Energy resources

Why is energy important in agriculture

• fuel for machinery e.g. combine harvesters

• manufacture of fertilisers

• food processing

• transport of harvested food

• pumping water for irrigation

Why is energy important in fishing

• fuel for fish farm aeration

• processing of seafood

• transport of seafood

• cold storage

• fuel for fishing boats

Why is energy important in industry

• machinery operation e.g. conveyor belts

• heat to melt materials

• energy for chemical reactions e.g. metal smelting

• heat for distillation (crude oil)

Why is energy important in water supplies

• water treatment for public supply

• sewage treatment

Why is energy important in transport

• transport of goods (ships, trains, trucks)

• transport of people (cars, buses, trains, planes)

Why is energy important in domestic life

• space heating

• lighting

• running appliances, e.g. fridges, dishwashers

Renewable

resources naturally re-form relatively quickly so using them doesn’t necessarily reduce future availability

Non-renewable

resources either not re-forming or re-forming so slowly that current use reduces the amount available for future use

Depletable

resources where use can reduce future availability

Non-depletable

resources where use won’t reduce future availability

Abundance

the amount of the resource that exists

Intermittency

if an energy resource isn’t available at all times when it is needed

Ease of storage

ease ability to store the energy at times of surplus for later use at times of need

Ease of transportation

ease of ability to transport energy resources to areas with highest demand

Main method(s) of transportation for coal

ship and train

Main method(s) of transportation for crude oil

pipeline, ship and rail tanker

Main method(s) of transportation for refined oil products

pipeline, ship tanker, rail tanker and truck

Main method(s) of transportation for natural gas

pipeline, liquefied natural gas, ship tanker and rail tanker

Main method(s) of transportation for fissile fuels

soil fuel rod/pellets by rail or truck

Main method(s) of transportation for biofuels

road, rail or ship

Main method(s) of transportation for solar/wind/HEP/tidal/geothermal

conversion to another energy form which can be transported

Main method(s) of transportation for electricity

high voltage AC or DC electricity grid

Reasons governments may decide to provide assistance to particular sections of the energy industry

• to support development costs of a new technology

• to increase national energy security

• to reduce environmental impacts

What forms of support can governments provide to local energy industries

• financial grants

• a guaranteed price or market for the energy produced

• less strict planning regulations/permission to develop favourable sites

• financial support/compensation for affected communities

Why will the ways in which energy is supplied change in the future

• some existing resources e.g. fossil fuels/wood are becoming depleted

• concerns over environmental damage are affecting political policies and public opinion

• current supplies can’t meet growth in demand caused by increasing affluence/population growth

• new technologies are becoming available to harness, store, transport, or convert energy into forms that are required

What features of fossil fuels made them ideal for use

• easy to store

• high energy density

• often found in very abundant local deposits

Features of fossil fuels

• chemical energy easy to store

• high energy density

• finite resource

• available resource

• technologies to exploit them are well developed

• political and international trade problems

There are lots of fossil fuel deposits but why may large-scale use not be possible

• it isn’t economically viable

• it may cause unacceptable pollution

• will involve habitat damage in areas that are ecologically sensitive

• its extraction processes may cause local earth tremors

Features of fossil fuels: chemical energy

The chemical energy of fossil fuels is easy to store + easy to convert into the heat energy that’s usually required

Features of fossil fuels: energy density and its uses

• smelting of metal ores

• produce high pressure steam which can spin turbines and generators in power stations

• a small mass of fuel does a lot of work, so 5 litres of petrol can carry 1tonne of car for 80km

• 75t of aviation fuel can carry a 400t Boeing 747, including 400 passengers, for 5600km

Finite

a resource that will eventually become depleted

Features of fossil fuels: finite resource

Many small industrial towns rely on local fuel supplies such as the Ruhr region of Germany. When supplies deplete they will have to import fuel which may be expensive.

Features of fossil fuels: available resource

The total quantity of fossil fuels is very large, but many deposits aren’t included in the total estimate of reserves because the technology to exploit them hasn’t been developed/it wouldn’t be economically viable to do so

Examples of unexploitable fossil fuel deposits

• lots of oil and coal deposits are too deep, found in small amounts or located in areas which are difficult to reach

• lots of natural gas is trapped in fine-grained impermeable shale deposits

How does level of technological development influence energy resource choice

Industrial societies have developed using fossil fuels so technologies to exploit them are well developed. To change the main source to other types of energy would involve many changes in the infrastructure of society

Fossil fuels: political and international trade problems

• Increasingly high demand drives energy-hungry countries to satisfy their own energy needs. This can influence political decisions to protect future supplies, at the expense of reducing local and global environmental impacts

• Crude oil deposits are unevenly distributed across the globe, with most in the Middle East, which is why it’s the focus of both trade and political interest

Fossil fuels: economic issues

• Economic activity and international trade can drive countries to make decisions based on the cheapest options

• Fossil fuels generate economic costs such as pollution damage that are paid for by non-fossil fuel industries e.g. agriculture, forestry, health service

Extraction methods for coal

• Deep mining - smaller tunnels dug deeper underground. Machinery can’t usually be used. Overburden is largely avoided

• Open cast mining - large, wide pit dug at surface. Machinery can be used. Overburden must be dug up

Environmental impacts of coal exploitation

Habitat loss/fragmentation, noise pollution, dust pollution, turbid drainage water, spoil heaps, acid mine drainage, methane releases, derelict sites

Extraction methods for oil and gas

A pipe is drilled down to oil/gas reservoirs.

• Oil is forced to the surface either by natural pressure of gas above or by water beneath the oil that is pumped

• Natural gas is forced to the surface by its own natural pressure

Environmental impacts of oil extraction and transport

Oil pollution and habitat damage caused by pipeline construction

Environmental impacts of natural gas exploitation

Atmospheric pollution from burning surplus gas on oil rigs to prevent explosions, habitat damage caused by drilling

Environmental impacts of combustion of fossil fuels

Ash disposal and atmospheric pollution (CO2, SO2, NOx, CO, SPM)

Main uses of crude oil

• Liquid vehicle fuels: petrol, diesel, aircraft fuel, ship fuel oil

• Gas fuels for heating: propane, butane

• Petrochemicals: plastics, fertilisers, pharmaceuticals

Main uses of natural gas

• Domestic/industrial heating

• Electricity generation

• Chemicals: nitrate fertilisers

Main uses of coal

• Electricity generation

• Iron and steel industry

New technologies: coal gasification

Coal that’s too deep to be mined can be burnt underground under controlled conditions to produce a mixture of fuel gases including H, CO and CH4

New technologies: coal liquefaction

Involves the conversion of coal to liquid hydrocarbons which have applications that solid coal can’t perform such as liquid vehicle fuels. The coal may be converted to liquids directly using solvents or indirectly using gasification then chemical changes to convert gaseous hydrocarbons to liquid

New technologies: primary oil recovery

Well-established method, uses natural pressure of water below the oil, or gas that’s present above the oil/dissolved in it. Pressure forces oil up the production well to surface. 20% of the oil is usually extracted. A pump-jack fitted at ground level on the production well may be used to increase the flow rate

New technologies: secondary oil recovery

Water or natural gas pumped down an injection well to maintain pressure and flow of oil. Total recovery rate 40%. Some CCS schemes pump the recovered CO2 underground to increase oil recovery in addition to storing the CO2

New technologies: tertiary oil recovery (Enhanced Oil Recovery)

Techniques are used to reduce the viscosity of the oil

• Steam pumped down to heat oil

• Controlled underground combustion heats oil

• Detergents/solvents reduce surface tension of oil

• Bacteria partially digest heavy oil, producing lighter oils and CO2 that helps maintain pressure and flow

Total recovery 60%

New technologies (oil): directional drilling

Allows wells to be drilled that aren’t vertical. Advantages:

• Many wells can be drilled from 1 platform

• Possible to drill underneath locations where drilling rigs can’t be placed e.g. urban areas

• Drilling can follow weaker/softer rock strata to make drilling quicker + can target multiple small reservoirs, significantly increasing total recovery rates

New technologies (oil): subsea production wells

Located on the seabed and have no platform at the sea surface. Allow operations in water up to 2000m deep, although new developments will allow operations at greater depths

New technologies (oil): ROVs (remotely operated vehicles) and AUVs (autonomous unmanned vehicles)

Used to carry out seabed surveys and to inspect underwater production equipment and pipelines

New technologies (oil/natural gas): fracking

large volumes of crude oil/natural gas are trapped in shale rock. Hydraulic fracturing uses high pressure to open fissures in the surrounding shale rock along which the oil/gas can flow towards a recovery well. Water/sand grains/solvents may be pumped into the fissures to increase recovery rate

Concerns over fracking

• Natural gas may enter aquifer water

• Chemicals injected underground may enter aquifers or pollute at the surface

• Toxic metals naturally present in the rocks may be mobilised

• Large volumes of water are needed

• Earthquakes: continental drift and isostatic movements from fracking may cause earthquakes

Restrictions on fracking to reduce impacts

• Collection and treatment of waste water to be reused

• Restrictions on the location of fracking sites in sensitive areas

Unconventional oil

Liquid hydrocarbons produced from tar sands and oil shales

New technologies (oil): Extraction of tar sands

• Sands quarried using large excavators

• Treated with hot water, producing an emulsion of oil droplets

• Waste sand backfilled into mine

• 75% recovery rate

Extraction of oil shales

In-situ production

• Steam injection, solvent or controlled combustion in deep deposits to produce liquid oil that can be pumped to surface

• Extraction is expensive due to high energy inputs

New technologies (natural gas): enhanced gas recovery

Increases gas recovery rates using techniques such as injection of CO2 or N2 around the edge of the gas field to maintain pressure and gas flow

New technologies (natural gas): methane hydrate

• Water heating - hot water pumped into sediments, melting the hydrate crystals releasing the CH4

• Depressurisation - drilling into the sediments causes pressure to drop. CH4 dissociates from hydrate crystal

• CO2 injection - CO2 bonds to ice crystals, displaces CH4 which can be collected

Methane hydrate

a solid ice-like crystalline solid found in locations at low temperatures, such as polar regions, or under high pressure such as in oceanic sediments around continents

Carbon capture and storage CCS

Involves a range of developmental technologies which would store CO2 produced by fossil fuel use and reduce CO2 releases. Likely used at large power stations rather than for small sources e.g. vehicles

Nuclear fission

The nuclei of the isotopes of some elements with large nuclei may be split if they are hit by neutrons, releasing more neutrons and large amounts of energy

Why is nuclear power usually used for ‘base-load’ electricity supplies that are needed all the time

The power output of nuclear reactors normally changes quite slowly

Factors that have restricted the growth of nuclear fission

• Technology is very complex so it’s difficult to use in less technologically advanced societies which can’t support the industrial infrastructure needed

• Complex technology involved is very expensive

• Strong public opposition to nuclear power in some countries due to safety concerns, especially due to past reactor accidents that had short and long term health and environmental impacts

• Concerns about possible links between nuclear materials for civil uses and military/terrorist uses

• Uncertainty over permanent disposal of radioactive waste

• Uncertainty over total costs of nuclear power since no commercial reactor has been fully decommissioned

Examples of nuclear reactor accidents

• Three Mile Island, USA, 1979

• Chernobyl, Ukraine, 1986

• Fukushima, Japan, 2011

Features of nuclear fission: energy density

Nuclear fuel used in power stations has a very high energy density, a small amount of fuel releases a large amount of energy. 1kg of 0.7% uranium-235 can release as much energy as 13 tonnes of coal

Main uses of nuclear fission

• Generation of electricity

• Propel about 150 ships and some submarines

• Caesium-137 used for food irradiation and americium-241 in smoke alarms

Nuclear fission: embodied energy

High embodied energy as the processes required to produce the fuel and the complexity of nuclear power stations require a lot of energy. Uranium must be purified, concentrated and chemically processed

Nuclear fission: finite resource

Fissile materials e.g. uranium and thorium are non-renewable resources so the quantity that exists declines as they’re used

Nuclear fission: level of technological development

Uranium reactors currently being built are described as 3rd generation since they have been used since the 1950s. Improvements in reactor design:

• longer reactor life (60+ years instead of 40+ years)

• more reliable operation

• lower fuel consumption

Thorium reactors are less developed

Environmental impacts of nuclear fission

• Mining/processing of fissile fuel - habitat loss, noise, dust, turbid drainage water, hazardous wastes

• High embodied energy of materials - contributes to GCC

• Reactor accidents and radioactive waste - health risks of ionising radiation

Nuclear fission: political and international difficulties

The possible link between civil nuclear electricity and preparation of weapons-grade fuel has led some countries to try to restrict the availability of technology to other countries that are considered untrustworthy

Nuclear fission: economic issues

New nuclear power stations are such large engineering projects that they’re very expensive. Inclusion of new design features/unforeseen problems often cause total costs to far exceed original estimates. Very few old reactors have been fully decommissioned as costs have proved to be much greater than anticipated and funds weren’t put aside from income in operating years to pay for decommissioning

Nuclear fission: future use

Nuclear fuel has a very high energy density so reactors require very little fuel. Power stations can be located where transport of lots of fuel with lower energy density would be a problem. A reactor only needs to have a few tens of tons of fuel replaced each year compared with 10,000t of coal burnt each day to provide a similar electricity output

Nuclear fission new technologies: uranium extraction

• Polymer adsorption - U dissolved in seawater adsorbs onto certain polymers placed in the sea

• Phosphate mining - U often present in P deposits + can be separated from the material extracted in P mines

• Coal ash - U can be extracted from coal ash. This will become economic if the price of U rises enough

Nuclear fission new technologies: molten salt reactors

Using molten salt as a reactor coolant increases efficiency of electricity generation as the reactor can operate at a much higher temp without needing high pressure to prevent the coolant boiling. Liquid cooled reactors are much smaller than gas-cooled reactors, so they’re cheaper to construct

Nuclear fission new technologies: plutonium reactors

U-235 only makes up 0.7% of U in mined ore, other 99.3% fertile U-238 which is converted to P-239 by neutron bombardment in a reactor. Breeder reactions release energy for electricity and can produce more new fissile fuel than they use.

Nuclear fission new technologies: thorium reactors

thorium-232 is fertile but not fissile. Through bombardment with neutrons it’s converted to uranium-233 which is fissile

Nuclear fission new technologies: advantages of thorium reactors

• Thorium 3x more abundant than uranium

• Much more difficult to make weapons than when using uranium

• Much less radioactive waste produced

• Radioactive waste has shorter half-lives

• No fuel enrichment needed

Nuclear fission new technologies: disadvantages of thorium reactors

• Breeding rate for U-233 is slow, so fuel is expensive

• U-233 releases alpha radiation so it’s very hazardous

• Being less-developed than U reactors, remaining development costs high

Nuclear fusion

Involves the joining of the nuclei of small atoms e.g. deuterium and tritium

Extraction of fuel for nuclear fusion

• Deuterium extracted from water

• tritium produced by neutron bombardment of lithium (collected from seawater using polymer adsorption)

Conditions needed for fusion to occur on earth

• Hydrogen in the form of plasma - repelling negatively charged electrons must be removed

• Heavy nuclei - nuclei with greater mass = more momentum

• Very high temp - increase kinetic energy of nuclei

• Vacuum - so plasma isn’t cooled by air

• Magnetic field - holds plasma centrally, prevents it touching the sides and cooling

Nuclear fusion: laser fusion

The High Power laser Energy Research project will research the possibilities of using laser fusion. A proposed small-scale fusion technology that avoids the problems of plasma containment and refuelling that exist in the torus reactors. Small spheres of frozen deuterium and tritium dropped into an intense laser beam to initiate fusion

Properties of renewable resources

• Intermittency

• Predictability

• Energy density

• Ease of storage

• Application to current uses of energy

• Environmental impacts

• Geographical constraints

• Size of available resource

• Level of technological development

• Economic issues

Solar power: problematic properties

• Intermittent - availability/intensity of sunlight depends upon daily/seasonal cycles

• Unreliable - changes in energy intensity caused by changes in cloud cover can’t be accurately predicted

• Low energy density - requires very large areas of solar collectors to harness significant amounts of energy

Solar power: locational constraints

Solar most viable where light levels are highest e.g. dry, sunny deserts. Parabolic reflectors only work where there’s no cloud so rays of light are parallel and reflect onto the absorber

Harnessing solar power: photothermal solar power

Photothermal systems absorb sunlight to produce heat used to heat water or for low-temp uses e.g. space heating or domestic hot water. Heat harnessed by photothermal panels can be retained in a thermal store for later use, usually a well-insulated tank containing water, sand or concrete. Molten salt used if energy has been concentrated to produce higher temps

Harnessing solar power: passive solar architecture

Buildings can be designed to maximise absorption of sunlight for heating without use of active working equipment. Overheating in summer reduced with fixed solar screens that deflects sunlight, adjustable screens or by ventilation

Harnessing solar power: heat pumps

A heat pump uses the change in state of a fluid from liquid to gas to absorb heat from the environment + releases it within a building when the gas condenses to a liquid. Change in state caused by pressure changes using a compressor pump, a pressure release valve boils the liquid.

Harnessing solar power: photovoltaic solar power

PV cell absorbs photons of light, electrons dislodged from atoms in upper layer of PV cell. Flow along electrical conductor from negatively charged layer to relatively positive lower layer. Moving electrons provide electric current to power electrical appliances.

Harnessing solar power: types of PV cells and their maximum efficiency

• Multi junction 46%

• Single junction gallium arsenide 29.1%

• Crystalline silicon 27.6%

• Organic cells 20.1%

• Amorphous silicon 13.6%

Environmental impacts of solar power: manufacture of solar panels

Making solar panels requires extraction + processing of materials e.g. metals, plastic, paints, silicon. Making PV solar panels produces toxic wastes e.g. silicon tetrachloride + small amounts of cadmium

Environmental impacts of solar power: impacts during use

Solar panels don’t require much maintenance. Cleaning requires water which may be scarce in areas most viable for solar power. Large solar farms can occupy land that could have been used for other purposes, urban roof space could be used to avoid land use conflicts

New solar power technologies: multi-junction PV cells

Multiple layers made of different materials, each of which absorbs different wavelengths of light. A greater amount of the available light absorbed + converted to electricity

New solar power technologies: anti-reflective surfaces

PV cells with smooth surfaces reflect about 30% of light hitting them. Grooved or textured surfaces reflect light into the cells instead. Some designs mimic the structure of the corneas of moth eyes with are very efficient at absorbing light

New solar power technologies: concentrating solar power with thermal storage

Parabolic reflectors increase energy density. Light absorbed by tubes of oil which heat molten salt in large insulated tanks. Salt heated up to 550 degrees C, can be used to boil water/drive steam turbines when electricity is required. Overcomes problem of solar power being intermittent