How can we make electricity sustainable in South Africa? The answer is innovative and long-lasting. Renewable energy!
"Doing all we can to combat climate change comes with numerous benefits, from reducing pollution and associated health care costs to strengthening and diversifying the economy by shifting to renewable energy, among other measures." David Suzuki
Is Eskom currently load shedding?
How many hours is Stage 2 load shedding?
Is there load shedding in Johannesburg?
What is Stage 4 load shedding?
These are just some of the questions South Africans find themselves "Googling." Everybody wants to know why load shedding happens and whether there is a reliable alternative to energy or electricity supply. Here is the short answer, yes! That YES is backed up by information found by experts in renewable energy at C2ES. This article discusses the benefits of renewable energy, how other countries use renewable energy, particularly the United States of America, as well as advances in the sector. If you have a few minutes to invest and would like to learn about alternative, renewable energy sources in full, please read along, worth every minute!
- Renewable energy is the fastest-growing energy source in the United States, increasing 100 percent from 2000 to 2018.
- Renewables made up more than 17 percent of net U.S. electricity generation in 2018, with the bulk coming from hydropower (7.0 percent) and wind power (6.6 percent).
- Solar generation (including distributed) is projected to climb from 11 percent of total U.S. renewable generation in 2017 to 48 percent by 2050, making it the fastest-growing electricity source.
- Globally, renewables made up 24 percent of electricity generation in 2016, much of it from hydropower (16 percent).
- Renewable ethanol and biodiesel transportation fuels made up over 12 percent of total U.S. renewable energy consumption in 2018, up from 7 percent in 2006.
Renewable Supply and Demand
Renewable energy is the fastest-growing energy source globally and in the United States.
Eighteen percent of the energy consumed globally for heating, power, and transportation was from renewable sources in 2017 (see figure below). Nearly 60 percent came from modern renewables (i.e., biomass, geothermal, solar, hydro, wind, and biofuels) and the remainder from traditional biomass (used in residential heating and cooking in developing countries).
Renewables made up 26.2 percent of global electricity generation in 2018. That’s expected to rise to 45 percent by 2040. Most of the increase will likely come from solar, wind, and hydropower.
The International Energy Agency notes that the development and deployment of renewable energy technologies will depend heavily on government policies and financial support to make renewable energy cost-competitive.
Estimated Global Renewable Energy Share of Total Final Energy Consumption (2017)
Types of Renewable Energy
Renewable energy comes from sources that can be regenerated or naturally replenished. The main sources are:
Water (hydropower and hydrokinetic)
Solar (power and hot water)
Biomass (biofuel and biopower)
Geothermal (power and heating)
All sources of renewable energy are used to generate electric power. In addition, geothermal steam is used directly for heating and cooking. Biomass and solar sources are also used for space and water heating. Ethanol and biodiesel (and to a lesser extent, gaseous biomethane) are used for transportation.
Renewable energy sources are considered to be zero (wind, solar, and water), low (geothermal) or neutral (biomass) with regard to greenhouse gas emissions during their operation. A neutral source has emissions that are balanced by the amount of carbon dioxide absorbed during the growing process. However, each source’s overall environmental impact depends on its overall lifecycle emissions, including manufacturing of equipment and materials, installation as well as land-use impacts.
L2 gigawatts (GW) of global capacity, hydropower produced an estimated 4,210 terawatt hours (TWh) of the 26,700 TWh total global electricity in 2018.
The United States is the fourth-largest producer of hydropower after China, Brazil, and Canada. In 2011, a much wetter than average year in the U.S. Northwest, the United States generated 7.9 percent of its total electricity from hydropower. The Department of Energy has found that the untapped generation potential at existing U.S. dams designed for purposes other than power production (i.e., water supply, flood control, and inland navigation) represents 12 GW, roughly 15 percent of current hydropower capacity.
Hydropower operational costs are relatively low, and hydropower generates little to no greenhouse gas emissions. The main environmental impact is that a dam to create a reservoir or divert water to a hydropower plant changes the ecosystem and physical characteristic of the river.
Waterpower captures the energy of flowing water in rivers, streams, and waves to generate electricity. Conventional hydropower plants can be built in rivers with no water storage (known as “run-of-the-river” units) or in conjunction with reservoirs that store water, which can be used on an as-needed basis. As water travels downstream, it is channeled down through a pipe or other intake structure in a dam (penstock). The flowing water turns the blades of a turbine, generating electricity in the powerhouse, located at the base of the dam.
Other Hydroelectric Power Generation
Small hydropower projects, generally less than 10 megawatts (MW), and micro-hydropower (less than 1 MW) are less costly to develop and have a lower environmental impact than large conventional hydropower projects. In 2016, the total amount of small hydro installed worldwide was 78 GW. China had the largest share at 51 percent. China, Italy, Japan, Norway and the United States are the top five small hydro countries by installed capacity. Many countries have renewable energy targets that include the development of small hydro projects.
Hydrokinetic electric power, including wave and tidal power, is a form of unconventional hydropower that captures energy from waves or currents and does not require dam construction. These technologies are in various stages of research, development, and deployment. In 2011, a 254 MW tidal power plant in South Korea began operation, doubling the global capacity to 527 MW. By the end of 2018, global capacity was about 532 MW.
Low-head hydro is a commercially available source of hydrokinetic electric power that has been used in farming areas for more than 100 years. Generally, the capacity of these devices is small, ranging from 1kW to 250kW.
Pumped storage hydropower plants use inexpensive electricity (typically overnight during periods of low demand) to pump water from a lower-lying storage reservoir to a storage reservoir located above the power house for later use during periods of peak electricity demand. Although economically viable, this strategy is not considered renewable since it uses more electricity than it generates.
Hydroelectric Power Generation
Wind was the second largest renewable energy source (after hydropower) for power generation. Wind power produced more than 5 percent of global electricity in 2018 with 591 GW of global capacity (568.4 GW is onshore). Capacity is indicative of the maximum amount of electricity that can be generated when the wind is blowing at sufficient levels for a turbine. Because the wind is not always blowing, wind farms do not always produce as much as their capacity. With around 210 MW, China had the largest installed capacity of wind generation in 2018. The United States, with 96.5 GW, had the second-largest capacity; Texas, Oklahoma, Iowa, and Kansas provide more than half of U.S. wind generation.
Although people have harnessed the energy generated by the movement of air for hundreds of years, modern turbines reflect significant technological advances over early windmills and even over turbines from just 10 years ago. Generating electric power using wind turbines creates no greenhouse gases, but since a wind farm includes dozens or more turbines, widely-spaced, it requires thousands of acres of land. For example, Lone Star is a 200 MW wind farm on approximately 36,000 acres in Texas.
Average turbine size has been steadily increasing over the past 30 years. Today, new onshore turbines are typically in the range of 2 – 5 MW. The largest production models, designed for off-shore use can generate 12 MW; some innovative turbine models under development are expected to generate more than 14 MW in offshore projects in the coming years. Due to higher costs and technology constraints, off-shore capacity, approximately 22.6 GW in 2018, is only a small share (about 4 percent) of total installed wind generation capacity.
Wind Turbine Sizes
Solar energy resources are massive and widespread, and they can be harnessed anywhere that receives sunlight. The amount of solar radiation, also known as insolation, reaching the Earth’s surface every hour is more than all the energy currently consumed by all human activities each year. A number of factors, including geographic location, time of day, and weather conditions, all affect the amount of energy that can be harnessed for electricity production or heating purposes.
Solar photovoltaics are the fastest-growing electricity source. In 2018, around 100 GW of global capacity was added, bringing the total to about 505 GW and producing a bit more than 2 percent of the world’s electricity.
Solar energy can be captured for electricity production using:
A solar or photovoltaic cell, which converts sunlight into electricity using the photoelectric effect. Typically, photovoltaics are found on the roofs of residential and commercial buildings. Additionally, utilities have constructed large (greater than 100 MW) photovoltaic facilities that require anywhere from 5 to 13 acres per MW, depending on the technologies used.
Concentrating solar power, which uses lenses or mirrors to concentrate sunlight into a narrow beam that heats a fluid, producing steam to drive a turbine that generates electricity. Concentrating solar power projects are larger-scale than residential or commercial PV and are often owned and operated by electric utilities.
Solar hot water heaters, typically found on the roofs of homes and apartments, provide residential hot water by using a solar collector, which absorbs solar energy, that in turn heats a conductive fluid, and transfers the heat to a water tank. Modern collectors are designed to be functional even in cold climates and on overcast days.
Electricity generated from solar energy emits no greenhouse gases. The main environmental impacts of solar energy come from the use of some hazardous materials (arsenic and cadmium) in the manufacturing of PV and the large amount of land required, hundreds of acres, for a utility-scale solar project.
Concentrating Solar Power
Biomass energy sources are used to generate electricity and provide direct heating, and can be converted into biofuels as a direct substitute for fossil fuels used in transportation. Unlike intermittent wind and solar energy, biomass can be used continuously or according to a schedule. Biomass is derived from wood, waste, landfill gas, crops and alcohol fuels. Traditional biomass, including waste wood, charcoal and manure, has been a source of energy for domestic cooking and heating throughout human history. In rural areas of the developing world, it remains the dominant fuel source. Globally in 2017, traditional biomass accounted for about 7.5 percent of total energy consumption. The growing use of biomass has resulted in increasing international trade in biomass fuels in recent years; wood pellets, biodiesel, and ethanol are the main fuels traded internationally.
In 2018, global biomass electric power capacity stood at 130 GW. In 2018, the United States had 16 GW of installed biomass-fueled electric generation capacity. In the United States, most of the electricity from wood biomass is generated at lumber and paper mills using their own wood waste; in addition, wood waste is used to generate the heat for drying wood products and other manufacturing processes. Biomass waste is mostly municipal solid waste, i.e., garbage, which is burned as a fuel to run power plants. On average, a ton of garbage generates 550 to 750 kWh of electricity. Landfill gas contains methane that can be captured, processed and used to fuel power plants, manufacturing facilities, vehicles and homes. In the United States, there is currently more than 2 GW of installed landfill gas-fired generation capacity at more than 600 projects.
In addition to landfill gas, biofuels can be synthesized from dedicated crops, trees and grasses, agricultural waste and algae feedstock; these include renewable forms of diesel, ethanol, butanol, methane and other hydrocarbons. Corn ethanol is the most widely used biofuel in the United States. Roughly 38 percent of the U.S. corn crop was diverted to the production of ethanol for gasoline in 2018, up from 20 percent in 2006. Gasoline with up to 10 percent ethanol (E10) can be used in most vehicles without further modification, while special flexible fuel vehicles can use a gasoline-ethanol blend that has up to 85 percent ethanol (E85).
Closed-loop biomass, where power is generated using feedstocks grown specifically for the purpose of energy production, is generally considered to be carbon dioxide neutral because the carbon dioxide emitted during combustion of the fuel was previously captured during the growth of the feedstock. While biomass can avoid the use of fossil fuels, the net effect of biopower and biofuels on greenhouse gas emissions will depend on full lifecycle emissions for the biomass source, how it is used, and indirect land-use effects. Overall, however, biomass energy can have varying impacts on the environment. Wood biomass, for example, contains sulfur and nitrogen, which yield air pollutants sulfur dioxide and nitrogen oxides, though in much lower quantities than coal combustion.
Geothermal provided an estimated 175 TWh globally in 2018, one half in the form of electricity (with an estimated 13.3 GW of capacity) and the remaining half in the form of heat. (Total global electricity generation in 2018 was 26,700 TWh).
In the United States, 16 billion kWh of geothermal electricity was generated in 2018, making up about 4 percent of non-hydroelectric renewable electricity generation, but only 0.4 percent of total electricity generation. Seven states generated electricity from geothermal energy: California, Hawaii, Idaho, Nevada, New Mexico, Oregon and Utah. Of these, California accounted for 80 percent of this generation.
Traditional geothermal energy exploits naturally occurring high temperatures, located relatively close to the Earth’s surface in some areas, to generate electric power and for direct uses such as heating and cooking. Geothermal areas are generally located near tectonic plate boundaries, where there are earthquakes and volcanoes. In some places, hot springs and geysers have been used for bathing, cooking and heating for centuries
Generating geothermal electric power typically involves drilling a well, perhaps a mile or two in depth, in search of rock temperatures in the range of 300 to 700°F. Water is pumped down this well, where it is reheated by hot rocks. It travels through natural fissures and rises up a second well as steam, which can be used to spin a turbine and generate electricity or be used for heating or other purposes. Several wells may have to be drilled before a suitable one is in place and the size of the resource cannot be confirmed until after drilling. Additionally, some water is lost to evaporation in this process, so new water is added to maintain the continuous flow of steam. Like biopower and unlike intermittent wind and solar power, geothermal electricity can be used continuously. Very small quantities of carbon dioxide trapped below the Earth’s surface are released during this process.
Enhanced geothermal systems use advanced, often experimental, drilling and fluid injection techniques to augment and expand the availability of geothermal resources.