Scientific study denounces ethanol production from corn

A US study has cast a pall of doubt on the environmental benefits of corn-ethanol E85 fuel, concluding that at best it amounts to little other than ‘environmental problem-shifting’ and boosting the stocks of one of the industry’s more promising new players.

The publication of the study comes just three months after Coskata Inc, a startup company specialising in the manufacture of woodchip-derived cellulosic ethanol, announced its pending US$100 million initial public offering (IPO) on the Nasdaq.

Coskata’s proprietary gas fermentation technology has the potential to synthesise a range of chemicals and fuels from woodchips and waste biomass, most notably ethanol. The company claims high yields per input tonne at low cost. It estimates its commercial scale plant will be good for around 100 gallons of ethanol per dry ton of softwood feedstock via its hybrid biothermal process – about 30 to 50 per cent up on other thermochemical and biochemical processes respectively.

Based on a feedstock cost of $64 a ton of softwood, the company claims this will pan out to an unsubsidised operating cost of less than $1.50 a gallon, potentially solving one of the ethanol fuel industry’s biggest dilemmas.

Corn is the primary source of fuel ethanol in the US. The complex well-to-wheels study, found that taking the full matrix of environmental impacts into account, the overall environmental detriment of E85 using corn-sourced ethanol is anything up to 108 per cent greater than petrol.

The results of the study, run by a team from the Universities of Minnesota, Troyes (France), and California (Santa Barbara), have been published in the American Chemical Society’s (ACS) scholarly journal Environmental Science & Technology. The ACS is America's peak body of scientific inquiry in the field of chemistry. ES&T is one of a raft of journals it publishes covering the discipline’s interaction with other fields.

The authors of the study (‘Replacing Gasoline with Corn Ethanol Results in Significant Environmental Problem-Shifting’) aggregated the results in accordance with complex procedures and weights approved by the National Institute of Standards and Technology (NIST).

They concluded that the overall environmental detriment of E85 varies from six to 108 per cent (23 per cent on average) greater than that of petrol, depending on where and how the corn is produced. Those factors influence things considerably – with corn needing intensive irrigation, the impact of artificial fertilisers and the like, especially on local water supplies, varies dramatically from one locale and state to the next.

For the study, the team used a suite of environmental impacts common to both corn ethanol and petrol, extending to greenhouse gas emissions arising from changes in land use, factoring in areas of uncertainty to help smooth data.

At the ‘well’ end, the analysis took into account feedstock production, shipment of the feedstock to the refinery, refining/conversion, shipment of the fuel to the refuelling station, and vehicle operation. For petrol, it took into account that the majority of petroleum product hails from crude oil imported then refined domestically.

At the ‘wheels’ end, it used the established GREET greenhouse gas emissions measurement model, taking as a benchmark the amount of fuel needed to drive 1km in an average gasoline-powered car and a flex-fuel vehicle.

The initial procedures led the team to conclude that “E85’s heavy impacts on eutrophication, water use, and land occupation outweigh the modest benefits in other impact categories, such as global warming, ecological toxicity, and fossil energy consumption.”

Run through a so-called ‘Monte Carlo simulation’, using a computational method well established for validation in situations where multiple variables raise uncertainty and risk, the results were similar and conclusive enough to satisfy the Society’s publication criteria.

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