The Virgin Atlantic test flight was powered in part by coconut oil. But one critic (Jeff Gazzard of the Aviation Environment Federation, based in the UK) quoted an estimate published in Petroleum Week that if the flight had been made entirely on coconut oil, it would have consumed 3 million coconuts. By any standard, that’s a lot of coconuts.
Apparently, though, Petroleum Week made a slight miscalculation. According to Wikipedia, a thousand mature coconuts yield approximately 70 liters of coconut oil, which is to say that fourteen coconuts make one liter of the stuff. And according to the Boeing.com website, the 747 family of aircraft has an average fuel mileage consumption rate of nineteen liters per mile. So a flight of 221 miles would require 221 x 19 = 4,199 liters of coconut oil. And at the rate of fourteen coconuts per liter, the flight would require only 4,199 x 14 = 59,985 coconuts.
But that’s still a lot of coconuts. And people eat coconuts.
By contrast, both the Air New Zealand and Continental Airlines demonstration flights were powered in part by jatropha oil, which, because it’s made from a nonfood crop, at least had the advantage of avoiding the food-for-fuel problem (unless land normally used for food is displaced to grow the jatropha plants). Nevertheless, the global aviation industry currently burns through about 240 million tons of jet fuel per year, and one industry journal calculated that producing that amount of fuel from jatropha alone would require planting a land area that was twice the size of France.
So maybe biofuels really are the fuel of the future—and always will be.
If time travel ever becomes possible, the Carboniferous period, which lasted for some 74 million years, from about 360 million to 286 million years ago, would be a good era to avoid. Huge insects crawled, crept, and flitted across the earth. Two of them were the largest known insects of all time, the centipede Arthropleura, which grew to a length of more than eight feet, and the giant dragonfly Meganeura, which had a wingspan of some two and a half feet. These enormous dimensions were possible because at that time oxygen made up 35 percent of total air volume (rather than our current wimpy 21 percent).
Other flora and fauna of the period included several tree species, seed-bearing plants, mosses, and fungi; sponges, corals, sharks, and other fish in the oceans and lakes; and on land, numerous varieties of four-footed animals including lizards and reptiles. The emergence of reptiles was a product of a major evolutionary innovation that took place during the Carboniferous, the development of the amniote egg, whose outer shell and inner membrane protected the embryo inside it from drying up.
It was also in the Carboniferous when the source of the planet’s current greatest scourge and atmospheric nightmare originated, fossil fuels. Fields of coal, petroleum, and natural gas are thought to have been laid down during this time. The term “Carboniferous” means carbon-bearing, “carbon” being the Latin word for coal. The earth’s coal beds were the product of the vast swamps and forests that covered most land masses. The dead plants washed into the sea and sank into the mud, where tectonic forces subjected them to great pressure and heating that, across millions of years, converted them into coal.
Petroleum is thought to have originated in a similar manner, but not from the bodies of dead dinosaurs, as many have imagined. That idea is arguably a relic of the Sinclair Oil Company’s decades of advertising using the image of “Dino,” its trademark green Brontosaurus, which was an instantly recognizable corporate symbol. Unfortunately for Sinclair, the dinosaurs were creatures of the Mesozoic, which followed the end of the Carboniferous period by some 35 million years. Which means that the oil was already in the ground and mellowing long before dinosaurs even existed.
But if the dinosaurs didn’t give us petroleum, then what did? For a long time the answer to this was controversial, and in his 1979 book Energy from Heaven and Earth, the physicist Edward Teller (the so-called father of the H-bomb) studied the question and reported, “I have gone to the best geologists and the best petroleum researchers, and I can give you the authoritative answer: no one knows.” Indeed, when he wrote those words, matters were not so clear as they have subsequently become. Even today, however, there is a generally accepted “official” theory of petroleum’s origin, as well as a competing alternative theory.
According to the orthodox view, petroleum was formed from the decomposition of organisms that settled to the sea bottom. These organisms may have been phytoplankton (microscopic plants floating in water), zoo-plankton (small animals), or both. Petroleum supposedly arose from them in the way that decaying plants gave rise to coal. Over the eons, the zoo-plankton and/or the phytoplankton became buried under increasing amounts of rock. This rock buildup created pressures that were great enough, as well as temperatures that were high enough, to cause the organic material remains to go through a series of chemical reactions that transformed them into the hydrocarbons of crude oil.
This is the so-called biogenic theory of petroleum’s origin. Supporting it is the fact that many oil reserves are found underwater, which explains the widespread practice of offshore drilling. In addition, oil contains bio-markers, molecular structures associated with biological and plant organisms. If oil didn’t arise from these organisms, the argument goes, then how did the biomarkers get there? While these points would seem to settle the issue, the alternative theory of the origin of petroleum, the abiogenic theory, offers a different explanation of both the biomarkers and the underwater location of oil reserves.
The abiogenic theory holds that the ingredients that make up petroleum were brought here at the very beginning, as part of the earth’s formation. They came with the planet, as it were, and were here all the time, hidden beneath the earth’s crust. If the abiogenic theory is correct, then petroleum and natural gas are not fossil fuels at all because they did not arise from fossils. As an account of petroleum’s origin, the abiogenic theory at least has the virtue of simplicity.
Also in favor of the abiogenic view, whose most vocal proponent in the United States was the Cornell astrophysicist Thomas Gold, are the facts that carbon is the fourth most abundant element in the universe, and that it exists predominantly in the form of hydrocarbons. In our own solar system, furthermore, huge amounts of methane (a hydrocarbon) are found in the atmospheres of Jupiter, Saturn, Uranus, and Neptune. But if the universe in general, and the solar system in particular, is teeming with hydrocarbons, then why do we need any special act of creation of petroleum based on the decomposition of organisms?
The abiotic theory claims that petroleum’s biomarkers got there as a result of contamination. A distinct class of organisms, the so-called ex-tremophiles, exist at depths where petroleum drilling takes place, and the oil becomes commingled with biological materials (i.e., the biomarkers) during the drilling process. (The underwater location of oil reserves is explained by the fact that about 70 percent the earth’s surface is water.)
The simplicity of the abiogenic theory makes it intuitively plausible, but that apparent straightforwardness masks several deeper layers of complexity. (There is even a duplex theory, propounded by the British synthetic organic chemist Sir Robert Robinson, that holds that young, or juvenile, oils arose biogenetically whereas older, ancient oils did so abiogenically.)
The dominant theory today, however, and the one held by most geologists, is that oil arose from microorganisms. In 2006 the British chemist Geoffrey Glasby published an exhaustively researched study of the abiogenic theory and concluded on the basis of several technical factors that the theory doesn’t work. Even he, however, conceded that “the relative roles of bacteria in the formation of petroleum, in degrading the initially formed petroleum to heavy oil and in supplying biomarkers to hydrocarbon deposits are still not fully understood.”
Whether or not petroleum came from microorganisms or was here from the very beginning, there are more sources of diesel oil, gasoline, and jet fuel than the crude oil pumped from the ground. Living organisms can be coaxed to create more of any desired “fossil fuel.” The question is whether
they can do so at a competitive cost.
Biofuels are nothing new. Wood was the first biofuel, used for heating and cooking. During the nineteenth century, whale oil was used for lighting (as well as for soap making). At the 1900 World’s Fair (Exposition Universalle) in Paris, Rudolf Diesel ran his eponymous engine on peanut oil. He was an early advocate of biofuels, saying at one point that oils derived from vegetables and other plants “make it certain that motor power can still be produced from the heat of the sun, which is always available for agricultural purposes, even when all our natural stores of solid and liquid fuels are exhausted.” An optimist. Henry Ford built cars that ran on ethanol, babassu nut oil, and soybean oil.
Those same oils, plus many others, have been proposed by biofuel proponents as substitutes for petrochemicals or as feedstocks from which biofuels can be made. The list of potential biofuel sources is rather grand, and includes corn, peanuts, coconuts, babassu nuts, wheat, sugar cane, sugar beets, molasses, cassava chips, canola oil, castor oil, cottonseed oil, pumpkin seed, beechnut, chestnut, lupine seed, poppy seed, rapeseed, linseed, peas, olives, sunflowers, palm, fish, animal fat, soybeans, jatropha, mahua, mustard, sweet sorghum, camelina, switch grass, Miscanthus grass, straw, seaweed, pine chips, plus miscellaneous organic waste, hemp, and shea butter, among other things.
However, there are good and sufficient reasons why, even in an age in which biofuels already enjoy a cachet, conventional oil continues to win by a landslide in the marketplace. Consider it against ethanol, for example, which is a widely used biofuel. In favor of ethanol are two main facts: one, the corn from which it is made is a fast-growing, cheap crop that is planted and harvested all over the globe, making it a renewable resource par excellence. Second, ethanol is a net zero emissions fuel because the CO2 produced when a car burns it is offset by the CO2 sequestered by the corn’s growth process.
Nevertheless, corn-based ethanol is hardly the ideal fossil fuel replacement. For one thing, it has a lower energy density than gasoline, which means that a gallon of ethanol produces less energy than a gallon of gasoline—some 35 percent less, which means that you have to burn more of it to get the same amount of energy out of it. This explains why a biofuels company that I co-founded, LS9, which produces renewable petroleum by means of designer microbes, takes as its corporate slogan, “The best replacement for petroleum is petroleum.”
Second, making ethanol from corn removes corn from the global food market, and also from people’s mouths. In fact, the process of ethanol production gives rise to a whole train of unintended consequences and ripple effects, effects that bring to mind the parable by Frédéric Bastiat, the French economist who in 1850 wrote Ce qu’on voit et ce qu’on ne voit pas (“that which is seen and that which is unseen”). In the parable, a shopkeeper’s son accidentally breaks the store’s large window, an act that is universally seen as a boon to the glazier who replaces it for six francs. (And window breakage more generally is popularly regarded as a windfall to glaziers.)
But that is only what is seen, says Bastiat. “It is not seen that as our shopkeeper has spent his six francs upon one thing, he cannot spend them upon another. It is not seen that if he had not had a window to replace, he would, perhaps, have replaced his old shoes, or added another book to his library. In short, he would have employed his six francs in some way, which this accident has prevented.”
In 2007 a group of researchers studied the unseen consequences of a large-scale replacement of fossil fuels by corn-based biofuels such as ethanol. In “The Ripple Effect: Biofuels, Food Security, and the Environment,” the authors argued that a switch to such fuels would have a range of adverse and unintended effects: increased food prices, coupled with reduced availability, as corn was diverted to biofuel production. (And because corn is used for cattle feed, higher corn prices would raise the price of beef.) In addition, some lands formerly used for agricultural purposes would now be diverted toward biofuel production, thus also raising the price of farmland. That price rise would in turn drive farmers to boost crop yields by greater use of fertilizers, with the result of increased groundwater pollution and higher atmospheric levels of nitrous oxide, a greenhouse gas. And so on.
During the second half of 2010, the price of corn rose 73 percent in the United States, in large part due to the use of corn for ethanol production. Hence the appeal of biofuels that are not made out of foodstuffs but are rather synthesized—grown—by microbes.
When the Continental Airlines Boeing 737–800 made its biofuels demonstration flight in January 2009, a fraction of its fuel component had been made by algae cultivated by Sapphire Energy of San Diego, California. Sapphire, along with Solazyme, was a biofuel success story. Financed by venture capital firms owned by Bill Gates and by the Rockefeller family, the company had produced its jet fuel in a field of open ponds on a 100-acre algae farm near Las Cruces, New Mexico, using nothing but natural (non-genetically modified) algae, CO2, nonpotable water, and sunlight. The process took about two weeks from start of growth to the harvesting of their so-called green crude. This green crude was then processed to yield what biofuel advocates like to call fungible fuels, those that are functionally interchangeable with 91 octane gasoline, 89 cetane diesel, and jet fuel (with a sub-47 degrees C freeze point to permit high-altitude flight).
For a while, algae appeared to be the microbe of choice for producing crude oil. The term “algae” covers a group of photosynthetic organisms that range in size from microalgae (e.g., single-cell creatures such as diatoms), to macroalgae (including large seaweeds such as kelp). Even smaller than microalgae are cyanobacteria, which are bacteria not algae.
Regardless of size, they all have the ability to turn carbon dioxide and water into carbohydrates and other products through the chemical transformations of photosynthesis (albeit across wide variations in efficiencies).
Photosynthesis is a sequence of reactions that occur in green plants and photosynthetic bacteria, in which light energy from the sun is used to produce carbohydrates and all the rest of the plant’s materials. Schematically the reaction is:
carbon dioxide + water + light energy → carbohydrates + oxygen
As a petroleum-producing organism, algae has a number of advantages. First, with the exception of its incarnation as seaweed, algae is not a food crop. Second, algae can be grown virtually anywhere that there’s sunlight, and on land that’s unsuitable for conventional crops—in deserts, for example. Third, it doesn’t need potable water for growth, but can thrive in brackish water, seawater, or even on wastewater, meaning that it doesn’t compete for the world’s scare drinking water supplies. Like any other photosynthetic organism, algae consumes CO2, meaning that it actually removes carbon dioxide, a greenhouse gas, from the atmosphere. And its end products—fatty-acids (lipids) or other oils, and even some types of long-chain hydrocarbons—can be processed into any of the three classic petroleum distillates: diesel oil, gasoline, and jet fuel.
Finally, algae can be genetically modified in an effort to maximize its efficiency or yield, or to fine-tune the chemical characteristics of its output. Given all these features, algae would appear to be an excellent biofuels production platform.
But it also has its shortcomings. To begin with, algae does not simply secrete its product in such a way that it can be siphoned off or skimmed from the top, like cream. Instead, the stuff must be separated from the organism by brute force—by centrifugation, for example. This builds in an extra layer of inefficiency, like an orange juice manufacturer that extracted the juice by hand, one orange at a time, rather than by mass-production extraction machinery.
Second, once separated, the algae-produced fatty acids must be refined, more or less like ordinary raw crude oil, into the desired fungible end products. That process takes energy, which has to come from somewhere. And if it comes from coal-burning power plants, it puts even more CO2 into the atmosphere.
Third, algae growth requires nutrients, such as nitrogen and phosphorus, which often come from pe
troleum feedstocks. The microbe therefore utilizes in its growth process some of the very substances it was intended to replace.
Fourth, algae is an excellent light blocker, which means that the open ponds in which it is grown cannot be very deep. Indeed, the actual light penetration is less than 1 millimeter, which means that vigorous mixing and hundreds of gallons of water are required for every gallon of oil produced. This in turn makes for major space requirements. In fact, one study concluded that growing enough algal fuel to supply the world’s entire jet fleet would require a land area the size of Maryland.
Clearly, the algae-to-biofuels road is not a smooth one, and even with the research on algal fuels now being done by Craig Venter’s Synthetic Genomics (with $300 million in funding provided by ExxonMobil), it’s far from certain that algae will turn out to be the preferred biofuels production platform.
But as we have seen, algae is not the only microbe that can make biofuel; so can the industrial microorganism E. coli.
In 2005 Chris Somerville, a professor of plant and microbial biology at the University of California–Berkeley, Jay Keasling, David Berry, and I co-founded a private start-up company whose objective was to use engineered E. coli to produce commercial quantities of renewable diesel fuel (as well as stocks of sustainable, green chemicals). We called the company LS9 because it was the ninth life sciences firm to be funded by the venture capital group Flagship Ventures. One of the primary attractions of using E. coli as our production platform was that unlike algae, E. coli can be engineered to make its fungible petroleum products directly—the microbe does not need to be broken up in order to release its end product. Instead, we would create these fuels according to a streamlined, one-step synthesis protocol known as consolidated bioprocessing. The microbes would consume feedstock molecules and secrete the desired fuels or chemicals, which would float to the top of a fermenter column where they could be skimmed off like cream—no centrifugation, distillation, or other intermediate steps would be required. Using this protocol, making new petroleum would be as simple and straightforward as brewing beer.
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