Energy Sources & Sustainability (HL IB ESS OLD COURSE - IGNORE)
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
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
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)
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
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
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
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
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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