7.2 Energy sources — uses and managementIB Environmental Systems and Societies HL: Revision notes

Renewable sources (solar, wind, hydroelectric, tidal, geothermal, biomass if replanted) are replaced naturally at least as fast as they are used. Non-renewable sources are finite stocks used faster than they form. Renewable does not mean impact-free.

Global energy consumption is rising because of population growth and rising per capita demand. About four-fifths of the world's energy still comes from fossil fuels.

The sustainability of energy sources varies significantly. Compare sources by renewability, life-cycle emissions, pollutants, land use and reliability. IPCC median life-cycle emissions (g CO₂e/kWh) are roughly: coal 820, natural gas 490, solar PV 48, nuclear 12, onshore wind 11.

A country's choices depend on resource availability, cost, government policy, technology, public attitudes, infrastructure and political relationships. Example: Germany's Energiewende replaced nuclear and fossil fuels with renewables, but reliance on Russian gas until 2022 exposed it to supply risk.

Wind and solar output is intermittent, creating the need for energy storage (pumped hydroelectric storage, batteries, molten salt, hydrogen).

Conservation means using less; efficiency means getting the same service from less energy. Both reduce demand and so reduce the need to import energy, helping a country to be less dependent on imported resources.

(HL) Energy security for a country means access to affordable and reliable sources of energy. A country can improve its energy security by:

• Energy-efficiency measures that reduce demand.
• Decreasing reliance on imported energy supplies, e.g. developing domestic renewables.
• Diversification: using many sources and many suppliers, so that one failure does not cut supply.

Example: Germany's rush to build LNG import terminals in 2022 after Russian gas supplies were cut.

(HL) The global economy mostly depends on finite reserves of fossil fuels: coal, oil and natural gas. These are used faster than they form, and burning them is the main source of greenhouse gas emissions.

(HL) Nuclear power is a non-renewable, low-carbon means of electricity production. Operation releases no CO₂, and life-cycle emissions are low (about 12 g CO₂e/kWh). Limitations: uranium is finite and mined, radioactive waste needs safe storage for thousands of years, accident risk, high capital cost. Example: France generates about two-thirds of its electricity from nuclear power.

(HL) Battery storage is required on a large scale to meet global requirements for reducing carbon emissions, because wind and solar are intermittent. But batteries need mining, transporting, processing and construction, all of which produce emissions and pollution and can cause sociopolitical tensions.

Example: lithium extraction from brine in the Salar de Atacama, Chile, uses large volumes of water in a dry region and has caused concern among Indigenous Lickanantay communities. Cobalt is mined mostly in the Democratic Republic of the Congo, creating dependence and concerns over working conditions.