How Is Bioenergy Made?

Bioenergy is any type of fuel or power that is produced from biomass. "Biomass" refers to materials produced by living organisms, for example the plant material generated through photosynthesis. Thus, bioenergy is a renewable source of energy, which means that production of this energy does not deplete actual resources. For industrial-scale bioenergy production, methods include the use of power boilers, combined heat and power systems (CHP) and gasifier systems.

Forms of Bioenergy

• Bioenergy takes both traditional and contemporary forms. For example, humans have used wood for cooking from the dawn of civilization. Today, bioenergy includes high-energy motor fuel and electricity, produced by converting biomass into high-quality energy products such as methanol.

Power Boilers and Combined Heat and Power (CHP) Systems

• The heat produced from power boilers generate steam, which is further utilized to generate electricity, with the help of turbines. Paper mills use recovery boilers similarly, so as to recycle black liquor and produce steam to drive the pulping process. Steam-turbine power boilers have an efficiency of 40 percent.

  A CHP system produces both heat and electrical power. Here, the steam produced powers other industrial processes. The efficiency of this system can be as high as 70 to 80 percent.

Gasifier System

• The gasifier system is used for advanced energy recovery. Gasification supports small-scale power delivery, helpful for villages and small-scale industry. The small-scale plants cost less and are easily accessible.

Wood Pellet Furnaces

• Wood pellet furnaces product bioenergy on a small-scale. For this alternative technology, wood pellets are produced from wood waste, such as sawdust and shavings. Once this raw material is dried and apportioned to size, it is extruded under immense pressure to form pellets.

First- and Second-Generation Biofuels

• Bioenergy also includes liquid and gaseous fuels. These fuels are referred to as either first generation or second generation. The first-generation biofuels are those are produced from food crops, such as bioethanol and biodiesel. Second-generation biofuels develop from other natural products, such as the lignin and cellulose components of plants.

Bioethanol and Biodiesel

• Bioethanol production consists of two steps: hydrolysis and fermentation. In hydrolysis, enzymes (called cellulases) break down long carbohydrate chains, such as cellulose, into small fragments of sugars. This is left to ferment, which breaks down the sugars into alcohol such as bioethanol.

  Biodiesel is produced from oilseed crops by extracting oil from the crops or by converting biomass residues at high temperatures to oils. The resulting oil is refined to form biodiesel.