Renewable Energy UPSC

Renewable Energy

Renewable energy is energy that is generated from natural resources that are continuously replenished. This includes sunlight, geothermal heat, wind, tides, water, and various forms of biomass. This energy cannot be exhausted and is constantly renewed.

Source 

Primary source - renewable energy like solar, wind, geo-thermal.

Secondary source - non-renewable energy generated through the conversion of coal, oil, natural gas etc.

1. Solar Energy

Energy generated from Sun.

India is one of the few countries naturally blessed with long days and plenty of sunshine.

There are two ways we can produce electricity from the sun light:

• Photovoltaic Electricity – uses photovoltaic cells that absorb the direct sunlight to generate electricity 

• Solar-Thermal Electricity – uses a solar collector that has a mirrored surface which reflects the sunlight onto a receiver that heats up a liquid. This heated up liquid is used to make steam that produces electricity.

Potential of solar energy in India 

• India has the potential to generate 35 MW/km2 using solar photovoltaic and solar thermal energy.

• Solar energy of about 5,000 trillion kWh per year is incident over India’s land area with most parts receiving 4-7 kWh per sq. m per day. Hence both technology routes (solar thermal and solar photovoltaic) for conver-sion of solar radiation into heat and electricity can ef-fectively be harnessed providing huge scalability for solar power in India.

• The states with very high solar radiation are Rajasthan, northern Gujarat and parts of Ladakh region, Andhra Pradesh, Maharashtra and Madhya Pradesh.

2. Wind Energy

Wind energy is the kinetic energy associated with the movement of atmospheric air. Wind turbines transform the energy in the wind into mechanical power, further con-verting to electric power to generate electricity.

Potential of wind energy in India 

The National Institute of Wind Energy (NIWE) has recently launched Wind Energy Resource Map of India at 100 meter above ground level (AGL) on online Geographic Information System platform. 

The wind energy potential in the country at 100 m AGL is over 302 GW. Gujarat has the maximum potential followed by Karnataka, Maharashtra, Andra Pradesh according to the resource map.

Wind energy target of India

• 60000 MW (60 GW) by 2022 

• 200000 MW (200 GW) by 2022 

Capacity installed in India

• Tamil Nadu – 7200 MW 

• Maharastra – 4000 MW 

• Karnataka – 2700 MW 

• Rajasthan – 2700 MW

3. Biomass Energy

Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. 

It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, grassy and woody plants, residues from agriculture or for-estry, oil-rich algae, and the organic component of municipal and industrial wastes. 

Biomass is a good substitute for the conventional fossil fuels for heating and energy generation purposes.

Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels. However, fossil fuels release carbon dioxide captured by photosynthesis over its formative years. Biomass, on the other hand, releases carbon dioxide that is largely balanced by the carbon dioxide captured in its own growth (depending how much energy was used to grow, harvest, and process the fuel). 

Hence, Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel.

4. Ocean Thermal Energy

Large amounts of solar energy is stored in the oceans and seas. 

On an average, the 60 million square kilometre of the tropical seas absorb solar radiation equivalent to the heat content of 245 billion barrels of oil. 

The process of harnessing this energy is called OTEC (ocean thermal energy conversion). 

It uses the temperature differences between the surface of the ocean and the depths of about 1000m to operate a heat engine, which produces electric power.

5. Geothermal Energy

Geothermal generation refers to harnessing of the geothermal energy or the vast reservoir of heat stored in the earth’s inner core. 

Below the earth’s crust, there is a layer of hot and molten rock called ‘magma’. 

Heat is continually produced there, mostly from the decay of naturally radio-active materials such as uranium and potassium.

The most common current way of capturing the energy from geothermal sources is to tap into naturally occurring “hydrothermal convection” systems where cooler water seeps into the earth’s crust, is heated up and then rises to the surface. When heated water is forced to the surface, it is a relatively easy to capture that steam and use it to drive electric generators.

Potential of India

India has a potential for producing around 10,600 MW of power from geothermal resources. 

Although India was amongthe earliest countries to begin geothermal projects since the 1970’s, at present there are no operational geo-thermal plants in India.

6. Fuel Cells

Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and very efficiently into electricity (DC) and heat, thus doing away with combustion. The most suitable fuel for such cells is hydrogen or a mixture of compounds containing hydrogen. A fuel cell consists of an electrolyte sandwiched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, and they react electrochemically to generate electricity, water, and heat.

7. Co-generation

Co-generation is producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may be electricity or mechanical energy.

As the low-pressure steam has a large quantum of heat which is lost in the process of condensing, the efficiency of conventional power plants is only around 35%. 

In a cogeneration plant, the low-pressure exhaust steam coming out of the turbine is not condensed, but used for heating pur-poses in factories or houses and thus very high efficiency levels, in the range of 75%–90%, can be reached.