Energy from waste Flashcards
Roughly what proportion of the UKs energy demand is due to heat
Roughly 40%
How much of the UKs heat energy comes from renewable sources
12%
What sort of solids are viable to produce energy from combustion of waste
Lingo-Cellulosic
Municipal waste
Construction and demolition waste
How can wet biomass be used to produce energy
Though production of gas which can be burnt
eg from anaerobic digestion
How can power plants use their waste heat
For other applications such as there is a power plant that uses its waste heat to produce heat for a swimming pool
What biomass feedstocks have a typical energy per volume and which have a low one
High for low moisture wood, paper and sugar cane
Low for grass, dung, straw
What are examples of Biochemical biomass conversion
Fermentation, Anaerobic and aerobic digestion
What are examples of thermochemical biomass conversion methods
Pyrolysis, Gasification, Liquification
What does the combustion of hydrogen produce
Water
What does the combustion of carbon produce
CO2 and water
What will combustion of nitrogen produces
Nitrous oxides at high temperatures
What gasses produced from combustion may lead to acid rain
Nitrous oxides
Sulphurous oxides
Hydrogen chloride
Give an example of a power station that uses biomass to produce power
Eye power station produces electricity from the combustion of chicken droppings and straw
What is the drawback from combined heat and power stations heat and power
Cannot produce heat and power at max efficiency, to obtain usable heat the electricity efficiency must go down
What can be done to power plant exhausts to try and reduce environmental impact and what are the drawbacks
Filters and scrubbers can be used but this reduces efficiency and cant remove all pollutants
What do we need to produce electricity from biomass
Combustion chamber, Pollution control, boiler, turbine, compressor
What is a good and a bad use of ash
Can be used as a fertiliser but can also go to landfill
What are the benefits from burning waste as a fuel
Uses waste
Prevents dumping to landfill
Allows destruction of dangerous contaminants
What are some disadvantages of burning waste as fuel
Much of the energy may have Been stripped from the material and pollutants may have been added
What are the features of a goof feedstock for combustion
Homogenous in composition Uniform in size small particles mixed well with air high calorific value
What are the disadvantages if making biomass more suited to combustion
Drying requires energy but waste heat from overall system can be used for this.
What feedstocks produce high, low and intermediate ash content
High- sewage sludge
intermediate- animal waste
low-paper
How does combustion by moving grates work
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
How does combustion by fluidised beds work
A bed of incombustible material such as sand is stimulated with air so it behaves like a fluid and biomass is fed into bed
