Can We Grow Our Own Electricity?

Apparently we can! Viaspace, a producer of renewable Giant King Grass that can be used as a low carbon fuel for electricity generation, has signed a supply contract with bioenergy project developer ReSource Bioenergy to supply its energy grassfor bioenergy projects in Jamaica through its affiliate Jamaica Bioenergy.

According to Viaspace, Giant King Grass is suitable as a fuel for direct combustion in biomass-to-electricity generating power plants. Today, biomass power plants are fueled by agricultural and forestry waste such as corn straw, wheat straw, rice husks and wood waste. The price of agricultural waste has increased globally due to market demand, and in many areas, growing Giant King Grass as a dedicated energy crop has been reported to be less expensive and more reliable than using waste.

Another challenge with agricultural waste is that it is seasonal, since it is only available after the food crops have been harvested. The reliability, consistency and cost of biomass fuel are the major issues facing biomass power plants today. However, Viaspace claim is that a dedicated Giant King Grass plantation co-located with a power plant is a cost effective and reliable solution to producing clean electricity.

The Giant King Grass, which is said to have undergone several independent testing, has energy content (18.4 MJ/kg or 4400 kcal/kg or 7900 BTU/lb), physical properties and ash properties very similar to corn straw that is used routinely as a fuel in biomass power plants. The Giant King Grass, due to its promised fast-growing nature and dependable characteristics, should allows power plants to run 24 hours a day, seven days a week without interruption or variable output due to availability or inconsistent performance of the fuel.

Schematic of Direct Combustion Biomass Power Plant

In order to generate electricity, a direct combustion biomass plant burn bio-waste in boilers to produce high pressure steam. The steam then turns a turbine that is connected to a generator (alternator), as the turbine rotates, the generator turns, and electricity is produced. This is the simplest and oldest way to generate electricity from biomass. To increase the energy-producing efficiency, a direct combustion biomass power plant is normally configured as co-generation facilities, which all for capture and reuse of waste heat and secondary steam to heat buildings and provide steam and heat for industrial processes.

Agricultural waste and Giant King Grass have different properties than coal and require a different boiler technology. Biomass power plants are usually 10 to 30 MW in size which is much smaller than coal power plants and thus make a great match for electricity grids in the Jamaica and the Caribbean. Most of the world’s biomass power plants use direct combustion to produce renewable and low carbon electricity.

In terms of capital cost a direct combustion biomass power plants have a much lower capital investment than other renewable energy technology, and much of the technology is widely available. Also depending on the availability of feed stocks, the cost of electricity is much cheaper than electricity produced using fossil fuels, furthermore, biomass can produce low carbon electricity 24 hours a day which makes it a great substitution for fossil fuel plants that provide firm capacity.

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