Biomass energy cubes: alternative to coal

A biomass briquette that could become to coal what ethanol has been to gasoline, is being made from a mix of plant materials that include wood, corn stalks and switch grass. Unlike raw biomass, the cubes can be blended with or substituted for coal in existing burners with little or no modifications. This advantage might enable fuel cubes to enable companies to use biomass without building new facilities.

Burning these fuel cubes creates far less pollution than fossil fuels and producing them has potential to boost rural economies. As with ethanol, there are concerns about whether harvesting material for the cubes will generate side effects that outweigh their value as an alternative.

The aggregate is not limited to wood, corn stalks and switchgrass, which is what makes this idea so versatile. Other grains (such as alfalfa), grasses, agricultural residues or even municipal solid waste can also be used as substitutes or in addition to these items. The process compresses the substances into dense, coal-like briquettes and processes them until just the right moisture content is achieved much like the process used to make BBQ grill briquettes.

They generate nearly twice as much energy as other biomass, putting it on par with coal from the western United States. The cost is competitive with coal in some markets.

When burned, the cubes emit 90% less sulfur dioxides, 35% less particulate matter and 30% less acid gases compared to coal. That’s based on testing at the University of Iowa with supervision by the U.S. Environmental Protection Agency.

Burning coal and gas releases carbon into the atmosphere that has been stored underground for centuries and was therefore not part of the natural balance. Using prairie grasses or grains won’t contribute because the carbon emitted was only recently stored in the plant material. Harvesting trees as a raw material would release carbon that had been stored there for decades as well as increasing pressure to clear forests. So the claim that using these briquettes instead of coal won’t contribute to global warming is true, depending on the raw material used.

A push is underway by a subgroup of Clean Energy Minnesota that is trying to come up with a system for scoring biomass fuels based on things like how much net energy they produce, how much carbon they divert from the atmosphere, and how else they affect the economy and environment.

Just as with the debate over using food products for ethanol based fuel, there is likely to be disagreements over using wood for biomass energy which could result in higher material prices for other industries.

The briquettes, cubes or pellets need to be produced close to the point at which they are grown in order to realize a transportation cost savings, because shipping costs for unprocessed biomass are far greater than for fossil fuels as they contain less energy per unit volume than fossil fuels.

For further reading:

Twin Cities Daily Planet

Biomass Energy

Role of Native Grasses in Wisconsin’s Bio-Energy Economy