A few years ago, everybody talked about biofuels. U.S. politicians were particularly enamored with corn ethanol, seeing it as a path to "energy independence" (and probably also a way to shower subsidies on powerful lobbies), while greener folks preferred biodiesel made from waste cooking oil (still a great choice, but it doesn't scale up and can be problematic with newer diesel engines). Fans of biofuels said that these were supposed to be just a bridge to second-generation biofuels like cellulosic ethanol and algae biodiesel; these wouldn't be made from food crops or limited feedstocks, and they would be much greener overall.
That was a good vision, but somewhere along the way, the dream seems to have fizzled out. Many are still working on making it happen, but most next-gen biofuel projects seem to have been cancelled or scaled back, and 40% of America's corn production is still going to ethanol production, raising food prices for everyone and using fertile arable land to make fuel that isn't that much greener than what it replaces...
That's what this very interesting piece by The Economist tries to explain:
By 2013, America was supposed to be burning nearly 3,800m litres a year of “cellulosic” biofuels made from woody plants.
But instead of roaring into life, the biofuels industry stalled. Start-ups went bust, surviving companies scaled back their plans and, as prices of first-generation biofuels rose, consumer interest waned. [...] By 2012 America’s Environmental Protection Agency (EPA) had slashed the 2013 target for cellulosic biofuels to just 53m litres.
From 3,800m liters to 53m... Ouch. Yet one more example of why we should never rely completely on forecasts, either good or bad.
Making a second-generation biofuel means overcoming three challenges. The first is to break down woody cellulose and lignin polymers into simple plant sugars. The second is to convert those sugars into drop-in fuels to suit existing vehicles, via a thermochemical process (using catalysts, extreme temperatures and high pressures) or a biochemical process (using enzymes, natural or synthetic bacteria, or algae). The third and largest challenge is to find ways to do all this cheaply and on a large scale.
In 2008 Shell, an energy giant, was working on ten advanced biofuels projects. It has now shut most of them down, and none of those that remain is ready for commercialisation. “All the technologies we looked at worked,” says Matthew Tipper, Shell’s vice-president for alternative energy. “We could get each to produce fuels at a lab scale and a demonstration scale.” But bringing biofuels to market proved to be slower and more costly than expected.
In my opinion, the electrification of transportation (via both plug-in hybrids and fully electric vehicles) will happen a lot faster than experts were predicting just a few years ago, and biofuels will then have to compete not only with gasoline and diesel, but also with the much higher efficiency and 'fuel source agnosticism' of electric vehicles (meaning they can be powered with electricity from any source, including wind, solar, hydro, etc).
If we go back to the basics, that fight will never be fair. Biofuels are basically just another kind of solar energy, but plants are only a couple of percent efficient at converting light into energy, and then the farming process and biofuel refining process each also use a bunch of energy and further reduce the energy yield. Finally, internal combustion engines are only between 20-40% efficient, wasting the rest of the energy as heat.
Compare that to a 15-25% efficient solar panel and a 90%+ efficient electric motor and we're talking about orders of magnitude in delta between the two technologies. The energy spent on biofuels could be spent on increasingly cheap solar panels if the goal is to power our vehicles with solar energy (though EVs also have the benefit of working with other sources, as I said above). There more details about this critique of biofuels here.
Where I think next-gen biofuels could play a big role for a long time to come is in aviation. Airplanes aren't going electric soon, and while we could reduce the amount of flying that people do, I don't think it's going away anytime soon. But if we could fly on truly carbon neutral biofuels that aren't made from food crops, it would make the act of flying much, much better for our planet.
But back to biofuels:
Even if second-generation processes can be economically scaled up, however, that might in turn highlight a further problem. To make a significant dent in the 2,500m litres of conventional oil that American refineries churn through each day, biofuel factories would have to be able to get hold of a staggering quantity of feedstock. Mr Ghisolfi of Beta Renewables points out that a factory with an annual output of 140m litres needs 350,000 tonnes of biomass a year to operate. “There are only certain areas, in Brazil and some parts of the US and Asia, where you can locate this much biomass within a close radius,” says Mr Ghisolfi. “I am sceptical of scaling to ten times that size, because getting 3.5m tonnes of biomass to a single collection point is going to be a very big undertaking.”
Via The Economist