Green Environment

INTRODUCTION

Environmental technology (envirotech), green technology (Genentech) or clean

technology (cleantech) is the application of one or more of environmental, green

chemistry, environmental monitoring and electronic devices to monitor, model and

conserve the natural environment and resources, and to curb the negative impacts of

human involvement. The term is also used to describe sustainable energy generation

technologies such as photovoltaics, wind turbines, bioreactors, etc. Sustainable

development is the core of environmental technologies. The term environmental

technologies is also used to describe a class of electronic devices that can promote

sustainable management of resources. Of the 52 percent of the country’s population that

lives in rural areas, 22 percent reside in or near forests. A majority of these people rely on

forest resources for their livelihood, making sustainable land and forest management a

critically important challenge for the Philippines. This section presents the major trends

in land and forest resources management in the country over the past five to ten years.

While there has been some increase in forest cover owing to reforestation efforts and

natural regeneration, per capita forest cover in the Philippines is still the lowest in Asia.

Moreover, the remaining primary or intact forests remain under threat.

The term is also used to describe sustainable energy generation

technologies such as photovoltaic’s, wind turbines, bioreactors,

etc. Sustainable development is the core of environmental

technologies.

Green Energy – “any sustainable energy source that comes from

natural environment.”

Some Aspects of Renewable Energy

It exists perpetually and in abundant in the environment

It is a clean alternative to fossil fuels

“energy that is derived from natural process that are

replenished constantly”.

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Contribution of Renewable Energy in World Electricity

Production:-

Fig-1 Contribution of Renewable Energy in World Electricity Production.

Major Renewable Energy Sources:-

Solar Energy

Wind Energy

Hydro Energy

Biomass Energy

Tidal Energy

Geothermal Energy

Wave Energy

Bio-fuel

Biogas

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Fig-2 Major Renewable Energy Sources.

PRESENT INSTALLED CAPACITY OF RENEWABLE

ENERGY SOURCES IN INDIA:-

The installed capacity in respect of RES is as on 30.06.2012 is based on MNRE email of

dated 12.07.2012 from the Ministry of Renewable Energy where cumulative Grid

interactive power installed capacity has been indicated as 25409.33 MW. Reconciliation

of installed capacity of Hydro capacity resulted in transfer of 135 MW from conventional

to SHP-RES and retrieval of installed capacity of 67.20 from SHP-RES to conventional

Hydro has resulted in net addition of 67.8 MW to SHP under RES. Also 30 MW of

capacity in the nature of Waste Heat Recovery Power Plant at Goa Energy Private

Limited under U&I category of RES. Out of this installed capacity due to wind and small

hydro amounting to 508.67 MW appearing in captive capacity has been deducted to

arrive at installed capacity of utilities in respect of RES.(25409.33-

508.67+67.8+30=24998.46).

Sector MW %age

State Sector 86,881.13 41.51

Central Sector 62,373.63 29.66

Private Sector 60,321.28 28.82

Total 2,09,276.04

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Fuel MW %age

Total Thermal 140206.18 66.99

                                             Coal 120,103.38 57.38

                                             Gas 18,903.05 9.03

                                             Oil 1,199.75 0.57

Hydro (Renewable) 39,291.40 18.77

Nuclear 4,780.00 2.28

RES** (MNRE) 24,998.46 11.94

Total 2,09,276.04 100.00

Table-1 Total Installed Capacity in India

Renewable Energy Source Present Installed Capacity

Wind 10200 MW

Small Hydro 2100 MW

Bagasse 750 MW

Biomass 620 MW

Solar 2 MW

Total RE Installed Capacity – 13672 MW

Table-2 Total Installed Capacity of Renewable Energy in India

SOLAR ENERGY:-

Solar power is by far the Earth's most available energy source, easily capable of

providing many times the total current energy demand. Solar power is the conversion of

sunlight into electricity.

Two main commercial ways of conversion of sunlight into electricity.

Concentrating Solar Thermal Plant (CSP)

Photovoltaic Plants (PV)

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CSP and PV both have their markets. PV is very successful in decentralized applications,

whereas CSP offers advantages for central and large-scale applications. CSP power plants

are the most cost-efficient way to generate and to store dispatch able CO2-free electricity.

However, there is no competition between both. Rather, they have to be seen as

complementary technologies.

PLF of CSP – In the range of 20 % to 30 %

PLF of PV – In the range of 15 % to 20 %

Photovoltaic systems (PV system) use solar panels to convert sunlight

into electricity. A system is made up of one or more solar photovoltaic

(PV) panels, an AC/DC power converter (also known as an inverter), a

racking system that holds the solar panels, and the interconnections

and mounting for the other components. A small PV system may

provide energy to a single consumer, or to an isolated device like a

lamp or a weather instrument. Large grid-connected PV systems can

provide the energy needed by many customers. Solar cells can be

electrically connected in series or in parallel to give any desired

voltage and current output. Photovoltaic cells are typically sold in

modules (or panels) of 12 volts with power outputs of 50 to 100+

watts. These are then combined into arrays to give the desired power

or watts.

Fig-3 PV Cells

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FUNCTIONING OF PV CELLS:-

PV functionality relies upon the absorption of light within a bulk or

semiconductor material, most commonly a silicon pn diode, providing a

medium in which incident photons can be converted to energy, usually

in the form of heat. When absorbed, a photon transfers energy to an

electron in the absorbing material and if the magnitude of incident

photon energy is greater than the electron’s work function, the photon

may raise an electron’s energy state or even liberate an electron. Once

liberated, the electrons are then free to move around the

semiconductor material influenced by present phenomena of diffusion,

temperature, and electric field. The quantum theory of semiconductor

devices states that all semiconductors have a gap between their

valence and conduction bands. The valence band represents all

allowable energies of valence electrons that are bound covalently to

neighboring host atoms, and the conductive band represents all

allowable energies of electrons which have received some form of

energy and are no longer bound to host atoms. Semiconductors,

characterized as being perfect insulators at absolute zero, become

increasingly conductive as temperature is increased. As temperature

becomes greater, sufficient energy is transferred to a small fraction of

electrons, causing them to move from the valence band to the

conduction band and holes to move from the conduction band to the

valence band. The increase in temperature responsible for this entire

process is a direct result of external energy; in the case of PV systems,

it is incident photons due to illumination. Under the photoelectric

effect, because photons incident upon a pn diode can create electron-

hole pairs at a cross material junction, an electric potential difference

across this junction can be established. Under no illumination,

electrons and holes are separated at n and p regions respectively due

to the diode characteristic unidirectional current path. When

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illuminated, PV cells are impacted by incident photons which bombard

cell electrons creating electron hole pairs. These electron hole pairs

then separate in response to the electric field created by the cell

junction, causing electrons to drift back into the n region, and holes

into the p region. A bidirectional current path is created and energy

can be harnessed. With basic PV function understood, a solar cell can

now be designed.

Fig-3 Function of PV Cell

WIND ENERGY:-

Wind power is the conversion of wind energy into a useful form of energy, such as

using: wind turbines to make electrical power, windmills for mechanical power, wind

pumps for water pumping or drainage, or sails to propel ships. A large wind farm may

consist of several hundred individual wind turbines which are connected to the electric

power transmission network. Offshore wind farms can harness more frequent and

powerful winds than are available to land-based installations and have less visual impact

on the landscape but construction costs are considerably higher. Small onshore wind

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facilities are used to provide electricity to isolated locations and utility companies

increasingly buy surplus electricity produced by small domestic wind turbines Wind

power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean,

produces no greenhouse gas emissions during operation and uses little land. Any effects

on the environment are generally less problematic than those from other power sources.

As of 2011, Denmark is generating more than a quarter of its electricity, and 83 countries

around the world are using wind power on a commercial basis. In 2010 wind energy

production was over 2.5% of total worldwide electricity usage, and growing rapidly at

more than 25% per annum. The monetary cost per unit of energy produced is similar to

the cost for new coal and natural gas installations. Although wind power is a popular

form of energy generation, the construction of wind farms is not universally welcomed

due to aesthetics. Wind power is very consistent from year to year but has significant

variation over shorter time scales. The intermittency of wind seldom creates problems

when used to supply up to 20% of total electricity demand, but as the proportion

increases, a need to upgrade the grid, and a lowered ability to supplant conventional

production can occur. Power management techniques such as having excess capacity

storage, dispatch able backing supplies (usually natural gas), storage such as pumped-

storage hydroelectricity, exporting and importing power to neighbouring areas or

reducing demand when wind production is low, can greatly mitigate these problems.

Differential heating of the earth’s surface and atmosphere induces vertical and

horizontal air currents that are affected by the earth’s rotation and contours of the

land and generates WIND. A wind turbine obtains its power input by converting

the force of the wind into a torque (turning force) acting on the rotor blades. The

amount of energy which the wind transfers to the rotor depends on the density of

the air, the rotor area, and the wind speed. PLF of Wind Farm is normally in the

range of 20 % to 30% depending upon the site conditions and WTG rating.

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Fig-4 Wind Turbine.

Hydro Energy :-

Hydro power plants are based on a rather simple concept Hydro power plants harnes

water's energy and use simple mechanics to convert that energy into electricity. Water

flowing through a dam turns a turbine which turns a generator. Hydroelectricity is the

term referring to electricity generated by hydropower; the production of electrical power

through the use of the gravitational force of falling or flowing water. It is the most widely

used form of renewable energy, accounting for 16 percent of global electricity

consumption, and 3,427 terawatt-hours of electricity production in 2010, which continues

the rapid rate of increase experienced between 2003 and 2009.

Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32

percent of global hydropower in 2010. China is the largest hydroelectricity producer, with

721 terawatt-hours of production in 2010, representing around 17 percent of domestic

electricity use. There are now three hydroelectricity plants larger than 10 GW: the Three

Gorges Dam in China, Itaipu Dam in Brazil, and Guri Dam in Venezuela.

The cost of hydroelectricity is relatively low, making it a competitive source of

renewable electricity. The average cost of electricity from a hydro plant larger than 10

megawatts is 3 to 5 U.S. cents per kilowatt-hour.[1] Hydro is also a flexible source of

electricity since plants can be ramped up and down very quickly to adapt to changing

energy demands. However, damming interrupts the flow of rivers and can harm local

ecosystems, and building large dams and reservoirs often involves displacing people and

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wildlife.[1] Once a hydroelectric complex is constructed, the project produces no direct

waste, and has a considerably lower output level of the greenhouse gas carbon

dioxide (CO2) than fossil fuel powered energy plants.

Dam - Most hydropower plants rely on a dam that holds back water, creating a

large reservoir. Often, this reservoir is used as a recreational lake

Intake - Gates on the dam open and gravity pulls the water through the penstock,

a pipeline that leads to the turbine. Water builds up pressure as it flows through

this pipe

Turbine - The water strikes and turns the large blades of a turbine, which is

attached to a generator above it by way of a shaft. The most common type of

turbine for hydropower plants is the Francis Turbine, which looks like a big disc

with curved blades. A turbine can weigh as much as 172 tons and turn at a rate of

90 revolutions per minute (rpm)

Generators - As the turbine blades turn, so do a series of magnets inside the

generator. Giant magnets rotate past copper coils, producing alternating current

(AC) by moving electrons.

Transformer - The transformer inside the powerhouse takes the AC and

converts it to higher-voltage current

Power lines - Out of every power plant come four wires: the three phases of

power being produced simultaneously plus a neutral or ground common to all

three

Outflow - Used water is carried through pipelines, called tailraces, and re-enters

the river downstream

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Fig-5 Hydro Energy

BIOMASS ENERGY:-

Biomass is a renewable energy source that is derived from living or recently living

organisms. Biomass includes biological material, not organic material like coal. Energy

derived from biomass is mostly used to generate electricity or to produce heat. Thermal

energy is extracted by means of combustion, torrefaction, pyrolysis, and gasification.

Biomass can be chemically and biochemically treated to convert it to a energy-rich fuel.

Biomass, as a renewable energy source, is biological material from living, or recently

living organisms. As an energy source, biomass can either be used directly, or converted

into other energy products such as biofuel. In the first sense, biomass is plant matter used

to generate electricity with steam turbines & gasifiers or produce heat, usually by direct

combustion. Examples include forest residues (such as dead trees, branches and tree

stumps), yard clippings, wood chips and even municipal solid waste. In the second sense,

biomass includes plant or animal matter that can be converted into fibers or other

industrial chemicals, including biofuels. Industrial biomass can be grown from numerous

types of plants,

including miscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane, bam

boo, and a variety of tree species, ranging from eucalyptus to oil palm (palm oil).

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Fig-6 Sources of Biomass

BIOGAS ENERGY:-

Biogas is clean environment friendly fuel that can be obtained by anaerobic digestion of

animal residues and domestic and farm wastes, abundantly available in the countryside.

Biogas is an important renewable energy resource for rural areas in India Biogas

generally comprise of 55-65 % methane, 35-45 % carbon dioxide, 0.5-1.0 % hydrogen

sulfide and traces of water vapor. Average calorific value of biogas is 20 MJ/m3 (4713

kcal/m3). Biogas like Liquefied Petroleum Gas (LPG) cannot be liquefied under normal

temperature and pressure. Critical temperature required for liquefaction of methane is -

82.1oC at 4.71MPa pressure, therefore use of biogas is limited nearby the biogas plant.

An estimate indicates that India has a potential of generating 6.38 X 1010 m3 of biogas

from 980 million tones of cattle dung produced annually. The heat value of this gas

amounts to 1.3 X 1012 MJ. In addition, 350 million tones of manure would also produce

along with biogas.

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Table-3 Biogas Production From Different Material

CONCLUSION:-

Environmental Technology (envirotech), green technology (greentech) or clean

technology (cleantech) is the application of one or more of environmental science, green

chemistry, environmental monitorin and electronic devices to monitor, model and

conserve the natural environment and resources, and to curb the negative impacts of

human involvement. The term is also used to describe sustainable energy generation

technologies such as photovoltaics, wind turbines, bioreactors, etc. Sustainable

development is the core of environmental technologies. The term environmental

technologies is also used to describe a class of electronic devices that can promote

sustainable management of resources.

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REFERENCES:

Environmental and Renewable Energy Innovation Potential among the States:

State Rankings. Applied Research Project. Texas State University.

http://ecommons.txstate.edu/arp/291/

Hermann Scheer “Energy Autonomy: The Economic, Social & Technological

Case for Renewable Energy”

Mark Diesendorf “Greenhouse Solutions with Sustainable Energy”.

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