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Renewable energy

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Renewable energy, often called green energy, comes from natural resources that replenish themselves on a human timescale. The International Energy Agency defines these as energy sources derived from natural processes that replenish faster than they are consumed. This distinguishes them from fossil fuels, which take millions of years to form. These resources are essential for modern life because they can provide electricity, heat water, and power transportation. Today, renewable energy is being used to replace conventional fuels in many different sectors.

Global Renewable Energy Production by Countries and Sources in 2023
Global Renewable Energy Production by Countries and Sources in 2023

There are several main ways we harness these natural forces. Solar power captures energy from the sun through two primary methods. Solar thermal converts sunlight into heat, while photovoltaics, or PV, convert light directly into electricity. PV is currently more widespread and is growing much faster than solar thermal.

1975 – Price of solar panels as a function of cumulative installed capacity
1975 – Price of solar panels as a function of cumulative installed capacity

Wind power uses the movement of air to generate electricity. Hydropower uses the movement of water, often through large structures like dams.

Three gorges dam from space
Three gorges dam from space

Geothermal energy taps into the heat from deep inside the Earth. Finally, bioenergy uses biological materials to create power.

Metz biomass power station
Metz biomass power station

Scientists categorize these energy sources based on how they behave. Some are considered variable or intermittent energy sources. Solar and wind are the most common examples because they fluctuate. Solar energy requires daylight and clear skies to work most effectively. Wind power can change significantly from day to day or even month to month.

20240706 Energy storage - renewable energy - battery - 100 ms
20240706 Energy storage - renewable energy - battery - 100 ms

In contrast, other sources are considered controllable. Dammed hydroelectricity, bioenergy, and geothermal power can provide a steady supply of energy. This allows grid operators to produce the specific amount of electricity required at any given time.

To manage the variability of wind and solar, we use electrical energy storage. This involves collecting energy when production exceeds consumption and returning it to the grid when production falls. Pumped-storage hydroelectricity is currently the most common method, accounting for more than 85% of all grid power storage.

Batteries are also being used more often for domestic storage and grid services. Another method involves green hydrogen, which can serve as a more economical way to store energy over the long term. These technologies help ensure that electricity is available even when the sun is not shining or the wind is not blowing.

Renewable energy has seen massive growth and cost reductions over the last 30 years. Between 2011 and 2021, the share of global electricity from renewables grew from 20% to 28%. During this time, solar and wind power were the main drivers, growing from a combined 2% to 10% of the supply. By 2024, renewables accounted for over 30% of global electricity generation. Experts project that this figure will reach over 45% by 2030.

2011- Renewable energy capacity - International Energy Agency
2011- Renewable energy capacity - International Energy Agency

In some locations, installing solar or wind is now the cheapest way to build new electricity capacity.

Transitioning to these sources is a major part of the global effort to address climate change. Most countries have committed to reaching net zero greenhouse gas emissions. This involves replacing fossil fuels with low-emissions energy sources to reduce the greenhouse gases that cause climate change. At the 2023 United Nations Climate Change Conference, about three-quarters of the world's countries set a goal to triple renewable energy capacity by 2030. The European Union has also set a goal to generate 40% of its electricity from renewables by 2030.

Share of electricity production (from renewables)
Share of electricity production (from renewables)

While the benefits are many, there are still significant challenges to overcome. The deployment of renewables faces obstacles like fossil fuel subsidies and local opposition to land use. There are also risks regarding energy security and infrastructure. For example, 90% of the supply chain for photovoltaic solar is centralized in China. This creates risks for the global supply. Additionally, renewable infrastructure can be vulnerable to extreme weather events like heat waves or storms.

2024-2025 Change in electricity sources and demand
2024-2025 Change in electricity sources and demand

Despite these hurdles, the shift toward a cleaner, more distributed energy system continues to accelerate.

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File:Global Renewable Energy Production by Countries and Sources in 2023.svg
Global Renewable Energy Production by...
File:20240706 Energy storage - renewable energy - battery - 100 ms.gif
20240706 Energy storage - renewable...
File:Renewables need flexible backup not baseload.png
Renewables need flexible backup not baseload.png
File:2011- Renewable energy capacity - International Energy Agency.svg
2011- Renewable energy capacity -...
File:1975 – Price of solar panels as a function of cumulative installed capacity.svg
1975 – Price of solar panels as a...
File:Wind energy generation by region, OWID.svg
Wind energy generation by region, OWID.svg
File:Pretty flamingos - geograph.org.uk - 578705.jpg
Pretty flamingos - geograph.org.uk - 578705.jpg
File:Fentonwindpark1.jpg
Fentonwindpark1.jpg
File:ThreeGorgesDam-China2009.jpg
ThreeGorgesDam-China2009.jpg
File:Three gorges dam from space.jpg
Three gorges dam from space.jpg
File:Metz biomass power station.jpg
Metz biomass power station.jpg
File:Soybeanbus.jpg
Soybeanbus.jpg

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