Companies focus on plant waste to make ethanol
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Making fuel from food sources is drawing substantial negative reaction, including rising prices. The answer, according to several companies, is to use plant wastes and even industrial and household wastes.
What if Toronto could not only stop trucking its garbage to Michigan, but avoid burying it in its newly acquired St. Thomas landfill site as well? And what if, instead of paying steeply to dispose of it, the city could actually generate revenue by selling that garbage.
Such seemingly far-fetched ideas could well become feasible realities within the next few years if the current promises of cellulosic ethanol production are realized.
The reputation of ethanol (ethyl alcohol) made from corn, which is the feedstock for almost all the current North America supply, has been sullied recently by questions over the wisdom of using food crops for fuel, the effect such production has on food prices, and uncertain lifecycle energy and environmental benefits
"Those first-generation biofuels have served their purpose," according to Larry Burns, executive vice-president responsible for research and development at General Motors, one of fuel ethanol's biggest boosters.
They have supported the building and sale of over 7 million flex-fuel vehicles capable of running on gasoline-ethanol mixtures of up to 85 per cent ethanol (E85) – if it were available.
But even without an E85 infrastructure, we are going to need more ethanol just to satisfy the recently-mandated federal government requirement that all gasoline contain 5 per cent of the alcohol by 2010.
Ontario's gasoline is already at that concentration and set to increase to 10 per cent in 2010, and U.S. requirements for ethanol use are even more demanding.
To meet that demand and offset the negatives associated with corn-based ethanol, the focus has now shifted to second-generation biofuels, according to Burns, such as so-called "cellulosic" ethanol, which are produced from non-food sources.
Those sources incude the non-edible parts of plants such as corn and sugar cane, wheat straw, switchgrass or prairie grass, and plain old wood.
Canadian companies such as Enerkem and Iogen are among many in North America at the forefront of this development, and several commercial-scale plants are now planned or under construction.
But a few companies are working on processes that go further to accommodate an even broader range of feedstocks, including both industrial and household wastes.
One such company, Coskata, burst into public prominence in January when GM announced that it was not only supporting its work but investing in the company.
I recently visited Coskata's laboratories on the outskirts of Chicago to witness first-hand the production process, and learn how it works.
Unlike other cellulosic processes, which begin by breaking down the lignocellulose in plant matter using chemical or biological methods, the first step in the Coskata process is gasification of the feedstock, explained company president and CEO Bill Roe.
That feedstock can include cellulosic materials such as wood chips, corn stover and other biomass, but also discarded materials such as tires and other municipal and industrial wastes – even animal byproducts.
Three or four different gasification processes can be used, depending on the feedstock, Roe said, but the one most suitable for gasifying a broad range of wastes is a plasma process already developed and proven by Westinghouse for other purposes.
It effectively decomposes the raw materials into a synthetic gas (syngas) and ash at very high temperature, without combustion.
The syngas then becomes the raw material for conversion to ethanol in a bioreactor, via treatment with proprietary microbes that have been evolved by Coskata to provide a high level of efficiency. The resultant product is pure ethanol, which is extracted from water by distillation.
Roe says the process can produce more than 100 gallons (U.S.) of ethanol per ton of feedstock (about 400 litres/tonne), which is significantly better than most other processes, and that it can be cost-advantageous to gasoline.
It also has an energy ratio (energy out to energy in) that is five times better than for corn-based ethanol, uses far less water to produce, and releases only a minimal amount of CO2.
A pilot plant incorporating the complete process, now under construction at an established Westinghouse plasma gasifier site in Pennsylvania, is scheduled for completion early in 2009. And full-scale commercial production is scheduled for 2011.
Not only could such a process keep wastes out of landfill, it could turn them into valuable resources.
And because production plants could be located close to major population centres, the transportation costs involved in both waste disposal and fuel delivery could be substantially reduced – a multiple-win situation, according to Roe.
So much so, suggested Wes Bolsen, Coskata's chief marketing officer, that 10 years from now, "any company that is still putting waste into a hole in the ground had better be prepared to face the wrath of its shareholders."
Presumably city governments will be similarly accountable to their electors as well.
We can hope.
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