Energy - Physical Flashcards
How does affluence impact energy usage?
- People with more money can afford to use more energy.
- Can travel more, more heating and light, appliances etc.
How does cost of energy impact energy usage?
- If energy sources are locally abundant, can be very cheap to extract and utilise.
- Petrol cheaper in USA - encourages large trucks.
- If prices are lower, energy conservation is a low priority.
How does the type of industry impact energy usage?
- Primary and secondary industries which extract and process will use lots of energy.
- These industries have moved away from developed countries, who have adapted light industries instead (IT, finance etc).
Define intermittency.
An energy source not available at times when needed. e.g. wind.
Define predictability.
How much energy is available, and whether it will meet demand for energy.
Define abundance.
Amount of the resource that exists.
What is resource depletion?
- For non-renewable sources, even with discovery of new resources, improved tech, and increased market prices, the supplies have a limit.
- Many reserves of fossil fuels that have not been exploited, but rate of discovery declined dramatically since 1980s.
What is economic sustainability?
- Depleted resources will become more expensive, whilst some technologies are expensive on a long term basis, reducing future affluence.
- Failure to invest in future supplies will result in shortages, as there will be a lag to develop the necessary technology and infrastructure.
What are some features of fossil fuels?
- Chemical energy - easy to store and convert into heat energy.
- High energy density - relatively small mass of fuel can do a lot.
- Finite resource - resources will eventually be depleted.
How can coal be extracted?
- Deep mining.
- Open cast mining.
How can crude oil be extracted?
Crude oil flows through permeable rock and collects in pores. When a pipe is drilled down, the natural pressure from below forces it to the surface.
What is coal gasification?
Coal that is too deep to be mined can be burned underground to release a mixture of natural gases.
What is coal liquefaction?
Coal can be converted into liquid hydrocarbons either directly using solvents or indirectly through chemical reactions from the hydrocarbons from gasification.
What is primary oil recovery?
Uses natural pressure of water below oil/gas dissolved in it, to force oil to the surface.
What is secondary oil recovery?
Pumping water or natural gas to maintain pressure.
What is tertiary oil recovery?
Uses solvents or bacteria to reduce the viscosity of oil.
What are some advantages of directional drilling?
- Many wells from a single platform.
- Drilling underneath locations where you could not otherwise build a platform.
- Can drill through softer rock and can target smaller reservoirs.
- Remotely operated vehicles can also be used to carry out surveys and inspect underwater equipment.
What is hydraulic fracturing? What are the potential problems?
Uses high pressure to open fissures on shale rocks with low permeability so the oil or gas in them can flow towards a recovery well. Water, sand grains, and solvents may be pumped into fissures to increase recovery rate.
- Natural gas may enter aquifer water.
- Toxic metals naturally present in rocks may become mobile.
- Large volumes of water needed.
- Chemicals injected underground may enter aquifers or reach surface and cause pollution.
What are oil shales and tar sands?
- Deposits of liquid oil is too viscous in these, or has solid hydrocarbons.
- Tar sands can be extracted by excavating the sand and treating with hot water to produce oil droplets.
- In-situ production involves steam or solvents being injected to produce liquid oil.
- Can be expensive.
What is enhanced gas recovery?
Already recover 80-90% but more can be collected.
Involves injecting carbon dioxide or nitrogen to maintain pressure.
How can methane gas be released?
- Pumping hot water to melt the methane hydrate crystals.
- Depressurisation by drilling into sediments.
- Injecting CO2 to displace the methane.
