Biobutanol (C4H10O) or butyl alcohol is a second generation biofuel that can be produced from biomass and can be used either as an industrial chemical or as a transportation fuel. Biobutanol can run in any gasoline engine with no modifications and, like ethanol, has a higher octane rating than normal gasoline. It has the additional advantages that it has a higher energy density than ethanol, can be transferred in our existing pipelines, and can be used as an additive in either gasoline or diesel fuel.
Like ethanol, biobutanol is fermented by microorganisms from sugars, which are broken down from raw feedstocks and mixed with water. For the butanol process, the microbes have been genetically modified to produce an alcohol with a longer chain of hydrocarbons. The fermentation step is followed by a separation step in which the alcohols are separated from the fermentation steep. Since butanol doesn’t mix with water at high concentrations, the finished fuel can be stored easily and transported within existing gasoline pipelines.
Since the cost of the feedstock is the major cost factor, the ability to use low cost non-food feedstocks is a major challenge to cost effective butanol production and much work is being done to develop microbes that can be used with a variety of feedstocks.
The other key research challenge that must be resolved is that butanol production inhibits microbial growth even at low concentrations. The result is that the maximum butanol concentration in the steep of a conventional (ABE) process is about 1.3 % butanol. The overwhelming majority of the fermentation broth is water and an energy-intensive distillation step has traditionally been used for separation of the butanol from the water. This has caused the production of industrial butanol by fermentation to be abandoned. Much research is now being done to develop microbes are sustainable in higher concentrations of butanol, so as to reduce the power consumption of the separation process. At the same time, separation process are being developed that are less energy intensive.
Cobalt Biofuels, Mountain View, California, recently announced that it has raised $25 million in equity to accelerate the commercialization of biobutanol. The Series C equity round was co-led by LSP and Pinnacle Ventures and included both new and existing investors.
"With this round of funding Cobalt Biofuels will move aggressively toward commercial production of cost effective, non-food based biobutanol,” said Pamela Contag, President and CEO of Cobalt Biofuels. New Energy and Fuel reported that Cobalt is using these funds to expand from laboratory scale production to a pilot scale facility with a capacity of 35,000 gallons of fuel per year .
Cobalt has proprietary technologies in microbial physiology, strain development, fermentation and low-energy fuel separation, which they claim make possible a new generation of fuels that burn cleaner, are more cost-effective, and enhance environmental sustainability.
According to Cobalt, biobutanol is a next generation biofuel that can be used as a standalone transportation fuel, as an additive to gasoline or diesel fuel and as an additive to improve the properties of ethanol. Unlike ethanol, biobutanol can be used at full strength in today’s automobile engines and can be distributed through existing pipelines.
Cobalt technology will change the biofuel industry by:
- Allowing production of biofuels from local feedstocks based on regional agricultural priorities, including plants that are not subject to food price fluctuations
- Increasing the rate of biofuel production through continuous fermentation
- Improving yield by optimally pairing fermentation organisms with a diversity of feedstocks
- Its patented vapor compression distillation separation system significantly reduces energy and water requirements