Renewable energy sources

RENEWABLE ENERGY SOURCES

ABSTRACT

Non-conventional energy is also called as renewable energy. Renewables are those which are renewed by the nature again and again and their supply is not affected by rate of consumption. The demand for energy is rising rapidly with growing population and industrialization. Non-Conventional energy resources are these which do not get replenished after their consumption. The energy resources which are formed very slowly in nature and which are likely to be exhausted in a few more decades (or) centuries are called Non- conventional.

World is presently dependent on such resources. Non conventional energy sources are presently under development. Non-conventional energy resources are likely to have more and more share of energy market in coming decades. Non conventional energy sources are those which are non traditional. They are alternatives to the energy conservation.

Conservation of energy:

The available non-conventional energy sources for electrical generation are,

Ø Solar energy

Ø Geothermal energy

Ø Wind energy

Ø Biomass energy

Ø Tidal energy

Ø Magneto hydrodynamics (MHD)

PRESENT STATUS OF NON-CONVENTIONAL ENERGY RESOURCES IN INDIA:

The estimated power shortage in India in the next five years will be 43,000 MW while the total potential of non-conventional energy is about 50,000 MW. The power production status of non-conventional energy in India is shown in Table

Power production status of conservation of energy in India:

SOLAR ENERGY:

Introduction:

Solar energy is an important cheap, clean and easily available renewable energy. The sun radiates head and light.

The sun produces enormous amount of heat and light through sustained nuclear fission reactors. The solar energy received in the form of radiation is used for heating and producing electrical energy.

Study Plan for Heat Transfer

Ø Energy conservation, heat diffusion equation.

Ø Conduction: thermal resistance concept, extended surface/fin analysis.

Ø Transient heat transfer: lumped capacitance method, spatial effects, Heisler charts.

Ø Free convection

Ø Radiation: Planck emission, blackbody emission, absorption, transmission & reflection, greenhouse effect, shape factor.

Ø Heat exchanger design.

Application:

Ø Passive heating applications without any special device for energy conservation.

Ø Low temperature applications for solar energy are cooking, drying, green houses etc.

Ø Medium & high temperature applications are producing process heat, steam & producing electrical energy through solar power plant.

Merits:

Ø Renewable energy available free of cost

Ø Available naturally in most parts of the world

Ø Cheep and pollution free

Ø Solar PV systems are economical at feasible for remote, stand alone power plant

Ø Cost effective technologies are being evolved.

Limitations:

^Ø Low energy density 0.1 to 1kw/m²

Ø Large area covers by solar collectors

Ø Direction of rays charges continuously. This will make the collection different. Varies during day season and with weather conditions.

Ø Energy note available at night and during cloudy

Ø Energy storage is essential.

Ø High cost of convection.

Ø Solar central power plants in MW range are not economically competitive.

Solar energy collection:

The first step in the solar energy utilization is collection of this energy. This is done through collectors whose surfaces are designed for high absorptive and low emissive.

Functions:

Ø To observe the Solar energy and converted into heat energy

Ø Reduces the thermal losses from the collection system

Ø One or more glass plates or transparent plastic to reduce the upward heat from the collector surface.

Ø Tubes or channels remove the heat energy from the collector to the storage tank.

Ø The cover plate is transparent to incoming radiation but opaque to infrared radiation of the collector and thus the heat losses.

Characteristics of collectors:

Ø It should be withstand for Low temperature, medium temperature and High temperature

Ø Non tracking type or tracking in one plate or tracking in two plate

Ø Simple and low cost

Solar energy’s role in Energy conservation:

Since it is used for cooking, water heating, lighting and generation of electrical energy. It consrvates the liquid petroleum of cooking, electricity bill and fuel etc.

GEOTHERMAL ENRGY:

Introduction:

The thermal energy contained in the inferior of the earth is called the geothermal energy. The geothermal energy is enormous and will cost for several millions of years and is therefore called renewable.

It is the form of hot water, steam, geothermal, mixture of these fluids. It is available deep inside the earth at a depth more than about 80km. Hence generally not possible to extract. In a few locations in the world, deposits or at depth of 300m to 3000m. Such locations are called the geothermal field.

Deep production wells are drilled in the geothermal fields. The hot steam/water/brine is extracted from the geothermal deposits by the production wells by pumping is by natural pressure.

The installed capacity of geothermal plant in the world is around 10000MW

Application:

Ø Hot water for baths, medical therapy

Ø District heating, space heating

Ø Hot water irrigation in cold countries

Ø Air conditioning

Ø Green house heating

Ø Process heat

Ø Electrical power generation.

Form of Geothermal energies:

Ø Hot water springs

Ø The geysers

Ø Fumaroles

Ø Volcanic eruption

Types of Geothermal deposits:

Ø Hydro-geothermal energy resources

Ø Petro-geothermal

Geothermal gradients:

The average increase temperature of earth with increasing depth is expressed in terms of geothermal gradient.

Merits and Demerits of petro geothermal over hydro geothermal

Ø Operational flexibility

Ø Water flow and temperature may be selected by different depths of production wells.

Ø Large heat resources can be tapped.

Ø Several wells can be drilled in the geothermal field to obtain high flow rate essential for larger plants.

Ø Long life of production wells 10 to 30 yards

Types of Geothermal power plants:

Ø Steam geothermal power plant

Ø Petro geothermal power plant

Ø Flashed steam Geothermal power plant

WIND ENERGY

Introduction:

In the continuous search if clean, safe and renewable energy sources, wind power is certainly one of the most attractive solutions.

The oil crisis of 1973 together with environmental consciousness has however renewed the interest in the wind power all over the world. Wind energy is one of the important renewable.

By 1990’s wind energy to electrical energy has become economically competitive in areas if favorable wind and wind energy system are now on the forefront of renewable energy utilization.

The range of wind turbine generators covers wind range from 0.5kw to 14kw. The broad classification is as follows.

Very small - 0.5 to 1kw

Small - 1 to 1.5kw

Medium - 1.5kw to 200kw

Large - 250kw to 1000kw

Very Large - 1000kw to 6000kw

The figure shown gives the simple wind connected system

Merits:

Ø Energy available at free cost

Ø Clean, pollution free

Ø Low operating cost

Ø Economically competitive

Demerits:

Ø Low energy density

Ø Favorable winds are available only in a few geographical locations, away from cities, forest

Ø Direction of wind changes and is never constant

Ø Large area is required since space between two tower should be large.

Ø Smaller units are more reliable but have higher capital cost.

BIOMASS ENERGY

Introduction:

Organic matters derived from biological organisms are called biomass. The energy obtained from biomass is called Biomass energy. They are available from botanical plants vegetal ion, algae, animals and organisms living on land ion.

Biomass resources are broadly classified into two categories.

ü Biomass from cultivated fields, crops, forests and harassed periodically. Biomass derived from waste, agricultural, forest, animal, urban, fishery etc. Biomass is considered as a renewable source of energy because the organic matter is generated every day/year.

ü The use of biomass as a fuel is well known and wide spread. Biomass energy is produced by green plants by photosynthesis in presence of sunlight Biomass energy is a result of solar energy converted to Biomass energy by green plants.

Since the conventional energy sources are depleting day by day, it is necessary to took step into

ENERGY CONSERVATION SOURCES. By increasing the Non-conventional power plants we can get the electrical energy always. If we go on depleting the available energy sources, then there will be scarcity of energy production due to raw material shortage. Ex. Hydel, coal, etc. So it is a necessary one to preserve and generate electricity from the non-conventional energy sources. If we doing so in India our country will be a powerful country in 2020.