If the present is problematic, that doesn’t mean the future has no potential. We have railed against the catastrophe in progress throughout the tropics, as the last rainforests are razed to grow sugar cane and oil palms. Over and over, we’ve reminded readers to beware of carbon taxes and carbon trading schemes, because European carbon offset payments are funding the destruction of Asian rainforests to grow biofuel. And considering the epic scale of the destruction occurring, right now, global environmental groups are virtually silent. But what about the future of biofuel?
|Tropical corn doesn’t grow ears in
the long days of temperate latitudes,
and has high sugars in the stalk.
(see “Tropical Maize”)
Last week Vinod Khosla, arguably the high priest of biofuel, made a lunch presentation at the Think Equity “Think Green” conference in San Francisco. Khosla is a numbers guy, which we absolutely love. His comments on the future of energy were unwaveringly optimistic, which we also love, and wholeheartedly agree with. He claims there are three nascent sources of energy that are rapidly scaleable; solar, “enhanced geothermal,” and biofuel. We cover solar avidly, and enhanced geothermal is something we’re going to need to get more familiar with – but back to biofuel.
In his remarks Khosla presented two charts showing “what’s possible” with biofuel. On the summary chart, the first year projection was for 2012, where he stated 5.0 million acres could yield 16.5 billion gallons of ethanol. The final year projection was for 2027, where he stated 49 million acres could yield 139 billion gallons of ethanol. We have crunched these numbers a bit, and here’s what we’ve determined:
The 2012 projections equate to 3,300 gallons per acre, or put another way, 50,286 barrels per square mile per year. His 2027 projections actually come in with slightly lower yields, 2,837 gallons per acre or 43,226 barrels per square mile – this probably reflects the assumption that by then most of the ethanol is extracted from cellulose, which has a somewhat lower yield per acre. But the real story is what this yield represents compared to today’s biofuel yields.
Currently the best ethanol yields anywhere come from Brazilian sugar cane, which using Khosla’s own data, are 6,000 litres per hectare; for comparison that equates to 9,775 barrels per square mile per year. Based on the research we’ve done, that is on the high side. But it is certainly in the ballpark, and here’s the question: How are you going to go from a yield of 9,775 barrels per square mile per year today to 50,286 barrels per square mile per year within the next 10-20 years, an increase of 5.1x? The implications are huge; at a yield of 50,000 barrels per square mile per year it would only take 160,710 square miles of farmland for bioethanol crops to replace 100% of the roughly 8.0 billion barrels of oil consumed each year in the USA. That is only 25% of the arable farmland in the USA, a not unthinkable amount to give over to these crops.
If we take that extraordinary higher yield and calculate how how much the refined fuel extracted from the land each year would cover the land if it were poured over the surface, it actually only amounts to 0.12 inches in depth. So in terms of passing the smell test, this extraordinary yield of 50,000 barrels per square mile per year really doesn’t seem far fetched. Can we get there, and can we be sure there won’t be unintended environmental consequences?
Khosla Ventures has funded several companies working on advanced cellulosic extraction methods as well as ways to extract ethanol from other feedstock including various waste streams – some of these are Lanza Tech, Mascoma, Verenium, Range Fuels, and Coskata. Cellulosic fiber comes from plant mass, not from the fruit of plants, meaning there is far more material to break down into ethanol. Khosla mentioned a few other points relating to ethanol of interest – he claims agronomists now believe proper crop management can allow high yield ethanol crops to be grown that actually improve soil quality over the years. He also stated that higher compression internal combustion engines will get greater mileage from ethanol than standard high efficiency ICEs can get today from gasoline. Clearly ethanol is not something to bet against.
The difference between extracting 10,000 barrels per year from standard crops such as sugar cane in Brazil (or somewhat less than that from corn in America’s midwest), and extracting 50,000 barrels per year per square mile from plant mass using cellulosic methods is the difference between developing a supplemental fuel of some economic value, and a scaleable, viable fuel alternative that could literally replace petroleum.