Energy from waste

Question 1

Roughly what proportion of the UKs energy demand is due to heat

Answer 1

Roughly 40%

Question 2

How much of the UKs heat energy comes from renewable sources

Answer 2

12%

Question 3

What sort of solids are viable to produce energy from combustion of waste

Answer 3

Lingo-Cellulosic
Municipal waste
Construction and demolition waste

Question 4

How can wet biomass be used to produce energy

Answer 4

Though production of gas which can be burnt

eg from anaerobic digestion

Question 5

How can power plants use their waste heat

Answer 5

For other applications such as there is a power plant that uses its waste heat to produce heat for a swimming pool

Question 6

What biomass feedstocks have a typical energy per volume and which have a low one

Answer 6

High for low moisture wood, paper and sugar cane

Low for grass, dung, straw

Question 7

What are examples of Biochemical biomass conversion

Answer 7

Fermentation, Anaerobic and aerobic digestion

Question 8

What are examples of thermochemical biomass conversion methods

Answer 8

Pyrolysis, Gasification, Liquification

Question 9

What does the combustion of hydrogen produce

Answer 9

Water

Question 10

What does the combustion of carbon produce

Answer 10

CO2 and water

Question 11

What will combustion of nitrogen produces

Answer 11

Nitrous oxides at high temperatures

Question 12

What gasses produced from combustion may lead to acid rain

Answer 12

Nitrous oxides
Sulphurous oxides
Hydrogen chloride

Question 13

Give an example of a power station that uses biomass to produce power

Answer 13

Eye power station produces electricity from the combustion of chicken droppings and straw

Question 14

What is the drawback from combined heat and power stations heat and power

Answer 14

Cannot produce heat and power at max efficiency, to obtain usable heat the electricity efficiency must go down

Question 15

What can be done to power plant exhausts to try and reduce environmental impact and what are the drawbacks

Answer 15

Filters and scrubbers can be used but this reduces efficiency and cant remove all pollutants

Question 16

What do we need to produce electricity from biomass

Answer 16

Combustion chamber, Pollution control, boiler, turbine, compressor

Question 17

What is a good and a bad use of ash

Answer 17

Can be used as a fertiliser but can also go to landfill

Question 18

What are the benefits from burning waste as a fuel

Answer 18

Uses waste
Prevents dumping to landfill
Allows destruction of dangerous contaminants

Question 19

What are some disadvantages of burning waste as fuel

Answer 19

Much of the energy may have Been stripped from the material and pollutants may have been added

Question 20

What are the features of a goof feedstock for combustion

Answer 20

Homogenous in composition 
Uniform in size 
small particles 
mixed well with air 
high calorific value

Question 21

What are the disadvantages if making biomass more suited to combustion

Answer 21

Drying requires energy but waste heat from overall system can be used for this.

Question 22

What feedstocks produce high, low and intermediate ash content

Answer 22

High- sewage sludge
intermediate- animal waste
low-paper

Question 23

How does combustion by moving grates work

Answer 23

Waste is loaded onto a moving great where it passes through a furnace and deposits ash at the end, Air is blown across and from bellow to prevent overheating

Question 24

How does combustion by fluidised beds work

Answer 24

A bed of incombustible material such as sand is stimulated with air so it behaves like a fluid and biomass is fed into bed

Question 25

What is produced by anaerobic digestion

Answer 25

CH4, digestate, CO2 and potentially NH3 and H2S depending of feedstock