October 20, 2009 | General

Why Modular Units Balance Local Carbon

BioCycle October 2009, Vol. 50, No. 10, p. 45
Biomass Energy Outlook
Mark Jenner

WE are all drawn to BioCycle because of our fascination with biomass utilization, yet we are each likely motivated by different facets. Near the top of my list is the benefit of local biomass generation and use, or balancing local available carbon. The longer I work with biomass economics the more impassioned I become about balancing local biomass supplies with local biomass demand.
Recent growth in the availability of modular units helps close the loop on the ability of communities to balance local biomass supplies with local demand. They also level the economic playing field between large centralized systems and small distributed systems such as home pellet stoves.
Modular technology in this case referrs to the reduced version of a commercial-scale process, or multiple processes, in one unit. Emerging technologies include ethanol and biodiesel plants as well as liquid and solid biomass-fueled power plants. Each successful modular system developer has taken multiple technologies and bundled them together as a sort of “black box.”
Depending on the technology, the user adds liquid or solid biomass fuel on one end, and gets a specific value-added product out on the other end. For example, IST Energy’s GEM technology includes a waste conditioner, gasifier and electricity generator. IST markets the unit as accepting waste in and delivering electricity out. Modular, here, means a small system of technologies within one integrated unit.
Small-scale, single technologies like recycling, composting, and generating power with wood function as components within a greater biomass management and utilization system. They have some of the same economic attributes as modular systems, e.g., balancing local biomass supplies with local demand, reduced capital cost and reduced marketing requirements. Small-scale technologies like pellet fuel production can become part of a local, efficient biomass management and utilization system.
Local biomass feedstocks frequently include residuals and wastes. For example, methane recovered at landfills, or generated at wastewater treatment facilities and manure digesters is fulfilling a dual role of waste treatment and energy production. Balancing local carbon includes the benefits of using local biomass to augment conventional waste treatment systems and become energy self-sufficient.


Biomass is costly to transport, so the closer it can be utilized to its point of origin, the lower the costs of using it. Raw biomass is less dense than fossil fuels. When the heat value and density are both considered, a fuel like wheat straw takes 14 cubic feet to provide the same energy content of one cubic foot of coal.
Modular units have the ability to better match local energy demand to local supply. Currently, even the economic viability of commercial-scale biofuel, power and fuel pellet facilities is challenged due to restrictions related to end market infrastructure development. The most difficult component of selling renewable energy is getting a fair market price.
For example, a manure digester for two similar farms may be feasible in one location, but not feasible in another simply because a fair price for electricity is not available. Additional complications arise in meeting standards for electricity, liquid fuels and natural gas. Progress is being made in opening up markets for distributed generation.
Smaller local systems encourage on-site use. By balancing available biomass to a local demand, smaller units avoid the need for either a market price or achieving market quality standards. Using as much biomass energy on-site as possible allows small producers to capture the highest value.
Modular units also can be mass produced. Designed to be turnkey systems, they can be installed and ready to go because all the necessary components are part of the package. As a result, these smaller units are sophisticated cost less on a per unit basis than separate feedstock, conversion technology and energy transformation processes. Siting a smaller capacity modular unit that balances local biomass supply and use will also be more cost-effective than siting a commercial-scale facility that imports and exports feedstocks and energy.
Modular technologies lower conventional costs further because they come packaged with an internal marketing infrastructure imbedded in the technology. If a modular technology uses MSW as a feedstock, it may bypass commercial feedstock processing costs that may be handled by a materials recovery facility. This lowers or completely removes the transaction costs of the intermediate products. In the case of the GEM technology mentioned above, no market is necessary to transfer intermediate products from one process to another outside of the black box. The biomass moves from feedstock preparation to gasification to power generation with effectively zero transaction costs.
This year, I have also become aware of two manufacturers producing small-scale home fuel pellet mills. These household units convert waste paper, cardboard and wood into fuel for the home. While I’m not advocating fuel use over recycling, in rural America recycling isn’t always an option. The development of another biomass technology component, like these home-heating pellet mills, adds another option in the carbon management toolbox.
There are economic reasons that make balancing local carbon appealing. Establishing a large, specialized commercial facility may not be the best economic solution. By reducing the high cost of transporting biomass and by capitalizing on increased efficiencies, these small, modular conversion technologies provide viable alternatives to the “Bigger is Better” axiom.

Mark Jenner, PhD, operates Biomass Rules, LLC and has over 25 years of biomass utilization expertise. Burning Bio News, the Biomass Rules newsletter, is available at

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