Where’s Butanol, or Other Substitutes for Gasoline besides Ethanol?
by Jim Lane (Biofuels Digest) … Is there some fundamental reason that the automotive biofuels people haven’t shifted to butanol or iso-butanol or some other compound that would be more compatible with gasoline and the present highly evolved gasoline engines? Is there some fundamental thermodynamic barrier that makes conversion of biomass to butanol impossible?
For sure, the quick answer is “new fuels are on the way” — Gevo is producing in small quantities, but it is producing at a commercial-scale facility and selling fuels. Butamax has been less visible in terms of timelines, but they also produce isobutanol from corn sugars. And Global Bioenergies is making progress with a renewable gasoline made from isobutene.
Why so few technologies, why so little commercial progress on gasoline substitution, excepting ethanol?
The chemistry of value
The answer lies to some extent in what we might term “the chemistry of value”. Theoretical yields for making isobutanol from sugars, for example, hover in the 41 percent range, while theoretical ethanol yields are in the 51 percent range. Yields for making isoalkanes and aromatics from sugar— typical components of gasoline — are in the low 40s, too.
Absolutely, you get 1.3 RINs for a gallon if isobutanol vs 1.0 RINs for a gallon of ethanol, because of the higher energy density of butanol, but it washes out when you take into account the lower yield in gallons.
So, right now, the market is not rewarding isobutanol makers with a premium price in the road transport market. Sadly, not in the jet fuel market, either.
But, the processes to produce substitutes for gasoline, besides ethanol, from cellulose are still in the R&D phase.
Now, one of the attractive uses of an isobutanol fuel in the marine sector is that marinas are not obligated parties under the Renewable Fuel Standard, but isobutanol is a qualifying fuel. Hence, a marina owner can blend a gallon of renewable fuel and detach the RIN that comes with every gallon of renewable fuel, and sell it into the marketplace.
Those RINs are selling today at $0.89 each, and you get 1.3 of them for every gallon, as we mentioned above. That’s another $1.16 in value.
Total value created, $4.39 per gallon. That’s excluding value created from a bushel of corn with the distiller’s grains — that’s just the fuel fraction.
Gevo’s production price?
Gevo recently affirmed that they remain on track to reach a production cost of $3.00-$3.50 per gallon for isobutanol by the end of the year — as long as corn doesn’t get more expensive. READ MORE