Biomass

Question 1

Explain the term Biomass; {1}

Answer 1

Biomass is a general term for material derived from plants or animals. {1}

Question 2

Define what is meant by the term biomass. {1}

Answer 2

Material that is derived from growing plants or animal manure. {1}

Question 3

Identify three crops that are commercially grown to produce biomass. {2}

Answer 3

Maize
Sugar Cane
Willow

Question 4

Briefly describe the global debate that surrounds farmers growing crops for energy. {2}

Answer 4

Global population increasing at a dramatic rate. This is increasing demand for food for basic human survival. Should farm land be used to grow energy crops instead of food produce? {1}

Question 5

Identify two different advantages of replacing coal with biomass at a power station. {2}

Answer 5

Biomass fuel is a renewable energy source can be replaced in a human lifetime whereas coal cannot.

Combustion of biomass contributes much less to carbon dioxide levels than coal, biomass doesn’t contribute (as much) to global warming.

Question 6

Identify two different disadvantages of replacing coal with biomass at a power station. {2}

Answer 6

Biomass is more expensive to use compared to coal.

Biomass is less efficient compared to fossil fuels.

Biomass requires more land for production.

Question 7

State the typical (%) of energy from combustion that is obtained from biomass. {1}

Answer 7

90%

Question 8

State the main process used to obtain energy from biomass. {1}

Answer 8

Combustion / burning. {1}

Question 9

Explain the term energy density. {1}

Answer 9

Energy density is the amount of energy stored in a given space per unit volume or mass. {1}

Question 10

State two properties which could be compared and contrasted when assessing different types of wood-chip for use as biomass fuel. {2}

Answer 10

Moisture content.

Energy density

Question 11

Explain the effect of moisture content on one property of woodchip fuels. {2}

Answer 11

Higher moisture content results in woodchip with lower energy density {1}. As energy must be used to evaporate the water before combustion occurs {1}.

Question 12

Outline the process of gasification in relation to biomass. {2}

Answer 12

Converts organic or fossil based materials into carbon monoxide, hydrogen and carbon dioxide. {1}

This is achieved at high temperatures, without combustion, with a controlled amount of oxygen and / or steam to produce syn-gas. {1}

Question 13

Describe the process of gasification of biomass. {3}

Answer 13

Biomass is converted into a mixture of carbon monoxide {1}

And hydrogen {1}

Commonly known as syngas. {1}

Question 14

State four applications in which the main product of the

gasification of biomass can be utilised. {3}

Answer 14

ammonia. {1}
methanol. {1}

Used as an intermediate in producing synthetic petroleum. {1}

Used as lubricant in chemical processes. {1}

Question 15

Certain types of biomass can undergo anaerobic digestion. Describe the process of anaerobic digestion. {2}

Answer 15

Anaerobic digestion is a biological process that results in the breakdown of organic matter {1}
by naturally occurring bacteria in an environment that has an absence of oxygen {1}

Question 16

State two advantages and two disadvantages of using commercial anaerobic digesters. {2}

Answer 16

+ Treats waste and reduces greenhouse gases.
+ Produces a bio-gas that can be used as a fuel.

• Requires a steady supply if a consistent feedstock.
• The process is slow in winter months and may require extra heat.

Question 17

Outline three advantages of using commercial anaerobic digesters. {3}

Answer 17

+Treats waste and produces biogas that can be used as a fuel.

+Methane that would be released from landfill is used for the generation of electricity.

+AD can take place close to where organic waste is produced, reducing the need for transportation, local
jobs, electricity supply, and waste management options.