Friday, May 22, 2009

Biomass to Energy Two Different Ways

Cellulosic biomass to ethanol, Ecostrat Biorefinery project in Missouri:
Jordon Solomon of Ecostrat explains how the critically important supply of biomass for the Marshall, Missouri biorefinery will be obtained initially and then maintained for the long haul.
The intake of biomass for ethanol production is expected to be 450,000 tons yearly. The annual intake for power production is expected to be 200,000 tons.

"The initial woody biomass needs to come from quite far away. There just isn't 650,000 tons within 100 miles of your town available sustainably," said Solomon.

About 10 percent of the biomass taken in by the facility will be waste, said Solomon, and he mentioned Galveston, Texas, where "almost half a million tons of hurricane debris (is) sitting there, rotting, emitting its carbon into the atmosphere, and shouldn't that be coming here and being made into ethanol?"

The remaining 90 percent of biomass will be "more traditional biomass," he said.

"When you're putting up a large-scale production like this, the most important element is reliable biofuel supply."

During the first three years of the complex's operation, woody biomass provided by Ecostrat will be used. Between years four and six, the refinery will transition to an energy crop. After seven years, the transition will have been completed, and the complex will operate only on the energy crop.

The energy crop Ecostrat has identified is called Miscanthus giganteus, a perennial sterile grass that can grow to more than 13 feet tall. It grows in the spring and will return for 10 or more years after rhizomes are planted. It requires no fertilizer besides leftover leaves, requires no pesticides and can be grown on less-than-fertile land that Solomon called "class three land," meaning it has high clay or sand content. _Bioenergy
If a bioenergy plant cannot get its biomass feedstock, it may as well be a lump of iron sitting in the rain for all the good it will do. The Ecostrat cellulosic ethanol plant intends to start at near full capacity, without having built up its local biomass supply in advance. There is some risk involved in that approach. Better would be a scaled up, modular approach to match growing local supplies of feedstock that are locked in. Whether miscanthus, switchgrass, poplar, or willow, the underlying cellulose source simply has to be available.
The second bioamass-to-energy approach is gasification. In particular, we will look at plasma gasification (at up to 20,000 degrees F). The high temperatures achievable via plasma gasification provide an ultra-clean syngas product.
In plasma gasification, biomass is fed into a closed chamber and superheated to temperatures of up to 20,000 degrees fahrenheit. The intense heat transforms biomass into syngas, which is then reformulated using into ethanol and green diesel, hydrogen, methanol or methane. A secondary process can convert the base materials into other industrial chemicals.

S4 Energy Solutions’ initial focus will be to process medical and other segregated commercial and industrial waste streams. The company’s future commercialization plans may also include the processing of municipal solid waste once the technology has been demonstrated to be economical and scalable for such use. The S4 technology is designed with unique advances in plasma technology that increase the lifespan of high-cost elements such as the refractories.

Tests of the unit have shown that there is no creation of dangerous dioxins, and the process produces hydrogen and carbon monoxide in a 1:1 ratio, while recovering 50-70 percent of the BTUs in the waste. _BiofuelsDigest
Part of the syngas is used to power gas turbines for electricity, to power the plasma itself. Excess electricity is sold to the utility. Excess syngas not used for electricity production can be used for multiple purposes including liquid fuels production and high value chemicals production.

Heat can be recovered from the process and used to power a steam cycle turbine for additional electricity, and to provide process heat -- or to produce environmental heat for commercial or residential use.

Municipal waste is a good feedstock for such a process, since the final product is purified so thoroughly by the 20,000 degree F temperatures. But should many of these plants be built, there will not be enough municipal waste to power them all, and they will need to contract with biomass suppliers in the agricultural and forestry sectors.

Biomass has the advantage of containing built-in solar energy storage. But it is not nearly as energy-dense as fossil fuels. Humans need to use a bit of ingenuity to find efficient ways of densifying biomass. Pyrolysis, gasification, torrefaction, etc. accomplish densification as an intermediate step.

Prior to those processes one needs to harvest, collect, dry, and often compress the biomass close to the source, before moving to intermediate processing above. As long as the biomass is produced locally and regionally for local and regional processing, transportation costs are kept to a minimum.

Producers of bioenergy need to be planting now, in order to have ample supplies of biomass available in a few years when they are ready to produce power and fuels.

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Blogger Peat said...

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10:35 PM  
Blogger al fin said...

Interesting, thanks.

3:49 AM  

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