New Energy Economics: Field Peas As An Ethanol Feedstock

Corn has become the mainstay of ethanol production. However, many firms are investigating new feedstocks, such as switchgrass, forest products and algae, to produce cellulosic biofuels that meet pending federal and state regulations.

Biofuel production from most of these alternative feedstocks has not been commercialized as yet. Moreover, numerous agronomic and environmental challenges also exist, given rotational restrictions, fertility needs and residue management.

One crop that has potential as a biofuel feedstock and is wel adapted to small-grain rotations in the northern Plains is field peas. Two NDSU graduate students, Abhishik Goel and Andrew Wilhelmi, recently completed research projects investigating the potential of field peas.

Agronomically, field peas fix nitrogen, which lowers production costs and reduces the crop’s carbon footprint. If you recall, greenhouse gas considerations are an important aspect in future biofuels. In addition, field peas can break disease cycles prevalent in traditional small-grain rotations.

Field peas must be fractionated before being used for ethanol production. Fractionation is a process where raw field peas are ground and then separated into component parts, which primarily are starch and protein. The protein portion is sold in traditional marketing channels as livestock feed. The starch portion is blended by up to 10 per cent with corn and fed directly into an ethanol plant.

There are two advantages of utilizing more field pea starch, which is more concentrated, when producing ethanol. First, because the feedstock is concentrated, less material has to be handled. This increases plant efficiency and leads to higher throughput and productivity. Second, our research found that the addition of pea starch to corn accelerates the fermentation process, which again increases plant capacity.

Field peas are price competitive when corn rises above $4.34 a bushel. The graduate researchers also found that local field pea availability reduces corn supply risk. While North Dakota has considerable corn acreage, a significant portion of the crop is fed to livestock and marketed out of state. Therefore, in a short crop year, ethanol plants periodically have to purchase corn elsewhere and incur high rail freight charges. An increase of field pea acres could diversify ethanol plant feedstock supplies.

At present, the investment cost of fractionation equipment is a significant financial impediment. Commercialscale equipment to support a 100-million-gallon-per-year ethanol plant is not available. In our study, three small systems were included, but their cost was much higher than one large machine would have been. If industry demand for larger fractionation equipment evolves, investment cost per dry weight of peas processed likely will fall, which in turn would increase field pea biofuel profitability.

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