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One Size Doesn't Fit All-Designing the Right Biomass System for You

By Tera Buckley | May 31, 2010
Renewable energy advocates are praising the 30 states and the District of Columbia for adopting regulatory policies requiring the increased production of renewable energy and the five states that set voluntary goals. It's a good thing right? After all, those states will be limiting fossil-based carbon emissions and will create green energy jobs to counter the effects of the recent recession.

But some of these renewable portfolio standards aim to achieve 25 percent renewable energy in just a decade or so, with much of that energy coming from biomass. Relying on biomass, without a good basis for that reliance, may violate some of the basic principles of supply and demand.

No biomass is uniformly available across the U.S. or even within individual counties. The fact is one size doesn't fit all, and there is no single ideal biomass source. While some sources may have ideal combustion and cofiring properties, such as wood, other sources such as corn and soybeans are optimal feedstocks for fuel production.

The Energy & Environmental Research Center is advancing a suite of technologies that can be tailored to the resources available and the needs of each client.

The best biomass resource for a particular energy production scenario will depend on multiple factors that need to be assessed on a case-by-case basis:

Availability and cost of biomass depends on supply and demand. Many biomass sources are already used in other applications and may not be accessible or economical to use as an energy source. For example, agricultural residues are generally difficult to collect and are composted in the field to maintain soil quality.

Physical and chemical properties of the biomass will vary depending on the species, geography, climate and harvest time. This variability is of particular concern when the impact is considered on the slagging, fouling and particulate emissions associated with utilizing the biomass as an energy source.

Energy content/heating value can range from 14,000 Btu per pound, found in scrap railroad ties with nearly no moisture, to 2,600 Btu per pound, typical of leaves and grass clippings with up to 60 percent water.

Transportation costs will likely be the determinant of acceptable moisture and energy content for given biomass applications. Transportation logistics also need to be considered for each scenario.

Land ownership impacts biomass availability and future growth potential. About one-half of the total acreage in the U.S. has some potential for growing biomass. Nearly 60 percent of the land in the U.S. is privately owned, and the federal government owns 28 percent.

Plant logistics such as size; feed ratio with coal (for cofiring scenarios); resource processing requirements (drying, shredding, pulverizing, separating); storage options; and availability of process utilities for conditioning as-received resources also need to be considered.

The right mix takes a multitude of factors into consideration-not because the government mandates it, not because environmental groups support it, but because it makes sense for the particular situation.

The EERC has conducted numerous resource and technology assessments that utilize biomass, and in every case, it has been imperative to verify the information on a local level and test the specific biomass source to be used.

Each application requires a thorough technoeconomic assessment and analysis of available feedstocks prior to being selected for energy generation or product development. In this way, biomass can be made to fit.


Tera Buckley is a marketing research specialist at the EERC. Reach her at tbuckley@undeerc.org or (701) 777-5269.
 

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