What Is Renewable Energy?
In an era where global warming has been recognised as a major threat to the future of our planet and greenhouse gas emissions being a main contributor to the problem, we hear renewable energy being cited as a way of cutting down on these harmful gas emissions. What exactly is renewable energy and how does it cut down harmful emissions?
Renewable energy is derived from the earth’s natural resources which are infinite and will not run out in the way in which fossil fuels will. Wind, sunlight and water can all be used to generate power by harnessing their natural energy and offer an alternative to burning fossil fuels, making them much less harmful to the environment.
Wind Power
Generating electricity from wind power is becoming the most widely used method of generating clean energy. Wind farms generate electricity by spinning the blades of wind turbines which convert the kinetic energy of the spinning blades to electric energy via a drive shaft and gear box connected to a generator. This electricity is then fed into the national grid. These turbines have sensors which detect the strength and direction of the wind and adjust the direction of the turbine to suit, so that the maximum use is made of the wind. The pitch of the blades can also be adjusted to allow for strong and gale force winds which would cause damage to the installation. Hills, mountains and deep valleys can all affect the strength and direction of the wind and therefore a flat landscape is best suited for wind turbines. This makes offshore sites and hilltops ideal for wind farms.
As of the third quarter of 2021, wind energy contributed around a quarter of the UK’s total electricity generation. In comparison to other methods of power generation, constructing a wind farm is a relatively short term project which makes this form of power generation a firm favourite for expanding our green energy capacity. By 2022, the UK had over 11 thousand wind turbines with a total installed capacity of over 25 gigawatts.
Solar Power
Solar power is the most eco-friendly generation source; it produces no harmful gas emissions or pollution, and poses no threat to wildlife. It can be used virtually anywhere and can be harnessed in remote locations where there is no electrical grid.
Solar energy is generated by using Solar Photovoltaics (PV) Panels. These consist of cells made from layers of semi-conducting material, most often silicon. When light shines on the panels a flow of electricity is created and converted into direct current (DC) electricity, which can be further converted into alternating current (AC) using an inverter. This can then be used in the same way as electricity generated by burning fossil fuels. Once again, because nothing is being burned to generate electricity, there are no greenhouse gas emissions to worry about. The cells don’t need direct sunlight to work and can even work on cloudy days. However, the stronger the sunshine, the more electricity generated.
Solar panels can either be used in large installations, with the UK’s largest covering over 220 acres and generating in excess of 72megawatts, or in domestic situations requiring in the region of 10 PV panels with each panel generating around 355W of energy in strong sunlight to be installed, normally on the roof of a property.
In a domestic setting having a solar panel installation may mean that you should go against all recommendation to use more power at night when demand is lower and tariffs probably more favourable. Your PV panels will generate most power during daylight hours, especially in strong direct sunlight, so it would make sense to utilise your high usage appliances such as washing machines, dishwashers and irons to coincide with your maximum power input. The alternative is to install batteries which your panels would charge up during the day and allow you to use the stored power at a later time. A ten panel solar installation would cost around £5000, adding batteries would roughly double that outlay.
Hydroelectricty
Hydroelectricity is a renewable energy source which uses the energy of running water, rather than the water itself, to produce electricity. Hydropower supplies one sixth of the world's electricity and almost three quarters of renewable energy, which was almost 4500 terawatts in 2020. When most people think of a hydroelectric plant they see a large dam with a substantial reservoir of water held behind it. The water is allowed to flow through a gate valve or sluice and as it flows downward it can be channelled through the blades of a turbine causing them to turn which generates electricity. The water then continues to flow downstream in the same state that it left the reservoir in. If the demand for power increases the flow of water through the turbines can be increased accordingly.
Sadly large hydroelectric schemes involve huge construction projects and stopping the flow of a river to form the reservoir. This is expensive and highly disruptive to both wildlife and the communities around the scheme, although the resultant body of water can be used to provide leisure facilities for water sports.
Smaller scale, less intrusive hydroelectric plants can involve forming a diversion channel in a river and again directing the flow of water through a turbine to generate electricity. Alternatively, a Pumped Storage facility consists of a small reservoir at the top of a hill and when called on to generate power, some of that water is allowed to flow down the hill via a turbine. On reaching the bottom of the hill, the water can be pumped back up to the reservoir using stored electricity generated from either solar or wind.
Wave energy is a form of renewable energy that can be generated from the motion of the waves. As waves are formed in the ocean, they create kinetic energy which is used to power turbines and create energy that can be converted into electricity.
This form of energy generation is zero waste and produces no damaging gases, it is also available 24/7 all year round. Wave energy is only available to countries which have coastal areas for obvious reasons. As the technology is still very much in its infancy there are concerns still over the cost of energy generated in this way and there is also uncertainty over the longevity of the equipment due to the potentially harsh environment in which it operates.
Biomass
Biomass is another source of renewable energy, generated from burning wood, plants and other organic matter, such as manure or in some cases, household waste. It releases carbon dioxide when burned, but much less than fossil fuels and is considered to be a renewable energy source, provided the plants, wood or other organic materials being burned are replaced. Some will argue that in replacing these trees and plants to make biomass fuels sustainable, we also counteract the carbon dioxide emissions from the fuel when we burn it with the carbon dioxide these new plants absorb as they grow. We also need to effectively manage the deforestation required to give us timber for use as biomass.
The use of biomass fuels varies from using wood burner stoves in the home to powering reactors at Drax power station and is very much an expanding resource. Biofuels are also now being used in cars and other fossil fuelled vehicles and this will increase as sales outlets for the fuels become more accessible.
As the planet moves closer to a climate crisis brought on mainly by the emission of harmful greenhouse gases, we all need to look seriously at our own carbon emissions and take steps to reduce the harm we do to the planet. If not for our own benefit, then for that of our children and future generations. By using renewable, carbon free methods of power generation whether it be to give us electricity to heat and light our homes or power our vehicles,