direct energy conversion lecture ii.pdf

7/27/2019 Direct Energy Conversion lecture II.pdf

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LECTURE II



ENERGY NEEDS

1. The world population rose from 2000 million to 4000 million since theturn of the century and will increase to 6000 million by the year 2000.

2. World energy demand is increasing rapidly due to which Gas and Oildeposits will be running low by the next century. This puts extrapressure on coal.

Also the unequal distribution of fuel e.g. USA being 1/6 of the worldpopulation but it consumes 1/3 of the worlds fuel.

The unequal distribution of physical resources.

Environmental constraints on the exploration of non-renewable energyresources E.g. green house effects, high temperatures, which meltsice on the poles, Resulting in floods.



RENEWABLE ENERGY

Energy Resource Origin Solar Energy: Mother of all energy resources

Wind Energy: Due to Difference in

temperature

Biomass: Organic substance

Geothermal Energy: Heat Energy under earth

Wave Energy: Wind Energy

Tidal Energy: Gravitational force between

earth and moon

Fuel Cell: man Made process



RESOURCES FORM OF

DELIVERED

ENERGY CURRENT

DISTRIBUTE

ON REMARKS/ COMMENTS

1. SOLAR Total solar radiation absorbed by

the earth and its

atmosphere is

3.8x 1024 J/Y

Low Temp heat(space heating)

Low temp heat

(water heating)

Electricity

LARGESMALL

NEGLIGIBLE

The Sun maintains ambienttemperature of the planet at 200-

300 Celsius degrees above absolute

zero in addition passive solar gains

through windows and .walls meet a

large fraction of world space

heating demand. In UK 15-20 % of

domestic heating is obtained fromsolar energy 10-15 MW of solar

cells are installed. 1-2 MW of

Power towers are in operation.

2. WIND

The kinetic energy

available in the

atmosphere circulation

is

7.5 x1022 j

ELECTRICITY NEGLIGIBLE Several Multi MW wind turbines

are in operation, e.g. 4 MW

machines for wind farm iii Hawaii.

There are about one million wind

pumps in use. The total capacity is

1 GegaWatt. Sailing ships have

traditionally been used for in shore

and off shore shipping.



3. BIOMASS

The total solar radiation

absorbed by the

planet is 1.3x lO21J/Yr

The worlds standing

biomass has an energy

constant of about 1.5xlO22J

High Temp

Heating

Biogas

Alcohol

SIGNIFICANT

SMALL

NEGLIGIBLE

Biomass principally wood. It accounts

for about 15% of the world’s fuel

consumption. It provides 80% of

the energy need of many

developing countries.

4. GEOTHERMAL

The heat Flux from the

earth's interior

through the surface is

9.5x1020 j/yr

Low Temp Heat

(Bathing)

Low Temp Heating

(space & water

heating)

Electricity

SMALL

SMALL

Negligible

Geothermal energy supplies 5350 MW

of heat for use in bathing,

principally in Japan but in 1

Hungary and Iceland about 100000

houses are supplied with heat from

geothermal wells. The installedelectricity capacity is 2500 MW

and is expected to increase more

than 7 folds by the year 2000.

5. HYDRO: Hydro by

annual precipitation

over

Land amounts to 1.1x107 Kg of water. Taking the

average elevation of

the land area as 840

M the annually

accumulated potential

energy would be 9x

1020 J.

Electricity SIGNIFICANT. Large Hydro schemes provide about 1/4

of the world’s total electricity and

more than 40% of the electricity

used in developing countries. Theinstalled capacity is 363 Gega

Watts.



6. TIDAL: Energy

dissipation in

connection with

slowing down the earth

ns a result of tidal

action is around lO20

J/Yr.

Electricity NEGLIGIBLE Only one large tidal barrage is in

operation in France. There are also

small schemes in Russia and

China. Total installed capacity is

240 MW.

7. WAVES: The amount

of energy stored as

kinetic and potential

energy in waves may

be of the order of lO9 J.

Electricity NEGLIGIBLE The Japanese wave energy

research vessel has an installed

capacity of 1 MW. There are in

addition several hundred wave

powered navigational setups.



SOLAR PROSPECTS

1.The Sun is the potential source of energythat can replace oil, gas and coal. It isbasically a fusion reactor.

2.Incoming energy absorbed by earth and

its atmosphere in one year is 3.8X10^24 J,which is 15 to 20 times the amount of energy stored in all of the worlds resourcesof renewable hydrocarbons.

3.Unlike capital energy resources,renewable can not be exhausted onlylimitation is, the rate at which they areused.



4. Renewable already supply major parts of the worlds energy needs.

BIOMASS accounts for l/7th of all the fuel

consumed and supplies 90% of energy needsof the third world countries.

Hydro generates l/4th of the world electricityand 2/3rd of that is used in 35 Countries.



Sun contributes directly to space heating in virtually all the buildings, throughwalls and windows.

Renewable energy technology is in manyways more attractive than theconventional energy technology.

They can be matched in scale to theneed and can be built close to the site

where it is required thus minimizing thecost. They can be produced in large number

and introduced quickly. Rapid planning and construction lowers unit cost.

Diversity of systems available alsoincreases flexibility and security of supply.

Comparing to other non renewableresources they are less hazardous.



SUN

Solar energy is a source of life. It maintains a temperature of 150°C onthe earth surface; also Oxygen in the atmosphere (upper) reacts withsun rays to form ozone which protects from ultraviolet radiations. Sunalso causes circulation of the air, differential heating of earth's surfacewhich generates high and low pressure regions thus causing movementof air which blows forming waves of the oceans. Sun is also responsible

for evaporating surface waters which leads to rain and feed themountain streams. Plants can not grow without sun light. Plants andother organic matter collectively are known as 'BIOMASS'. Water, Windand Waves are all form of solar energy. They are by definition renewablebecause they are continuously being regenerated by the Sun.

direct energy conversion lecture ii.pdf

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