Biomass is a sustainable energy resource consisting of organic matter which typically comes from recently living organisms. The majority of biomass resources are composed of plant material or derived from plant material. These sources are regenerated constantly by plant growth. A common example of biomass is wood, which is often burned for heat energy.
Other types of biomass include native grasses, corn materials, soybeans, coconut husks, fruit pits, sugar cane, and some types of waste material.Top
An energy crop is grown specifically for its fuel value. These include food crops such as corn and sugarcane, and nonfood crops such as poplar trees and switchgrass. They are usually fast growing species that can be ready for harvest in a short period of time. A feedstock is organic material that can be processed into a form of energy.Top
Good energy crops have a high yield of dry material per unit of land. This reduces the land needed for energy production and lowers the cost of biomass energy. Additionally, these crops require low inputs in relation to the energy they provide.Top
Gasification is the partial burning of biomass material to create specific gases, generally referred to as "Producer Gas" (or "Synthesis Gas"), which is similar to natural gas. This gases can be used in various energy production systems such as direct heating, fuel for internal combustion engines, and production of industrial chemicals such as methanol.
The gasification process has been used for well over 180 years. Until the widespread availability of natural gas in the 1950's, coal gasification was used to produce the gases used in many city street lights. Commercial development was not seriously explored for decades due to the expanding use of less-expensive petroleum-based products. During the oil crisis of the 1970's, research and development in biomass gasification technologies were once again brought to the forefront. With the increasing cost and potential availability problems of petroleum, biomass gasification has once again returned to the forefront as a economically viable renewable energy source.
To maximize production and minimize costs, a consistent, quality, and sufficient supply of biomass materials should be in close proximity to gasification facilities. This requires the development of new and efficient technologies for obtaining and storing biomass materials.Top
Fossil fuels were formed from organic material compressed over thousands of years and have a very high energy density due to their chemical composition. This means they can be easily transported and utilized as an energy source. Biomass, on the other hand, has a lower energy density, thereby requiring a larger volume to produce an equivalent amount of energy. Fossil fuels require thousands of years to generate, whereas biomass can be easily generated annually making it a renewable and sustainable product.Top
The production of ethanol and the resulting producer gas of biomass gasification require very different processes. Ethanol is produced through the breakdown of starches and sugars in a low oxygen environment to create alcohol fuel. The process of biomass gasification involves heating biomass to create producer gases to be used in various applications.Top
To reduce costs, biomass should be located within 20-50 miles of the gasification facility. Appropriate (and potentially large) storage facilities need to be located in close proximity to the facility. Most importantly, however, is ensuring that a quality and sufficient supply of biomass can be obtained.Top
The gasification of biomass does produce some pollutants. However, unlike many fossil fuel based facilities, biomass gasification facilities create pollutants that are more easily removed and handled. Specifically, biomass gasification facilities do not generate pollutants including metals (such as mercury), as these metals are not present in the biomass material. As an example, corn stover when gasified creates chlorine gas which reacts with hydrogen to create hydrochloric acid (HCl). To remove the HCl from the emissions stream, emissions are processed with a sodium hydroxide mixture in a scrubber which neutralizes the HCl and reduces the associated risks of exposure. Additionally, scrubbers are installed to 'clean' the emissions stream to acceptable and safe levels.Top
When biomass is converted to energy with the gasification process, all of the carbon released was captured (by the biomass) during its life cycle. This results in no additional carbon added to the environment (unlike resulting carbon emissions from the processing and consumption of fossil fuels, whose carbon has been 'locked up' for thousands of years).
There are concerns that the growing biofuels market is placing strain on the food supply -- the thought that increasing biofuel production using grain and animal feed products limits the availability of food products. Corn stover (stalks, cobs, leaves, etc.) gasification only uses the byproducts and waste generated during the corn harvesting process. As a result, the food supply is not directly affected by the consumption of biomass. Research is also being done on using marginal lands (land with low production agricultural value) to produce biomass products, which would not interfere with food production.Top