 quads (thermal) of energy, less than half of current US consump-tion (Table 1.1) This level of energy production would require about 159 million ha

of land (17% of US land area) This percentage is an estimate, and could increase

or decrease depending on how the technologies evolve and energy conservation isencouraged

Worldwide, approximately 473 quads of all types of energy are used by thepopulation of more than 6.5 billion people (Table 1.1) Using available renewableenergy technologies, an estimated 200 quads of renewable energy could be pro-duced worldwide on about 20% of the world land area A self-sustaining renewableenergy system producing 200 quads of energy per year for about 2 billion people(Ferguson 2001) would provide each person with about 5,000 L of oil equivalentsper year, approximately half of America’s current consumption per year, but anincrease for most people of the world (Pimentel et al 1999)

The first priority of the US energy program should be for individuals, ties, and industries to conserve fossil fuel resources and reduce consumption Otherdeveloped countries have proved that high productivity and a high standard of livingcan be achieved with the use of half the energy expenditure of the United States(Pimentel et al 1999) In the United States, fossil energy subsidies of approximately

communi-$40 billion per year should be withdrawn and the savings invested in renewableenergy research and education to encourage the development and implementation

of renewable technologies If the United States became a leader in the development

of renewable energy technologies, then it would likely capture the world market forthis industry (Shute 2001)

The current subsidies for ethanol production total $6 billion per year (Koplow2006) This means that the subsidies per gallon of ethanol are 60 times greater thanthe subsidies per gallon of gasoline!

1.13 Conclusion

This assessment of renewable energy technologies confirms that these techniqueshave the potential to provide the nation with alternatives to meet nearly half offuture U.S energy needs To develop this potential, the United States would have tocommit to the development and implementation of non-fossil fuel technologies andenergy conservation People in the U.S would have to reduce their current energyconsumption by more than 50% and this is entirely possible Eventually we will

be forced to reduce energy consumption The implementation of renewable energytechnologies now would reduce many of the current environmental problems asso-ciated with fossil fuel production and use

The United States’ immediate priority should be to speed the transition from thereliance on nonrenewable fossil energy resources to reliance on renewable energytechnologies Various combinations of renewable technologies should be developedconsistent with the characteristics of the different geographic regions in the UnitedStates A combination of the renewable technologies listed in Table 1.3 should pro-vide the United States with an estimated 46 quads of renewable energy by 2050

These technologies should be able to provide this much energy without interferingwith required food and forest production.

If the United States does not commit itself to the transition from fossil to newable energy during the next decade or two, the economy and national securitywill suffer It is of critical importance that U.S residents work together to conserveenergy, land, water, and biological resources To ensure a reasonable standard ofliving in the future, there must be a fair balance between human population densityand use of energy, land, water, and biological resources

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Can the Earth Deliver the Biomass-for-Fuel

we Demand?

Tad W Patzek

Abstract In this work I outline the rational, science-based arguments that question

current wisdom of replacing fossil plant fuels (coal, oil and natural gas) with fresh plant agrofuels This 1:1 replacement is absolutely impossible for more than a few

years, because of the ways the planet Earth works and maintains life After these fewyears, the denuded Earth will be a different planet, hostile to human life I argue that

with the current set of objective constraints a continuous stable solution to human life cannot exist in the near-future, unless we all rapidly implement much more

limited ways of using the Earth’s resources, while reducing the global populations

of cars, trucks, livestock and, eventually, also humans

Keywords Agriculture · agrofuel · biomass · biorefinery · boundary · crop ·

ecology · energy · ethanol · fuel production · model · mass balance · net energy

value· plantation · population · sustainability · thermodynamics · tropics · yield

2.1 Introduction

The purpose of this work is to:

1 Show that the current and proposed “cellulosic” ethanol (a “second generation”agrofuel) refineries are inefficient, low energy-density concentrators of solarlight

2 Prove that even if these refineries were marvels of efficiency, they still would

be able to make but a dent in our runaway consumption of transportation fuels,because the Earth simply has little or no biomass to spare in the long run.The fundamental energy unit I use in this work is

1 exajoule (EJ) or 1018joules

A little over four joules heats one teaspoon of water by 1 degree Celsius Onestatistical American develops average continuous power of almost exactly 100 W(Patzek, 2007) One exajoule in the digested food feeds amply 300 million people1

for one year The actual food available for consumption in the US is ca 2 EJ yr−1,and the entire food system uses∼ 20 EJ yr−1(Patzek, 2007) Currently, Americans

are using about 105 EJ yr−1 (340 GJ (yr-person)−1), or 105 times more primaryenergy than needed as food The EU countries use 80 EJ yr−1of primary energy or55% less energy per capita than US

Current consumption of all transportation fuels in the US is about 33 EJ yr−1, seeFig 2.1 A barely visible fraction of this energy comes from corn ethanol According

to current government plans, the amount of ethanol produced in the US will reach

35 billion gallons in 2017, see Fig 2.2, but it is difficult to imagine that a 30 billiongallon per year increase will come from corn ethanol

Before peaking2in 2006, the world production of conventional petroleum grewexponentially at 6.6% per year between 1880 and 1970, see Fig 2.3 The Hubbert

Fig 2.1 Currently, the US consumes about 33 times more energy in transportation fuels than is

necessary to feed its population This amount of energy is equivalent to 381 billion gallons of ethanol per year The amount of energy in corn-ethanol is barely visible and it shall always remain

so unless we drastically (by a factor of two for starters) lower liquid fuel consumption Current consumption of ethanol is about 1.2% of the total fuel consumption (without considering energy inputs to the production system)

Source: DOE EIA

1 The US population in 2006.

2 The short-lived rate peak around 1978 was caused by OPEC limiting its oil production.

19800 1985 1990 1995 2000 2005 2010 2015 2020 5

2017 − Bush’s Goal

Fig 2.2 By an exponential extrapolation of ethanol production during the last 7 years at 18.5%

per year, one may arrive at 35 billion gallons per year in 2017 The less optimistic logistic fit of the data plateaus at 14 billion gallons per year Where will the remaining 21 billion gallons of ethanol come from each year?

Sources: DOE EIA, Renewable Fuels Association (RFA)

Fig 2.3 Exponential growth of world crude oil production between 1880 and 1970 proceeded at

6.6% per year

Sources: lib.stat.cmu.edu/DASL/Datafiles/Oilproduction.html, US EIA

20000 2020 2040 2060 2080 2100 2120 2140 2160 2180 2200 20

270 billion gallons of ethanol per year

World Oil Production

US Oil Consumption

Fig 2.4 The estimated decline of conventional petroleum production in the world is the red curve.

If nothing changes, the current petroleum consumption of petroleum in the US will grow with its estimated population and intercept the global production about 35 years from today

Sources: US EIA, US Census Bureau, (Patzek, 2007)

curves are symmetrical (Patzek, 2007) and predict world production of conventionalpetroleum to decline exponentially at a similar rate within a decade from now, or so.This decline can be arrested for a while by heroic measures (infill drilling, horizontalwells, enhanced oil recovery methods, etc.), but the longer it is arrested the moreprecipitous it will become

If the current per capita use of petroleum in the US is escalated with the expected

growth of US population, the US will have to intercept the entire estimated

produc-tion of convenproduc-tional petroleum3in the world by 2042, see Fig 2.4 In this scenario,

the projected increment of US petroleum consumption between today and 2042 is

equivalent to 270 billion gallons of ethanol per year

2.2 Background

Humans are an integral part of a single system made of all life and all parts of the

Earth’s near-surface shown in Fig 2.5 Thus, as President Vaclav Havel said on July

4, 1994: “Our destiny is not dependent merely on what we do to ourselves but also

3I stress again that I am referring to conventional, readily-available petroleum There will be an offsetting production from unconventional sources: tar sands, ultra-heavy oil, and natural gas liq-

uefaction, all at very high energy and environmental costs.