| The term Alternative Energy is generally used to | | | | Both these methods are being actively tried out in |
| indicate non-traditional energy systems whichdo | | | | various places. Experts feel that tidal energy has a |
| not use fossil fuels and have low environmental | | | | great potential as an alternative energy source. . |
| impact. There are many non-fossil fuel based | | | | Biomass Power as Alternative Energy Source |
| energy systems either already in use or being | | | | Biomass refers to biological materials including |
| evolved and developed to counter the harmful | | | | trees, grass, agricultural and urban waste matter, |
| effects of increasing use of fossil fuels. | | | | etc. Biomass contains energy received from the |
| We shall briefly look at the major alternative | | | | sun. Chlorophyll in plants uses solar energy to |
| energy systems. | | | | convert carbon dioxide (from air) and water |
| Solar energy | | | | (from ground) into carbohydrates. When these |
| Wind energy | | | | carbohydrates are burnt they release carbon |
| Tidal (Wave) Power | | | | dioxide and water, and energy that had been |
| Biomass | | | | trapped in it is released. This is as if the |
| Geothermal | | | | carbohydrates act as storage battery for solar |
| Nuclear | | | | energy - they hold the energy and release it at a |
| Solar Power as Alternative Energy Source | | | | later time when burnt as an effective alternative |
| Solar radiations cover a very wide spectrum of | | | | energy source in place of fossil fuels. |
| frequencies - from infrared through the visible to | | | | From time immemorial biomass has been burnt to |
| ultraviolet frequencies. The visible radiations give | | | | recover sun's energy as heat. By using modern |
| us light and the infrared radiations give us warmth. | | | | technology we can produce heat, steam and |
| From ancient times people have been using the | | | | electricity from biomass more efficiently and |
| solar radiation for heating - heating water and | | | | cleanly; we can also convert it into liquid fuels or |
| warming houses in winter. In recent years many | | | | produce combustible gases from it. |
| developments have taken place; now apart from | | | | In US alone, about 50 billion kWh of electricity |
| domestic hot water supply or space heating of | | | | (about 1.2% of total consumption), about four |
| large buildings, solar energy is being used to | | | | billion gallons of ethanol (about 2% of the liquid fuel |
| provide hot water and steam for industrial | | | | used in vehicles) are produced from biomass. DOE |
| processes and even to supplement power | | | | believes that by 2030 about 20% of |
| generation in large thermal power stations. | | | | transportation fuel could be produced from |
| Photovoltaic generation of electricity as an | | | | biomass. There is obviously a vast potential for |
| alternative energy source is a modern | | | | use of biomass the world over. |
| development. A photovoltaic (PV) cell is made of | | | | Geothermal Power as Alternative Energy Source |
| Silicon metal; it exhibits strong photovoltaic | | | | The most recent (1994) estimate of temperature |
| properties converting visible solar radiation into | | | | at the core of earth is about 7500 deg. C. Energy |
| electricity. | | | | obtained by tapping into the hot interior of the |
| Individual solar cells are small and give only a small | | | | earth is called the geothermal energy. Geothermal |
| amount of power. Now PV cells are assembled in | | | | energy is an alternative energy source for |
| different configurations as arrays and panels; | | | | generation of electricity; it is also used for heating |
| these solar arrays and panels can be used for | | | | houses in cold countries, and for supplying process |
| generating sufficient electricity for practical | | | | heat requirements. |
| applications. Arrays or panels of solar cells are | | | | Building a geothermal power station is expensive |
| being used in remote and inaccessible communities | | | | but the low operating costs and absence of |
| to obtain clean power; they are being used to run | | | | carbon emission into atmosphere are two major |
| cars, to supply power on satellites and space | | | | benefits of this system. |
| stations and even to supplement power | | | | Power plants based on geothermal energy fall into |
| generation in large power stations of hundreds of | | | | three types depending upon the method used: |
| MW. | | | | Those plants that take steam directly from |
| Since the year 2000 solar electric production has | | | | fractures/holes in the ground and drive turbines |
| grown at an average rate of 40% per year and | | | | directly from this steam are called Dry steam |
| by 2007, the installed capacity is about 10.6 GW. | | | | plants. |
| Wind Power as Alternative Energy Source | | | | In a Flash plant hot water, usually at more than |
| Wind energy for pumping water and grinding | | | | 200 deg C, , is taken out of the ground and |
| grains has been used since the medieval times. | | | | allowed to boil as it rises to the surface; steam is |
| Wind energy is now mainly used for generation of | | | | separated from it and run through turbines. |
| electricity; wind mills drive turbines for generation | | | | In binary plants, hot water taken from ground |
| of electricity which is connected into the grid of | | | | flows through heat exchangers, where it imparts |
| the local utility. Due to variability of wind speeds | | | | heat to an organic fluid to boil it; this organic fluid |
| from time to time, generally wind energy supplies | | | | runs through turbines driving them. |
| only a small proportion of the total utility load. | | | | In all the three types, the remaining geothermal |
| By the end of the last year, the total | | | | fluid and condensed steam are injected back into |
| wind-powered generator-capacity worldwide was | | | | the hot rock crust to recycle. |
| 94.1 GW contributing only 1% of world-wide | | | | A 1999 study shows that the worldwide |
| electricity use. Wind power generation has | | | | geothermal electrical generation capacity using |
| increased by over 500% since 2000 and is | | | | existing technologies is between 35,000 to 70,000 |
| expected to spiral upward. | | | | MW; using the new technologies it could be twice |
| Tidal Power as Alternative Energy Source | | | | as much. |
| Tidal power utilizes the rise and fall in sea levels | | | | Nuclear Power as Alternative Energy Source |
| due to the tides. This alternative energy source | | | | Popularly nuclear reaction is equated with atom |
| had been realized by man long ago and in Europe | | | | bombs. However, controlled nuclear reaction is |
| tide mills had been in use for grinding grains over a | | | | used as an alternative energy source for |
| thousand years ago. It is possible to utilize this | | | | generation of electricity for the last 50 years. |
| energy for generating of electricity and efforts | | | | Nuclear reaction releases enormous energy which |
| are on in many countries around the world to | | | | is used to raise steam as is done by burning oil or |
| harness this energy. | | | | coal in conventional thermal power stations and |
| Tidal energy, being derived directly from the | | | | this in turn is used to generate electricity. Today |
| interaction of the sun and the moon and the | | | | more than 50 countries are generating over 370 |
| earth's rotation, is an inexhaustible alternative | | | | 000 MW of electricity by using nuclear power |
| energy source. The only limitation is that it can be | | | | reactors. |
| put to use only in select places around the world. | | | | Constructing and maintaining nuclear power plants |
| The two methods by which energy of the tides | | | | is expensive. Moreover they produce nuclear |
| can be harnessed are: | | | | waste which is hazardous, and there is the |
| The tidal stream system which will make use of | | | | potential for enormous nuclear disasters. The |
| moving water in much the same manner as wind | | | | nuclear waste is highly toxic and can not be |
| energy being used by windmills; and | | | | destroyed or recycled. Unless properly stored in a |
| The barrage system which will use the difference | | | | secure location it can create hazardous |
| in the height between the low and the high tide in | | | | environment. |
| an estuary. | | | | |