This document discusses the relative demerits of various renewable energy sources including wind energy, solar energy, geothermal energy, biomass, nuclear energy, tidal energy, and hydroelectric energy. For each energy source, it provides a brief definition and then lists several demerits or disadvantages. Common demerits across many sources include high costs, low energy conversion efficiencies, intermittency of supply, need for energy storage, and negative environmental impacts such as land use.

1. RELATIVE DEMERITS OF
RENEWABLE ENERGY
SOURCESM.Tech Environmental Engineering, BirlaVishvakarma Mahavidyalay,V.V.Nagar,
Anand.

2. LIST OF RENEWABLE ENERGY
SOURCES
 Wind Energy
 Solar Energy
 Geothermal Energy
 Biomass
 Nuclear Energy
 Tidal Energy
 Hydroelectric Energy

3. WIND ENERGY
 What is it?
 Wind turbines are used to generate electricity from the wind.
 The wind turns the large blades and the blades turn a generator.

4. DEMERITS OFWIND ENERGY
 Depending on how energetic a wind site is, the wind farm may or may
not be cost competitive.
 Wind energy cannot be stored (unless batteries are used)
 Good wind sites are often located in remote locations
 Wind resource development may compete with other uses for the
land and those alternative uses may be more highly valued than
electricity generation.
 sometimes birds have been killed by flying into the rotors
 For most locations, wind power density is low
 Wind velocity must be greater than 7 mph to be usable in most areas
 Problem exists in variation of power density and duration
 Need better ways to store energy
 Land consumption
 High overall weight
 Noisy operation
 System are not maintenance free

5. SOLAR ENERGY
What is it?
 Solar power uses energy from the Sun.
 Solar panels transfer the Suns energy to heat water.

6. DEMERITS OF SOLAR ENERGY
 Solar panels are expensive.
 When it is cloudy or at night there is not enough light.
 Solar panels aren't very good at converting sunlight to electricity
 Most solar panels have at best a 20% efficiency rate
 Solar power stations can be built but they do not match the
power output of similar sized conventional power stations.They
are also very expensive
 Large areas of land are required to capture the suns energy.
Collectors are usually arranged together especially when
electricity is to be produced and used in the same location.
 Solar power is used to charge batteries so that solar powered
devices can be used at night. However, the batteries are large
and heavy and need storage space.They also need replacing
from time to time.

7. GEOTHERMAL ENERGY
What is it?
 Rocks under the ground are hot.
 Water can be pumped through these hot rocks and warmed up

8. DEMERITS OF GEOTHERMAL
ENERGY
 There are not many places where we can build geothermal power
stations.
 Harmful gases and minerals may occasionally come up from the
ground below.These can be
 difficult to control.
 Most of the sites, where geothermal energy is produced, are far from
markets or cities, where it needs to be consumed.
 Total generation potential of this source is too small.
 There is always a danger of eruption of volcano.
 Installation cost of steam power plant is very high.
 There is no guarantee that the amount of energy which is produced
will justify the capital expenditure and operations costs.

9. BIOMASS
What is it?
 Biomass, is a renewable energy source made of biological
material from living, or recently living organisms.
 Energy is released by combustion.

10. DEMERITS OF BIOMASS
 Inefficient (only 30% efficiency).
 Releases harmful solid carbon particles into the atmosphere.
 Cost of construction of biogas plant is high.
 Continuous supply of biomass is required to generate biomass energy.
 Some people don’t like to cook food on biogas produced from sewage
waste.
 Biogas plant requires space and produces dirty smell.
 Due to improper construction many biogas plants are working
inefficiently.
 It is difficult to store biogas in cylinders.
 Transportation of biogas through pipe over long distances is difficult.
 Many easily grown grains like corn, wheat are being used to make
ethanol.This can have bad consequences if too much of food crop is
diverted for use as fuel.
 Crops which are used to produce biomass energy are seasonal and are
not available over whole year.

11. NUCLEAR ENERGY
What is it?
 Radiation is released from the nuclei of metal atoms.
 The radiation can be used to generate electricity.

12. DEMERITS OF NUCLEAR ENERGY
 Radioactive minerals are unevenly distributed around the world and are found in limited
quantities.
 Supply of high quality uranium, one of the raw material, will last only for few decades.
 Nuclear waste from nuclear power plant creates thermal(heat) pollution which may
damage the environment.
 A large amount of nuclear waste is also created and disposal of this waste is a major
problem.
 The danger of accidental discharge of radio activity also exists
 Starting a nuclear plant requires huge capital investment and advanced technology.
 Nuclear plants are opposed on moral grounds, by many groups, because of their close
linkage with development of nuclear weapons.
 There are number of restrictions on the export or import of nuclear technology,fuels etc.
 Nuclear power stations are always at the risk from terrorist attack.
 Aftermaths of Chernobyl cannot be forgotten easily.

13. TIDAL ENERGY
What is it?
 Waves force air in and out of a chamber.
 The air causes a turbine to generate electricity.

14. DEMERITS OFTIDAL ENERGY
 Cost of construction of tidal power plant is high.
 There are very few ideal locations for construction of plant and they too are
localized to coastal regions only.
 Intensity of sea waves is unpredictable and there can be damage to power
generation units.
 Influences aquatic life adversely and can disrupt migration of fish.
 The actual generation is for a short period of time.The tides only happen twice
a day so electricity can be produced only for that time.
 Frozen sea, low or weak tides, straight shorelines, low tidal rise or fall are some
of the obstructions.
 This technology is still not cost effective and more technological
advancements are required to make it commercially viable.
 Usually the places where tidal energy is produced are far away from the places
where it is consumed.This transmission is expensive and difficult.

15. HYDROELECTRIC ENERGY
What is it?
 Flowing water is used to turn a turbine which generates
electricity.

16. DEMERITS OF HYDROELECTRIC
ENERGY
 It can be generated only in areas with heavy rainfall and sufficient
supply of water.
 Hydel power generation stations are to be located in hilly mountainous
terrains where waterfalls as well as ideal sites for dams are located. In a
region/country without hills hydel power generation is not possible.
 Loss during transmission is very high, sometimes up to 30%.
 Dams are expensive to build.
 Building a dam affects the environment and wildlife of adjoining areas.
Nearby low-lying areas are always under the threat of floods.
 Building of dam causes lot of pollution.
 If rains are scarce, there might not be enough water to turn turbines.

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