From the onset of the Industrial Revolution, fossil fuels have been undoubtedly the most widely used energy sources by mankind. There exists many different forms of fossil fuels with petroleum, coal and natural gas being the most popularly used. These find applications in various facets of the economy including; heat and electrical power generation in coal, gas and diesel engines and power plants, transport and industrial sectors as well as in other less obvious ways as to make products used in homes to facilitate smooth, happy and productive lifestyle.
Source: world energy sources 2013
The preference for the utilization of fossil fuels has been attributed to the fact that technologies used to harness the energy from fossil fuels are the most developed of all the existing technologies. Also,unlike renewable energy sources, they are very reliable and have higher conversion efficiencies compared to the other forms of energy. Moreover, they can be easily transported for harnessing at different locations.
However, over the years, the use of fossil fuels has been the subject of heated debates around the world, particularly pertaining to its sustainability, safety and usage control among many other aspects that have ultimately branded these forms of energy the most inappropriate in this age.
Fossil fuels have been regarded as the main cause of global warming and consequently causing environmental degradation and pollution all which pose great threat to both human,plants and animals existance.
Consequently, a number of structural changes have occurred to facilitate the diversification of the energy sector resulting into increased interest in the exploitation of other alternative energy sources.
Among the various renewable energy sources currently gaining popularity include;
Solar Power
This is cleanest and most abundant renewable energy source available and is the energy converted from sunlight to electricity or thermal heat, either directly using photovoltaics (PV), indirectly using concentrated solar power, or a combination of both using hybrid solar thermal systems. Concentrated solar power systems use lenses or mirrors and tracking systems to focus the incident solar radiation to the conversion surface.
Different solar energy technologies can harness sunlight for a variety of uses including generating electricity and heating water for domestic, commercial or industrial utilisation. However, among the challenges of solar energy exploitation is the limitation of solar energy resource in most parts of the world though researchers have been able to develop special types of PV modules like the heterojunction thin film solar technologies capable of converting over a wide range of frequency in the solar radiation spectrum compared to the conventional silicon solar cells. Solar energy technology has found use majorly in grid connected systems where households generate electricity for their domestic use and feed the surplus to the grid using the bidirectional smart meter system or for autonomous electricity generation in grid isolated locations. The bidirectional smart meter plan has become very popular in Europe and the rest of the world and helps cut the expenditure on electricity since the user only pays for the net difference between the power consumed and that supplied to the grid. Also, several arrays of PV modules can be connected into a photovoltaic system network to generate large scale power to boost the electric grid capacity.
Wind Power
Wind power also offers a sustainable alternative in the pursuit of renewable energy. The kinetic energy of the moving air is tapped by the wind turbine blades whose rotary motion is transmitted to a shaft that is coupled to the rotor of the wind turbine. This mechanical energy is then transformed into electrical energy in the motor of the wind turbine. Wind turbines can be installed either in residential properties to generate power for domestic home use or grouped together to form a wind farm as in large fields or offshore farms to generate large scale power for electric grid connection.
Wind power has a great potential in Europe and Asian continents due to the great wind resource endowment.
Hydroelectric Power
This type of energy is produced from flowing water. The kinetic energy is created when the water falls from a great height through the penstock which is then directed to spin the turbine at a faster rate to produce power.
Hydroelectric power is the most consistent and flexible of the renewable energy sources and consequently dominates renewable energy sector for electric power generation by contributing up to 70% of the total renewable energy power and 17% of the total world electricity. China is the leading country in the production of hydroelectric power at 1180.7 terawatt hours while Russia comes in 5th at 178.31 twh per year (as at 2016)
A hydroelectric power plant
Geothermal Energy
Geothermal energy is produced when hot water or steam is pumped to the surface either through naturally occurring springs or by drilling to tap the heated water from the earth’s heated interior.
The working mechanism of geothermal power station is synonymous to those of other steam turbine where a fuel source (earth’s core for geothermal stations) is used to raise the temperature of the working fluid to produce steam which then drives a turbine of a generator to produce electricity. The steam is then condensed and returned to the heat source to replenish the reservoir.
A geothermal power station
There exists three types of geothermal power plants: dry steam, flash steam, and binary cycle.
Dry steam stations are the simplest and oldest design. They directly use geothermal steam of 150 °C or greater to turn turbines while flash steam power plants use geothermal reservoirs of water with temperatures greater than 182°C. They are the most common type of the geothermal power technology.
Binary cycle power plants on the other hand operate on water at lower temperatures of about 107°-182°C. These plants use the heat from the hot water to boil a working fluid, usually an organic compound with a low boiling point.
Other renewable energy sources that have equally drawn the interest of investors include biomass, ocean (tidal, wave and ocean thermal) energy.
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