Syllabus Edition

First teaching 2024

First exams 2026

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Energy Storage & Conservation (DP IB Environmental Systems & Societies (ESS))

Revision Note

Energy Storage

  • Energy storage is important for managing the supply of energy, especially from renewable sources

  • This is because many renewable sources do not produce a consistent flow of energy

  • By storing energy, countries can ensure a reliable supply even when renewable sources like wind or solar power are not generating electricity

The need for energy storage

  • Some renewable energy sources, such as wind and solar, produce energy intermittently

  • This means they only generate power when conditions are right:

    • Wind power: only produces electricity when the wind is blowing

    • Solar power: only generates electricity during the day when there is sunlight

  • Because of this, there can be times when energy supply does not meet demand

  • Energy storage systems help solve this problem by:

    • Storing excess energy when production is high

    • Releasing it when demand exceeds supply

Energy storage solutions

There are several ways to store energy to ensure supply can meet demand, including the following:

Batteries

  • Store electricity as chemical energy, which can be released when needed

    • Uses: common in electric vehicles and home solar systems

    • Example: Tesla Powerwall batteries store energy from solar panels and can supply power to homes during outages or high demand periods

Pumped hydroelectricity storage (PHS)

  • PHS stores energy by pumping water to a higher reservoir when there is surplus electricity

  • When electricity demand is high, the water is released back down to a lower reservoir, turning turbines to generate electricity

    • Uses: large-scale energy storage used by national grids

    • Example: Dinorwig Power Station in Wales is one of the largest PHS systems and is used to balance electricity supply in the UK

  • Advantages of PHS:

    • Large capacity: can store huge amounts of energy from excess electricity generated during periods of high renewable energy production (e.g. when the wind is blowing strongly or during peak solar energy generation)

    • Reliable: provides quick response to sudden demand increases (known as peak-shaving)

    • Long lifespan: PHS plants can operate for decades with low maintenance, contributing to their sustainability

  • Disadvantages of PHS:

    • Geographic limitations: requires specific landforms (mountains, valleys) and large reservoirs, limiting where it can be built

    • Environmental impact: constructing dams and reservoirs can damage ecosystems and disrupt local wildlife

    • Economic costs: can have very high initial costs to build

Diagram illustrating pumped-storage hydroelectricity. Water pumped uphill using renewable energy, released during high demand, generates electricity via a turbine.
Pumped hydroelectricity storage

Fuel cells

  • Fuel cells convert stored chemical energy (often hydrogen) directly into electricity

    • Uses: used in transportation (e.g. hydrogen-powered vehicles) and backup power systems

    • Example: Japan is investing in hydrogen fuel cells for its energy transition, particularly for powering vehicles and buildings

Thermal storage

  • Stores heat energy, which can be used to generate electricity later or provide heating

    • Uses: often used with solar power plants, where excess solar energy is stored as heat and converted to electricity during low sunlight

    • Example: the Crescent Dunes Solar Energy Project in the US uses molten salt to store solar energy as heat, which is then used to generate electricity after sunset

Managing energy demand: peak-shaving

  • Energy storage systems can be used for peak-shaving

    • This is the process of levelling out periods of high demand to ensure supply meets demand

  • When there is a peak in electricity usage (like during cold winter evenings), stored energy can be released to meet the extra demand

    • This avoids blackouts or the need to turn on extra power plants

Energy Conservation & Efficiency

What is energy conservation?

  • Energy conservation means changing our behaviour to use less energy

  • It includes small daily actions such as:

    • Turning off lights when not in use

    • Reducing the use of heating or air conditioning by wearing appropriate clothing or using natural ventilation

    • Travelling less by fuel-driven vehicles and opting for walking, cycling or public transport instead

What is energy efficiency?

  • Energy efficiency means using technologies and designs that require less energy to perform the same task

  • This can include:

    • Installing low-energy LED lighting in homes and buildings

    • Using energy-efficient appliances (e.g. the latest washing machines and fridges with high energy-efficiency ratings)

    • Developing fuel-efficient transportation methods, such as electric vehicles (EVs)

    • Designing buildings to conserve heat through better insulation, reducing the need for heating and cooling

      • For example, the use of double-glazed windows in homes increases energy efficiency by keeping heat inside, reducing the need for heating systems

The importance of energy conservation and efficiency

  • Energy conservation and efficiency help reduce energy demand and waste

  • These strategies make countries less dependent on importing energy resources

    • This reduces costs and improve energy security

  • They also contribute to reducing carbon emissions

    • This helps combat climate change

Examples of energy conservation and efficiency

Smart lighting systems

  • Energy-efficient lighting like LED bulbs and motion sensors are designed to reduce electricity use

  • Motion sensors ensure that lights are only on when needed, reducing waste in public spaces and large buildings

  • Effectiveness:

    • LEDs use up to 80% less energy than traditional bulbs, making them a cost-effective solution for reducing electricity use

Passive solar building design

  • Passive solar design uses natural sunlight to heat buildings, reducing the need for artificial heating

  • Buildings are designed with large windows facing the sun and materials that store and release heat efficiently

  • Effectiveness:

    • Passive solar design is effective in regions with consistent sunlight, helping reduce energy bills and making homes more energy-efficient

Designing goods to be easily recycled

  • The circular economy aims to reduce waste by designing products that can be easily reused, repaired or recycled

  • By creating products with longer lifespans and using recyclable materials, less energy is needed for producing new items

  • Effectiveness:

    • Designing goods to be recycled reduces the energy needed for producing new materials, cutting down energy demand in industries

Commercial shipping with sails

  • One innovative way to improve energy efficiency in the shipping industry is by designing ships with sails (wind-assisted propulsion)

  • Modern ships can use large, automated sails, known as rotor sails or kite sails, to harness wind energy and reduce fuel consumption

    • This reduces greenhouse gas emissions

  • Effectiveness:

    • Ships using wind-assisted propulsion can reduce fuel consumption by 10-30%, depending on wind conditions

A green cargo ship labeled "E-Ship 1" with rotor sails on the deck, sailing on the ocean, featuring the "Enercon" logo and slogan "Energy for the World."
Cargo ship with four large rotor sails (photo by Alan Jamieson, from Wikimedia Commons)

Examiner Tips and Tricks

Remember that energy conservation focuses on behaviour change, while energy efficiency focuses on technology and design improvements. Energy efficiency practices can be used and implemented to achieve energy conservation.

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Alistair Marjot

Author: Alistair Marjot

Expertise: Biology & Environmental Systems and Societies

Alistair graduated from Oxford University with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems & Societies. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University.

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