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Clean Energy

What Are the Five Major Types of Renewable Energy?



The Renewable Energy Age

This was originally published on June 8, 2022, on Elements.

Awareness around climate change is shaping the future of the global economy in several ways.

Governments are planning how to reduce emissions, investors are scrutinizing companies’ environmental performance, and consumers are becoming conscious of their carbon footprints. But no matter the stakeholder, energy generation and consumption from fossil fuels is one of the biggest contributors to emissions.

Therefore, renewable energy sources have never been more top-of-mind than they are today.

The Five Types of Renewable Energy

Renewable energy technologies harness the power of the sun, wind, and heat from the Earth’s core, and then transforms it into usable forms of energy like heat, electricity, and fuel.

The above infographic uses data from Lazard, Ember, and other sources to outline everything you need to know about the five key types of renewable energy:

Energy Source% of 2021 Global Electricity GenerationAvg. levelized cost of energy per MWh
Hydro 💧 15.3%$64
Wind 🌬 6.6%$38
Solar ☀️ 3.7%$36
Biomass 🌱 2.3%$114
Geothermal ♨️ <1%$75

Editor’s note: We have excluded nuclear from the mix here, because although it is often defined as a sustainable energy source, it is not technically renewable (i.e. there are finite amounts of uranium).

Though often out of the limelight, hydro is the largest renewable electricity source, followed by wind and then solar.

Together, the five main sources combined for roughly 28% of global electricity generation in 2021, with wind and solar collectively breaking the 10% share barrier for the first time.

The levelized cost of energy (LCOE) measures the lifetime costs of a new utility-scale plant divided by total electricity generation. The LCOE of solar and wind is almost one-fifth that of coal ($167/MWh), meaning that new solar and wind plants are now much cheaper to build and operate than new coal plants over a longer time horizon.

With this in mind, here’s a closer look at the five types of renewable energy and how they work.

1. Wind

Wind turbines use large rotor blades, mounted at tall heights on both land and sea, to capture the kinetic energy created by wind.

When wind flows across the blade, the air pressure on one side of the blade decreases, pulling it down with a force described as the lift. The difference in air pressure across the two sides causes the blades to rotate, spinning the rotor.

The rotor is connected to a turbine generator, which spins to convert the wind’s kinetic energy into electricity.

2. Solar (Photovoltaic)

Solar technologies capture light or electromagnetic radiation from the sun and convert it into electricity.

Photovoltaic (PV) solar cells contain a semiconductor wafer, positive on one side and negative on the other, forming an electric field. When light hits the cell, the semiconductor absorbs the sunlight and transfers the energy in the form of electrons. These electrons are captured by the electric field in the form of an electric current.

A solar system’s ability to generate electricity depends on the semiconductor material, along with environmental conditions like heat, dirt, and shade.

3. Geothermal

Geothermal energy originates straight from the Earth’s core—heat from the core boils underground reservoirs of water, known as geothermal resources.

Geothermal plants typically use wells to pump hot water from geothermal resources and convert it into steam for a turbine generator. The extracted water and steam can then be reinjected, making it a renewable energy source.

4. Hydropower

Similar to wind turbines, hydropower plants channel the kinetic energy from flowing water into electricity by using a turbine generator.

Hydro plants are typically situated near bodies of water and use diversion structures like dams to change the flow of water. Power generation depends on the volume and change in elevation or head of the flowing water.

Greater water volumes and higher heads produce more energy and electricity, and vice versa.

5. Biomass

Humans have likely used energy from biomass or bioenergy for heat ever since our ancestors learned how to build fires.

Biomass—organic material like wood, dry leaves, and agricultural waste—is typically burned but considered renewable because it can be regrown or replenished. Burning biomass in a boiler produces high-pressure steam, which rotates a turbine generator to produce electricity.

Biomass is also converted into liquid or gaseous fuels for transportation. However, emissions from biomass vary with the material combusted and are often higher than other clean sources.

When Will Renewable Energy Take Over?

Despite the recent growth of renewables, fossil fuels still dominate the global energy mix.

Most countries are in the early stages of the energy transition, and only a handful get significant portions of their electricity from clean sources. However, the ongoing decade might see even more growth than recent record-breaking years.

The IEA forecasts that, by 2026, global renewable electricity capacity is set to grow by 60% from 2020 levels to over 4,800 gigawatts—equal to the current power output of fossil fuels and nuclear combined. So, regardless of when renewables will take over, it’s clear that the global energy economy will continue changing.

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Clean Energy

3 Learnings for Scaling Up Wind and Solar Power

Streamlining processes, investing in infrastructure, and promoting local manufacturing can pave the way for wind and solar adoption.



An infographic showing how streamlining processes, investing in infrastructure, and promoting local manufacturing can pave the way for wind and solar adoption

3 Learnings for Wind and Solar Power Scale-Up

To keep the increase in global temperatures to 1.5°C, the International Energy Agency (IEA) states that the world must triple its renewable power capacity by 2030.

However, swift and widespread adoption depends on the removal of various bottlenecks in project pipelines worldwide.

We’ve partnered with the National Public Utilities Council to visualize data from the IEA and the Energy Transitions Commission to highlight three areas of improvement, critical to the rapid adoption of renewables.

1. Planning and Permitting

Currently, regulatory and administrative barriers lead to lengthy project timelines worldwide.

A wind project, for example, can take 10–12 years of development, while solar projects can take four years.

The Energy Transitions Commission suggests a faster process, including quicker site mapping, permit applications, and environmental surveys.

Policymakers can help reduce project timelines by allocating land for renewables, setting permit targets, and digitalizing the permit application process. As a result, the development time for wind projects could be reduced to 4.5–5.5 years, and solar projects could be online in one year.

2. Grid Availability for Solar and Wind 

Connecting renewable energy projects to the grid has posed a challenge.

As of 2023, almost 1,500 gigawatts (GW) of wind and solar projects in advanced stages of development were still off the electricity grid. 

Excluding China and India, transmission and distribution investments have increased by only 1% annually since 2010. According to the IEA, however, government and stakeholder investment in grids must double to over $600 billion annually to meet climate targets.

3. Supply Chain Diversification

The final area for improvement, when it comes to expediting global wind and solar power scale-up, is supply chain diversification.

Currently, China heavily concentrates the global manufacturing capacity on clean energy, leading to a heavy dependency on imports for the rest of the world.

Share of Manufacturing Capacity, 2021Wind (Onshore)Wind (Offshore)Solar PV
North America10%0%1%
Asia Pacific9%4%11%
Central & South America5%0%0%
Middle East0%0%0%

Global manufacturing capacity share is calculated by averaging the global manufacturing shares of individual components (i.e., wind: tower, nacelle, blade; solar: wafers, cells, modules). Percentages may not add up to 100 due to rounding.

According to research by ONYX Insight, almost 60% of wind farm operators reported that supply chain issues were their biggest challenge over the next 2–3 years.

International collaboration and investment, however, can help diversify manufacturing outside of China. In addition, policymakers can also implement policies and incentives that encourage the growth of local manufacturing capacity for renewables. 

All in all, streamlining processes, investing in infrastructure, and promoting local manufacturing can pave the way for a cleaner, more sustainable energy future.

Download the 2023 Decarbonization Report.

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Clean Energy

Visualizing All the Nuclear Waste in the World

Despite concerns about nuclear waste, high-level radioactive waste constitutes less than 0.25% of all radioactive waste ever generated.



Graphic cubes illustrating the global volume of nuclear waste and its disposal methods.

Visualizing All the Nuclear Waste in the World

Nuclear power is among the safest and cleanest sources of electricity, making it a critical part of the clean energy transition.

However, nuclear waste, an inevitable byproduct, is often misunderstood.

In collaboration with the National Public Utilities Council, this graphic shows the volume of all existing nuclear waste, categorized by its level of hazardousness and disposal requirements, based on data from the International Atomic Energy Agency (IAEA).

Storage and Disposal

Nuclear provides about 10% of global electricity generation.

Nuclear waste, produced as a result of this, can be divided into four different types:

  • Very low-level waste: Waste suitable for near-surface landfills, requiring lower containment and isolation.
  • Low-level waste: Waste needing robust containment for up to a few hundred years, suitable for disposal in engineered near-surface facilities.
  • Intermediate-level waste: Waste that requires a greater degree of containment and isolation than that provided by near-surface disposal.
  • High-level waste: Waste is disposed of in deep, stable geological formations, typically several hundred meters below the surface.

Despite safety concerns, high-level radioactive waste constitutes less than 0.25% of total radioactive waste reported to the IAEA.

Waste ClassDisposed (cubic meters)Stored (cubic meters)Total (cubic meters)
Very low-level waste758,802313,8821,072,684
Low-level waste1,825,558204,8582,030,416
Intermediate level waste671,097201,893872,990
High-level waste3,9605,3239,283

Stored and disposed radioactive waste reported to the IAEA under the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. Data is from the last reporting year which varies by reporting country, 2019-2023.

The amount of waste produced by the nuclear power industry is small compared to other industrial activities.

While flammable liquids comprise 82% of the hazardous materials shipped annually in the U.S., radioactive waste accounts for only 0.01%.

Learn how the National Public Utilities Council is working towards the future of sustainable electricity.

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