Chapter12

ENERGY: RESOURCES AND CRISIS

Before the use of fire, our ancestors needed only 200 kcal of energy perday per person. The energy was in the form of food. Later people domesticatedanimals, engaged in agriculture and used fuels for heating and cooking. Thefuels burnt for these pyrposes were firewood and dung. Per capita averageconsumption of energy rose to 2,000 kcal. By 1860, ~mall amounts of coal weremined, heat engines had been invented and per capita consumption advanced to70,000 kcal. There was tremendous increase in energy consumption during 20lh

century. Because, our industry, agriculture, transportation and living all areenergy dependent. The present society can not operate without electrical power,because lightening, entertainment, home conveniences are dependent on it .so much so that even to grind few seeds of black pepper, a housewife makesuse of an electric grinder. In 1980, per capita consumption of an American was230,000 kcal.

The energy resource::; c;urren:ly available Illdy iJe ulvideo Iflto twocategories: a) Non . newable resources, tnose with a supply that can be used up

. or exhausted (e.g. oil, gas, coal, uranium, etc), b) Renewable resources, thosethat can be replenished by either physical or biological means (e.g. solar,geothermal, tidal, biomass, or wild energy). Fig. 12.1 shows worldwidecommercial energy use. Fossil fuels (petroleum, natural gas, and coal) nowprovide about 85% of all commercial energy in the world. Biomass fuels such asfirewood and charcoal contributes 7%. Other renewable sources solar,geothermal and hydroelectric make up 4 - 5% of our commercial power. Nuclearpower is roughly equal to hydroelectric power.

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Energy utilization has become a key to human progress. Energyconsumption is the index of prosperity. Higher energy consumption means highergross national production and this, in turn, is associated with higher per capitaincome. It will be interesting to note that richest countries (having a total of 20%of world population) consume nearly 80% of natural gas, 60% of oil and 50% ofcoal each year. USA alone with a total population of 4.5%, consumes Wh of thetotal available energy. In contrast, India (with 16% of global population) andDakistan (with 2.4% of global population) consume only 3% and 0.5% of the;Jlobal supply respectively. Another statistic to think about: In 1992, the 256nil lion people in the United States used more energy for air-conditioning alonehan 1.2 billion people in China used for all their needs.

,On average, each person in USA and Canada uses morethan 300 GJ (equivalent to about 60 barrels of oil) per year. Bycontrast in poorest countries like Ethiopia, Nepal, Bhutan, eachperson generally consumes less than 1 GJ per year. In otherwords, each person in USA and Canada consumes, on average,almost as much ene,rgy in a single day as a person in the poorestcountry ina year.

It has been estimated, that solar radiations that fall on our planet, everyfifteen minutes are enough to meet energy needs of humans for a year or thesolar energy that falls over 0.4 million square kilometers area only of Saharadesert (which is spread over 9 million square kilometers) is enough to providenecessary energy to whole world for a day. But unfortunately cheap technology isnot available to trap, concentrate and store solar energy. At present, costinvolved in harnessing solar energy is huge. For example, it costs 500 dollars toproduce one kilowatt electricity from a fossil fuel plant; 750 dollars from nuclearplant, the production of one kilowatt electricity from an electric solar cell costs2,500 dollars.

So far the most important use of direct solar energy ~s to collect 0\11(;

concentrate it by solar collectors for heating water and buildings.' No success hd'been made in its commercial utilization. Another probability of harnessing Soldlenergy is the use of photovoltaic cells (or solqr cells). At much lower scale, sol,Hcells are already being used in watches, toys and calculators. Researches d'

underway to produce photovoltaic cells at cheap cost for commercial utilization.

Advantages of solar energy are, a) its supply is limitless, b) it is cheap, ,,)can be installed quickly, d) need little maintenance, e) solar cells are made )fsilicpn, an element which is most abundant' in earth's crust, f) produces no -'ir',water or thermal pollution, g) produces no noise, h) produces no harmful wastesand i) no possibility of a large scale explosion. or disaster.

Renewable energy resources account for about 16% of world energy use,and biomass makes 3,4lh of that renewable energy supply. Biomass resourcesused as fuels, include wood, wood chips, barks, branches of trees, crop residuesand animal waste (dung).

Various types of biomass can be used in solid, liquid or gaseous forms forspace heating, cooking, production of electricity and propelling vehicles.

·A. Burning of Crop residues: In agricultural areas, crop resid.ues suchas, cotton stalks, wheat straw, corn stacks, coconut shells, peanuthulls and animal manure can be collected and burned or convertedinto bio-fuels. Generally crop residues are burned in small powergener~ting plants located near areas where the residues areproduced. Otherwise, it takes too much energy, time and money tocollect and transport the residue to power plants. An increasingnumber of cities in Japan and USA have built incinerators that burntrash and then use heat released to produce electricity. Analysis,however, suggest that more energy can be saved by composting thetrash and using it in recycling of paper. Again, burning of trashreleases a number of pollutants.

B. Burning of solid biomass, the Wood: About 70% of the peopleliving in less developed countries heat their homes and cook their.food by burning firewood or charcoal (made from wood). In mostdeveloped countries, 20% homes are heated by wood. Thedisadvantages of burning wood are: a) harvesting and burning wood

\ can cause accidents, b) burning of wood emits 1000 times as muchparticulate matter as by a gas furnace, c) cause a number ofrespiratory diseases, d) results into deforestation.

C. Burning of liquid biomass, the Methanol and Ethanol: Someanalysts believe that methanol ano ethanol can be used as liquid fuelsto replace petrol and diesel when oil becomes too scarce or tooexpensive. Liquid fuel can be produced )from sugarcane, sugar beet,sorghum, or corn plants by fermentation and distillation. Methanol canbe used in propelling cars and other vehicles with little enginemodifications. The disadvantages of liqLJj}Jbio-fuels are, a) producelarge volume of waste, b) require frequent fill up or large fuel tank, c)more land is required to plant crop (it has been calculated that 9 timesmore land is required to meet the fuel need of an American for a yearthan to feed one American per year), and d) the production cost istwice as high as th.e conventional petrol.

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.D. Burning of gaseous biomass, the Bio-gas: Plants, sewage, organicwaste and cow-dung can be converted by bacteria or variouschemical processes into gaseous bio-fuel called bio-gas. It ismainly composed of 60/\ methane and 40% carbondioxide. In China,anaerobic bacteria in estimated 7 million biogas plants, convertorganic plants and animal wastes into methane fuel for heating andcooking. India has about 750,000 such plants (popularly known asGobar Gas Plants). Biogas plants, however, are slow andunpredictable. Development of new and more reliable models isneeded to increase the efficiency of these plants.

Energy derived from the heat of earth's crust is call.ed Geo-thermalenergy. At various places, below the earth's crust are present dry steam, wetsteam or hot water reservoirs that can provide a useful source of energy. If,thesegeothermal sites are close enough to earth's suriace, wells can be drilled .toextract the dry steam (i.e. steam wit.h no water droplets), wet steam (i.e. steamwith water droplets) or hot water trapped beneat.h the earth's crust. This thermalenergy can be used for space heating and to produce electricity.

Currently, about 20 countries are extracting energy from geothermal sitr:sand supplying heat and electricity to nearly 2 million homes. In Iceland, mosthouses and buildings are heated by geothermalstnarn.

The advantages of this energy are a) long-life b) no mining c) notransporting of fuels d) very little waste· disposal and e) comparatively lesspollution.

The disadvantages are: a) geothermal sites are not found every where, b)technology is very expensive, c) underground water is often contaminated withsulphur compounds which would cause pollutiOn, and d) occurrence of noisepollution from steam pressure relief valves.

The power of wind has been used since antiquity to pump water, to sailships, and to grind grain. With modern technology, it has become possible tobuild "windmills" to generate electricity. It is estimated that if total wind-power is .commercially tapped it can produce 20 million megawatt electricity.

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. Worldwide, by 1991, there were over 20,000 wind turbines mostly inSweden, Denmark and USA (California). They produced electricity equal to thatfrom 1000-megawatt coal-burning power plant. Wind-power experts project thatby middle of 21st century, wind power could supply about 10% of world'selectricity.

Wind energy, like other non-traditional energy, has advantages anddisadvantages. Advantages are that· it is limitless resource, non-polluting,causing minimal environmental disruption and cheaper than nuclear technology

The disadvantages are that a) it can be used in areas with sufficient windonly, b) winds do not always blow, and therefore some form of stored energywould be required during non-windy period, c) noise from windmills andinterference with local TV transmissions have been probjems and d) a largesurface area is required to build large groups of windmills.

Ocean tides and waves contain enormous amount of energy that can beharnessed if tidal dam is build and a turbine is ~nstallecJ. Japan, Norway, UK,USA and USSR have built small experimental plants to evaluate the potential ofthis energy. None of these plants has produced electricity at a competitive price,but some designs do show promise.

The Rance River Power Station in France is successfully operating since1966, producing 160 megawatt electricity. A tidal dam works like a hydroelectricpower dam, with its turbines spinning as the tide flow through them.

The disadvantages are that a) only few coastal areas provide right.conditions for building a dam, b) construction cost of dam is very high, c)equipments are damaged by saltwater corrQsion, d) severe storms might uprootthe installations.

In large-scale hydropower p(ojects, high dams are built across largerivers to create large reservoirs. The stored water is then allowed to flow throughhuge pipes at controlled rates, spinning turbines and producing electricity. In1989, hydroelectric power supplied 20% of the world's electricity. In lessdeveloped countries, 50% of electricity is supplied by hydropower projects.

The advantages of hydropower are, a) non-polluting, b) low operatingcost, c) large dams help control flooding, d) supply a regular flow of irrigationwater, and e) reservoir can be used for fish culture and recreation.

\The disadv'antages are a) high construction cost of dam, b) lack of

suitable sites, c) displace people, d) destroy wildlife, e) opposition fromenvironmentalists a[ld, f) degradation of land adjoining darn .

. Petroleum is perhaps the most versatile fossil fuel. It is derived formorganic molecules created by living organisms millions of years ago and buriedunder sediments where high pressure and temperature concentrated andtransformed them into energy rich compounds.

Crude oil, as it is pumped from the ground is a heavy dark black liquid.The oil is refined to produce many different materials, such as, propane,gasoline, diesel, kerosene oil, jet fuel, motor oil. and road tar. Some of thechemicals in oil are extracted and used for the manufacture of plastics,medicines and many other products.

Fig. 12.2 shows world's proven oil reserves. In 1999, the proverlresource,s of oil were roughly one trillion barrels. At the current consumption rateof 22 billion barrels per .year, these reserves will last another 45 years or so. It isdifficult to imagine what would happen to our civilization if the supply of this liquidfuel ran out. Automobiles, aeroplanes, ships and many appliarices could not

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Petroleum became favoured fuel because it is cleaner burning than coal.It is easy to transport and store. It is raw material for a number of byproducts.The drawbacks are, a) affordable supplied are expected to exhaust within next45 years, b) its burning release carbondioxide which could alter globaltemperature, c) releases pollutants like sulphurdioxide and nitrogen oxide whichdamage people, animals and crops, and d) oil leakage causes water pollution.

Coal is fossilized plant material preserved by burial in sediments. Mostcoal was laid down during Carboniferous period when the earth's crust waswarmer and wetter than it is now. formation of coal takes millions of years, henceit is essentially a non-renewable resource.

JOOFig. 12.3 $hows coal reserves. Total estimated reserves are 10 trillion

metric tons. At current rate of consumption, the supply may last for another 220years. About 60% of coal extracted is used in boilers to produce electricity.

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At present, coal is burned to generate 44°A of world's electricity. Theadvantages of coal are a) it is cheap, b) high-8nergy yield, and c) most abundantand widely distributed.

The disadvantages are a) it is dirtiest fossil fuel to burn, b) produces anumber of pollutants in air, water and soil, c) surface mining of coal results intodegradation of soil and into huge piles of residues, and d) is expensive to movecoal from one place to another.

It is composed maihly of methane. When a natural gas field is tapped,propane and butane gases are liquefied as LPG (liquid petroleum gas) which isstored in pressurized cylinders. It is world~s third largest commercial fuel, makingup 23% of global energy. World's proven gas reserves are shown in Fig. 12.4.

The proven world reserves of natural gas are 3200 thousand trillion cubicfeet. At present usage rate, the current gas reserves will last for another 60years.

JOINatural gas is an ideal fuel a) because it is clean burning, b) more

abundant and widespread, c) produces less pollution than coal and oil, and d)can be transported easily by pipelines.

The use of nuclear energy for peaceful purposes and as an instrument ofprogress was. initiated in 1950. By 1991, more than 42·8 commercial nuclearreactors in 26 countries were producing 19(0 of world's electricity.

As described earlier, our main sources of energy are fossil fuels (i.e. coal,oil and natural gas). As people are burning these fuels allover the world, thereserves are declining rapidly. Thus, the nuclear fission will be the only energyalternative left with us in future. However, to meet world energy demand, at least,1500 atomic reactors will be needed.

The development of nuclear energy has its own problems, such as, a) it isvery expensive and beyond the reach of poorer nations, b) nuclear technology isavailable to only few countries, and c) it poses several dangers like disposal ofwaste, accidental leakage, atomic proliferation, sabotage, terrorism andblackmail. .

One of the important questions of our time and most difficult to answerconcerns, how long our fossil fuels (coal, oil and gas) supply will last? Allestimates such as our present fossil reserves, rate of human population growthand consequent increase in the rate of fuel consumption are subject to largeerrors. 'According to an estimate, the energy consumption is doubling every 22years.

Conservationists argue that if energy consumption continues to gro'w untilsuddenly serious coal or oil shortages develop, the world economy will collapsedisastrously. Fuel shortage would cause widespread unemployment. Factorieswould be forced to shut down and billions of workers will be laid off.

We, off course, cannot create fossil fuels but we can do search for otherenergy alternatives and conserve our present resources to avert energy crisis.Following measures are suggested.

1. More funds should be made available for research in various fieldsrelated to energy. This includes ways and means to harness, inparticular, the hydrogen gas and solar energy.

2. Human population growth should be subsided.3. Make use of energy efficient cars and other appliances.4. Power consumption for advertising and display should be cut down.5. The use of air conditioner should be minimized. There are various

ways to do it, such as, by using electric. fans, by properly insulatinghomes in buildings, etc.

6. Drive less; use public transports or use telecommunication and mailinstead of going places in person.

7. Walk or ride bicycle for short distances.8. Turn-off lights, TV sets, computers, etc. when not in use.9. Fluorescent,lights are three times as affluent as incandescent lights.10. Reduce use of home appliances such as, bulbs, fans, iron, vacuum

cleaners, etc.11. Use stairs instead of lift or elevator.12. Dry clothes on line; dry hand-wash dishes on board (so as to save the

use of dryers.