7 Most Common Types of Renewable Energy
There are many benefits to implementing renewable energy for your business. These include reducing the risk of energy price fluctuations and service disruptions during extreme weather events, as well as receiving a good return on your investment. Clearly, all of this depends on a variety of factors, including your organization’s size, physical location and structure, the type of renewable energy selected and the type of contract entered into.
While most organizations are familiar with wind and solar energy, many are not aware that there are other types of renewable energy available. Even though most businesses may not currently have ready access to some of these other technologies, it is still worth noting them for future reference, as the market is rapidly evolving.
There are seven types of renewable energy that are most commonly used and referred to in today’s market, although the last can be considered renewable or non-renewable. Note that books can be written on each of these topics – this overview is to be used as a starting point for further exploration of the topic.
1. Wind
Wind energy technology takes advantage of the natural power of wind, which turns large turbines that collect the wind energy. The wind flows over and spins airfoil shaped blades, which are connected to a drive shaft that turns an electric generator to produce electricity. There is an estimated 72 TWh of wind energy on Earth that potentially can be commercially viable, however, not all the energy created by wind flowing past the blades can be captured or recovered. To put it in perspective, 1TWh can power twice the number of homes that exist in the US.
There are three types of wind energy:
Utility-scale: This consists of large wind turbines that start at 100 kilowatts and go to several megawatts. This energy is harnessed and delivered to the power grid, and distributed to the end user by the utilities.
Distributed: Otherwise known as ‘small’ wind turbines, these turbines are under 100 kilowatts, can be used to power a home or small business and are not connected to the grid.
Offshore: Large turbines (larger than those onshore) that are placed in large bodies of water and can generate even larger amounts of power that is then transmitted to the grid via undersea cables.
2. Solar
Until relatively recently, the two most common types of solar power technologies were photovoltaics (in the form of rigid glass panels) and solar thermal. This is in addition to the traditional daylighting, skylights and (more recently) solar tubes used to bring in more light to spaces.
Photovoltaics produce energy from the chemical reaction of solar cells. Solar thermal uses the sun’s heat to generate passive heating, hot water or thermal cooling.
More recent additions to the mix include flexible thin-film photovoltaics, concentrated solar power (CSP) and concentrated PV (CPV) systems.
Thin film solar cells: Use layers of semiconductor materials only a few micrometres thick, and can be applied to roofing materials and building facades.
CSP: Uses mirrors or lenses to concentrate a large area of sunlight onto a small area. That light is then converted into heat that drives a steam turbine connected to a power generator. This technology can be used for power plants, instead of fossil fuel or nuclear energy.
CPV: Uses conventional PV technology and adds an optical system that focuses a large amount of sunlight on each cell.
3. Geothermal
Geothermal energy comes from the Earth’s natural heat - part of which is from the planet’s original formation while a greater portion stems from ongoing radioactive decay of minerals. The temperature difference between the surface of the planet and the molten core causes a continual movement of heat energy from the core to the surface which provides a constant source of this energy from the Earth. The energy is converted into electricity via one of three types of geothermal power plants. The plants use the steam from the hot water beneath the earth’s surface to turn turbines that power a generator, which in turn produces electricity.
Geothermal can be incorporated into a commercial utility’s energy solutions or can be implemented at the local level. The three types of power plants are dry steam, flash steam and binary cycle plants. The main advantage of geothermal power over wind and solar is that it provides a more stable base-load power resource with a capacity factor close to 95% over a 24-hour period. Its reliability, a crucial issue for utility and business operation, allows geothermal to compete with other renewable resources that have been more popular - and more visible, such as solar and wind.
4. Hydroelectric
Generating electricity from hydropower involves harnessing the kinetic energy contained in water that is being forced by gravity from a high place to a lower place. The water flows via channel or penstock to a waterwheel or turbine where it strikes the bucket of the wheel, causing the shaft of the waterwheel or turbine to rotate. When generating electricity, the rotating shaft, which is connected to an alternator or generator, converts the motion of the shaft into electrical energy. This electrical energy may be used directly, stored in batteries, or inverted to produce utility-quality electricity.
A small-scale hydroelectric facility requires that a sizable flow of water and a proper height of fall of water is obtained without building elaborate and expensive facilities. Small hydroelectric plants can be developed at existing dams and are commonly constructed in conjunction with river and lake water-level control and irrigation schemes. By using existing structures, only minor new civil engineering works are required, reducing the cost of this component of a development.
5. Biomass & Biofuels
Biomass is organic material made from plants or animals - such as wood, crops, manure, etc. - that contain stored energy from the sun. With technological development, biomass is more often converted to other usable forms of energy like methane gas or transportation fuels such as ethanol and biodiesel.
The two most common types of biofuels are ethanol and biodiesel. Though similar in function, biodiesel and ethanol usually have differing sources and are produced differently. Ethanol is a type of alcohol, the same that is found in beer and wine, made from the sugars found in grains, including corn, sorghum, and wheat, as well as rice and yard clippings. Most of the ethanol produced in the United States comes from corn. Biodiesel fuel can be produced from a variety of natural crops, such as rapeseed, soybean, flax, etc. Pure biodiesel (B100) or biodiesel blended with petroleum in a proportion of 2% (B2) and 5% (B5) can be used instead of diesel fuels made from petroleum.
6. Ocean & Tidal Energy
Oceans, covering 71% of the Earth’s surface, store a large amount of energy that is consistent and predictable. Ocean energy can be mechanical or thermal. Mechanical energy harnesses the power of tides and waves, while thermal uses warm water surface temperatures to generate energy. In places where the wind blows constantly and generates continuous waves, wave power devices can be used to extract energy.
There are various types of offshore and tidal energy systems that are used to do this. Offshore systems are usually situated in deep water, more than 40 meters (approximately 131 feet) below the surface. There are several types of devices used for offshore systems. Tidal energy generators convert the energy of tides into electricity. Large turbines, which look like wind turbines, are placed underwater in areas with high tidal movements. Those turbines capture the kinetic motion of ocean tides to produce electricity.
7. Hydrogen
Hydrogen does not occur naturally as a gas, but can be found in organic compounds such as natural gas, methane and gasoline, and in water. Hydrogen can be a renewable or non-renewable resource, depending on the source of hydrogen. Pure hydrogen can be obtained through water electrolysis, although most hydrogen is currently produced from natural gas.
The advantage of hydrogen is that it is high energy and low pollution when burned. It is considered an energy carrier, not an energy source, and can deliver a large amount of energy. Currently, hydrogen in the US is used to refine petroleum, process foods, treat fertilizer and treat metals. Hydrogen fuel cells are used as an energy source, with hydrogen and oxygen combining to generate electricity. When consumed in a fuel cell, hydrogen produces only heat, water and electricity.
For a breakdown of the percent and types of renewable energy being used globally, check out the Renewable Energy section on the Our World in Data website.
If you are looking to get started going green at work, be sure to download our free Beginner’s Guide to Going Green, with suggested projects to get started.