Fossil Fuels: Coal, Oil and Gas Flashcards
Why has the use of oil for domestic heating decreased since the 1970’s?
It’s to expensive and has therefore been replaced by gas due to the UK reserves in the north sea and the building of a national pipe network system.
Which sectors does oil dominate?
Transport use for road and air transport
The dominate use for gas?
Electricity generation and for domestic use which is used for gas central heating systems
How is coal made?
Coal is derived from plant matter which has been subjective to high temeratures and pressures over million of years.
Coal is a hyrocarbon based fuel
What is the stages of coal formation?
Peat->Lignite->Bituminous->Anthracite
Peat - Plant matter accumulates underwater, and since oxygen is not present the organic matter will partially decompose
Lignite - forms when an accumulation of sediment on top of the peat causing an increase in vertical pressure
Bituminous - increasing pressure compacts the coal and brings about molecular reorganisation (coalification)
Anthracite - forms as a result of high pressure and temperatures
(Different types of coal depending on where in the process)
What is volatile matter?
Volatile matter is coal components that can be burned off easily - H, S, O, HC.
The further in the coal process the less volatile matter
How is the compostion effecting the coal?
The more carbon the more energy, the proportion of volatile matter makes it easier to ignite and the more ash and moisture you have the troublesome the coal is as a fuel.
Coal combustion process?
From a combustion perspective, three main energy producing reactions occur when reacting with oxygen (usually obtained from mixing with air in large quantities) as shown in the figure. See figure red square
How much CO2 do the typical coal power plant produce?
Millions of tonnes of CO2 per year
Longannet power plant (2400MW) running al year produce 10.5 million tonnes of CO2 per year
How is the formation of oil and natural gas?
Oil formed from the decomposition of aquatic animals and plant, in a seabed environment free from oxidation processes and buried under layers of rock to establish pressure and heat and a geological containment to store the oil. At high temperatures ( caused by the pressure) oil decomposes into natural gas
How do gas differ from coal and oil regarding CO2 emissions?
Gas produces far less CO2 than oil and coal.
Gas produce more energy
What is a different aspect in reducing CO2 that can be applied to a coal plant?
The plant can be more efficient meaning less coal used to produce the same amount of energy –> fewer emissions, 50 %
The remaining reduction will be achieved using carbon capture and storage.
What is carbon capture?
CO2 is removed either before combustion (for a new plant) and after combustion (for existing plant). The CO2 would then be dried, compressed and transported to permanent storage such as depleted oil resevoirs.
What are the three main carbon capture technologies?
- Post-combustion capture
- Pre-combustion capture
Removes nitrogen in the air before combustion - O2/CO2 recycle combustion capture
Removes nitrogen in the air before combustion
What is a downside with carbon capture?
Each method will reduce the overall plant thermal efficiency and current estimates indicate that this will be by approximately 10%.
While many of the processes have been used previously, there is very little knowledge on the economics of scaling them to power plant size and how to make it competitive with other energy conversion methods (renewables, nuclear etc).
