Introduction
Biomass energy, in the form of heat and power, is created by the combustion or gasification of carbon-based plant matter. Biomass energy is considered demand energy, available as/when needed. Woody biomass is the most commonly used form of biomass fuel. It is used directly as firewood, or it can be processed into woodchips or densified into pellets or bricks. Woody biomass is inherently a distributed resource: finding, acquisition and gathering, stacking, and storage are the initial challenges with biomass fuel.
Processing biomass ranges from the simple (bucking logs into suitable lengths), to chipping or chunking (chippers are commonly available machinery), to the more complex (densification that involves chipping, drying, and compressing biomass into pellets, bricks, or logs). As the levels of complexity rise, the benefits of proper handling and storage of the fuel become more pronounced.
How Biomass Works
Hydronic (hot water) furnaces and boilers combust stick-wood to heat water or other fluid, which can then be transported and used nearby as district heating for buildings, for example, or process heat for manufacturing. Alaska has nearly 12 million acres of available forested land, with an estimated 1.9 million cords (3.7 million tons) of annual growth. On average, over 1.5 million acres per year of forested land are subject to wildfires and beetle-kill. Some of the wood on these affected lands is salvageable as biomass fuel. Alaska grows substantially more biomass than it uses for energy.
Despite the obvious opportunities, there are also significant transportation and technical challenges related to the deployment of biomass energy devices in Alaska’s urban or rural communities. Some challenges are common to installations in any location, while others are more specific to Alaskan off-road communities.
Biomass Projects in Alaska
Larger scale wood-fired power systems are quite common throughout Europe, the United States, and Canada, especially at forest-products manufacturing facilities, places that have the basic ingredients for economic and technical feasibility: large demand for power, heat required for lumber drying or other processes, and plentiful wood waste that needs to be disposed or used. Conventional biomass-fired plants totaling over 60 MW in capacity operated at pulp and sawmills in Ketchikan, Sitka, Metlakatla, Haines, and Klawock into the 1990s. Retrofitting and re-permitting existing coal power plants to co-fire wood and other biomass represents another common bioenergy alternative in the Lower 48. In Alaska, Eielson Air Force Base’s coal power plant co-fired densified paper separated from the Fairbanks borough waste stream until 2007.
Stand-alone, small biopower or combined heat and power (CHP) technology is generally considered pre-commercial in the U.S. While European and Asian firms have commercial experience and demonstration projects abound in the Lower 48, most systems are complex and have significant technical and economic challenges.
Cordwood is commonly used for heating throughout Alaska. Cordwood-fueled community scale heating systems have been demonstrated in several communities in Alaska, in Dot Lake and Tanana, for example. A woodchip-fired school and community pool heating system was recently installed in Craig, and that heating system has been considered for other communities as well.
Small, wood-fueled Combined Head and Power (CHP) systems are planned by Chena (400 kW) and by the Cold Climate Housing Research Center (CCHRC) in Fairbanks (25 kW).
Challenges in Biomass Energy
While biomass produced energy has the benefit of reducing fossil fuel use, biomass also has the potential to be a pollutant. Incompletely burnt biomass (as with fossil fuels and biofuels) creates black carbon - the second largest contributor to greenhouse gas pollution. So, if biomass is to be used as an alternative fuel for the purpose of reducing one's carbon footprint, the proper infrastructure and combustion equipment is required.
Biomass Technology
| TECHNOLOGY SNAPSHOT: BIOMASS | |
|---|---|
| Installed Capacity (Worldwide) | Globally, biomass is the fourth largest energy resource after coal, oil, and natural gas. Uses: heating, cooking (biomass), transportation (biofuels), and electric power generation (biopower). NREL estimates 278 quadrillion BTUs of worldwide installed biomass capacity. EIA estimates >2.8 quadrillion BTUs of U.S. biomass energy consumption (2004) |
| Installed Capacity (Alaska) | Biomass – (heat & cooking) widely used; Biopower - 0 kWe (currently no commercial installations); Biofuels – (biodiesel, ethanol) demo projects |
| Resource Distribution | Potentially available to communities in all regions of Alaska with adjacent or transportable biomass resources. Alaska has >10 times more unused biomass energy resource potential than needed to offset all its diesel fuel used for power production in rural Alaska. |
| Number of communities impacted | 100+ SE Alaska and Interior |
| Technology Readiness | Biomass – commonly deployed (heat); Biopower – Pre-commercial to early commercial; Biofuels – limited deployments (fish oil/biodiesel) |
| Environmental Impact | With proper management, impact on local forest land and species is generally considered to be positive. 1.5 million acres are lost annually to wildfire in Alaska, and thinning reduces fire risk. |
| Economic Status | High confidence in cost savings and localization of benefits for heat. O&M creates local jobs and savings. Bio-Power has high projected cost with limited potential at this time. |
| Case Studies | Tanana (Heating System), City of Craig (Heating System), Village Power CCHRC 25kW Gasifier, Community CHP Fairbanks 400 kWe ORC, Sealaska’s wood pellet fired boiler |
| Biomass Working Group | |
To learn more about the technology behind biomass energy production, click on the link below:
BIOMASS TECHNOLOGY
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Links and Resources
- Biomass: A great .pdf detailing the idea behind biomass technology and energy production. A good introduction for beginning research.
- DOE, Energy Efficiency & Renewable Energy: Biomass Program Home Page.
