Renewable Energy Sources

Types of renewable energy sources

Renewable energy can be found in different types and forms and are linked with different phenomena in nature. Each energy renewable source has its own unique nature and thus can only be harnessed in a specific manner and in a specific environment.

Solar Energy

Solar energy is the energy derived from the sun. Both actively and passively, solar energy can be captured and used for different purposes. The captured energy is converted into electrical energy which we use to power our homes, offices and other devices. Solar panels are best located in places that receive sunlight throughout the year with little to no rainfall or cloud cover, but solar panels are effective even when clouds block direct sunlight because the light can still penetrate the clouds.

Actively, solar energy is harnessed using photovoltaic cells, which are then stored in a battery for future use.

The stored energy is used to generate electricity, which is later used for powering electrical appliances.

Passive solar energy refers to the direct use of solar energy by focusing the sun's rays onto a specific point to generate heat.

Sunlight being is captured by photovoltaic cells in a solar energy farm, justenergy.com

Passively, solar energy is used in everyday life. For example, the heating of water houses during the day, happens naturally without any human intervention.

Wind energy

Wind energy is the energy harnessed from the moving air. Over the centuries, wind energy has been used for a range of purposes. Ships used the wind to power their sails, and windmills used the power of the wind to grind grain into flour.

In the modern world, wind energy is harnessed using wind turbines to generate electricity. These are mostly located in places where wind flow is steady to facilitate the constant generation of energy, such as farmland, narrow mountain passages or even in the ocean (also known as offshore windmills). These windmills generate clean energy when we have a steady flow of wind.

Wind farm for large-scale energy generation. pinterest.com

Tidal Energy

Tidal energy is generated by flowing seawater, we can think of these as like windmills fitted below the sea near the seabed. The working principle is the same as that of a windmill. The movement of seawater during the changing tides causes the blade to rotate, leading to the generation of energy.

Tidal energy generation, source: Tidal energy Image

Hydroelectric energy

Hydroelectricity is generated by the falling of water which is stored in a reservoir. Dams block naturally flowing water, thus creating an artificial lake or a reservoir. A specific amount of water is allowed to flow through tunnels which turn the turbines in the opening of the dam, leading to electricity generation.

Hydroelectric energy generation, source: Hydel power

Geothermal Energy

The word “Geothermal” is composed of two words; 'geo' meaning Earth and 'thermal' meaning heat, hence the term geothermal means the energy that comes from the earth's core. In other words, it is the energy emanating from the core of the Earth, which is situated deep beneath the Earth's surface. The temperature is predicted to be over 6,000 °C (about 10,800 °F (ca. 5,982 °C)). This energy is difficult to harness as it is much too deep into the earth.

The energy is accessed using “geothermal heat pumps” which are loops of pipes inserted deep into the earth. The pipes are filled with moving water which is in turn heated up while it is underground, leading to the heating of houses, pavements, or parks. But these have low efficiency and are only feasible for small-scale usage.

In addition to this, natural outlets of geothermally heated groundwater known as natural geysers can be used to access geothermal energy. The heated water can then be used to turn a turbine, thus producing energy. A lot of fresh water is wasted while it is used for heating, which is one of its major disadvantages.

Geothermal energy generation, Geothermal energy

Disadvantages of renewable energy sources

Although renewable energy sources provide several environmental advantages, they have quite a few disadvantages which need to be addressed if their practical use is to be considered.

Let's look at some disadvantages of using renewable energy sources:

• The commercial viability of these sources of energy could be a problem: This is due to the immobile nature of the source of production as they are produced and collected at specific locations due to the specific nature of the conditions needed for these sources of energy to be reliably sourced, e.g., availability of sunlight and wind, which implies that transfer and distribution networks need to be widespread if these energy sources are to be widely accessible to broader society. These networks of energy transportation require huge capital investments, and in some cases, existing networks cannot be used due to infrastructural restrictions. Large overhead costs often dissuade investors due to the perceived low probability of a profitable return.

• Some sources are seasonal and location-specific in nature: For example, Solar energy is heavily dependent on weather and the location of the source of production. The same concerns exist for wind energy and tidal energy, which makes it difficult to harness according to the requirements of the country or any organizations, leading to a lack of use in some communities.

• Storage capabilities for renewable energy: Many forms of renewable energy require a large storage facility for long-term storage as they are generated during some specific periods of the day, in contrast to traditional sources of energy which are being produced throughout the day 24/7. Hence, strong backup facilities are of high importance, which overall can increase the net cost of production. For example, sunlight won't appear at night or wind speeds are not consistent throughout the day or even the tidal energy is not strong enough to generate electricity.

• Pollution is still a problem with renewable energy sources: We know that renewable energy is meant to be 'green' and 'clean' for the environment, which is true in most cases. But in the case of biomass energy, we need to burn a lot of biomass for the production of energy, which creates greenhouse gases, thus increasing the carbon footprint of biomass fuels. Creating the infrastructure had to produce renewable energy sources is also energy-intensive and often requires a high carbon expenditure.

• Land requirements: Some forms of renewable energy sources require a lot of space for set-up and running. For example, solar energy and wind energy require acres of land for the wind turbines and solar panels to occupy which in turn reduces the space for human habitation or agriculture, both of which are of high importance. Possible solutions to these concerns include hybrid usage of space; for example, solar panels placed on the top of buildings.

The images describe the space requirements for the setting up of renewable sources; Solar panel image