Energy Sources & Sustainability (HL IB ESS OLD COURSE - IGNORE)

Revision Note

Renewable & Non-renewable Energy Sources

  • Energy sources are classified into renewable and non-renewable categories

    • This is based on their ability to regenerate within a human lifespan

What are renewable energy sources?

  • Renewable energy comes from energy sources that will not run out and includes:

    • Wind energy

    • Solar energy

    • Tidal energy

    • Biomass (wood)

    • Geothermal energy

    • Hydropower

  • Once in place, these renewable energy sources do not produce any greenhouse gas emissions (except for biomass)

    • It is important to note that greenhouse gases may be emitted in the production, construction and transport of the equipment required for renewable energy sources

  • Advantages of all:

    • Reduces dependence on fossil fuels and foreign energy sources

      • This promotes energy independence and security

    • The renewables industry creates jobs in manufacturing, installation, operation and maintenance of renewable infrastructure

Wind energy

  • Wind energy harnesses the kinetic energy of moving air to generate electricity

    • It involves the use of wind turbines

    • These have large blades that spin when the wind blows

    • The rotating blades transfer kinetic energy to a generator, which converts it into electrical energy

  • Advantages:

    • Abundant energy source

    • No greenhouse gas emissions or air pollutants produced during operation

    • Land beneath turbines can often still be used for farming or other purposes

    • Can be installed offshore (in the sea) to minimise land use conflicts

    • Installation and running costs have decreased significantly, making it competitive with non-renewable energy sources

    • Can be small- or large-scale

  • Disadvantages:

    • Intermittent (non-constant) energy source dependent on wind availability

    • Visual and noise pollution can affect local communities

    • Initial high capital investment for turbines and infrastructure

    • Potential impact on wildlife, particularly birds and bats flying into the turbine blades

    • Wind farms require large areas of land, which can have an impact on agricultural or natural landscapes

Birds flying in front of wind turbines set against a background of green fields and a clear blue sky.
Wind farms can be harmful to wildlife, which may mean they shouldn't be built in certain areas

Solar energy

  • Solar energy uses photovoltaic (PV) panels that transfer energy from sunlight to produce an electrical current, generating electrical power

  • Advantages:

    • Abundant energy source

    • No greenhouse gas emissions or air pollutants produced during operation

    • Suitable for various scales of application (from house rooftops to very large solar farms)

    • Can be integrated into existing buildings and infrastructure

    • Solar is progressively becoming less expensive and more efficient

    • Solar energy can be generated in remote places where they don't have electricity (e.g. to power solar street signs in rural areas)

  • Disadvantages:

    • Intermittent (non-constant) energy source dependent on sunlight availability

    • Initial high capital investment for solar panels and equipment

    • Requires significant land area for solar farm installations (which could otherwise be used for agriculture)

    • Energy storage solutions needed for night-time or cloudy days

    • Potential environmental impact during manufacturing and disposal of panels (electronic waste)

    • Some people dislike the appearance of large solar farms (visual pollution)

Illustration of six solar panels on a grassy hill under a sunny sky with two clouds, representing solar energy generation.
Solar PV panels use energy from sunlight to produce electricity

Tidal energy

  • Tidal energy uses the energy of rising and falling tides to turn a turbine and generate electricity

  • Advantages:

    • Abundant energy source

    • No greenhouse gas emissions or air pollutants produced during operation

    • Predictable and reliable source of energy due to regular tidal patterns

    • Can produce a large amount of electricity at short notice

    • Minimal visual impact when installed underwater

    • Long lifespan of tidal turbines with minimal maintenance

  • Disadvantages:

    • High initial costs

    • Limited availability of suitable sites

    • Potential environmental impact on marine ecosystems and fish migration

    • Maintenance challenges and costs due to underwater installations

    • Possible interference with shipping lanes and navigation

Diagram showing a barrage and turbine generating energy from incoming and outgoing tides. Top: High tide with water flowing from ocean to river. Bottom: Low tide with reverse flow.
Tidal barrages can generate electricity from the movement of water, both as the tide comes in and as it goes out again

Biomass (wood)

  • Biomass energy uses organic materials such as wood to generate heat or electricity

  • Advantages:

    • Renewable resources and carbon neutral if managed sustainably

    • Readily available in many regions, especially rural areas

  • Disadvantages:

    • Carbon dioxide and air pollution from combustion emissions

    • Deforestation risk and habitat loss if not sustainably managed

    • Impact on indoor air quality if not properly ventilated

Geothermal energy

  • Geothermal energy harnesses heat from within the Earth's crust for electricity generation or heating purposes.

    • The Earth's interior is extremely hot

    • Water can be poured into shafts below the Earth's surface

    • The water is heated and returned via another shaft as steam or hot water

    • Steam can be used to turn a turbine and generate electricity

    • The hot water can also be used to heat homes

  • Advantages:

    • Sustainable energy source

    • Reliable and stable source of energy available at all times

    • Small land footprint compared to other renewable sources (e.g. wind and solar)

    • Geothermal power stations are usually small compared to nuclear or fossil fuel power stations

    • Long lifespan of geothermal plants with low operating costs

  • Disadvantages:

    • Site-specific; limited to regions with near-surface geothermal activity

    • High initial drilling and exploration costs

    • Can result in the release of greenhouse gases from underground

    • Geological risks such as earthquakes or ground subsidence

Geothermal energy process diagram showing hot water extracted to produce steam, turning turbine and generator, with used water cooled and injected back into the ground.
Cold water is heated by natural geothermal energy underground and then returned as hot water or steam, which can be used to generate electricity

Hydropower

  • Hydropower uses flowing water to generate electricity through turbines in dams

  • Advantages:

    • Reliable and predictable source of energy

    • Low greenhouse gas emissions during operation

    • Multi-purpose benefits, including flood control and irrigation

    • Long lifespan of hydroelectric plants with low operating costs

    • Can respond to demand quickly, generating large scale amounts of electricity in a short period of time

  • Disadvantages:

    • Disruption of river ecosystems and fish migration routes

    • High initial capital costs for dam construction and infrastructure

    • Dam construction and reservoir formation floods habitats and can require relocation of human communities

    • Climate change impacts on water availability is affecting reservoir levels, making them less reliable

Diagram of a hydroelectric power plant showing a water inlet from a reservoir, a dam, a powerhouse with a turbine and generator, and transmission lines for electricity.
A hydroelectric dam transfers the gravitational potential energy of the water to kinetic energy in order to generate electricity

What are non-renewable energy sources?

  • Non-renewable energy comes from energy sources that will eventually run out, including:

    • Fossil fuels

    • Nuclear energy (using uranium as a fuel)

Fossil fuels

  • Fossil fuels include:

    • Coal

    • Crude oil, which is refined into petrol, diesel and other fuels

    • Natural gas (mostly methane), which is used in domestic boilers and cookers

  • Fossil fuels are formed from the remains of plants and animals

    • Chemical energy stored in fossil fuels originally came from sunlight

    • Energy from the sun was transferred to chemical energy stores within plants through photosynthesis (plants use energy from sunlight to make food)

    • Animals ate the plants and the energy was then transferred to their chemical store

Illustration of fossil fuel examples with images of coal, an oil barrel, and a gas stove burner with flames, each labeled "COAL," "OIL," and "NATURAL GAS."
Fossil fuels include coal, oil and natural gas
  • Advantages

    • The current systems of transport and electricity generation used by human societies rely heavily on fossil fuels

      • These fossil fuels are generally readily available on a daily basis

    • In the past, fossil fuels have been reliable for large-scale energy production (although this is changing as supplies start to become depleted and prices rise)

    • Efficient—fossil fuels typically have a high energy density (they produce a large amount of energy per kilogram)

  • Disadvantages

    • It takes millions of years for fossil fuels to form:

      • This is why they are considered a non-renewable energy resource

    • The increasing demand for decreasing supply causes prices to increase

      • Fossil fuels are predicted to completely run out within the next 200 years

    • Burning fossil fuels pollutes the atmosphere with harmful gases such as:

      • Carbon dioxide, which contributes to the greenhouse effect

      • Sulphur dioxide, which produces acid rain

      • Both carbon and sulphur can be captured upon burning, preventing them from being released into the atmosphere, but this is expensive to do

    • Oil spills can occur during transport of fossil fuels, which damage the marine environment and wildlife over very large areas

    • Prices fluctuate rapidly

    • Conflict and political disagreements (such as the war in Ukraine) can have an impact on supplies

Nuclear Energy

  • Energy stored in the nucleus of atoms can be released when the nucleus is broken in two:

    • This is known as nuclear fission

  • Nuclear power stations use fission reactions to create steam to turn turbines to generate electricity

  • Nuclear power is a low-carbon, low-emission, non-renewable resource

    • However, it is controversial due to the radioactive waste it produces and the potential scale of any accident

  • Advantages

    • No pollution released into atmosphere

    • Nuclear reactors are perfectly safe as long as they are functioning properly (rigorous safety checks must be routinely carried out and rigorous safety procedures followed)

    • Nuclear power stations can generate electricity reliably on a large scale to be available as needed

    • Small amounts of uranium are needed, and large reserves are available

    • Reduces reliance on fossil fuels

    • Increases energy security

  • Disadvantages

    • There is a finite supply of uranium ore, so nuclear power is a non-renewable resource

    • Nuclear fuels produce radioactive waste, which needs to be stored for thousands of years

    • Safe ways of storing radioactive waste are very expensive

    • If an accident occurs at a nuclear reactor, radioactive waste can leak out and spread over large areas

    • The cost of decommissioning (shutting down) nuclear power plants is very high

Examiner Tips and Tricks

Make sure you can discuss the relative sustainability of different energy sources with examples.

Sustainability of Energy Sources

  • Energy sustainability refers to meeting current energy demands without compromising the ability of future generations to meet their needs

  • The sustainability of energy sources can vary greatly depending on:

    • Whether they are renewable or non-renewable

    • Their environmental impact

Environmental cost of non-renewable energy

Fossil fuels

  • Extraction: mining for coal and drilling for oil and gas can destroy habitats and lead to soil erosion and water contamination

  • Refining crude oil: this process releases harmful chemicals and contributes to air and water pollution

  • Liquefaction of natural gas: turning gas into liquid for easier transportation emits carbon dioxide and other greenhouse gases

Nuclear energy

  • Mining of uranium: extracting uranium for nuclear power plants is energy-intensive and leaves behind radioactive waste

  • Nuclear waste: long-term storage of nuclear waste is difficult, as it remains hazardous for thousands of years

Environmental cost of renewable energy Sources

  • Renewable energy comes from sources that can be naturally replenished, such as the sun, wind and water

  • These sources tend to have a lower environmental impact

  • However, they can still have significant (sometimes 'hidden') environmental costs, including:

    • Manufacturing: producing renewable energy devices requires energy and raw materials, leading to environmental damage

    • End-of-life management: recycling components from solar panels, wind turbines and batteries is often expensive and not always efficient, leading to waste and pollution

Examples of renewable energy devices

  • Wind turbines

    • Challenges:

      • Wind turbines require rare earth elements for magnets and motors, such as neodymium

      • At the end of their life, turbine blades are difficult to recycle and often end up in landfills

  • Solar panels

    • Challenges:

      • The production of solar panels requires mining for materials like silicon and rare earth elements

      • Solar panels have a limited lifespan (20-30 years) and need careful disposal to avoid chemical pollution

  • Tidal barrages

    • Tidal barrages use the movement of tides to generate energy

    • Challenges:

      • Building tidal barrages can disrupt local ecosystems, affecting fish and marine life

      • Barrages are large and expensive to construct and maintain

Rare earth elements in renewable energy

  • Renewable technologies, like electric vehicles (EVs) and wind turbines, rely on rare earth elements for efficient energy conversion

  • However, these elements are difficult to mine and refine, leading to sustainability issues, including:

    • Energy-intensive extraction:

      • Extracting rare earth elements requires significant energy (e.g. for mining machinery), contributing to greenhouse gas emissions

    • Mining impacts:

      • Mining for rare earth elements can cause severe environmental damage, including:

        • Water contamination: mining processes release toxic chemicals into nearby water sources, affecting both surface water and groundwater

        • Habitat destruction: clearing land for mining operations and access routes can destroy local ecosystems, disrupt wildlife habitats and cause deforestation

        • Dust pollution: dust from cutting, drilling and blasting rocks accumulates in surrounding areas, leading to air pollution and increasing the risk of respiratory diseases for nearby communities

Examiner Tips and Tricks

Don’t just assume renewable energy is always 'green'. Remember that the sustainability of renewable energy devices also depends on the materials used in their production; e.g. mining for rare earth elements and recycling challenges can make renewable energy less sustainable than it first appears.

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