Illinois plant biology professor Stephen P. Long and his collaborators have engineered sugarcane so that it accumulates oil in its stems that can be made into biodiesel. They now have an “oilcane” that accumulates 2 percent oil by weight, and their research suggests they can eventually raise this to 20 percent. Their work will be exhibited at the 2015 Energy Innovation Summit in Washington, D.C. Long spoke to News Bureau life sciences editor Diana Yates about the implications for food and biofuels.
Why turn a plant like sugarcane into an oil-producing crop?
Sugarcane is the most productive crop plant in the world. We know how to grow it and extract its stem contents. It is less demanding on soils and fertilizers than our major food crops. We chose a highly productive plant, so that once it is successfully engineered, it will deliver far more oil per acre than any other crop. For example, even at 2 percent oil, our “oilcane” delivers three times the amount of oil that can be obtained from a soybean crop. At 20 percent, this would be 30 times the amount. This would move biodiesel from a niche market to a replacement of a large proportion of the nation’s bioenergy. The oil also could be chemically treated to produce jet fuel. Even at 2 percent oil, our plant is economically viable. We have developed a simple separation process (patent pending) that would allow mills to separate the oil from the sugar extracted from the stem. But our eventual target is a 20 percent oilcane that produces only oil.
Won’t this new plant face political and regulatory hurdles as a genetically modified crop?
Undoubtedly it will. The major political argument in this country against biofuels is that they cost more than fossil fuels. Because sugarcane production and processing is a mature technology, as is separation of oils from plant material, it was possible for us to build a detailed techno-economic model to determine the cost per gallon of biodiesel from oilcane. Taking account of land, capital and operating costs, the cost per gallon came to about 75 cents less than the 2014 cost of diesel. BP Biofuels conducted a completely independent analysis of our system and came to a very similar figure.
The major regulatory hurdle will be that this is a genetically modified crop. Our purpose is proof-of-concept, to show that this is possible. We expect this to spur industry partners to take this to the next level. It might take 15 to 20 years to take this crop from innovation to planting at scale in farm fields. This will be enough time for the GMO traits to be tested and deregulated. This sounds like a long time, but this is likely to occur at the same time that some of our newly accessed shale and fracking oil sources start to become depleted. So this could be an opportune time to add oilcane fields – which, unlike fossil fuel oil fields, will never run out.
What are the economic advantages of oilcane?
We already have a farming and processing community with the know-how to grow and process cane, so there is no learning curve. Canes are perennial plants, avoiding the cost of annual replanting. They also have a low demand for fertilizers. A highly productive crop, it will also give the maximum return per acre. We calculate a maximum of $1,924 profit per acre. Our crop can be grown on about 23 million acres of underutilized land in the southeastern U.S., which means revenue of more than $44 billion annually.
Will oilcane even grow in the United States?
Sugarcane is grown today in southern Florida, Louisiana and Texas, mainly. It was also once grown at large scale in Hawaii and Puerto Rico. It requires a wet and warm climate. However, we have worked extensively with a close relative of sugarcane, miscanthus, which is grown as far north as southern Canada. We have hybridized sugarcane with miscanthus to transfer some of its cold tolerance. These hybrids in turn are being hybridized with oilcane. We expect to be able to make cultivars that can be grown further north in the southeastern states. We also are starting to make an oil sorghum, by making the same changes in sweet sorghum. This crop may be grown in colder climates or used to extend the harvest season in areas where oilcane can be grown.
Won’t oilcane displace other important crops?
Our target area is the southeastern U.S. This region has warmth and ample rainfall, but the soils are often poorer than those of the Midwest Corn Belt. This has made much of this region uncompetitive for food crop production. Since the end of the Civil War, the amount of land in the southeastern U.S. in crop production has been in continual decline. This decline has even accelerated recently as the greening disease of citrus has progressed. We have mapped the abandoned and underutilized acres in this region and calculated that, if grown on this land, oilcane could provide about one-quarter of the nation’s current liquid fuel used in transportation. This would be 70 percent of the 2022 target set in the Renewable Fuel Standard.
How carbon-intensive is the process of growing oilcane?
Ethanol produced from sugarcane is about the least carbon-intensive of all biofuels when the full life cycle analysis is considered, based on analyses by Argonne National Laboratory. These suggested it is about one-fifth of the carbon intensity of corn ethanol. Biodiesel from oilcane will have a very similar life cycle to ethanol from sugarcane. However, it will not require the fermentation and energy-intensive distillation steps of ethanol production. This will make oilcane even less carbon-intensive, requiring less than one fossil-fuel carbon input for every 10 outputs. A further gain is that, unlike ethanol, the product can use exactly the same transportation containers and pipelines as conventional oil.
Can this new plant be used as food?
Our targeted oilcane, which will have 20 percent oil in its stems and very little sugar, is not intended as a food; it will be a purely industrial crop. However, the current oilcane, with 2 percent oil, can also be processed for sugar. We have already developed, at Illinois, a separation technique that removes the oil. The sugar, which will of course enter the food chain, is obtained by crystallization – a process that removes any remaining traces of oil. However, the oil is not harmful. It is the same as that produced naturally by plants and very similar to most cooking oils.