Cellulosic ethanol has arrived. And ironically, as the innovations that make it more affordable, more efficient and more sustainable continue to improve, the economic, technological and political costs to extract petroleum are going up.

We’ve seen this shift in technology before. But this time the incumbent fuel source is about to be replaced by a truly sustainable alternative that doesn’t come from underground.

Today, four commercial-scale cellulosic ethanol plants are online in the United States — the achievement of hundreds of innovators in biotechnology, engineering and agriculture. And thankfully, throughout their years of study, the people behind these facilities ignored the noise of detractors who said it couldn’t be done.

Well they did it. And that spells trouble for the old guard.

The technology that drives these biorefineries is tuned to work with cellulosic material from corn — the stalks, leaves, cobs and other fibrous materials from the harvest of commodity corn — but performs with nearly any cellulosic biomass.

Cellulosic ethanol's environmental benefits are what make it such a remarkable alternative to gasoline:

• A nearly 90% reduction in greenhouse gas emissions
• Up to 21 billion additional gallons of clean, renewable fuel through the Renewable Fuel Standard (RFS)
• The ability to use a wide variety of inputs, from agricultural and forestry wastes to municipal solid waste
  
• Technology that can be use around the globe in regions that can’t produce starchy grains

To understand why cellulosic ethanol is the sleeping giant of renewable fuel, it’s important to understand that first-generation, or grain-based ethanol, paved its way. The ethanol molecule is identical whether it comes from grain starch or plant cellulose. The distinction is the source, or what kind of,  polysaccharides are used to make ethanol. 

Start with ethanol as it’s been made for millennia:

Why does beer come from barely and wheat? Why does vodka come from potatoes? Why does whisky come from corn or rye? Why does sake come from rice?

Answer: because all those crops are rich in starch, a polysaccharide carbohydrate. And starch is very easy to break down into simple sugars that can be fermented into alcohol.

That’s grain-based ethanol for you. It’s so easy to make, people do it as a hobby. Home brew, anyone?

Although first-generation, or starch-based, ethanol is basically moonshine, community based companies in the U.S. have perfected it on an industrial scale to be the lowest-cost source of fuel on the planet. It comes mainly from commodity corn — a hard, inedible grain packed with starch. And American farmers are the best in the world at growing it — enough to produce clean fuel for millions of cars and nutritous feed for millions of livestock animals.

But that's only one source of renewable carbohydrates. Plant cellulose is another — and it’s orders-of-magnitude more abundant than grain. In fact, cellulose the most abundant organic compound on the planet.

Look at grass, trees, bushes, stalks of corn or wheat — anything green and growing that maintains its shape — and you’re looking at cellulose. It’s a fabulously complex chain of carbohydrates locked together by powerful molecular bonds that are strong and difficult to break apart. This gives cellulose a rigid structure, which is why leaves, stalks, sticks, branches, and tree trunks can grow tall and firm and survive the onslaught of the elements. Cellulose makes them resilient.

With enough time, plant cellulose will decompose into simpler carbohydrates. In an industrial setting, people have been able to accelerate this process for quite some time. The challenge has been to do it economically.

And that challenge has been met.

Today, those commercial-scale cellulosic ethanol plants in Iowa and Kansas are making the most of the successful and economical footprint of grain-based ethanol by squeezing even more value out of corn. Now both starch in the kernels and cellulose in the stalks and leaves of the corn plant will deliver sugars that can be broken down and fermented at a cost that is lower than gasoline. (And have we mentioned that makers of gasoline continue to cling to subsidies from Uncle Sam?)

That makes this a special moment. Cellulosic ethanol is about to do to petroleum extraction what kerosene did to whalers.

Sound bold? Well let’s not be afraid to speak truth to power. If whaling barons had their way, we’d still be paying them to plunder the oceans so we could light our homes according to their preference. And if petrogarchs had their way, we’d pretend there was no legitimate alternative to gasoline in advanced biofuel.

Watch this space, because we expect that as advanced biofuels begin to proliferate, the beneficiaries of the status quo —  those “whales” we call “Big Oil” —  will not let go quietly.