Energy From Biomass Flashcards
Explain the term biomass
Biomass is a general term for material derived from plants or animal manure
Identify two crops that are commercially grown to produce biomass
Willow
Poplar
Elephant grass
Maize
Sugar cane
Briefly describe the global debate that surrounds farmers growing crops for energy
Food versus fuel
Global population increasing at a dramatic rate. This is increasing the demand for food for basic human survival. Should farm land be used to grow energy crops instead of food produce?
(I) identify two different advantages of replacing coal with biomass at this power station
(II) state one disadvantage of converting all six units to burn biomass instead of coal
(I) biomass fuel is a renewable energy source/ can be replaced in a human lifetime whereas coal takes millions of years to form/ cannot be replaced in a human lifetime.
Combustion of biomass contributes much less to atmospheric carbon dioxide levels/is carbon neutral/ does not contribute to global warming
(II) biomass is more expensive to use compared to coal
Biomass is less efficient compared to fossil fuels
Biomass requires more land for production
State the typical (%) of energy from combustion that is obtained from biomass
In the range of 90%
State the main process used to obtain energy from biomass
Combustion/ burning
Explain the term energy density
Energy density is the amount of energy stored in a given system or region or space per unit volume or mass
State two properties which could be compared and contrasted when assessing different types of woodchip for use as biomass fuel
Moisture content
Porosity
Bulk density
Energy density
Woodchip is a form of biomass that can be commercially produced. Explain the effect of moisture content on one property of woodchip fuels
Higher moisture content results in woodchip with lower energy density. As energy must be used to evaporate the water before combustion occurs
Outline the process of gasification in relation to biomass
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide
This is achieved by reacting the material at high temperatures, without combustion, with a controlled amount of oxygen and/ or steam to produce syngas
Describe the process of gasification of biomass
Biomass is converted into a mixture of carbon monoxide
And hydrogen
Commonly known as syngas
State three applications in which the main product of the gasification of biomass can be utilised
Used in the production of ammonia
Used in the production of methanol
Used as an intermediate in producing synthetic petroleum
Or can be used as lubricant in chemical processes
Syngas is combustible and often used as a fuel of internal combustion engines
Certain types of biomass can undergo anaerobic digestion. Describe the process of anaerobic digestion
Anaerobic digestion is a biological process that results in the breakdown of organic matter by naturally occurring bacteria in an environment that has absence of oxygen
Discuss the advantages and disadvantages of using commercial anaerobic digesters
Advantage;
Treat waste and reduces greenhouse gases
Produces a biogas that can be used as a fuel
AD can take place at a location local to where waste or energy crop is produced- therefore reduces the need for transportation
Disadvantages;
Requires a steady supply of a consistent feedstock
Quality of the gases produced will vary, therefore potentially increasing the need for a gas cleansing process to protect the combustion equipment
The process can be slow, particularly during the winter months and may require the addition of extra heat
Outline three advantages of commercial anaerobic digesters
AD offers an option to treat waste and produce biogas that can be used as a fuel
AD diverts the methane that would be released from landfill into the generation of electricity, thereby reducing atmospheric methane levels/ greenhouse gas emissions
AD can take place at a location close to where organic/farm waste is produced therefore reducing the need for transportation/ providing local jobs/providing electricity supply/providing waste management options
