When will the oil run out? Various estimates put this anywhere from 20 years from now to more than a century in the future. The shortfall in energy might eventually be made up by developments in nuclear fusion, fuel cells, and solar technologies, but what can substitute for gasoline and diesel in all the internal combustion engine — powered vehicles that will continue to be built worldwide until then? And what will stand in for petrochemicals as sources of building blocks for the extensive range of “synthetics” that became indispensable during the twentieth century?

Cellulose — in particular, cellulose in “lignocellulosic biomass” — embodies a great dream of the bioorganic chemist, that of harnessing the enormous power of nature as the renewable source for all the chemicals needed in a modern, bioscience — based economy.1 From that perspective, the future is not one of petroleum crackers and industrial landscapes filled with the hardware of synthetic organic chemistry, but a more ecofriendly one of microbes and plant and animal cells purpose-dedicated to the large-scale production of antibiotics and blockbuster drugs, of monomers for new biodegradable plastics, for aromas, fragrances, and taste stimulators, and of some (if not all) of the novel compounds required for the arrival of nanotechnologies based on biological systems. Glucose is the key starting point that, once liberated from cellulosic and related plant polymers, can — with the multiplicity of known and hypothesized biochemical pathways in easily cultivatable organisms — yield a far greater multiplicity of both simple and complex chiral and macromolecular chemical entities than can feasibly be manufactured in the traditional test tube or reactor vessel.

A particular subset of the microbes used for fermentations and biotransforma­tions is those capable of producing ethyl alcohol — ethanol, “alcohol,” the alcohol whose use has both aided and devastated human social and economic life at various times in the past nine millennia. Any major brewer with an international “footprint” and each microbrewery set up to diversify beer or wine production in contention with those far-reaching corporations use biotechnologies derived from ancient times, but that expertise is also implicit in the use of ethanol as a serious competitor to gasoline in automobile engines. Hence, the second vision of bioorganic chemists has begun to crystallize; unlocking the vast chemical larder and workshop of natu­ral microbes and plants has required the contributions of microbiologists, microbial physiologists, biochemists, molecular biologists, and chemical, biochemical, and metabolic engineers to invent the technologies required for industrial-scale produc­tion of “bioethanol.”

The first modern social and economic “experiment” with biofuels — that in Brazil — used the glucose present (as sucrose) in cane sugar to provide a readily available and renewable source of readily fermentable material. The dramatic rise in oil prices in 1973 prompted the Brazilian government to offer tax advantages to those who would power their cars with ethanol as a fuel component; by 1988, 90% of the cars on Brazilian roads could use (to varying extents) ethanol, but the collapse

in oil prices then posed serious problems for the use of sugar-derived ethanol. Since then, cars have evolved to incorporate “dual-fuel” engines that can react to fluctua­tions in the market price of oil, Brazilian ethanol production has risen to more than 16 million liters/year, and by 2006, filling up with ethanol fuel mixes in Brazil cost up to 40% less than gasoline.

Sugarcane thrives in the equatorial climate of Brazil. Further north, in the mid­western United States, corn (maize, Zea mays) is a major monoculture crop; corn accumulates starch that can, after hydrolysis to glucose, serve as the substrate for eth­anol fermentation. Unlike Brazil, where environmentalists now question the destruc­tion of the Amazonian rain forest to make way for large plantations of sugarcane and soya beans, the Midwest is a mature and established ecosystem with high yields of corn. Cornstarch is a more expensive carbon substrate for bioethanol production, but with tax incentives and oil prices rising dramatically again, the production of ethanol for fuel has become a significant industry. Individual corn-based ethanol production plants have been constructed in North America to produce up to 1 million liters/day, and in China 120,000 liters/day, whereas sugarcane molasses-based facilities have been sited in Africa and elsewhere.2

In July 2006, the authoritative journal Nature Biotechnology published a cluster of commentaries and articles, as well as a two-page editorial that, perhaps uniquely, directed its scientific readership to consult a highly relevant article (“Ethanol Frenzy”) in Bloomberg Markets. Much of the discussion centered on the economic viability of fuel ethanol production in the face of fluctuating oil prices, which have inhibited the development of biofuels more than once in the last half century.3 But does bioethanol production consume more energy than it yields?4 This argument has raged for years; the contributors to Nature Biotechnology were evidently aware of the controversy but drew no firm conclusions. Earlier in 2006, a detailed model-based survey of the economics of corn-derived ethanol production processes concluded that they were viable but that the large-scale use of cellulosic inputs would better meet both energy and environmental goals.5 Letters to the journal that appeared later in the year reiter­ated claims that the energy returns on corn ethanol production were so low that its production could only survive if heavily subsidized and, in that scenario, ecological devastation would be inevitable.6

Some energy must be expended to produce bioethanol from any source — in much the same way that the pumping of oil from the ground, its shipping around the world, and its refining to produce gasoline involves a relentless chain of energy expenditure. Nevertheless, critics still seek to be persuaded of the overall benefits of fuel ethanol (preferring wind, wave, and hydroelectric sources, as well as hydrogen fuel cells). Meanwhile its advocates cite reduced pollution of the atmosphere, greater use of renewable resources, and erosion of national dependence on oil imports as key factors in the complex overall cost-benefit equation.

To return to the “dream” of cellulose-based chemistry, there is insufficient arable land to sustain crop-based bioethanol production to more than fuel-additive levels worldwide, but cellulosic biomass grows on a massive scale — more than 7 x 1010 tons/year — and much of this is available as agricultural waste (“stalks and stems”), forestry by-products, wastes from the paper industry, and as municipal waste (card­board, newspapers, etc.).7 Like starch, cellulose is a polymeric form of glucose; unlike starch, cellulose cannot easily be prepared in a highly purified form from many plant sources. In addition, being a major structural component of plants, cellulose is com­bined with other polymers of quite different sugar composition (hemicelluloses) and, more importantly, with the more chemically refractive lignin. Sources of lignocel — lulosic biomass may only contain 55% by weight as fermentable sugars and usually require extensive pretreatment to render them suitable as substrates for any microbial fermentation, but that same mixture of sugars is eminently suitable for the produc­tion of structures as complex as aromatic intermediates for the chemical industry.8

How practical, therefore, is sourcing lignocellulose for bioethanol production and has biotechnology delivered feasible production platforms, or are major develop­ments still awaited? How competitive is bioethanol without the “special pleading” of tax incentives, state legislation, and (multi)national directives? Ultimately, because the editor of Nature Biotechnology noted that, for a few months in 2006, a collection of “A-list” entrepreneurs, venture capitalists, and investment bankers had promised $700 million to ethanol-producing projects, the results of these developments in the real economy may soon refute or confirm the predictions from mathematical mod — els.9 Fiscal returns, balance sheets, and eco audits will all help to settle the major issues, thus providing an answer to a point made by one of the contributors to the flurry of interest in bioethanol in mid-2006: “biofuels boosters must pursue and pro­mote this conversion to biofuels on its own merits rather than by overhyping the rela­tive political, economic and environmental advantages of biofuels over oil.”10

Although the production of bioethanol has proved capable of extensive scale up, it may be only the first — and, by no means, the best — of the options offered by the biological sciences. Microbes and plants have far more ingenuity than that deduced from the study of ethanol fermentations. Linking bioethanol production to the syn­thesis of the bioorganic chemist’s palette of chemical feedstocks in “biorefineries” that cascade different types of fermentations, possibly recycling unused inputs and further biotransforming fermentation outputs, may address both financial and envi­ronmental problems. Biodiesel (simple alkyl esters of long-chain fatty acids in veg­etable oils) is already being perceived as a major fuel source, but further down the technological line, production of hydrogen (“biohydrogen”) by light-driven or dark fermentations with a variety of microbes would, as an industrial strategy, be akin to another industrial revolution.11

A radically new mind-set and a heightened sense of urgency were introduced in September 2006 when the state of California moved to sue automobile manufactur­ers over tailpipe emissions adding to atmospheric pollution and global warming. Of the four major arguments adduced in favor of biofuels — long-term availability when fossil fuels become depleted, reduced dependence on oil imports, develop­ment of sustainable economies for fuel and transportation needs, and the reduction in greenhouse gas emissions — it is the last of these that has occupied most media attention in the last three years.12 In October 2006, the first quantitative model of the economic costs of not preventing continued increases in atmospheric CO2 pro­duced the stark prediction that the costs of simply adapting to the problems posed by global warming (5-20% of annual global GDP by 2050) were markedly higher than those (1% of annual global GDP) required to stabilize atmospheric CO2.13 Although developing nations will be particularly hard hit by climate changes, industrialized

nations will also suffer economically as, for example, rising sea levels require vastly increased flood defense costs and agricultural systems (in Australia and elsewhere) become marginally productive or collapse entirely.

On a more positive note, the potential market offered to technologies capable of reducing carbon emissions could be worth $500 billion/year by 2050. In other words, while unrestrained increase in greenhouse gas emissions will have severe consequences and risk global economic recession, developing the means to enable a more sustainable global ecosystem would accelerate technological progress and establish major new industrial sectors.

In late 2007, biofueled cars along with electric and hybrid electric-gasoline and (in South America and India) compressed natural gas vehicles represented the only immediately available alternatives to the traditional gasoline/internal combustion engine paradigm. Eventually, electric cars may evolve from a niche market if renew­able energy sources expand greatly and, in the longer term, hydrogen fuel cells and solar power (via photovoltaic cells) offer “green” vehicles presently only known as test or concept vehicles. The International Energy Agency estimates that increasing energy demand will require more than $20 trillion of investment before 2030; of that sum, $200 billion will be required for biofuel development and manufacture even if (in the IEA’s assessments) the biofuels industry remains a minor contributor to trans­portation fuels globally.14 Over the years, the IEA has slowly and grudgingly paid more attention to biofuels, but other international bodies view biofuels (especially the second-generation biofuels derived from biomass sources) as part of the growing family of technically feasible renewable energy sources: together with higher-effi­ciency aircraft and advanced electric and hybrid vehicles, biomass-derived biofuels are seen as key technologies and practices projected to be in widespread use by 2030 as part of the global effort to mitigate CO2-associated climate change.15

In this highly mobile historical and technological framework, this book aims to analyze in detail the present status and future prospects for biofuels, from ethanol and biodiesel to biotechnological routes to hydrogen (“biohydrogen”). It emphasizes ways biotechnology can improve process economics as well as facilitate sustainable agroindustries and crucial elements of the future bio-based economy, with further innovations required in microbial and plant biotechnology, metabolic engineering, bioreactor design, and the genetic manipulation of new “biomass” species of plants (from softwoods to algae) that may rapidly move up the priority lists of funded research and of white (industrial biotech), blue (marine biotech), and green (environ­mental biotech) companies.

A landmark publication for alternative fuels was the 1996 publication Hand­book on Bioethanol: Production and Utilization, edited by Charles E. Wyman of the National Renewable Energy Laboratory (Golden, Colorado). That single-volume, encyclopedic compilation summarized scientific, technological, and economic data and information on biomass-derived ethanol (“bioethanol”). While highlighting both the challenges and opportunities for such a potentially massive production base, the restricted use of the “bio” epithet was unnecessary and one that is now (10 years later) not widely followed.16 Rather, all biological production routes for ethanol — whether from sugarcane, cornstarch, cellulose (“recycled” materials), lignocellulose (“biomass”), or any other nationally or internationally available plant

source — share important features and are converging as individual producers look toward a more efficient utilization of feedstocks; if, for example, sugarcane-derived ethanol facilities begin to exploit the “other” sugars (including lignocellulosic com­ponents) present in cane sugar waste for ethanol production rather than only sucrose, does that render the product more “bio” or fully “bioethanol”?

As the first biofuel to emerge into mass production, (bio)ethanol is discussed in chapter 1, the historical sequence being traced briefly from prehistory to the late nineteenth century, the emergence of the petroleum-based automobile industry in the early twentieth century, the intermittent interest since 1900 in ethanol as a fuel, leading to the determined attempts to commercialize ethanol-gasoline blends in Brazil and in the United States after 1973. The narrative then dovetails with that in Handbook on Bioethanol: Production and Utilization, when cellulosic and lig- nocellulosic substrates are considered and when the controversy over calculated energy balances in the production processes for bioethanol, one that continued at least until 2006, is analyzed. Chapters 2, 3, and 4 then cover the biotechnol­ogy of ethanol before the economics of bioethanol production are discussed in detail in chapter 5, which considers the questions of minimizing the social and environmental damage that could result from devoting large areas of cultivatable land to producing feedstocks for future biofuels and the sustainability of such new agroindustries.

But are bioethanol and biodiesel (chapter 6) merely transient stopgaps as trans­portation fuels before more revolutionary developments in fuel cells usher in biohy­drogen? Both products now have potential rivals (also discussed in chapter 6). The hydrogen economy is widely seen as providing the only workable solution to meet­ing global energy supplies and mitigating CO2 accumulation, and the microbiology of “light” and “dark” biohydrogen processes are covered (along with other equally radical areas of biofuels science) in chapter 7. Finally, in chapter 8, rather than being considered as isolated sources of transportation fuels, the combined production of biofuels and industrial feedstocks to replace eventually dwindling petrochemicals — in “biorefineries” capable of ultimately deriving most, if not all, humanly useful chemicals from photosynthesis and metabolically engineered microbes — rounds the discussion while looking toward attainable future goals for the biotechnologists of energy production in the twenty-first century, who very possibly may be presented with an absolute deadline for success.

For to anticipate the answer to the question that began this preface, there may only be four decades of oil left in the ground. The numerical answer computed for this shorter-term option is approximately 42 years from the present (see Figure 5.13 in chapter 5) — exactly the same as the answer to the ultimate question of the uni­verse (and everything else) presented in the late 1970s by the science fiction writer Douglas Adams (The Hitchhiker’s Guide to the Galaxy, Pan Books, London). The number is doubly unfortunate: for the world’s senior policy makers today, agreement (however timely or belated) on the downward slope of world oil is most likely to occur well after their demise, whereas for the younger members of the global popu­lation who might have to face the consequences of inappropriate actions, misguided actions, or inaction, that length of time is unimaginably distant in their own human life cycles.

Four decades is a sufficiently long passage of time for much premier quality sci­entific research, funding of major programs, and investment of massive amounts of capital in new ventures: the modern biopharmaceutical industry began in the early 1980s from a scattering of research papers and innovation; two decades later, biotech companies like Amgen were dwarfing long-established pharmaceutical multination­als in terms of income stream and intellectual property.

But why (in 2008) write a book? When Jean Ziegler, the United Nations’ “inde­pendent spokesman on the right to food,” described the production of biofuels as a “crime against humanity” and demanded a five-year moratorium on biofuels pro­duction so that scientific research could catch up and establish fully the methods for utilizing nonfood crops, he was voicing sentiments that have been gathering like a slowly rising tide for several years.17 Precisely because the whole topic of biofu­els — and especially the diversion of agricultural resources to produce transporta­tion fuels, certainly for industry, but also for private motorists driving vehicles with excellent advertising and finance packages but woefully low energy efficiencies — is so important, social issues inevitably color the science and the application of the derived technology. Since the millennium, and even with rocketing oil prices, media coverage of biofuels has become increasingly negative. Consider the following selection of headlines taken from major media sources with claims to international readerships:

Biofuel: Green Savior or Red Herring? (CNN. com, posted April 2, 2007) Biofuels: Green Energy or Grim Reaper? (BBC News, London, September 22, 2006)

Scientists Are Taking 2nd Look at Biofuels (International Herald Tribune, January 31, 2007)

Green Fuel Threatens a ‘Biodiversity Heaven’ (The Times, London, July 9, 2007) Biofuel Demand to Push Up Food Prices (The Guardian, London, July 5, 2007) Plantation Ethanol ‘Slaves’ Freed (The Independent, London, July 5, 2007)

The Biofuel Myths (International Herald Tribune, July 10, 2007)

Biofuel Gangs Kill for Green Profits (The Times, London, June 3, 2007)

Dash for Green Fuel Pushes Up Price of Meat in US (The Times, London, April 12, 2007)

The Big Green Fuel Lie (The Independent, London, March 5, 2007)

How Biofuels Could Starve the Poor (Foreign Affairs, May/June 2007)

Biofuel Plant ‘Could Be Anti-Green’ (The Scotsman, Edinburgh, July 5, 2007)

To Eat… or to Drive? (The Times, London, August 25, 2007)

These organizations also carry (or have carried) positive stories about biofuels (“The New Gold Rush: How Farmers Are Set to Fuel America’s Future” or “Poison Plant Could Help to Cure the Planet,”18) but a more skeptical trend emerged and hardened during 2006 and 2007 as fears of price inflation for staple food crops and other concerns began to crystallize. In the same week in August 2007, New Zealand began its first commercial use of automobile bioethanol, whereas in England, the major long­distance bus operator abandoned its trials of biodiesel, citing environmental damage and unacceptable diversion of food crops as the reasons. On a global ecological basis, plantations for biofuels in tropical regions have begun to be seriously ques­tioned as driving already endangered wildlife species to the edge of oblivion.

Perhaps most damning of all, the “green” credentials of biofuels now face an increasing chorus of disbelief as mathematical modeling erodes the magnitudes of possible benefits of biofuels as factors in attempts to mitigate or even reverse greenhouse gas emissions — at its most dramatic, no biofuel production process may be able to rival the CO2-absorbing powers of reforestation, returning unneeded croplands to savannah and grasslands.19 The costs of biofuels escalate, whereas the calculated benefits in reducing greenhouse gas emissions fall.20 The likely impact of a burgeoning world trade in biofuels — and the subject already of highly vocal complaints about unfair trade practices — on the attainment of environmental goals in the face of economic priorities21 is beginning to cause political concern, especially in Europe.22

But why write a book? The Internet age has multiple sources of timely information (including all the above-quoted media stories), regularly updated, and available 24/7. The thousands of available sites offer, however, only fragmentary truths: most are campaigning, selective in the information they offer, focused, funded, targeting, and seeking to persuade audiences or are outlets for the expression of the views and visions of organizations (“interested parties”). Most academic research groups active in bio­fuels also have agendas: they have intellectual property to sell or license, genetically engineered microbial strains to promote, and results and conclusions to highlight in reviews. This book is an attempt to broaden the discussion, certainly beyond bioetha­nol and biodiesel, placing biofuels in historical contexts, and expanding the survey to include data, ideas, and bioproducts that have been visited at various times over the last 50 years, a time during which widely volatile oil prices have alternately stimu­lated and wrecked many programs and initiatives. That half century resulted in a vast library of experience, little of it truly collective (new work always tends to supplant in the biotech mind-set much of what is already in the scientific literature), many claims now irrelevant, but as a body of knowledge, containing valuable concepts sometimes waiting to be rediscovered in times more favorable to bioenergy.

Each chapter contains many references to published articles (both print and electronic); these might best be viewed as akin to Web site links — each offers a potentially large amount of primary information and further links to a nexus of data and ideas. Most of the references cited were peer-reviewed, the remainder edited or with multiple authorships. No source used as a reference requires a personal subscription or purchase — Internet searches reveal many thousands more articles in trade journals and reports downloadable for a credit card payment; rather, the sources itemized can either be found in public, university, or national libraries or are available to download freely. Because the total amount of relevant informa­tion is very large, the widest possible quotation basis is required, but (as always with controversial matters) all data and information are subject to widely differing assessments and analyses.

Meanwhile, time passes, and in late 2007, oil prices approached $100/barrel, and the immediate economic momentum for biofuels shows no signs of slackening. Hard choices remain, however, in the next two decades or, with more optimistic estimates of fossil fuel longevity, sometime before the end of the twenty-first century. Perhaps, the late Douglas Adams had been more of a visionary than anyone fully appreciated when he first dreamed of interstellar transportation systems powered by equal measures of chance and improbability and of an unremarkable, nonprime, two-digit number.