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Energy demand is growing as a result of:

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• Increasing population - more people requires more energy

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• Changes in consumer demand - people are demanding more energy (e.g. electricity, fuel) for a wider variety of uses

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• Demand from sectors:
• Transportation (globalisation)
• Domestic use (appliances)
• Industry (processes)
• Agriculture (machinery)�
• Development and improving quality of life - across the world, the richest use the most energy�
• Climate change - adapting to climate (e.g. infrastructure, air conditioning)

Energy security is the uninterrupted availability of energy at an affordable price.

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Energy underpins much of what we do in modern life and in a developed economy.

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Energy is unevenly distributed:

• Some countries have access to a lot of natural resources used for energy (e.g. oil and gas, wind, geothermal)
• Energy in some countries is extracted and used by companies and economies from overseas

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This leads to issues such as:

• War - sanctions and stopping flow of energy
• Changing prices - this makes it unaffordable and difficult to predict
• Inequality - some people can access energy whilst others can’t

Methane (natural gas) found in the shale = shale gas

Shale - impermeable, sedimentary rock laid down in layers.

Drill rig - vertical, then horizontal

Hydraulic fracturing creates fissures in the shale, which allows the gas to flow along and be extracted

Chemicals - dissolve minerals in the rock

Sand - keeps fissures open

Water - transports sand & chemicals

Shale gas (methane) is used in power stations to generate electricity.

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It can also be used directly in people’s houses to power gas ovens or gas �boilers.

Benefits of shale gas:

• Increased energy security - more sources of natural gas & reducing imports of natural gas
• Jobs - in more deprived regions & rural areas
• Widespread reserves - fewer concerns about running out

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Challenges of shale gas extraction:

• Greenhouse gas emissions - during extraction & in use
• Aquifer/groundwater contamination - could impact water security
• Induced seismicity - public perception
• Visual & noise pollution - drilling, pipelines, power plants

Uranium-235 is mined from the ground.

It is a useful for nuclear energy because:

• It has a very long half life (700 million years)
• It has a large nucleus

Half life is the time taken for a radioactive nuclei to decay by half.

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e.g. The half life of a substance is 4 hours. This means that after 4 hours it has decayed to 50%. After 8 hours it has decayed to 25% and after 20 hours it has decayed to 3.125%.

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Nuclear fission is when atoms, such as Uranium-235, are split, releasing energy. This also produces gamma radiation.

The rate of this reaction can be slowed by using control rods.

This energy can be used to create steam, which can be used to generate electricity in a nuclear power station.

Benefits of nuclear energy:

• Doesn’t emit greenhouse gases - contributes to climate targets and, if used to replace fossil fuels, can lower carbon emissions
• Produces a lot of energy for the amount of fuel used - 1kg of uranium produces 3 million times the energy of 1kg of coal.
• Increases energy security - reduces reliance on imports
• Safety records in high-income countries are high

Disadvantages of nuclear energy:

• Uranium is non-renewable - it is mined
• Nuclear power plants have a short lifetime (30-40 years) and long decommissioning (80 years and very expensive)
• Nuclear accidents - rare but do happen. Fukushima (2011 earthquake)
• Radioactive waste is generated and long term storage of this is uncertain

Hydrogen is an element. It can be used in a fuel cell to produce electricity.

Hydrogen is found naturally combined with other elements e.g. natural gas (CH₄), water (H₂O) and biomass (C_xH_XO_x).

We can separate the hydrogen out from the other elements by:

• Steam gas reforming - reacting natural gas with steam (+catalyst) at high temperatures
• Gasification/pyrolysis - reacting coal or biomass with steam at high temperatures
• Electrolysis - splitting water into hydrogen and �oxygen using electricity and an electrolyser �(a fuel cell). This can be renewable �(green hydrogen).

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Advantages of hydrogen power:

• Abundant & readily available - in water, fossil fuel and biomass forms
• Can lower GHG emissions - replaces traditional fuels (petrol, diesel) and if hydrogen is sourced in a green way - can reduce carbon emissions
• Fuel cell runs silently & no moving parts - reduction in maintenance costs and noise pollution
• Range is greater than electric - can be used in larger engines (e.g. lorries, trains)

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Disadvantages of hydrogen power:

• Can use more energy to produce hydrogen than is recovered - steam reforming or gasification/pyrolysis happen at high temperatures
• Low density - requires a large storage area, less practical for fuel stations
• Fuel cells are expensive - increased cost to consumer
• Infrastructure needed (e.g. refuelling) - commercial fuel stations few and far between
• Range is less than petrol/diesel cars