|With all of the attention and resources being focused on ethanol today for use in motor fuel, there are still serious shortcomings. For starters, its ready ability to absorb water makes pipeline transportation impractical. Also, corn-based ethanol can have an impact on the price of animal feedstock (and therefore meat) and corn used for human consumption. These hurdles can be addressed by the use of biomass ethanol, derived from such material as agricultural and forestry waste. Cellulose is the most abundant organic compound on the face of the Earth and production of fuel from cellulosic biomass displaces far more fossil fuel than is required to produce it.|
Unfortunately, producing ethanol from “biomass” has not been an not an easy process, since the sugars can be difficult to economically extract. A significant amount of research is being applied to overcome this issue, with one of the leading researchers having just been awarded Lemelson-MIT Award for Sustainability.
Lee Lynd, professor of engineering and adjunct professor of biology at Dartmouth College, and co-founder of Mascoma Corp., received the inaugural $100,000 Lemelson-MIT Award for Sustainability on April 2, 2007. This recognizes inventors whose products and processes enhance economic opportunity and community well-being, while protecting and restoring the natural environment.
“It was a tremendous honor — they could have given it to anybody in the world,” Lynd said in a NPN interview. “Frankly, I don’t know of anything I would rather be honored for than to be honored in the name of invention and the service of sustainability. In other respects, the cash amount of the award is certainly enabling, but the bigger piece for me is the validation that both the field of biofuels and my activities in it are worthy of this level of recognition. I am hoping that will make some sort of impression and maybe invite people to take a closer look at joining our efforts.”
Lynd and his colleagues’ inventions are at the forefront of advanced technologies for converting biomass feedstocks into motor-vehicle fuels. Lynd was recognized for these inventions, as well as his vision and long-term advocacy of biofuels as a sustainable alternative to fossil fuels.
Lynd’s vision for biofuels took shape in the late 1970s, when he realized that cellulose-utilizing bacteria that produced ethanol were known, and that the production and utilization of cellulosic biofuels could involve a sustainable carbon cycle with no net emissions of carbon dioxide. “I did my senior thesis on the subject in 1978 and have been involved ever since,” he said. “Prior to roughly the summer of 2005, this was not a field that people looked to make large societal contributions. All of a sudden it is, and the award is just another indication that that is true. We’ll see just how long this will last. This field is very much in the spotlight, and a lot of people wrote it off earlier are coming back to it with the thought that maybe they wrote it off too fast.”
Lynd has identified the one-step fermentation of cellulosic biomass into ethanol or other biofuels—a process configuration known as consolidated bioprocessing—as a potentially transformative breakthrough for low-cost processing. While the vast majority of research on processing cellulosic biomass has focused on separately-produced enzymes used in multi-step biological processing, Lynd’s group is the most active worldwide in research on the one-step, CBP approach.
“Developing a microbe that can convert cellulosic biomass to ethanol can be approached in one of two ways,” said Lynd. “Either start with organisms that are able to grow well on biomass and modify them to produce ethanol better, or start with organisms that produce ethanol well and modify them so that they can grow on biomass.” Lynd’s group is investigating both approaches. His group has recently engineered thermophilic bacteria – similar to those present in a compost heap – to produce ethanol as the only fermentation product. Working in collaboration with colleagues at the University of Stellenbosch, South Africa, the group has also engineered yeast to grow on cellulose.
“Originally, we were motivated to look at CBP by process engineering considerations – fewer tanks and fewer process steps,” said Lynd. “However, as we have learned more about how microorganisms utilize cellulose, we are finding additional, biological, advantages to the CBP strategy.”
Microbes grow on cellulose by producing cellulase enzymes, which hydrolyze cellulosic biomass into sugars that can be fermented to ethanol. Producing cellulases requires expenditure of the cell’s energy currency, a molecule called ATP. A key doubt about the feasibility of CBP was whether ethanol producing microbes could produce enough ATP to make cellulase in sufficient quantities to allow rapid cellulose hydrolysis. Lynd’s group showed, however, that a naturally-occurring cellulolytic bacterium actually has several ATP-generating mechanisms that are specific to cellulose utilization and that these mechanisms more than compensate for the ATP requirement of cellulase synthesis.
In an additional development, the Lynd group showed that cellulase enzymes are several-fold more effective when they are present on the surface of a metabolically-active cell as compared to when the enzymes act independently of cells. “Nature has solved many of the challenges associated with microbial cellulose utilization, which we are gradually discovering,” said Lynd.
Largely as a result of Lynd’s efforts, the potential of CBP has been increasingly recognized of late. For example, a recent DOE roadmap states, “CBP is widely considered to be the ultimate low-cost configuration for cellulose hydrolysis and fermentation.”
“I believe the biggest thing that inspired the award, as far as I can tell, is the idea of consolidated bioprocessing,” said Lynd. “Inventors get where they get because they were mavericks to some extent, and most of the field of biomass energy is assuming that it’s going to be at least the next 10 years to make cellulases using aerobic fungi and that we will always have a dedicated process step for enzyme production. I don’t think so. I think we’re going to be able to do this consolidated bioprocessing and I don’t think it’s going to take that long to come about. It’s pretty obvious it would be a transformative breakthrough if we can make it work well. I think the readers should be aware of what the transformative folks are working on and some of us out there think that breakthroughs can be attained sometime soon.”
In addition to Lynd’s invention work, he is also one of the leading analysts and advocates addressing the need to develop and adopt alternative fuels. He co-led a multi-institution research project that produced the seminal report, “Growing Energy: How Biofuels Can Help End America’s Oil Dependence,” published in 2004 by the National Resources Defense Council. Lynd was also the biofuels industry representative on an advisory committee to the Executive Office of President Clinton on reducing greenhouse gas emissions from personal vehicles, and has twice testified before Congress.
Another core concept with biomass is its integration into the active agriculture market, and not just with waste products. “I truly believe agriculture will respond to market forces and come up with all sorts of clever ways to co-produce this stuff and make an added buck on an acre,” Lynd said. “I think that over time, we’re not going to divide crops cleanly between food production and other uses. It turns out you can grow as much or more protein per acre per year growing grasses than soybean, and if you grew grass you can have huge quantities of raw materials to make ethanol while also meeting feed demand. You can also grow things like large biomass soybeans that have five times more aboveground biomass. You have winter cover crops and can take a field that now grows with a corn/soybean rotation and have an economic incentive to grow something in the winter while improving the soil quality for the summer crops. So I can see agricultural changing in ways that are very exciting from the point of view of the economic health of rural communities and also from the point of view of the ecological sustainability of those systems.”
Lynd was also a founder of the Mascoma Corporation, a cellulosic biomass-to-ethanol company with corporate offices in Cambridge, Mass. and R&D labs in Hanover, NH. Mascoma is leading the development of unique biotechnology and deployment of cellulosic production. Initial deployment activities are focused on strategic partnerships for conversion of wood-based cellulosic feedstocks into ethanol at relevant commercial scale.