Never heard of isoprene? Most of us haven’t and yet it’s an organic compound that plays a major role in our lives. Isoprene is a colorless, odorless gas found naturally in our breath and the environment — it is emitted from the leaves of many plants such as oak and poplar trees. Isoprene is used to make latex, rubber, plastics and pharmaceuticals. Yes, isoprene is the building block of latex extracted from trees, which is used to make natural rubber, but here’s something else you might not know — only 40% of the world’s rubber comes from rubber plantations. The other 60% comes from the petroleum industry. And there’s the “rub.”
Petroleum is not a renewable resource, it’s drying up and it’s expensive. So the Wisconsin Institute for Sustainable Technology (WIST) is working on a means to convert waste from paper mills into isoprene — essentially replacing a petroleum-based product with one that is biologically produced from renewable resources. In other words, one person’s garbage is another person’s…rubber or aviation fuel.
Biologically produced isoprene can be used to make renewable biofuels. Isoprene-based biofuels are uniquely suited to the aviation industry because aviation fuels need to contain a lot of energy in a very small space (enough energy to lift the plane, yet light enough not to bog it down). Isoprene is perfect. It’s a heat sensitive organic compound that has a high energy density and will remain in liquid forms at very low temperatures (in other words, when you’re flying at 40,000 feet in the air). Incredibly, there is four times more energy in a pint of this biofuel than bioethanol.
Using byproducts from the paper industry, WIST is working with American Science and Technology, of Wausau, to get “maximum conversion” of that waste into other products such as rubber and aviation fuel. The rubber and biofuel research, which is supported in part by the Department of Defense, involves fermenting wood sugars into isoprene, then capturing the isoprene from the vapors. This process has been successfully completed within the laboratory and is now moving into the pilot phase.
The researchers hope to provide a win-win-win situation: paper mills will no longer have to bear the cost of disposing of the residual sludge, the environment fares better when less waste is put into landfills, and consumers benefit from better aviation fuel and sustainable rubber.
For a synopsis of the isoprene project, watch Eric Singsaas, director of research, demonstrate the benefits of biofuels as alternatives to fossil fuels.