Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy sources are sustainable, some are not. For example, some biomass sources are considered unsustainable at current rates of exploitation. Renewable energy often provides energy for electricity generation to a grid, air and water heating/cooling, and stand-alone power systems. About 20% of humans' global energy consumption is renewables, including almost 30% of electricity. About 7% of energy consumption is traditional biomass, but this is declining. Over 4% of energy consumption is heat energy from modern renewables, such as solar water heating, and over 6% electricity.
Energy development is the field of activities focused on obtaining sources of energy from natural resources. These activities include production of renewable, nuclear, and fossil fuel derived sources of energy, and for the recovery and reuse of energy that would otherwise be wasted. Energy conservation and efficiency measures reduce the demand for energy development, and can have benefits to society with improvements to environmental issues.
Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs". Most definitions of sustainable energy include considerations of environmental aspects such as greenhouse gas emissions and social and economic aspects such as energy poverty. Renewable energy sources such as wind, hydroelectric power, solar, and geothermal energy are generally far more sustainable than fossil fuel sources. However, some renewable energy projects, such as the clearing of forests to produce biofuels, can cause severe environmental damage. The role of non-renewable energy sources in sustainable energy has been controversial. Nuclear power is a low-carbon source whose historic mortality rates are comparable to wind and solar, but its sustainability has been debated because of concerns about radioactive waste, nuclear proliferation, and accidents. Switching from coal to natural gas has environmental benefits, including a lower climate impact, but may lead to a delay in switching to more sustainable options. Carbon capture and storage can be built into power plants to remove their carbon dioxide emissions, but is expensive and has seldom been implemented.
Renewable energy in Australia includes wind power, hydroelectricity, solar PV, heat pumps, geothermal, wave and solar thermal energy.
Renewable energy commercialization involves the deployment of three generations of renewable energy technologies dating back more than 100 years. First-generation technologies, which are already mature and economically competitive, include biomass, hydroelectricity, geothermal power and heat. Second-generation technologies are market-ready and are being deployed at the present time; they include solar heating, photovoltaics, wind power, solar thermal power stations, and modern forms of bioenergy. Third-generation technologies require continued R&D efforts in order to make large contributions on a global scale and include advanced biomass gasification, hot-dry-rock geothermal power, and ocean energy. As of 2012, renewable energy accounts for about half of new nameplate electrical capacity installed and costs are continuing to fall.
According to preliminary data from the US Energy Information Administration, renewable energy accounted for about 12.6% of total primary energy consumption and about 19.8% of the domestically produced electricity in the United States in 2020.
The developing nations of Africa are popular locations for the application of renewable energy technology. Currently, many nations already have small-scale solar, wind, and geothermal devices in operation providing energy to urban and rural populations. These types of energy production are especially useful in remote locations because of the excessive cost of transporting electricity from large-scale power plants. The applications of renewable energy technology has the potential to alleviate many of the problems that face Africans every day, especially if done in a sustainable manner that prioritizes human rights.
Fossil fuel phase-out is the gradual reduction of the use and production of fossil fuels to zero. It is part of the ongoing renewable energy transition. Current efforts in fossil fuel phase-out involve replacing fossil fuels with sustainable energy sources in sectors such as transport and heating. Alternatives to fossil fuels include electrification, green hydrogen and biofuel. Phase-out policies include both demand-side and supply-side constraints. Whereas demand-side approaches seek to reduce fossil-fuel consumption, supply-side initiatives seek to constraint production to accelerate the pace of energy transition and reduction in emissions.
Low-carbon power is electricity produced with substantially lower greenhouse gas emissions than conventional fossil fuel power generation. The energy transition to low-carbon power is one of the most important actions required to limit climate change. Power sector emissions may have peaked in 2018. During the first six months of 2020, scientists observed an 8.8% decrease in global CO2 emissions relative to 2019 due to COVID-19 lockdown measures. The two main sources of the decrease in emissions included ground transportation (40%) and the power sector (22%). This event is the largest absolute decrease in CO2 emissions in history, but emphasizes that low-carbon power "must be based on structural and transformational changes in energy-production systems".
The renewable-energy industry is the part of the energy industry focusing on new and appropriate renewable energy technologies. Investors worldwide have paid greater attention to this emerging industry in recent years. In many cases, this has translated into rapid renewable energy commercialization and considerable industry expansion. The wind power, solar power and hydroelectric power industries provide good examples of this.
Renewable energy in developing countries is an increasingly used alternative to fossil fuel energy, as these countries scale up their energy supplies and address energy poverty. Renewable energy technology was once seen as unaffordable for developing countries. However, since 2015, investment in non-hydro renewable energy has been higher in developing countries than in developed countries, and comprised 54% of global renewable energy investment in 2019. The International Energy Agency forecasts that renewable energy will provide the majority of energy supply growth through 2030 in Africa and Central and South America, and 42% of supply growth in China.
100% renewable energy means getting all energy from renewable resources. The endeavor to use 100% renewable energy for electricity, heating, cooling and transport is motivated by climate change, pollution and other environmental issues, as well as economic and energy security concerns. Shifting the total global primary energy supply to renewable sources requires a transition of the energy system, since most of today's energy is derived from non-renewable fossil fuels.
Policy makers often debate the constraints and opportunities of renewable energy.
The energy transition is the ongoing process of replacing fossil fuels with low carbon energy sources. More generally, an energy transition is a significant structural change in an energy system regarding supply and consumption.
Most of Kenya's electricity is generated by renewable energy sources. Access to reliable, affordable, and sustainable energy is one of the 17 main goals of the United Nations’ Sustainable Development Goals. Development of the energy sector is also critical to help Kenya achieve the goals in Kenya Vision 2030 to become a newly industrializing, middle-income country. With an installed power capacity of 2,819 MW, Kenya currently generates 826 MW hydroelectric power, 828 geothermal power, 749 MW thermal power, 331 MW wind power, and the rest from solar and biomass sources. Kenya is the largest geothermal energy producer in Africa and also has the largest wind farm on the continent. In March 2011, Kenya opened Africa’s first carbon exchange to promote investments in renewable energy projects. Kenya has also been selected as a pilot country under the Scaling-Up Renewable Energy Programmes in Low Income Countries Programme to increase deployment of renewable energy solutions in low-income countries. Despite significant strides in renewable energy development, about a quarter of the Kenyan population still lacks access to electricity, necessitating policy changes to diversify the energy generation mix and promote public-private partnerships for financing renewable energy projects.
Ethiopia generates most of its electricity from renewable energy, mainly hydropower.
Renewable energy in Mexico contributes to 26 percent of electricity generation in Mexico. As of 2009, electricity generation from renewable energy comes from hydro power, geothermal, solar power and wind. There is a long term effort established to increase the use of renewable energy sources. The amount of geothermal energy used and harvested, places Mexico as number four in the world.
Although sun and wind could supply plenty of energy in Turkey, hydropower is the only renewable energy which is fully exploited, averaging about a fifth of national electricity supply. However in drought years much less electricity is generated by hydro. Over half of capacity is renewables, and it is estimated that over half of generation could be from renewables by 2026 but Turkey has invested less in solar and wind power than similar Mediterranean countries. Turkey lacks a renewable energy plan beyond 2023 which includes transport, industry, heating and cooling as well as electricity generation. More renewable energy could be used to reduce the nation's greenhouse gas emissions and thus avoid paying other countries' carbon tariffs. The country is a net exporter of wind power equipment, but a net importer of solar power equipment. Total non-hydro renewables overtook hydro in 2021.
Renewable energy in South Africa is energy generated in South Africa from renewable resources, those that naturally replenish themselves—such as sunlight, wind, tides, waves, rain, biomass, and geothermal heat. Renewable energy focuses on four core areas: electricity generation, air and water heating/cooling, transportation, and rural energy services. The energy sector in South Africa is an important component of global energy regimes due to the country's innovation and advances in renewable energy. South Africa's greenhouse gas (GHG) emissions is ranked as moderate and its per capita emission rate is higher than the global average. Energy demand within the country is expected to rise steadily and double by 2025.
