India has abundant solar energy potential from its average solar radiation levels and large land area. However, only about 12.5% of land, or 0.413 million square km, could theoretically be used for solar installations. If 10% of this was utilized, it could generate 8 million MW of solar energy per year, equivalent to 5,909 million tons of oil. Solar energy technologies include solar thermal technologies that use the sun's thermal energy, such as for heating water, and solar photovoltaic technology that converts sunlight directly to electricity using solar panels. A wide range of solar applications exist from large power plants to small home appliances.

1. India is endowed with rich solar energy resource. The average
intensity of solar radiation received on India is 200 MW/km square
(megawatt per kilometre square). With a geographical area of 3.287
million km square, this amounts to 657.4 million MW. However, 87.5%
of the land is used for agriculture, forests, fallow lands, etc., 6.7% for
housing, industry, etc., and 5.8% is either barren, snow bound, or
generally inhabitable. Thus, only 12.5% of the land area amounting to
0.413 million km square can, in theory, be used for solar energy
installations. Even if 10% of this area can be used, the available solar
energy would be 8 million MW, which is equivalent to 5 909 mtoe
(million tons of oil equivalent) per year.
However, solar energy is a dilute source. The energy collected by 1
m square of a solar collector in a day is approximately equal to that
released by burning 1 kg of coal or 1/2 litre of kerosene. Thus, large
areas are needed for collection. Besides, the efficiency of conversion
of solar energy to useful energy is low. Therefore, the energy
actually available would be order of magnitude lower than the
aforementioned estimates. Nonetheless, it is obvious that solar
energy can be a good source of meeting energy demands.

2. On the applications side, the range of solar energy is very large.
While at the high end there are megawatt level solar thermal
power plants, at the lower end there are domestic appliances such
as solar cooker, solar water heater, and PV lanterns. Then, in
between, there are applications such as industrial process heat,
desalination, refrigeration and air-conditioning, drying, large scale
cooking, water pumping, domestic power systems, and passive
solar architecture. Solar cookers and hot water systems based are
gaining popularity in India and to a large extent attained
commercial status. Solar energy can be harnessed to supply
thermal as well as electrical energy. Those technologies that use
solar energy resource to generate energy are known as solar
energy technologies.
Solar energy technologies consists of
solar thermal technologies, which utilize sun's thermal energy and
solar photovoltaic technology, which convert solar energy directly
in to electricity.

3. Solar thermal technologies
solar water and space heating ,
solar process heating for industrial applications ,
solar drying ,
solar refrigeration and air conditioning ,
solar cooking ,
solar passive architecture ,
solar water desalination and water purification ,
and
solar thermal power generation.

4. Solar photovoltaic technology (SPV) is primarily a semiconductor-
based technology used to convert solar radiation into direct
electricity. A basic PV system comprises PV modules and the
balance of systems (BOS). Balance of systems includes support
structure, wiring, storage, power electronics, etc.
Components of PV system
A PV system consists of the following components.
1 PV panels (also known as solar panels)
2 Battery
3 Charge controller
4 Inverter/converter
5 Mounting structure and tracking device
6 Interconnections and other devices

5. SOLAR PASSIVE
The sun is the prime source of energy. Passive solar
design refers to design that uses solar energy to
attain thermal and visual comfort. It encompasses a
wide range of strategies and options used in
buildings to reduce energy consumption and
increase occupant comfort. Passive solar design
emphasizes architectural design approaches that
minimize the demand for energy by measures such
as appropriate building siting, efficient envelopes,
appropriate fenestration, daylighting design, and
thermal mass. The basic intent of a passive design is
to allow daylight, heat and airflow into a building
whenever beneficial, store and distribute the heat
and cool by natural means.

6. WIND
• The sun’s energy falling on the earth produces large-
scale motions of the atmosphere causing winds,
which are also influenced by small scale flows
caused by local conditions such as nature of terrain,
buildings, water bodies, etc. Wind energy is
extracted by turbines to convert the energy into
electricity.
• A small-scale and large-scale wind industry exists
globally. The small-scale wind industry caters for
urban settings where a wind farm is not feasible and
also where there is a need for household electricity
generation. The large-scale industry is directed
towards contributing to countrywide energy supply.

7. Wind resource in India
• The wind resource assessment in India estimates the total
wind potential to be around 45 000 MW (mega watt). This
potential is distributed mainly in the states of Tamil Nadu,
Andhra Pradesh, Karnataka, Gujarat, Maharashtra, and
Rajasthan. The technical potential that is based on the
availability of infrastructure, for example the availability
of grid, is estimated to be around 13 000 MW. In India,
the wind resources fall in the low wind regime, the wind
power density being in the range of 250 - 450 W/m2. It
may be noted that this potential estimation is based on
certain assumptions. With ongoing resource assessment
efforts, extension of grid, improvement in the wind
turbine technology, and sophisticated techniques for the
wind farm designing, the gross as well as the technical
potential would increase in the future
• Status of wind power generation in India

8. • The word hydro comes from a Greek word meaning water. The
energy from water has been harnessed to produce electricity
since long. It is the first renewable energy source to be tapped
essentially to produce electricity.
• Hydro power currently suffices one fifth of the global electricity
supply, also improving the electrical system reliability and
stability throughout the world. It also substantially avoids the
green house gas emissions, thus complimenting the measures
taken towards the climate change issues.
• Hydro projects below a specified capacity are known as small
hydro. The definition of small hydro differs from country to
country, depending on the resources available and the prevalent
national perspective. The small hydro altas shows that the largest
of the projects (30 MW) is in US and Canada. Small hydro power
has emerged as one of the least cost options of harnessing green
energy amongst all the renewable energy technologies.

9. According to the power generated, small hydro power
is classified into small, mini/micro and pico hydro. In
India, it is being classified as follows.
Small hydro - 2 MW - 30 MW
Mini - 100 kW - 2 MW
Micro - 10 kW - 100 kW
Mico hydro - 1 kW - 10 kW
Projects with the range of 100 kW and above feed
power into the grid. They are commercial by nature.
Projects below 100 kW are mostly off grid options
being harnessed for rural village electrification.
They come under the social sector.

10. • Biomass has been one of the main energy sources for the
mankind ever since the dawn of civilisation, although its
importance dwindled after the expansion in use of oil and coal
in the late 19th century. There has been a resurgence of
interest in the recent years in biomass energy in many
countries considering the benefits it offers. It is renewable,
widely available, and carbon-neutral and has the potential to
provide significant productive employment in the rural areas.
Biomass is also capable of providing firm energy. Estimates
have indicated that 15% - 50% of the world?s primary energy
use could come from biomass by the year 2050. Currently,
about 11% of the world?s primary energy is estimated to be
met with biomass.
• For India, biomass has always been an important energy
source. Although the energy scenario in India today indicates a
growing dependence on the conventional forms of energy,
about 32% of the total primary energy use in the country is
still derived from biomass and more than 70% of the
country?s population depends upon it for its energy needs.

11. India produces a huge quantity of biomass material in
its agricultural, agro-industrial and forestry
operations. According to some estimates, over 500
million tonnes of agricultural and agro-industrial
residue alone is generated every year. This quantity,
in terms of heat content, is equivalent to about 175
million tonnes of oil. A portion of these materials is
used for fodder and fuel in the rural economy.
However, studies have indicated that at least 150-
200 million tonnes of this biomass material does
not find much productive use, and can be made
available for alternative uses at an economical cost.
These materials include a variety of husks and
straws. This quantity of biomass is sufficient to
generate 15 000-25 000 MW of electrical power at
typically prevalent plant

12. • Biomass Gasification
• Biomass gasification is the process through which solid biomass
material is subjected to partial combustion in the presence of a limited
supply of air. In what is known as a gasifier, solid fuel is convertedm by
a series of thermo-chemical processes like drying, pyrolysis, oxidation,
and reduction to a gaseous fuel called producer gas. The ultimate
product is a combustible gas mixture known as ?producer gas?. If
atmospheric air is used as the gasification agent, which is the normal
practice, the producer gas consists mainly of carbon monoxide,
hydrogen, and nitrogen. A typical composition of the gas obtained from
wood gasification, on volumetric basis, is as follows:
• Carbon monoxide 18 ? 22%
• Hydrogen 13 ? 19%
• Methane 1 ? 5%
• Heavier hydrocarbons 0.2 ? 0.4%
• Heavier hydrocarbons 9 ? 12%
• Water vapour 4%
• The calorific value of this gas is about 1000 ? 1200 kcal.Nm3

13. • Biomass gasifier based systems
• The major applications of a producer gas produced
from a biomass gasifier are as follows .
• i) Mechanical shaft power applications, i.e., water
pumping for irrigation/drinking and grinding, where
the gas is used as fuel for internalcombustion
engine running on dual fuel or 100% producer gas
mode.
• ii) Direct heat applications where it is burnt directly
in a boiler, furnace or kiln, burner for institutional
cooking, etc., to provide heat.
• iii) Electricity generation through shaft power
application viz., (engine coupled to an
alternator/generator set).

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