Hydroelectricity, or hydroelectric power, is electricity generated from hydropower. Hydropower supplies one sixth of the world's electricity, almost 4,500 TWh in 2020, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. However, when constructed in lowland rainforest areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitted.
Energy development is the field of activities focused on obtaining sources of energy from natural resources. These activities include the 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.
Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks, particularly where net metering is offered. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel. Micro hydro systems complement solar PV power systems because in many areas water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum. Micro hydro is frequently accomplished with a pelton wheel for high head, low flow water supply. The installation is often just a small dammed pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing. In low head sites, generally water wheels and Archimedes' screws are used.
Microgeneration is the small-scale production of heat or electric power from a "low carbon source," as an alternative or supplement to traditional centralized grid-connected power.
Marine currents can carry large amounts of water, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities, resulting in appreciable kinetic energy. The Sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with minimal changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines. Other effects such as regional differences in temperature and salinity and the Coriolis effect due to the rotation of the earth are also major influences. The kinetic energy of marine currents can be converted in much the same way that a wind turbine extracts energy from the wind, using various types of open-flow rotors.
The Gorlov helical turbine (GHT) is a water turbine evolved from the Darrieus turbine design by altering it to have helical blades/foils. Water turbines take kinetic energy and translates it into electricity. It was patented in a series of patents from September 19, 1995 to July 3, 2001 and won 2001 ASME Thomas A. Edison. GHT was invented by Alexander M. Gorlov, professor of Northeastern University.
Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amount of storage, in which case the storage reservoir is referred to as pondage. A plant without pondage is subject to seasonal river flows, so the plant will operate as an intermittent energy source. Conventional hydro uses reservoirs, which regulate water for flood control, dispatchable electrical power, and the provision of fresh water for agriculture.
Renewable energy in Australia includes wind power, hydroelectricity, solar photovoltaics, heat pumps, geothermal, wave and solar thermal energy.
100% renewable energy is the goal of the use renewable resources for all energy. 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.
According to the International Hydropower Association, Canada is the fourth largest producer of hydroelectricity in the world in 2021 after the United States, Brazil, and China. In 2019, Canada produced 632.2 TWh of electricity with 60% of energy coming from Hydroelectric and Tidal Energy Sources).
A water power engine includes prime movers driven by water and which may be classified under three categories:
- Water pressure motors, having a piston and cylinder with inlet and outlet valves: their action is that analogous of a steam- or gas-engine with water as the working fluid – see water engine
- Water wheels
- Turbines, deriving their energy from high velocity jet of jets, or from water supplied under pressure and passing through the vanes of a runner which is thereby caused to rotate
As of 2019, renewable energy technologies provide about 17.3% of Canada's total primary energy supply. For electricity renewables provide 67%, with 15% from nuclear and 18% from hydrocarbons.
Low-head hydropower refers to the development of hydroelectric power where the head is typically less than 20 metres, although precise definitions vary. Head is the vertical height measured between the hydro intake water level and the water level at the point of discharge. Using only a low head drop in a river or tidal flows to create electricity may provide a renewable energy source that will have a minimal impact on the environment. Since the generated power is a function of the head these systems are typically classed as small-scale hydropower, which have an installed capacity of less than 5MW.
Policy makers often debate the constraints and opportunities of renewable energy.
Renewable energy in Russia mainly consists of hydroelectric energy. Russia is rich not only in oil, gas and coal, but also in wind, hydro, geothermal, biomass and solar energy – the resources of renewable energy. Practically all regions have at least one or two forms of renewable energy that are commercially exploitable, while some regions are rich in all forms of renewable energy resources. However, fossil fuels dominate Russia’s current energy mix, while its abundant and diverse renewable energy resources play little role.
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.
Renewable energy in Afghanistan includes biomass, geothermal, hydropower, solar, and wind power. Afghanistan is a landlocked country surrounded by five other countries. With a population of less than 35 million people, it is one of the lowest energy consuming countries in relation to a global standing. It holds a spot as one of the countries with a smaller ecological footprint. Hydropower is currently the main source of renewable energy due to Afghanistan's geographical location. Its large mountainous environment facilitates the siting of hydroelectric dams and other facets of hydro energy.
Renewable energy in Thailand is a developing sector that addresses the country’s present high rate of carbon emissions. Several policies, such as the Thirteenth Plan or the Alternative Energy Development Plan, set future goals for increasing the capacity of renewable energy and reduce the reliance of nonrenewable energy. The major sources of renewable energy in Thailand are hydro power, solar power, wind power, and biomass, with biomass currently accounting for the majority of production. Thailand’s growth is hoped to lead to renewable energy cost reduction and increased investment.
Independent Power Producer (IPP) projects have had a significant presence in British Columbia since the 1980s. Their relationship with BC Hydro grew from the province's need to supply growing energy demands and implementation of the 2002 Energy Strategy, which mandated that BC Hydro would purchase its energy supply from IPPs rather than generating the supply itself. There are a variety of power projects in BC, with the most popular being hydroelectricity and biomass projects. In recent years, more attention has been placed on the environmental effects of IPP projects and the social implications it has to residents living around the project development sites. Despite the decline in demand for new IPP projects, in 2016 they supplied 20,000 GWh, one-third of BC Hydro's total.
A renewable portfolio standard (RPS) is a regulation that requires the increased production of energy from renewable energy sources, such as wind, solar, biomass, and geothermal. Other common names for the same concept include Renewable Electricity Standard (RES) at the United States federal level and Renewables Obligation in the UK.
