This is a short guide outlining the different types of renewable energy sources, with examples of each.
Summary – The Different Types Of Renewable Energy Sources
The different types of renewable energy are:
Solar (PV – photovoltaic, and thermal) – read more about the different types of solar in this guide
Wind (onshore, and offshore) – read more about the different types of wind in this guide
Hydropower (run-of-river, storage, pumped-storage) – read more about the different types of hydropower in this guide
Geothermal (steam, and water)
Some other notes of renewable energies are:
China is the main leader right now across many renewable energy investment, production and consumption statistics
Hydropower is the dominant source of renewable energy right now that we get electricity from (around 50% of renewable energy)
Wind and solar are receiving majority of the investment and growth of all the renewables over the period of the last decade or so
In the US, bioenergy is rapidly growing over the short term future
There is a difference between renewable, and clean/eco friendly energy.
Renewable means the energy comes from a natural source and can be replenished quickly, or within a human lifespan, without being depleted. Renewable doesn’t necessarily mean the energy is clean/eco friendly though.
Clean energies look at the full environmental and sustainable impact of the energy throughout it’s entire life cycle.
For example, some types of bioenergy might be renewable in some ways, but may not be an eco friendly type of energy because it requires land, water, sometimes fertilizer and pesticides, and has emissions/pollution, or waste to consider.
Compare this to solar or wind energy for example that requires no resource input (apart from land) and produces no waste product or air pollution while in operation.
Another example is nuclear which is not renewable, but is relatively clean while in operation (apart from the radioactive waste generated). So, each energy source has its own set up pros and cons.
Solar (PV – photovoltaic, and thermal)
Uses solar technology (usually solar panels) to convert solar radiation into DC electricity with semiconductors.
[Some of the biggest operational solar PV setups are in China and India]
Solar thermal technologies capture the heat energy from the sun and use it for heating and/or the production of electricity.
This is different from photovoltaic solar panels, which directly convert the sun’s radiation to electricity
[Some of the biggest operational solar thermal setups are in Morocco, the US and Spain]
Wind (onshore, and offshore)
Wind energy uses horizontal or vertical axis wind turbines/wind generators to turn mechanical energy from wind into electricity.
Wind energy farms that are built on main land, either more centrally or in very small set ups remotely.
[The US and China have some of the largest operational onshore wind farms]
Wind energy set up off the main land – usually on bodies of water, or on the ocean.
They are usually more expensive to set up than onshore wind farms.
[Some of the biggest operational offshore wind setups are in the UK, Netherlands, Germany, Denmark and China]
Hydropower uses a turbine and electricity generator to turn mechanical energy from running water (that naturally flows, or is mechanically pumped from a water storage area), into electricity.
Hydropower plants can often incorporate several or all of the below features and types of hydropower i.e. a run-of-river setup can also include a storage area and mechanical pumping.
Channels a running water source like a river to a turbine and hydropower plant
As long as the river is running, it provides a continuous supply of electricity (base load)
[traditionally, it has little or no water storage area – instead, relying on running water from the water source]
Water is stored in a dam or reservoir
Water is released into a turbine that turns and activates a generator
Can run consistently and provide baseload power, or can be be shut down and turned on again for temporary power to meet peak load demands
Can operate independently of an inflow of water for weeks and months
Has both a higher level reservoir of water, and a lower level one
Water can be pumped to the higher level reservoir, and can then be released back down to the lower level (which usually doesn’t require pumping, and pushes water through a turbine)
Can provide both peak demand energy supply, and low demand energy supply
The Three Gorges Dam in Hubei, China, and the Itaipu Dam in Brazil/Paraguay are two of the largest hydroelectricity plants in the world.
These plants can have varying electricity outputs because of variances in water availability and flow (wikipedia.org).
Geothermal energy makes use of heat energy – either very hot steam, or very hot water (high-temperatures of usually 300°F to 700°F) that comes from beneath the Earth’s surface – to power a turbine that creates electricity.
Dry steam wells or hot water wells are usually used, and they can be drilled by humans into the Earth.
There are three types of geothermal plants that use different systems for either vapor or water:
Dry steam (use steam)
Flash steam (takes high pressure water that is converted to steam)
Binary cycle plants (transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam)
– eia.gov, and wikipedia.org
Globally, geothermal power plants are widespread. The US has the largest installed geothermal power plant right now – The Geysers, located north of San Francisco. Italy, Mexico, the Philippines and Iceland also have some large geothermal power plants (wikipedia.org, and worldatlas.com)
Uses energy from waves (created when wind blows across the surface of water) in the ocean, that act upon wave energy devices (in an optimised array), to produce electricity.
Not widely commercially used yet due to the cost and a range of other problems for producing power at scale.
Some notable wave farm projects have been designed, and some built, in the UK, Australia, the US and Portugal (wikipedia.org)
Uses energy from the ocean’s tide motions and currents (caused by the gravitational pull of the Sun and Moon) to produce electricity via a tidal generator.
Like wave energy, tidal energy hasn’t been used to produce energy at scale because of cost issues.
Tidal energy also suffers from a lack of suitable sites, but technological breakthroughs in the future could change that.
A number of tidal tests, small projects and schemes have been conducted, built and designed worldwide (wikipedia.org).
Biomass is organic renewable matter like wood, or other plant based material (but technically includes living things like animals as well).
It usually comes from the growing of crops, or from waste from various sectors.
Biomass is used to generate heat or electricity by burning it directly, and biofuel type products for transport via conversion.
Bioenergy includes both traditional and modern bioenergy:
… Traditional use refers to the combustion of biomass in such forms as wood, animal waste and traditional charcoal.
Modern bioenergy technologies include liquid biofuels produced from bagasse and other plants; bio-refineries; biogas produced through anaerobic digestion of residues; wood pellet heating systems; and other technologies.
Brazil is the leader in liquid biofuels and has the largest fleet of flexible-fuel vehicles (irena.org)
However, the US is also expected to increase their modern bioenergy capacity in the short term future (iea.org)
Algal and aquatic biomass might be the new third generation of bioenergy.
A few good resources on bioenergy are:
Renewable Energy Investment, Installed Capacity, Production, & Consumption Worldwide, By Country & By Energy Source
Pros & Cons Of The Different Renewable Energy Sources
Biomass Energy Pros & Cons (can be both a renewable and alternative energy depending on various factors)