Researchers and producers optimistic about sweet sorghum as biofuel feedstock

Sorghum, a plant genetically similar to sugarcane is being considered as a future biofuel feedstock.  Many researchers, funded by both government and industry are breeding sorghum for traits desirable in bioenergy feedstock.  There are hundreds of sorghum varieties throughout the earth.  They are being bred to increase per acre yields, to increase drought resistance, and increase sugar content.  The sorghum genome is being mapped which will help scientists understand which genes do what, which will allow them to better control sorghum breeding.

Sweet Sorghum is being especially looked at for a number of reasons.  It requires roughly half the water per acre when compared to corn.  By it’s nature, it has a high simple sugar content (like sugarcane) which makes processing into ethanol easier.  Current models are expecting sorghum to be produced at roughly 20 tons per acre. This exceeds even miscanthus which comes up at roughly 15 tons per acre.  This would be economically competitive with gasoline.  Sorghum is also naturally drought resistant which will allow it to be planted in areas too dry for corn.

A lot of work right now is going into changing sorghum from a seed crop, which requires replanting every year to a perennial.  Perennials are easier to grow since the relatively costly process of planting every year can be neglected.  This happened with sugarcane in Brazil, so it is not unheard of.

A lot of the sorghum research currently is going on in Texas since the climate in Texas potentially could be ideal for mass sorghum production.   A lot more research is needed into this promising potential biofuel however as there is still a lot of uncertainty about the plant.

Hybrid Poplars: Energy of the Future?

It seems that for a while now I have been reading about how hybrid poplar trees are a potential source of cellulose for cellulosic ethanol. Every time they have been mentioned it I always thought, no way, trees grow far too slowly to be competitive with the likes of miscanthus and switchgrass. Apparently I have been mistaken. A couple days ago I read an article about ongoing research at Purdue to decrease lignin content in hybrid poplars to both increase cellulose content and increase the ease with which the cellulose can be broken down. Since then I have been reading more and more about these amazing trees and my past bias against them seems to have been flawed.

It turns out that hybrid Poplars can grow 10 feet per season. This can mean as much as 10 tons of wood per acre per year. If lignin content can be decreased somewhat (plants need at least some lignin just to hold the rest of the components together), and yields can be further increased, poplars could potentially be a serious contender for widespread utilization. This basically means that currently poplars would yield 700 gallons of ethanol per acre per year which is about the same as switchgrass although somewhat less than miscanthus. That is before any % lignin modifications or yield increases.

Poplars require very little maintenance once planted. “In the first year, weeds must be controlled using herbicides and/or mechanical methods. Additional weed control may be needed in years 2 and 3, but once the canopy closes, weeds are shaded out and further weed control is generally not needed. Insecticides are applied if necessary to control cottonwood leaf beetle during the rotation. Fertilizer applications are minimal and are called for only if nitrogen levels in the leaves fall below 3 percent on a dry weight basis. Typically this means that one or two applications of nitrogen of up to 50 lbs/acre (56 kg/ha) are required during the entire production cycle. Harvest utilizes standard forestry equipment widely available in the U.S.

As perennial crops, production of hybrid poplars can offer substantial environmental benefits compared to annual row crop production. Chemical and fertilizer applications are considerably lower, lessening the potential for chemical runoff and leaching. Hybrid poplars, as buffer strips, also intercept runoff of nutrients from fields near streams, rivers and wetlands. As perennial cover, wind and water erosion over the life of the rotation is less than that with annual crops. Hybrid poplars also provide increased year-round habitat for birds and small mammals compared to annual row crops.”

Poplars are similar to switchgrass in terms of the effect they have on soil carbon. Both have dramatically beneficial effects on the top-soil. There are two reasons for this. First, poplars form extensive root systems which decompose when the tree gets harvested (and thus killed). Second, every year when the leaves fall, they decompose and add to the fertility of the soil. These crops are especially better than corn in terms of soil fertility.

Wood to Wheels, Michigan Tech’s answer to “Turning down the carbon pump”

With all of the recent press regarding Mascoma’s new wood based cellulosic ethanol plant that will be built in northern Michigan and the assistance that they are receiving from Michigan’s universities, I thought it would be interesting to write about one such program that will be assisting them. The Wood to Wheels program at Michigan Tech is “a graduate enterprise in sustainable transportation utilizing fuels and co-products from forests and other biomass sources.” Basically Michigan Tech is trying to tackle many issues involving creating a sustainable means of fulfilling our nation’s energy requirements.

The four main objectives of the program are to “improve bioprocesses that will utilize woody biomass, improve forest management and apply biotechnology to increase forest biomass productivity/utilization per acre by 65%, demonstrate forest land management, fuels production, and vehicular technologies that close the carbon cycle and stabilize atmospheric CO2 levels, and optimize powertrain technologies that reduce fossil fuel consumption over the life cycle by up to 100% in vehicles that use these technologies.”

In their effort to improve the bioprocesses, wood to wheels participants are working on a number of things. They are trying to genetically enhance cellulase enzymes, take advantage of peptidomimetic modification of cellulase activity, genetically enhance the yeast organisms so that a higher yield of sugar can be converted into ethanol, and improve efficiency of the entire process to reduce waste.

The Wood to Wheels forest resources initiative seems to be slightly more general. They are researching wood formation, defense and fitness (of the plants), natural variation, and carbon sequestrations. Researchers are also looking at metabolite profiling and chemical fingerprinting.

From the Wood to Wheels site, the objective of their efforts to improve engine and vehicle designs is as follows: “Develop technologies that will optimize engines for the use of ethanol and ethanol/gasoline mixtures for vehicles including hybrid applications.” They hope to increase vehicle efficiency by 50% and improve the cold start for E85 to E100 ethanol vehicles.

Finally, their assessment initiative looks at broader issues. From environmental effects, to policy analysis, to huge life-cycle analyses.

Anyway, this program looks to be very promising and should be a boon to Mascoma’s efforts in the state.

Genetically Engineering Plants to Optimize Light Energy Capture

Biopact is running an interesting article about a JBC paper which summarizes a discovery involving plant directional growth towards or away from light.  The photoreceptors in the plant can sense blue light, and the plant then acts accordingly.  This phenomenon is known as phototropism.  Understanding this should lead to the ability to genetically modify a plant in order to maximize a plant’s energy intake and thus increase the energy that we can get out of the plant in the form of ethanol.  “The photosynthetic efficiency of crops, partly guided by their photoropic mechanisms, is currently below 0.4 per cent. The theoretical maximum efficiency however is around 4 per cent. Scientists and biotechnologists think it may be possible in the future to directly intervene in this complex natural mechanism, to improve the efficiency of the process and thus enhance plant growth by an order of magnitude.”