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Biorefineries: Curing our addiction to oil
04 July 2007
NewScientist.com news service
Jessica Marshall

Enlarge Figure 1

"ADDICTED to oil," that is what westerners like me are supposed to be. That may be true for drivers of gargantuan SUVs commuting from the suburbs but I hardly ever drive and, anyway, my car is tiny. Surely I'm not an oil addict.

The picture changes when I look around my house though. Without oil - poof! - the paint disappears from the walls. In the bathroom, the vinyl vanishes from the floor. Shower curtain, and the shower unit too, are gone in a splash. All my toiletries, and their containers, take their leave. With shampoo and soap washed away, personal hygiene is looking dicey. And so is my livelihood: computer, keyboard, printer, phone... none would exist without the plastics from petroleum. My electrical and phone cables are suddenly exposed. For those who depend on pharmaceuticals synthesised from oil-based building blocks - to control diabetes, hypertension or depression - doing without oil could be life-threatening.

The carbon in oil forms the basis for the world's trillion-dollar petrochemicals industry from which a profusion of industrial and household products are made: paints, inks, plastics, pharmaceuticals, adhesives, lubricants, flavouring agents, perfumes and more. It may not be that way for long, however. We're beginning to grow chemical building blocks alongside the growing of our fuel. As the "biorefinery" begins to supply our gasoline and diesel needs, it may also begin to satisfy other aspects of our oil use. New ways of processing biorefinery feedstocks are being developed to make products traditionally derived from oil. These measures, combined with a suite of strategies for changing how we heat our homes and power our transportation, point the way to a possible future without oil.

More and more governments are aiming for such a future. As climate change climbs the list of global priorities, countries are looking for ways to cut the carbon dioxide emissions that result from consuming over 80 million barrels of oil every day. Sweden, for example, plans to be independent of oil imports by 2020, using no oil for heating and halving its transport fuel consumption. Even for less green-minded nations, reducing dependence on oil imports is becoming a national security priority.

Depending on who you ask, global oil production will peak any time between now and 2030. The price of oil has already risen from around $25 per barrel in 2001 to almost $70 per barrel today, leaving consumers and businesses looking for alternative fuels and feedstocks for chemical processes.

Oil is a tough act to follow. There's a reason why we use it to power our trucks, planes and automobiles, and heat our homes: it is an extraordinarily convenient and compact way to transport energy. It's equally convenient as a source of chemicals. Its strands of carbon-based molecules can easily be vaporised and rearranged with the help of various catalysts. This quality sparked a generation of chemical engineers to develop ever more useful contortions of these molecules, which now constitute materials in everything from body armour to toothbrushes.

Almost 90 per cent of the oil that comes out of the ground goes on fuels, so any oil-free strategy must, above all, address this need by coming up with alternatives. Some of the options, including hydrogen, nuclear or wind power, need not even be carbon-based. The 3.6 per cent which goes to the chemical industry poses a different problem. Its sole function is to provide the carbon-based materials we have come to rely on. One indicator of its importance in this role is the fact that oil-based products command about the same in dollar value terms in the US market as the entire torrent of transport fuel (see Chart). So where will this carbon come from, if not from oil? "If you want a transition to a sustainable system, you only have one choice, which is biologically based feedstocks," says chemical engineer Brent Shanks of Iowa State University in Ames.

A look at the history of petroleum refining provides a road map to the future. In the mid-20th century, oil refiners making liquid fuels started looking for uses for the waste gases resulting from their processes. Oil refining produces large streams of carbon-based molecules and just a few of these - ethylene, propylene and benzene - formed the foundation for development of the petrochemical industry. These molecules' reactivity and size makes them useful building blocks for many other compounds. "It was a sequential development from these core chemicals," Shanks says.

The new breed of biorefineries is setting off down a similar road. While their primary function is to make biofuels, refiners are looking at the various types of biomass and the by-products of biofuel production, and asking what they can do with them. In the place of intermediate hydrocarbons, the building blocks at their disposal are a plant's sugars, starches, fats and proteins. "I think we'll have the flexibility over a couple of decades to make almost anything we want from plant material," says chemical engineer Bruce Dale of Michigan State University. Some chemicals will be synthesised using enzymes or genetically engineered microorganisms, and some will be produced using the inorganic catalysts used in traditional chemical processes, he predicts.

The biomass could be supplied by anything from corn, sugar cane, grasses, wood and soybeans to algae. The relatively modest biomass required to meet this demand means that corn or other food crops could be used without creating the competition for food that has arisen over corn-based ethanol fuel in the US, Shanks says. "You can actually talk about bringing biomass-derived chemicals online without perturbing food supplies."

For some products, we might even use animals. Already, a company called Changing World Technologies is converting 225 tonnes of inedible turkey guts into 500 barrels of oil every day, plus water, minerals and concentrated nitrogen fertiliser. Its process heats the waste under high temperatures and pressures in a two-step process that simulates the natural formation of oil underground.

There are two key motivations for using biomass, says Jim Stoppert, senior director of industrial bioproducts at agrochemical company Cargill in Minneapolis, Minnesota. "The first is that the cost of carbon has gone up dramatically. The second is there's a lot of pull from consumers seeking out environmentally friendly alternatives." Stoppert has been in discussion with a furniture company that asked for bio-based cushion foam that it says its customers want. He points out that decades of development have allowed petrochemical processes to become incredibly efficient, leaving little room for companies to make up for rising carbon prices by further streamlining their production. In contrast, the technologies for processing biomass are relatively underdeveloped, so there's plenty of room for improving efficiencies.

Governments are also demanding that industry reduce its oil consumption and go greener. By 2025, the US Department of Energy wants 25 per cent of industrial organic chemicals to be derived from biomass. In a 2004 report, the DOE identified the top 12 chemicals derived from biomass sugars that it says could become the ethylenes, propylenes and benzenes of the modern biorefinery - molecules with the potential to replace the keystones of today's petrochemical industry. In March this year, BioAmber - a joint venture between French company Agro Industrie Recherches et Développements and New York-based Diversified Natural Products (DNP) - announced plans to build a plant in Pomacle, France, that would make ethanol and one of the top 12 building blocks - succinic acid. Succinic acid can be used to make solvents, paints, adhesives, pharmaceuticals and other traditionally oil-based products. Wheat will be the Pomacle plant's raw material, providing the necessary sugars. The carbon dioxide by-product of ethanol production will be fed into the succinic acid process - which consumes CO2 as part of an oxygen-free fermentation process, says Dulim Dunwila of DNP. "There's the potential of designing a biorefinery with no net output of CO2," he says.

For all of the parallels to the oil refinery, there are some crucial differences. Oil represents plant matter that has been compressed for millions of years and transformed into a variety of molecules, while fresh plant matter still contains all the specialised compounds that the plant has synthesised for its survival. The structures of these plant compounds can be industrially useful, for example, many are already polymer chains. In some cases, plant compounds are of value as fragrances, flavours or nutritional supplements.

The value of biological molecules is particularly clear in pharmaceutical products, where "chirality" - the molecules' structural "handedness" - is often a key concern. When synthesised via traditional chemical processes, molecules typically end up with half of the chemical groups in one arrangement around a central atom and the other half in its mirror image; often dubbed the left and right-handed versions of the molecule. Biological systems often make only one of these forms, however, and in many pharmaceuticals, only one form is acceptable because the other form won't create the desired effect or can cause drastic side effects. All of this means that - unlike in petrochemicals where most chemicals are built from the bottom up - biofeedstocks already have some valuable products to skim off the top before being broken down and used to build new molecules.

The first biorefined products are already on the market. A corn-based ethanol refinery belonging to agricultural products giant Archer Daniels Midland in Decatur, Illinois, produces more than 20 products from the various by-products or "sidestreams" associated with ethanol production. These include corn syrups, lactic and citric acids, amino acids and industrial starches. They end up in detergents and animal feed, and are also used to make food additives. Most corn ethanol refineries make use of their sidestreams to generate animal feed. Sugar beet processing and paper mills also put sidestreams to good use.

Cargill has developed a process to make propylene glycol - found in cosmetics, lubricants, antifreeze and some plastics - from the glycerol produced when making biodiesel from soybeans. Brazilian company Dedini has built a plant to combine ethanol and biodiesel production. It uses biomass-derived ethanol in place of the methanol from fossil fuel that is traditionally used to convert plant oils into biodiesel. BioAmber is considering the same approach.

Biology to the rescue

Cargill is also using soybean oil to make urethane polyols - a component of polyurethanes, which are used to make foams, adhesives, paints, sealants and more. Indeed, given that the entire US soybean crop could only supply around 6 per cent of the nation's diesel demand, Shanks suggests that soy oils might be better used as chemical precursors in biorefineries than burned as diesel.

Companies considering bio-based raw materials, do not always aim for simple one-to-one substitutions of oil-based products. "If you're making an existing product, the market will value it based on price," says John Pierce, vice-president of bio bio-based technology at chemical giant DuPont. "Biology often helps you make new materials that can command a higher price, but then you have to create a market."

A case in point is DuPont's Sorona polymer, which is sold as a carpet fibre and for clothing. The company claims the product has inherent stain resistance, takes dyes better than other polymers, and is UV resistant. The properties of the nylon-like fibre had appealed to DuPont for decades; the hurdle was that synthesising one of its two building blocks, 1,3-propanediol (PDO), was too expensive. Then a biologist at the company looked at the chemical structure and realised that microbes could make the compound, says Pierce. Now the firm is using corn sugar as the feedstock for this process, resulting in a product that is nearly 40 per cent bio-based; the other raw material is still derived from petrochemicals. DuPont is now expanding its "Bio-PDO" applications, using it to make one of its existing plastics for various moulded parts. "We're starting to ask where else bio can play a role," Pierce says.

A number of companies worldwide are marketing 100 per cent bio-based plastics, largely for use in packaging and made from lactic acid polymers derived from corn and are biodegradable. One such company, Minneapolis-based NatureWorks, advertises itself as the first carbon-neutral polymer producer - though to meet that claim it has to purchase carbon offset certificates for the energy needed for the process. It says demand for its product is outstripping supply (New Scientist, 7 April, p 37). Such products are also enjoying a boon thanks to recently announced sustainable packaging initiatives from retailing giant Wal-Mart. Now that feedstocks like lactic acid and PDO are becoming available at a competitive price, companies are starting to ask what else they can be used for. For lactic acid, solvents, coatings and antifreeze could all be on the cards.

Examples like this illustrate the step-by-step emergence of the biomass-based chemical industry, just as the petrochemical industry emerged 80 years ago. "There are a lot of parallels," Stoppert says. "We'll get into a brainstorming session and the scientists get really excited because it is new science."

Some observers argue that enthusiasm for biorefineries will wane when they try to move on from those products conveniently adaptable to bio-based feedstocks and find that many other vital chemicals prove difficult to make without oil. "Too often, I think, we have this idea or hope that, 'Oh, we'll just go and replace all that bad petroleum stuff,' but I am quite sure that 100 years from now we'll still be making chemicals from petroleum," Pierce says. It will be difficult to compete with some oil-based products. Ethylene gas - one of the key oil-based building blocks for synthetic chemicals - remains so cheap that refineries sometimes just burn it.

Bio-based chemical products are also stalled by the same obstacles that face biofuels: the need to degrade the cellulose and lignin in plant matter into the sugars and other components that can be converted into products. Separating the products out of the water-based processes likely to be used will not be as easy as the distillations possible with petrochemicals. And bio-based chemical products in the US lack a huge economic incentive that is boosting biofuels: they do not qualify for government subsidies.

Nonetheless, biorefineries have the advantage of being profitable at far smaller scales than conventional refineries - both construction and costs are lower because they operate at lower temperature and pressure than petrochemical refineries, so they are less complicated to build. Conventional refineries cost so much to build that fewer than 150 operate in the US, and only around 720 worldwide. Yet there are already 120 ethanol refineries in the US alone. "They don't have to come in swinging, saying 'I'm going to put you out of business,'" Pierce says.

Ultimately, all agree that the outcomes will be driven by cost. "If the price of oil goes down to $10 a barrel, I think we'll all forget about this for a while," Shanks says. On the other hand, further rises in oil costs could make many pricey opportunities suddenly feasible. "When you have a $75 barrel of oil," Stoppert says, "a lot of things can happen." Perhaps then I'll finally be able to kick my oil habit.

Jessica Marshall is a freelance writer based in St Paul, Minnesota

From issue 2611 of New Scientist magazine, 04 July 2007, page 28-31

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