Renewable & Non-Conventional Sources Of Energy

Environment

Renewable & Non-Conventional Sources Of Energy

sources of energy renewable - non renewable sources of energy

With reference to two non-conventional energy sources called ‘coal bed methane’ and ‘shale gas’, consider the following ‘statements:

  1. Coal bed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks.
  2. In India abundant coal bed methane sources exist, but so far no shale gas sources have been found.

Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2

CBM = Methane

Shale gas = Lot of Methane + Little Ethane, Propane, & Butane + very little carbon dioxide, nitrogen, and hydrogen sulfide.

Abundant shale reserves occur in India.

Fuel

Production

Advantages

Limitations

Nuclear energy Nuclear fission (splitting of atom) and Nuclear fusion
  • High cost of construction of nuclear plant.
  • Fear of security and nuclear accidents.
  • Problem of safe disposal of nuclear waste.
Hydropower Dams built on river for electricity generation
  • World’s hydroelectricity capacity high
  • Ecosystems behind dams disturbed.
  • Human settlements up rooted.
  • Habitat loss and biodiversity loss.
  • Developmental cost high.
  • Fertile farmland lost
  • Amount of nutrient rich silt on down river agricultural fields reduced.
Solar energy From natural sunlight
  • Environment friendly
  • Ample or unlimited availability.
  • Limited capacity for storage of sunlight.
  • Cloud cover.
  • Collecting equipment expensive.
Wind energy Fans for directing winds in use from long for irrigation crops
  • No pollution
  • Available for free
  • Not available everywhere or intermittently available.
  • Fans of wind mills visual hazards for flying birds and aeroplanes (visual pollution).
Tidal energy Harnessing tidal power by suitable structures
  • Free and clean
  • Structures (plant) used for harnessing energy expensive.
  • Plant disrupts natural flow of estuary and concentrate pollutants in the area.
Geothermal energy Wells drilled to trap steam which powers electrical generators. Steam naturally produced from underground water which gets heated due to very high temperature that region.
  • Environment friendly
  • Steam contains Hydrogen Sulphide (H2S) having odour of rotten eggs.
  • Minerals in the steam corrosive to pipe lines and equipment causing maintenance problems.
  • Minerals in the water toxic to fish.
Biomass Cutting trees for fuel wood and burning them straight away
  • Cheap so popular in
    under developed and
    developing countries
  • Comparatively low level of energy.
  • Bulky so difficult to transport.
  • Burning wood causes air pollution.
  • Destruction of forests to obtain fuel wood and so desertification.
  • Release lot of fly ash.
Biomass conversion Obtaining energy from chemical energy. Stored in biomass (or live material). Burned directly for cooking or to produce electricity converted to ethanol or methane (biogas)
  • Renew able energy
  • May lead to food shortage because nutrients not returned to soil from biomass.
  • Growing maize for ethanol requires more energy expenditure than the amount of energy in the form of alcohol retrieved.
  • Land for growing food used for growing biomass for conversion into fuel.
Solid waste Waste sorted and burnable material separated
  • Decreases cost of fresh disposal
  • Reduces need for land fill sites
  • Causes air pollution for burning releases CO2 and other gases.
  • Waste such as bleached paper and plastics have chlorine containing compounds which form. dioxins which are highly toxic and suspected to be carcinogenic.

Biomass [Conventional Source]

  • Biomass is a renewable energy resource derived from plant and animal waste.
  • The energy from biomass (biomass conversion) is released on burning or breaking the chemical bonds of organic molecules formed during photosynthesis.
  • Biomass fuels can be used directly or they can be transformed into more convenient form and then used.

Sources of biomass

  • By-products from the timber industry, agricultural crops and their byproducts, raw material from the forest, major parts of household waste and wood.
  • Solid Biomass fuels: Wood logs and wood pellets, charcoal, agricultural waste (stalks and other plant debris), animal waste (dung), aquatic plants (kelp and water hyacinths) urban waste (paper, cardboard and other combustible materials).

Conversion to gaseous and liquid biofuels

  • Biomass can be converted into alcohol (liquid biofuels) by distillation.
  • Liquid Biofuels: Ethanol, Methanol, Gasoho, Biodiesel.
  • Gaseous Biofuels: Synthetic natural gas (biogas), Wood gas: Methane – 70% and CO2 – 30%.
  • Instead of burning loose biomass directly, it is more practical to compress it into briquettes (compressing them into blocks of a chosen shape) improve its utility and convenience of use.
  • Such biomass in the biomass briquettes can be used as fuel in place of coal in traditional furnaces or in a gasifier.
  • A gasifier converts solid fuels into a more convenient-to-use gaseous fuel called producer gas.

Uses of biomass

  • In the developed world biomass is becoming important for applications such as combined heat and power generation.
  • Biomass energy is gaining significance as a source of clean heat for domestic heating and community heating applications.

Advantages of biomass energy

  • Burning of biomass does not increase atmospheric carbon dioxide because to begin with biomass was formed by atmospheric carbon dioxide and the same amount of carbon dioxide is released on burning.
  • Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas.
  • Biomass is renewable and is abundantly available on the earth in the form of firewood, agricultural residues, cattle dung, city garbage etc.
  • Bio-energy, in the form of biogas, which is derived from biomass, is expected to become one of the key energy resources for global sustainable development.

Bagasse as biofuel

  • Indian sugar mills are rapidly turning to bagasse, the leftover of cane after it is crushed and its juice extracted, to generate electricity.
  • This is mainly being done to clean up the environment, cut down power costs and earn additional revenue.
Biogas plant
  • The biogas plant consists of two components: a digester (or fermentation tank) and a gas holder.
  • The gas holder cuts off air to the digester (anaerobiosis) and collects the gas generated.
  • Any biodegradable (that which can be decomposed by bacteria) substance can be fermented anaerobically (in absence of oxygen) by methane-producing (methanogenic) bacteria.
  • Cowdung or faeces are collected and put in a biogas digester or fermenter (a large vessel in which fermentation can take place).
  • A series of chemical reactions occur in the presence of methanogenic bacteria (CH4 generating bacteria) leading to the production of CH4 and CO2.

Petro crops (Plants)

  • Recent researches suggest that hydrocarbon producing plants can become alternative energy sources, which can be inexhaustible and ideal for liquid fuel.
  • These plants called petroplants/petrocrops can be grown on land which are unfit for agriculture and not covered with forests. Jatropa curcas is an important petro plant.
  • Biocrude can be obtained by tapping the latex of Jatropa curcas.
  • Biocrude is a complex mixture of liquids, terpenoids, triglycerides, phytosterols waxes, and other modified isoprenoid compounds.
  • Hydro cracking of biocrude can convert it into several useful products like gasoline (automobile fuel), gas oil and kerosene.
  • Some potential Petro-crop species belong to family Asclepiadaceae and Euphorbiaceae.

Geothermal Energy

  • Geothermal energy is natural heat from the interior of the earth that can be used to generate electricity as well as to heat up buildings.
  • The core of the earth is very hot and it is possible to make use of this geothermal energy.
  • These are areas where there are volcanoes, hot springs, and geysers, and methane under the water in the oceans and seas.
  • In some countries, such as in the USA water is pumped from underground hot water deposits and used for heating of houses.
  • Geothermal resource falls into three major categories: i) Geopressurized zones, ii) hot-rock zones and iii) Hydrothermal convection zones. Of these three only the first is currently being exploited on a commercial basis.

Geothermal energy in India

  • In India, Northwestern Himalayas and the western coast are considered geothermal areas.
  • The Geological Survey of India has already identified more than 350 hot spring sites, which can be explored as areas to tap geothermal energy.
  • The Puga valley in the Ladakh region has the most promising geothermal field.

Environmental impact of geothermal energy

  • Geothermal energy can pose several environmental problems which includes on-site noise, emissions of gas and disturbance at drilling sites.
  • The steam contains hydrogen sulphide gas, which has the odour of rotten eggs, and cause air pollution.
  • The minerals in the steam are also toxic to fish and they are corrosive to pipes, and equipment, requiring constant maintenance.

Hydrogen Energy

  • Many scientists believe that the fuel for the future is hydrogen gas.
  • When hydrogen gas burns in the air or in fuel cells, it combines with oxygen gas to produce non-polluting water vapour and fuel cells directly convert hydrogen into electricity.
  • Widespread use of hydrogen as fuel would greatly reduce the problem of air pollution and danger of global warming because there will not be any CO2 emission.
  • Hydrogen may be a clean source of energy but getting large amount of pure hydrogen for commercial purposes is a problem because hydrogen is present in combination with other elements such as oxygen, carbon and nitrogen thus hydrogen has to be produced from either water or organic compounds like methane etc. requiring large amounts of energy. This is a very costly proposition.
  • Producing hydrogen from algae in large scale cultures is possible. It may be possible to control photosynthesis so that green algae are able to produce hydrogen through the process of photosynthesis.
  • Hydrogen is a pollution free, cost effective manner and if technologies such as fuel cells can be made cost effective, then hydrogen has the potential to provide clean, alternative energy for diverse uses, including lighting, power, heating, cooling, transportation and many more.

Fuel Cell Technology

  • Fuel cells are highly efficient power-generating systems that produce electricity by combining fuel (hydrogen) and oxygen in an electrochemical reaction.
  • 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.
  • Hydrogen and phosphoric acid are the most common type of fuel cells, although fuel cells that run on methanol, ethanol, and natural gas are also available.
  • 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.
  • Though rapid progress has been made; high initial cost is still the biggest hurdle in the widespread commercialization of fuel cells.
  • The rapidly depleting fossil fuel sources of energy and escalating demand of energy have made it necessary to look for alternative sources of energy that are known as renewable or inexhaustible. We can define inexhaustible energy resources as ‘those resources which can be harnessed without depletion’. Most of these resources are free from pollution and some of them can be used at all places. These renewable energy resources are also known as non-conventional or inexhaustible or alternate energy sources. These energy sources are solar, flowing water, wind, hydrogen and geothermal. We get renewable solar energy directly from the sun and indirectly from moving water, wind and biomass. Like fossil fuels and nuclear power, each of these alternatives renewable sources of energy has their own advantages and disadvantages. We are going to discuss some of them in detail.

Solar Energy

  • Direct solar energy can be used as heat, light, and electricity through the use of solar cells.
  • Direct use of solar energy can be used through various devices broadly directed into three types of systems a) passive, b) active c) photovoltaic.

Passive solar energy

  • As you know some of the earliest uses of solar energy were passive in nature such as to evaporate sea water for producing salt and to dry food and clothes.
  • In fact solar energy is still being used for these purposes. The more recent passive uses of solar energy is for cooking, heating, cooling and for the day lighting of homes and buildings.

Active use of solar energy

  • Active solar heating and cooling systems rely on solar collectors which are usually mounted on roofs.
  • Such systems also requires pumps and motors to move the fluids or blow air by fan in order to deliver the captured heat.
  • A number of different active solar heating systems are available. The main application of these systems is to provide hot water, primarily for domestic use.

Solar cells or photovoltaic technology

  • Solar energy can be converted directly into electrical energy (direct current, DC) by photovoltaic (PV) cells commonly called solar cells.
  • Photovoltaic cells are made of silicon and other materials. When sunlight strikes the silicon atoms it causes electrons to eject. This principle is called as ‘photoelectric effect’.
  • A typical solar cell is a transparent wafer that contains a very thin semiconductor.
  • Sunlight energizes and causes electrons in the semiconductor to flow, creating an electrical current.

With reference to technologies for solar power production, consider the following statements:

  1. ‘Photovoltaics’ is a technology that generates electricity by direct conversion of light into electricity, while ‘Solar Thermal’ is a technology that utilizes the Sun’s rays to generate heat which is further used in electricity generation process.
  2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC).
  3. India has manufacturing base for Solar Thermal technology, but not for Photovoltaics.

Which of the statements given above is / are correct?

  1. 1 only
  2. 2 and 3 only
  3. 1, 2 and 3
  4. None
Explanation:

Photoelectric effect = When light strikes on a material, electrons are dislodged [photons dislodge electrons].

Photovoltaic = The dislodged electrons if channeled through a conductor will create electric current (voltage Or potential difference) = Solar Panels. [Electric current is nothing but movement of electrons from high potential to low potential area (more electrons to less electrons region)]

Solar thermal = converting light into heat = solar cooker, solar water heater.

Photovoltaics generate direct current (DC). [Rotating = AC, Stationary = DC. Electric generator, wind turbine generate AC while solar panels generate DC]

Solar thermal is mostly used for water heating purposes. Electricity can be generated by using hot water steam to rotate turbine = AC current.

In India both solar panels and solar cookers are manufactured. [Remember Indian – USA WTO ‘domestic content’ dispute?]

Answer: a) 1 only

Tidal energy

  • Tidal power projects attempt to harness the energy of tides as they flow in and out.
  • The main criteria for a tidal power generation site are that the mean tidal range must be greater than 5 metres.
  • The tidal power is harnessed by building a dam across the entrance to a bay or estuary creating a reservoir.
  • As the tide rises, water is initially prevented from entering the bay. Then when tides are high and water is sufficient to run the turbines, the dam is opened and water flows through it into the reservoir (the bay), turning the blades of turbines and generating electricity.
  • Again when the reservoir (the bay) is filled, the dam is closed, stopping the flow and holding the water in reservoir when the tide falls (ebb tide), the water level in the reservoir is higher than that in the ocean.
  • The dam is then opened to run the turbines (which are reversible), electricity is produced as the water is let out of the reservoir.
  • The dams built to harness the tidal power adversely affect the vegetation and wildlife.

Hydropower Energy

  • Hydroelectric power uses the kinetic energy of moving water to make electricity.
  • Generation of electricity by using the force of falling water is called hydroelectricity or hydel power. It is cheaper than thermal or nuclear power.
  • Dams are built to store water at a higher level; which is made to fall to rotate turbines that generate electricity.
  • One of the greatest advantages of hydropower is that once the dam is built and turbines become operative, it is relatively cheap and clean source of energy.
  • Hydropower also has some disadvantages, building of dam seriously disturbs and damages the natural habitats and some of them are lost forever.

Ministry of New and Renewable Energy (MNRE)

  • The ministry was established as the Ministry of Non-Conventional Energy Sources in 1992. It adopted its current name in October 2006.
  • The Ministry is mainly responsible for
  1. research and development,
  2. intellectual property protection, and
  3. international cooperation, promotion, and coordination in renewable energy sources such as wind power, small hydro, biogas, and solar power.

Aim

  • To develop and deploy new and renewable energy for supplementing the energy requirements of India.

Mission

  • Bring in Energy Security;
  • Increase the share of clean power;
  • Increase Energy Availability and Access;
  • Improve Energy Affordability; and
  • Maximise Energy Equity.

Initiatives

  • Jawaharlal Nehru National Solar Mission (JNNSM)
  • Remote Village Lighting Programme
  • National Biogas and Manure Management Programme (NBMMP)
  • Solar Lantern Programme LALA
  • Solar thermal energy Demonstration Programme
  • National Biomass Cookstoves Initiative (NBCI)[8]
  • National Offshore Wind Energy Authority

Key functional area

  • Indian Renewable Energy Development Agency (IREDA)
  • Integrated Rural Energy Programme (IREP);
  • Commission for Additional Sources of Energy (CASE);

Jawaharlal Nehru National Solar Mission (JNNSM)

  • Also known as the National Solar Mission
  • Objective
  1. To establish India as a global leader in solar energy, by creating the policy conditions for its diffusion across the country as quickly as possible.
  2. To promote ecologically sustainable growth while addressing India’s energy security challenges.
  • Major contribution by India to the global effort to meet the challenges of climate change.
  • One of the several initiatives that are part of National Action Plan on Climate Change.
  • The program was inaugurated in 2010.
  • Initial target was 20GW by 2022 and it was increased to 100 GW in 2015 Union budget.
  • Long term goal: Global leader in solar energy; maximum in energy production.
  • Immediate goal: Setting up an enabling environment for solar technology penetration in the country.

Targets are set for three phases

  1. First phase 2010-13
  2. Second phase 2013–17
  3. Third Phase 2017–22
  • At each stage progress will be reviewed and roadmap for future targets will be adopted.
  • Total target of 100,000 MW by 2022.
  • MNRE has proposed to achieve it through 40,000 MW through Rooftop Solar Projects and 60,000 MW through Large and Medium Scale solar projects.

Domestic content controversy

  • Guidelines for the solar mission mandated cells and modules for solar PV projects based on crystalline silicon to be manufactured in India.
  • This accounts to over 60% of total system costs.
  • For solar thermal, guidelines mandated 30% project to have domestic content.
  • A vigorous controversy emerged between power project developers and solar PV equipment manufacturers.
  • The former camp prefers to source modules by accessing highly competitive global market to attain flexible pricing, better quality, predictable delivery and use of latest technologies.
  • The latter camp prefers a controlled/planned environment to force developers to purchase modules from a small, albeit growing, group of module manufacturers in India.
  • Manufacturers want to avoid competition with global players and are lobbying the government to incentivize growth of local industry.
  • US Trade Representative has filed a complaint at World Trade Organization challenging India’s domestic content requirements citing discrimination against US exports.
  • WTO ruled in favor of USA.

Indian Renewable Energy Development Agency (IREDA)

  • IREDA is a Mini Ratna (Category – I) Government of India Enterprise.
  • It is under the administrative control of MNRE.
  • IREDA is Public Limited Government Company established as a Non-Banking Financial Institution in 1987 engaged in promoting, developing and extending financial assistance for setting up projects relating to new and renewable sources of energy and energy efficiency/conservation with the motto: “Energy For Ever”.

Objectives

  • To give financial support to specific projects and schemes for generating electricity and / or energy through new and renewable sources and conserving energy through energy efficiency.
  • To increase IREDA’s share in the renewable energy sector by way of innovative financing.

With reference to the Indian Renewable Energy Development Agency Limited (IREDA), which of the following statements is/are correct?

  1. It is a Public Limited Government Company.
  2. It is a Non – Banking Financial Company.

Select the correct answer using the code given below.

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 or 2

Answer: c) Both 1 and 2

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