Renewable energy sources provide the cleanest sources of energy. They don’t introduce pollutants into the environment. Compared with renewable energy technologies the conventional fossil fuel energy technologies aren’t clean. We continue to generate electricity from both renewable and non renewable energy sources.
The Sun’s light and energy are the prime sources of renewable energy. We can feel the power source of the Sun’s radiation. Its radiant heat and light energy are renewable energy sources. Many people associate alternative renewable energy sources with solar photovoltaic (PV) electricity generation.
There are many types of renewable energy sources that I will briefly cover below. Many (but not all) renewable sources of energy start from the sun.
Environmental Benefits of Renewable Energy Sources
When we invest to develop renewable energy sources, the spending goes to access land, capital and labour. The investor must secure the right site for the renewable energy project, and complete design work that demonstrates a project’s cost feasibility. Renewable energy projects may require the manufacture of specialist components and construction materials used to erect buildings, install plant and infrastructure. Some components and materials need import approvals. The skilled local labour workforce is usually preferred but workers may need to come from elsewhere.
After construction, local labour can be trained to operate and maintain the facility. Once the renewable energy sources are installed they need no further raw materials transported to make them operate. Energy sourced from fossil fuels, like coal or oil, need transport. There are carbon impacts for transporting materials sourced within country or as imports. Burning bulk physical energy sources (like coal) to generate electricity sometimes seems cheaper. Unfortunately, their wastes pollute and degrade the environment in the process.
With renewable energy projects the invested cash is often spent nearer to the plant site. The frequent spend can benefit the same town. Governments may use these renewable energy dollars to sustain the local economies and create long term jobs. Using renewable energy sourced technologies can develop the local community to build its capability. That local community’s up-skilled specialised capacity can then be on-sold interstate or even overseas.
Renewable Energy Sources From The Sun
Renewable energy sourced as direct sunlight can light our homes and office buildings during the day. Having opened or glazed doors, windows in walls, ceiling skylights or windows in the roof area will facilitate natural daylight. Heat from the sun will raise the direct temperature of a fluid within a solar thermal panel to produce hot water for heating airspaces or the water.
The sun’s energy that’s absorbed by water can evaporate to become water vapour. Water vapour is lighter than air so it rises in the atmosphere. As the water vapour cools it starts to condense, lose latent heat and form visible clouds. When precipitation falls and water moves into streams and rivers its energy can be stored in dams. The potential energy of the elevated water can be captured when the water is directed through turbines. This renewable energy sourced from the turbine is called hydroelectricity.
Sunlight and water are necessary for plant growth. Plants contain cellulose fibres known as biomass. Biomass can be harvested, processed and converted to bioenergy for heat, fuels, or electricity. Biomass is a widely used resource for cooking and heating in many parts of the world.
Wind Power – As Renewable Energy Sources
Wind is a popular renewable energy resource. It comes from a renewable energy source that is endlessly replenished so it will never run out. The sun’s heat is absorbed across the earth during the day, which creates air movement. Therefore, the sun drives the wind. The energy held in moving air can be captured with wind turbines. This turbine’s renewable energy source is wind power.
Renewable Energy’s Other Alternatives
The sun doesn’t provide every renewable energy source.
Water is a stable compound that is made up of hydrogen and oxygen. Hydrogen is abundant but not found as a natural part of air. H2 is the lightest gas on the element periodic table. Hydrogen is a non-metal having an element +1 charge when found in compounds.
Hydrogen gas can be separated from water by the process of electrolysis. H2 can be a by-product of chemical reaction of acid and metal as found in operating lead acid batteries.
Hydrogen can be collected and this compressed gas is a store of energy. It can be burned as a fuel and converted into electricity. H2 extraction and storage forms the basis of hydrogen cell technology.
Geothermal Ground Energy
The Earth’s internal heat can be accessed for electric power production. The hot rocks as well as thermal springs provide a renewable energy source. This turbine energy is called geothermal energy.
Heat pumps use the stable natural ground temperature for heating and cooling of buildings where the air temperatures vary. A fluid is pumped through buried pipes absorbing heat from the ground or releasing heat into it. A heat exchanger in the building circulates building air and returned fluid so that the air temperature is moderated.
Renewable Energy From The Ocean
Water is the most abundant element on the Earth’s surface appearing mostly as ocean seawater. The sun warms the surface of the ocean. Surface water absorbs more energy than the ocean at depth, which creates a temperature difference. Technology enables that temperature gradient to be used as a renewable energy source.
The ocean contains a renewable source of energy. Energy can be extracted from tidal water, waves and ocean currents. The ocean’s tides develop from the gravitational pull of the moon and the sun upon the Earth. The ocean water moves when the seawater is attracted by the gravitational pull of the orbiting moon. These significant water movements are tides.
Wall-like structures are constructed as obstacles in the path of moving tidal water. There are turbines built into these structures to extract energy from the moving tidal water.
The ocean’s waves pushed by tides and wind can be harvested as a renewable energy source. Buoys and fixed or floating actuators extract the ocean wave energy to produce electricity.
Solar Thermal Heating And Cooling
The direct current (DC) electricity from solar PV generation can be used to electrically heat water. A more efficient method of heating water uses solar thermal heating. A liquid absorbs the radiant heat of the sun in tubes to produce hot water. The hot water can stored and can also be used directly to heat buildings.
Interestingly, direct solar heating can be used to cool buildings. Heat is used to drive a turbine and compressor that forces an evaporation cooling cycle that produces chilled water. The chilled water is used for cooling. Solar cooling is applied to commercial and industrial uses.
Those solar thermal driven cooling systems provide an alternative to traditional air conditioning in hot climates. Solar thermal cooling systems use mechanical pressure to extract latent heat with phase change (evaporation or condensation of a liquid such as water, or ammonia). The process of heat exchange removes heat from a liquid coolant. Here water serves as the coolant. The cold fluid in pipes gets warmed as they remove heat from the adjacent room air in its environment.
When the gaseous coolant condenses back to water heat is given off. The heat that results from condensation is removed by a heat exchanger. The heat of condensation released in the process can be used elsewhere for heating. The cooling can be applied to air conditioning.
There is a conservation of energy in this phase change process. A physical relationship of the gas pressure, gas volume and the absolute temperature of gases were first explained in Boyles Law. The combined gas law which says that as long as the amount of gas doesn’t change, the ratio between the pressure-volume and temperature of a system is a constant.
Some countries are net exporters of fuel oil. Some countries need to supplement their production of fossil fuel with imports. The USA imports oil but its national oil production has increased so its dependence on oil supplies from other countries should be decreasing. Some ‘new oil’ volume is coming from the newly engaged technology of ‘fracking’.
The impact of using renewables is more widespread than just our national energy policy. Greater encouraged use of renewable energy sources provides a localised reliable energy base less dependant on oil costs. A decreased dependence on fuel oil for electricity means that ongoing fuel oil can be utilized in other ways. The outcome of using local renewable energy is that there will be greater energy security. If you are interested in a more in-depth visit to renewables I have written an e-Book about renewables.