Sustainable Energy

BP's Bet on Butanol

Forget ethanol: it’s hard to transport and gives bad mileage per gallon. Another alcohol, butanol, is a much better renewable fuel, says the president of BP Biofuels.

Alternative fuels such as ethanol could help reduce carbon-dioxide emissions and decrease oil imports, but so far these biofuels only make up a small fraction of fuel use. One of the biggest challenges to ramping up ethanol use is distributing it. That’s because ethanol can’t be transported in the same pipelines used to distribute gasoline. What’s more, ethanol delivers far less energy than gasoline does on a gallon-for-gallon basis.

Beet fuel: BP Biofuels is developing a process for converting some crops into butanol, an alcohol fuel that’s superior to ethanol in several ways. The first batch will likely come from a crop of sugar beets like the one featured here.

Philip New, president of BP Biofuels, a recently created company within the giant British oil producer, thinks it has a solution: butanol. While butanol, like ethanol, can be made from corn starch or sugar beets, its properties are a lot more like gasoline than like ethanol. That means it can be shipped in existing gasoline pipelines. And it contains more energy than ethanol does, which will improve mileage per gallon.

Last month BP announced that it will be working with the University of California, Berkeley, on a $500 million, 10-year program, part of which will be devoted to research on improving biofuels such as butanol. And last year BP announced a partnership with DuPont to develop new technology for making butanol. DuPont will provide expertise in biotechnology. Technology Review spoke with New about the company’s plans at a recent energy conference at MIT.

Technology Review: Why is BP interested in biofuels, which would seemingly be a direct competitor to your main business?

Philip New: It is possible–if the world now is really serious about climate change, and if people continue to be concerned about energy security–that given the breakthroughs in technology that now seem plausible, biofuels could represent a significant amount of the transport fuel mix in the future.

I think you have a choice. Either you can try to deny it and resist it and hold it back, or you can embrace it and welcome it and make it a part of your business. And clearly BP has chosen to do the latter.

TR: BP is focusing on a relatively obscure fuel: butanol. Why focus on butanol rather than on ethanol?

PN: Ethanol is a good start. But ethanol was not designed to be a fuel. No one sat down and said, “Let’s create a biomolecule that will operate in engines.” What happened was, people said ethanol can work in engines. As a lot of people are becoming aware, it’s good, but it has some drawbacks. Butanol is, we think, an innovation that overcomes many of the drawbacks.

You shouldn’t view butanol as being a competitor to ethanol. An ethanol plant can evolve into a butanol plant. And you can mix ethanol and butanol together, and it can actually help you use more ethanol.

TR: So how is butanol better?

PN: The key way is higher energy density. Whereas ethanol is around about two-thirds the energy density [of gasoline], with butanol we’re in the high eighties [in terms of percent].

It’s less volatile [than ethanol]. It isn’t as corrosive, so we don’t have issues with it at higher concentrations beginning to eat at aluminum or polymer components in fuel systems and dispensing systems. And it’s not as hydroscopic–it doesn’t pick up water, which is what ethanol can do if you put it in relatively low concentrations. So we can put it through pipelines.

TR: Why is water a concern with pipelines?

PN: In any fuel system, water gets in pipes. With gasoline, it just settles out of the bottom. Ethanol mixes with water. So you basically introduce water into the fuel mix. If you put aviation fuel down a pipe that starts to have some ethanol in it, then you have the potential of water contamination of the aviation fuel, which could be very bad news.

TR: How is butanol made now, and how do you propose to make it?

PN: The conventional way of making biobutanol is a fermentation process. There is a lot of work going on in various places to improve the efficiency of the process. And our target is to find a way of making butanol at a price that can compete with gasoline. More than that we cannot say.

TR: What feedstocks can you use?

PN: You can make butanol with exactly the same stuff you use to make ethanol. We can make it from sugar, we can make it from corn, we can make it from sugar beets. Any sugar-starch that’s going into the fermentation of ethanol you can [use to] make butanol.

TR: Ethanol today depends heavily on government subsidies. How economical is butanol?

PN: I’m not sure that it needs too much specific help. What I’d ask for more is a level playing field. For example, a transition away from subsidizing biofuels on the basis of volume towards subsidizing on the basis of energy content would represent a level playing field. By subsidizing volume, you’re effectively supporting less-energy-efficient alternatives.

TR: When can we expect to go to a BP station and fill up with some butanol?

PN: This is absolutely in a testing phase, and we’re looking to how we can move it into a pilot [plant] phase. We’ll be dealing with some trial quantities soon.

Before we get to a mass-market environment, to be honest, you have to give it a little bit of time. I would like to think that butanol could be broadly available before ligno-cellulosic ethanol [such as from wood chips and corn stover] is widely available. It’s almost just a function of the pace of engineering and permitting. To open a new ethanol plant today, it’s not going to be open until 2009, 2010. So that should help you range your expectations about the introduction of new technology.

TR: To be clear: are you waiting on biological advances before you can move forward, or are you already at a point where you can go ahead and build plants and start small-scale production?

PN: I think we’re in the world of optimizing biological processes. You don’t want to build a plant if you’re working with a suboptimal process.

TR: So there are no major breakthroughs needed?

PN: Both BP and DuPont are very positive, committed, and optimistic about the prospects of delivering butanol.

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