hemicellulose need to be separated from the lignin and then broken down into sugars suitable for fermentation into ethanol (ethyl alcohol). This can be accomplished through what is called enzymatic conversion; that is, the application of specialized enzymes. More has to be done on enzymes to make them more competitive.
The raw material for cellulosic ethanol is cheap. It may be crop residues or agricultural waste; for instance, the leftover corn stover or straw from wheat cultivation or the bagasse that is a waste product from fermenting sugarcane. It can also be other agricultural residue or wood waste or even some kinds of garbage. Or it can be obtained from various kinds of grasses that are grown on marginal land, such as the aforementioned switchgrass or micanthus or sorghum, a cousin of sugarcane.
But costs of processing are still high. It is estimated that building the facilities for manufacturing cellulosic ethanol can be four times as expensive or more as that for corn-based ethanol.
THE FORGOTTEN CHALLENGE
There is also what has been called the “daunting logistics”—the “forgotten challenge.” For compared with oil, biomass has a very low energy density. Therefore, a lot of it has to be gathered, and the costs of doing all that gathering, transporting, and storing are high. The energy density of oil is such that transporting it halfway around the world is economic. By contrast, biomass has what has been described as an “inherently local nature,” which, according to some, makes a 50-mile radius a potential outer limit. Consider a 6,000-barrel-per-day cellulosic plant. It could require as many as 50,000 semitrailer trips per year to supply it.
The refinery also needs a steady source of supply. If material is being harvested once or twice a year, then it needs to be stored, which is yet another logistical problem. Matter rots and decays. All this adds to the cost. And then, eventually, there will also be a price on the raw material itself.18
The industry cannot go to scale unless these logistical challenges can be met. One way to do that is by changing the raw material in the upstream—that is, the plant itself.
“TOUGHER THAN PEOPLE MAY HAVE EXPECTED”
Inspiration comes in many shapes. For Richard Hamilton, it came during the tenth grade in the form of an article in Newsweek about the IPO of Genentech in October 1980. This was the first public offering of a company from the new biotech industry, and it marked the opening of a whole new age of biotechnology.
The Genentech story captured Hamilton’s imagination. By the time he was in college, when people asked him what he wanted to do, he would knowingly reply, “Biotech.” They would look at him blankly. After all, this was still the early days for biotech.
After getting a Ph.D. in molecular biology, Hamilton spent a year as a postdoc at Harvard, where he honed ideas about using biotechnology and genetic engineering to create designer plants. He helped launch a company, Ceres, in 1997, to focus on plant genes. It was not until 2004, as the ethanol boom was building, that he focused on using biotech to create plants specifically designed as fodder for fuels to cope with the logistical challenges that will come with the growth of a cellulosic industry. Indeed, Hamilton and others in this field are bringing a new biological perspective to biofuels.
“Many people are focused on the refining technology and have worried less about feedstock,” he said. “But this will change as the industry tries to scale. High-yield density is one of the key enablers because of the logistics. Overall, cellulosic ethanol has proved to be tougher than people may have expected. The biggest challenge is that the timelines are determined by the life cycles of living organisms. We are dependent on the passage of seasons to see the results of our work.
“Our crops did not just spring forth from a mythical garden of Eden,” added Hamilton. “They have been bred and improved by man.” He held up his hand and pointed to his fingernail. “This is how big the first ears of corn were. We have had agriculture for 10,000 years. We did not know that DNA was the genetic material until 1946. The Green Revolution in the late 1960s was an example of beginning to apply modern biology to plant improvement.”19
Many of the people working in this field are applying the know-how that emerged from the sequencing of the human genome. Calling on the new fields of bioinformatics and computational biology, and using what is called highthroughput