MANAGEMENT

Long-term management of energyProf. M.W. Thring, Sc.D., F.Eng., F.I.Mech.E.

Indexing terms: Engineering and society, Power utilisation, Energy conversion and storage

Abstract: It is the author's view that, on a long term basis, a stable world free from major war is only possible ifthe developed countries reduce their energy consumption to about the present world average per-capita figure,i.e. about 2 tons of coal equivalent per capita per annum (2 TCE/c.a), and help the underdeveloped countries toachieve self sufficiency in energy and food at a comparable level. Both from this point of view and because ofthe cost of energy to the consumer in the rich countries, the author believes that the only feasible long-termpolicy for a developed country such as Britain is as follows:

(i) There should be investment in energy conservation by investing capital and by other methods (such as theelimination of built-in obsolescence) as if fossil fuels cost several times as much as they do.

(ii) Electricity is too precious a fuel to waste on the low-grade purposes of space and water heating, and sowe should not build any new power stations but convert old ones in cities to coal firing with pass-out heatsystems for houses and industry. This would give fruitful employment to the construction and heavy-engineering industries for many years.

(iii) Solid fuels (preferably smokeless) should be available for all space and water heating whenever pass-outheat from power stations cannot be made available. Research on manless coal mining should be carried outvery actively.

(iv) A substantial amount of Government money (e.g. 20% of that spent on defence) should be devoted to'intermediate' or 'alternative' technology, especially on the provision of village renewable energy systems.

1 Need for a long-term view

The first Industrial Revolution was based on a fairlysteady exponential expansion of energy consumption inthose countries that have benefited from it. The classicalexample is Britain's mining of coal which rose steadilythroughout the 19th century, having a value of 110 milliontons in 1870 and reaching a peak of 270 million tons in1913, at which time we were exporting about 70 milliontons. The coal production dipped to about 230 milliontons during and just after the First World War, and fellduring the subsequent depression and after the Germanconquest of France early in the Second World War, whichcut out British anthracite exports, to about 170 milliontons. Coal production rose during the latter part of theSecond World War and in the 1950s to 220 million tons,but has since been falling steadily to the present figure ofabout 110 million tons, most of which is used for electricityproduction. When I started working for the Coal Industryin research on combustion in 1937 I was told: 'You havehitched your wagon to a dying star'. On the face of it thiswas true, because although Britain's total energy consump-tion had, until the oil crisis of 1973, gone up fairly steadily,coal had been largely replaced by oil, to a lesser extent bynatural gas and to a very small extent by hydropower andnuclear energy. However, now the gas industry is fore-casting the coming of the 'second coal age', and activeresearch is going on again into making oil from coal.There are sufficient amounts of coal under Britain [1] toyield 200 million tons a year for well over 100 years.

Any study of energy management must take a long-term view for the sake of our grandchildren. It is no useassuming that we must have all we want now, no matterwhat happens in 40 years' time. The students we teach nowwill be just retiring then, and if we teach them all abouthandling fuels which will no longer be available or will beprohibitively expensive, they will not look back to ourteaching in gratitude.

As soon as one looks at the long-term energy situation,the problem looks entirely different compared with theviewpoint of decisions concerned either with winning the

Paper 2427A, first received 24th July and in revised form 16th December 1982

The author is with the Department of Mechanical Engineering, Queen MaryCollege, Mile End Road, London El 4NS, England

next general election or with some 19th century dogma.The first major consequence of taking a long-term view isthat we realise that neither Britain alone, nor even all therich countries alone, can assume that as long as they haveenough energy for their needs, that is all that matters. Thisconsequence is true even if we take a purely selfish butlong-term view, because it is no use having plenty ofenergy and then having our civilisation destroyed in athird world war. Anyone who takes a long-term view cansee quite clearly and definitely that continued arms escala-tion combined with the increasing world tensions, due tothe fact that the Third World population is increasing at3% p.a. [2] and their poverty is steadily increasing, mustlead to a third world war within 40 years if no adequateaction is taken [3-6]. This is not to say, of course, that thepoor countries will attack the rich ones, since, althoughdeveloped countries sell them arms whenever the poorcountries can afford to buy them, they will not sell themenough to match their own levels. Poor countries wouldnot be so foolish as to make a direct attack on a greatpower; what is much more likely to happen is that thepoverty of a certain area will cause the great powers toback opposite sides in revolutions or local wars which willbuild up explosively into a major war between the greatpowers. The world has been shrunk by technology inseveral aspects so that we are totally interdependent. Oneexample is the prevalence of air travel which can carry thegerms of a new type of influenza round the world in a fewdays, as well as making feasible a new form of piracy.Other examples are the oil tankers, ore carriers and foodships which carry millions of tons across the oceans for ourneeds. The most frightening of all is the intercontinentalballistic missile which can go right round the world inthree-quarters of an hour. Hence my first conclusion, thatany long-range energy policy must include the needs of thewhole world and not just those of one country.

The second main long-term conclusion arises from thevery well known fact that the readily accessible resourcesof oil are being used up at a rate that means that the era ofcheap oil will soon be over [2]. The same applies tonatural gas. It is one of the consequences of our short-sighted policy of economic development that we take,whatever is cheapest and most accessible as far as it iseconomic to do so, without considering the needs of ourgrandchildren. I have called this 'Thring's economic prin-

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ciple' [8], which is unfortunately true: 'Whatever is rightfor our grandchildren is always uneconomic now andalmost always impolitic'.

2 Essential steps towards a stable world

It follows logically from what I have said about the needfor the rich countries to help the poor countries to adecent life if the rich are not to destroy themselves in awar, that we have to find some way of stopping the popu-lation expansion of the poor countries. At present, thetotal world population is of the order of 4000 millionpeople, of which roughly one-third are in the rich countrieswhich have had the benefit of the Industrial Revolutionand have a population growth rate of less than 1%. Thepopulation growth rate of the poor countries of 3% [2]means that, by the year 2000, there will be 3-4 times asmany people in the poor countries as in the rich ones andthe total world population will be 7.3 billion. In the year2025, there will be 5.5 times as many people in the poorcountries as in the rich ones and the total world popu-lation will be 12 billion (Fig. 1). Even if we were to avoid a

x10b

12000

c 8000

U 000

1975 2000 2025year

Fig. 1 Present and future world populationWorld population growth

2.25% p.a. continuous growthdesirable levelling off

third world war for 50 years, this total world populationwould clearly be beyond the resources of the world tosupport, especially when we take account of the fact thatthe deserts of the world are steadily growing every year.Therefore the first priority of any world policy must be tolevel off the world population within the next generation.However much a country like Britain might isolate itselffrom the poorer parts of the world, this would clearlybecome impossible if hundreds of millions of those peoplewere dying of pestilence and starvation every year. Now,there are plenty of ways of reducing the world populationthat are totally unacceptable to anyone with a conscience,namely a third world war, plague, pestilence and star-vation. There is, however, only one humane way, based onthe observed fact that, when the standard of living of apopulation and its educational levels rise above a certainpoint, the people accept voluntarily the need to limit the

size of their families. Hence the first inescapable conclusionfor any long-term world energy policy is that we must findwithin one generation a way of giving all the peoples of theworld a fully adequate standard of living and education.

The second conclusion is very closely connected. Aslong as the people in the poor countries have a standard ofliving and access to the earth's limited resources substan-tially below that of people in the rich countries, and theylearn about this from television and journals, the worldtension due to jealousy will remain and is liable to escalateinto a third world war. They learn about the extravagantuse of energy in motor racing and excessively powerfulcars, gadgets like dune buggies or golf carts, the heating upof a whole lake by the waste heat from electricity gener-ation, and many other consequences of cheap energy. Thisis particularly true where there are peoples of differentreligion, sect or race living close together with widely dif-ferent standards of living, and these represent the potentialflash points. Thus the second main conclusion is that if weare to eliminate the terrifying danger of a third world warand reach a situation of stable world peace we must essen-tially eliminate the gap in standards of living and hence infuel consumption per capita between all groups of people.This does not, of course, mean that everybody in a groupconsumes exactly the same amount, and one can makeallowances for problems of domestic heating in the winter

• in the colder areas of the world, but the basic principle ofeliminating the gross inequalities must stand. At thepresent time, short-term strategic arguments in the devel-oped countries tend to be concerned with whether theenergy consumption per capita should rise at a fast growthrate of 4% p.a. or a slow growth rate of 2%. These growthrates are totally unrealistic, for example a 4% increase for100 years would involve an increase of more than 50 foldand in 30 years an increase of 3.4 fold. At present, inBritain, we are consuming some 5.5 TCE per head per yearand the USA is consuming more than twice as much perhead. If the present average figure for the developed coun-tries of 5.5 TCE per head per year were to increase at 2%per annum for 40 years and at the end of that 40 years wewere to give the same amount of energy to all the 12000million people of the world, the total energy consumptionof the world would be about eight times what it is now.This is clearly a totally unrealistic objective for fourreasons. First, even if we developed a method of winningall the earth's coal resources, this rate of energy consump-tion would exhaust them in about a century while the oiland natural gas would be drained dry, except for veryexpensive sources such as oil shales, within two or threedecades. Secondly, the capital cost of energy requirementsto set up local renewable energy systems or central nuclearpower stations with their distribution systems would be atotally impossible burden on the earth's limited mineralresources. Thirdly, we have the problem of thermal pol-lution, both from the generation of electricity and fromindustrial areas, and, fourthly, there is the 'greenhouse'effect due to the increase of carbon dioxide, resulting fromthe combustion of so much fossil fuel. There is little doubtthat the carbon dioxide of the atmosphere would rise to apoint at which the polar ice caps would begin to melt anda great part of the land of the world would then be flooded[9]. We are, therefore, forced to the third conclusion whichis that developed countries must bring their energy con-sumption per capita over the next 30 or 40 years to afigure not much greater than the present world averagefigure of 1.8 TCE per head per year. Over the same periodthe energy consumption in the poor countries must comeup from the present figure of about half a ton of coal

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5 0

0-50-18

UDCs average-food-

1975 2000year

Fig. 2 Present and future energy consumption per head per year

equivalent to this same figure of 1.8 TCE per head peryear. Fig. 2 shows this conclusion in graphical form. Thusthe only future that makes sense is for the rich countries tohave a negative growth scenario in which the energy con-sumption per capita goes down by 3.4% each year for thenext 30 years. In the USA the reduction figure would haveto be about twice as much. In the following Section I shallconsider how much of this reduction could be obtainedwithout any real reduction in the standard of living ofthese countries, that is by fuel economy.

Fig. 3 shows the relation between the energy consump-tion of various countries in equivalent tons of coal perhead per year and the gross national product (GNP) indollars per head per year at 1969 prices. The interestingthing is that the average energy consumption of the poorcountries actually went down between 1969 and 1975, theworld average per capita remained more or less constant,and the average in the rich countries rose by about oneton. The USA, Canada, Sweden, Japan and France allshowed very large increases in the gross national productin the 10 years from 1965 to 1975, together with-roughly

10

proportionate increases in fuel consumption. The Japanesefuel consumption more than doubled during this periodowing to the large increase in production. Britain showedonly a moderate increase in GNP and an almost constantenergy consumption. However, in 1969, Britain was thecountry showing the greatest displacement above theaverage of the band, that is to say we got the least financialbenefit from our energy consumption. By 1975 we hadcome to the middle of the band. Thus we see that theessential long-term strategy in energy for the rich countriesis a steady reduction in consumption. This is a clearexample of 'Thring's economic principle'.

The fourth conclusion relates to the premium fuels, oil,natural gas and, above all, electricity. Oil and natural gasare premium fuels because it was comparatively difficultfor nature to lay down large reserves, since they have to betrapped in a porous rock over water and under a dome ofimpervious rock, so the total quantities are of the order ofone-twentieth of the total quantity of coal reserves whichcould be laid down in strata anywhere. This does notapply to oil in shales or tar sands, but these are muchmore expensive to extract. Electricity is a premium fuelbecause it requires a very large high capital cost for itsgeneration and distribution and because, when it is madeby thermal processes, from fossil fuels or from nuclearenergy, the overall efficiency of conversion of the heat fromfuel energy to the final user of the electricity rarely exceeds30%. If our grandchildren are to have the benefits of thesevery convenient premium fuels, we shall have to reduceour present consumption of them by some 7% every year,and we shall have to learn to use them only for thosepurposes for which coal or renewable energy resources aretotally unsuitable. For example, for road and air transportit will almost certainly be necessary to convert coal oragricultural products to liquid fuels as oil becomes moreand more difficult to win. The fourth conclusion is thus'Premium fuels for premium purposes only'. The finalquestion relates to capital investment. It is perfectly clearthat the very expensive capital equipment involved in elec-tricity power stations and grid distribution systems and inmuch other heavy industry and even large agriculturalmachines in the developed countries could not be provided

USA

USA

Ni

UK

2 3 4GNP, $ x 103 per head per year (at 1969 prices)

1 9 7 5

Fig. 3 Coal equivalent energy consumption per head against GNP(1969)0 1969—1975C = CanadaF = FranceJ = JapanNi = NigeriaSw = SwedenUK = United Kingdom

Q 1969— 0W = worldP = poor countriesR = rich countries

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for the whole of the 8000 million people who will certainlybe on this earth before we can level the world's populationoff. Thus we reach the conclusion six, that only thosecapital developments which could be provided to 8000million people should be developed in the future.

3 Electricity

Electricity is a fuel with the highest possible 'virtue' [10]equivalent to heat at infinite temperature. The 'virtue' ofenergy was defined in Reference 10 as 'the amount ofenergy which could be converted into work in an ideallyperfect system'. The concept has been called 'exergy' inmore recent publications in Germany and Poland.

It is not too strong to say that it is to ignore the secondlaw of thermodynamics to turn heat into electricity andthen use the electricity for producing heat at very lowtemperatures for hot water or space heating. This meansthat the overall efficiency of the use of initial heatexpressed as chemical energy of fossil fuels or as massenergy converted to heat in the nuclear reaction will beless than 30%, whereas if one heated the system directlyone could obtain something like 80%, for example byusing a coal-fired boiler. In addition to this tremendouswastage of energy there is the very high capital cost of theplant for generating electricity and distributing it, and,although it may appear to the consumer that he is buyinga very cheap appliance for the purpose, namely an immer-sion neater or an electric fire, the extra capital required tocope with this extra load at the power station is manytimes the cost of his unit, and he has to pay this in theelectricity charge.

In 1971, the Institute of Fuel (now the Institute ofEnergy) held a conference on combined heat and power[11], or 'total energy' as it was then called, and concludedthat if on the one hand one burns a fossil fuel to makeelectricity and uses it for domestic space and water heatingas well as for domestic lighting and other purposes such asrefrigeration and power, for which electricity is the idealfuel, and on the other hand one generated electricity onlyfor essential uses and used the pass-out steam to providethe space heating and water heating, then one would getexactly the same result for less than half the primary fuelinput. The Battersea Power Station was built many yearsago to work on this cycle, and heating is provided inMoscow and Warsaw in this way. The pass-out steam can,of course, be used also for industrial purposes, and manyfirms have found that it is worth their while to generatetheir own electricity when they need a lot of steam, as inthe sugar industry, even though their boilers and gener-ators are much smaller than those of central power sta-tions. Combined heat and power for local industry whichrequires steam is being used in one case in Britain, but it isquite conventional in many other countries.

Clearly it is in the long-term interest of the ordinaryperson in Britain, both as a consumer of electricity andheat and as a potential victim of war, that instead of build-ing new power stations we should modernise the old oneslocated close to towns or industrial areas and convertthem to combined heat and power systems, both for dis-trict heating and for industrial steam provision. At thesame time the provision of the underground heat distribu-tion mains would be a form of capital investment givingfar greater employment than the building of new powerstations and with less capital cost. We should avoid cover-ing the country with derelict power stations, which, parti-cularly in the case of nuclear power stations, constituteeither a long-lasting hazard or a very expensive disman-

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tling process. The old power stations could be givenmodern coal-firing equipment, with good gas cleaning(particularly for SO2) probably fluidised-bed combustion,with all the coal handling dust free and fully mechanised,and the system would be arranged with the possibility ofworking with varying amounts of pass-out steam or hotwater by controlling the last stage of the turbine so that,when less heat was required, the electricity could be gener-ated with higher efficiency. In this way the overall effi-ciency of the use of the energy in the coal could be raisedto something like 70%, so that only half as much coalwould be used for the same result, which in itself halves theemission of pollution SO2 •

As has been said, it will never be possible to build bigcentral power stations and distribution systems to coverthe villages of a poor country such as Bangladesh becauseof the vast amount of fuel and metal ores required for theinstallation. The total amount of water power is also verylimited, and there are many cases where the damming of ariver, although it generates electricity, causes upsets, suchas the carrying down of silt for agriculture further downstream. Moreover, in many cases where dams have beenbuilt, the reservoir volume will be full of silt in 50 yearstime so that the capacity of the reservoir will no longer beanything like so great.

I had the privilege of being a member of a UNESCOteam visiting Bangladesh in 1979 and was able to studytheir village problems at first hand. The conclusion I cameto was that if you could give a few kilowatts of electricityto a village of 1000 people, together with a source of heatat 100°C for boiling rice, this could provide a very realessential need, as far as energy is concerned, for a greatlyimproved life. If one had a central generating system thevillage would have to buy several hundred kilowatts con-tinuously to justify the cost of the distribution (which theycertainly cannot afford), and in any case there would bethe national problem of providing the fuel to the centralpower station. For this reason we have been working on asolar concentrator [12] producing steam at 200°C whichcan either be used directly or stored as high-pressure waterin a 'steam accumulator' until the evening.

Fig. 4 shows the concentrator developed by JohnLowry. It consists of a small power tower in which a once-through boiler is located at the top of a telegraph polefacing downwards towards a group of 25 mirrors. Eachmirror has 2.5 times the area of the boiler and is made ofnine small square plain mirrors set in a curved plywoodframe so that it focuses on to the boiler. The assembly ofmirrors can be moved by a single lever to focus the sun onto the boiler. By using this system in a steam engine,exhausting at one atmosphere and 100°C,'one can convertnearly 10% of the solar energy absorbed into electricity orpower for pumping, and the remaining 90% is availablefor cooking. Water at 200°C can be stored in an insulatednest of gas cylinders so that the electricity and cookingheat are available after the sun has gone down. By usingone 5 W strip light in each house and a multi-compartmented community refrigerator, 2 kW of elec-tricity can serve a whole village.

4 Oil and gas as premium fuels

Many of the problems which at present face our energysituation are due to the fact that we have grown accus-tomed to really cheap oil and gas. Indeed, looking at theproblem from a long-term point of view, they are both stillfar too cheap, so that not only are we using them up tooquickly but also we are ensuring that our grandchildren

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-tiff

Fig. 4 Low-cost solar concentrator

will not be able to afford to do the things we do now. Themost obvious example is in road and goods transport. Westill advertise cars by their top speed, far above the speedlimit, or by their acceleration, and we have not begun totake seriously the problem of a really efficient car in theway we would take it seriously if, for example, the price ofpetrol were £5 a gallon. In the Mechanical EngineeringDepartment at Queen Mary College [13] we have beenworking for seven years on the hybrid diesel/electric car(Fig. 5) which could potentially travel 100 miles on agallon of fuel because it has a very small 2-cylinder dieselengine of power only adequate for cruising. It is what isknown as a parallel hybrid. It has a conventional gearbox,the input to which can come from either the diesel engineor an electric motor or both together. The diesel enginecan recharge the batteries by running the motor as a gen-erator when the vehicle is stopped or when the vehicle iscruising. By using the gearbox the system can have veryefficient regenerative braking down to low speeds. Com-pared with the all-electric car this system has the advan-tages that one still has cruising power if the battery iscompletely flat and that, if the diesel fuel runs out alto-gether, one can fetch some in a can.

Another solution to this problem to which not nearlyenough attention has been given so far is an electric carbased on a fuel cell fuelled by methanol/air. Like the inter-nal combustion engine, this has the advantages of using acheap liquid fuel and burning it with 14 times its ownweight of air which it picks up as it goes along. A conven-tional storage battery has to carry both its reagents andalso a fairly heavy system for collecting the electric currentfrom all the small reacting pellets. There is little doubt that

Fig. 5 Hybrid diesel/electric engine for small car

research could produce a methanol/air fuel cell, although itmight very well have to work at some elevated tem-perature and might therefore have to be heated up in themorning by a flame or by mains electricity.

Another wasteful aspect of motor cars, as far as energyis concerned, is that we build them to last only about 10years (a foreign maker claims, as a special asset, a life of 19years), basically because of corrosion of the bodies. Quite asmall increase in the initial cost, such as galvanising thebodies or the use of sheet steel with a rolled-in thin plasticcoat, would suffice to enable them to last 30-50 years.Each time a car is made several tons of coal or oil arerequired to produce the steel and other materials, and todo the work of manufacture. Again, if our grandchildrenare to have cars at all, we shall have to go over very soonto building cars that last 50 years.

When I was in Australia seven years ago I was dis-cussing the fact that, as oil gets scarcer, we should have toreturn to trains, and the simplest way of running trains oncoal is to electrify the lines and have central power sta-tions. However, it was pointed out that for long-distancelines, such as that from Sydney to Perth, one could neverpossibly electrify it because it carries too few trains. Wehave therefore been carrying out at Queen Mary College[14] studies on the possibility of a modern high-efficiencycondensing coal-fired steam locomotive. The preliminarystudy showed that the system was quite feasible and couldprobably give a higher overall efficiency than for the use ofthe coal in a power station and almost as high as that of adiesel-electric system. As the result of the publication ofthis work we have had interested inquiries from Australia,South Africa, South America and China. There is littledoubt that the primary system for transporting goods inthe 21st century will be the coal-fired train, combined withlocal lorries for the few miles from the station to the desti-nation. Suitable container-handling systems have beenworked out, and an incidental advantage of enormousvalue to the public would be the virtual elimination oflarge lorries from our towns, country lanes and motor-ways.

When fuel becomes really expensive we may even find itpays us to return to canal barges, and it is quite likely thatvery large airships capable of carrying 100 tons or moreacross land and sea at 100 mile/h will be developed. Thebasic problem with a helium filled airship is that onecannot afford to vent the helium when one wishes to comedown. A reasonable solution to this problem would be tohave a hydrogen (or possibly methane) bag occupying say20% of the volume at the upper side of the airship; the

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engines would be dual-fuelled, running either on liquid fuelor on the gas. At the beginning of the journey they wouldrun on the liquid fuel to increase the buoyancy. The energyconsumption for the carriage of heavy goods in airships isfar less than that of an aircraft which is held up by thelifting force on the wings which is inevitably associatedwith very considerable drag. Aeroplanes themselves willcontinue to run, probably eventually with liquid fuel madefrom coal or agricultural material, but they will have torun full and will probably have lower speeds and maymake use of boundary layer propulsion to reduce the fuelcosts of the drag.

Another aspect of waste to which we have grown accus-tomed is the flaring of natural gas at oil wells. In theMiddle East the natural gas flared in this way and totallywasted for our descendants has a calorific value of one-sixth of that in the oil we use. We are in such a hurry toget the oil that we are not prepared to spend the capitalcost on using the natural gas. In some cases it may bepossible to install a gas pipeline, in others it would prob-ably be necessary to instal equipment to convert the gasinto methanol which, being a liquid, could be much moreconveniently transported.

5 Coal

Research on the more efficient use of coal should clearly bestepped up and we shall undoubtedly have a return to theuse of coal for industrial furnace heating, steam raising anddomestic heating. I had developed a smokeless domesticstove to burn washed singles* in the mid-1950s at SheffieldUniversity, but the development was halted because at thattime the UK National Coal Board could not spare washedsingles for the domestic market. Coal will be the transitionfuel for the 21st century although, eventually, we shall haveto move over to the renewable fuels and this implies thatwe must have installed all the necessary capital equipmentby the time coal is exhausted. The immediate problem is tofind a method of mining coal without men going under-ground. Underground gasification and combustion dorequire men to go underground to set them up and in anycase only produce heat which has to be used locally.

Since we shall certainly need coal on the surface forturning into a substitute for oil and a substitute for naturalgas, for chemical products and to make the coke for a fuelfor iron making, we have to find a way of bringing it to thesurface so that it can be transported or converted to valu-able products in a coal-processing complex, such as pro-posed by the National Coal Board. The subject oftelechirs, or hands at a distance, has been developed overthe last 25 years for work in radioactive zones in space andunder the sea and does undoubtedly offer the possibility[15] that eventually we shall be able to do all the oper-ations of mining that men do at present by going down themine, with the men sitting in a control cabin on the surfaceand working telechirs down the pit. It will then no longerbe necessary to ventilate the mine, and we can win coalright across under the North Sea where there is as muchcoal as under Britain. Fig. 6 shows a model of a miningtelechir.

6 Renewable energy sources

There will be many places in the world in future, both inthe developed countries and in the less developed ones, in

* 'singles' = coal screened between 25-12.5 mm square-mesh sieves

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Fig. 6 Model of mining telechir

which windmills will be used for electricity generation,pumping and other power purposes. The basic problem ofwindmills are the storage of energy for periods when thereis no wind or an alternative source, and coping with theoccasional immense gales. It is my opinion that the mostlikely windmill for the future is what one might call thevillage windmill, producing, say, 20-100 kW, which is usedfor lighting, refrigeration, and even possibly to work heatpumps which have solar panels as their low-temperatureheat source. These will be required primarily for thoseareas that cannot afford distributed power but have anabove average wind speed.

Solar energy will be used as mentioned above in a com-bined heat and power system, and it is probable that thesolar cell will come down to a reasonable capital cost. Thebasic problem with solar energy is that one gets at most afew 100 W/m2 and, with low conversion efficiencies, thisbecomes a few tens of watt per square metre, so that forany reasonable system one has to cover very large areasand therefore the capital cost is very important. Anotheruse of solar energy which will become very important inthe future is the growing of crops that can produce a fuelas a byproduct. One example is the proposal we have putup [16] for baling rape and wheat straw and burning themin a continuous burning system at high intensity toproduce high-pressure steam. These byproducts are atpresent burned in the fields with considerable problems,pollution and fire hazard. It is possible either to run asteam tractor on straw burned in this way or to have afarmers' co-operative in which the participants fix theirown nitrogen using their baled straw as the energy source.At present, the cost of nitrogen fixation is rising veryrapidly as the cost of oil and natural gas rise. The work ofthe National Institute of Agricultural Engineering toproduce a high-density baler (0.5 instead of the presentsmall-bale figure of 0.1) would make this system very muchmore feasible.

Another alternative is to irrigate the deserts of theworld by solar distillation of sea water and then to growcrops in the desert which combine a food and fuel value.One example is to grow cotton, the refuse of the cottonplant can be hydrogenated to produce oil, as was shownby a student of mine at Sheffield University 25 years ago.The solar-distillation system consists of a shallow blackplastic-lined trough with a layer of sea water and coveredwith a transparent polythene roof held up by air pressure.The sun shines through the roof, distils the salt waterwhich condenses on the inside and runs down to growcrops between the stills. This is another example where wemust use our precious hydrocarbon resources before they

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are exhausted to instal equipment that will be able toproduce a continuing supply of food and energy.

7 Conclusion

Some of the objectives of a rational long-term energypolicy for Britain should be:

(a) to provide the British public and industry withenough heat, light and power for all their needs, as cheaplyas possible

{b) to provide as much employment, fruitful in terms offuture economy, as possible

(c) to contribute as much as possible to the reduction ofthe risk of a third world war

(d) to minimise the number of derelict or mothballedpower stations cluttering Britain.

To achieve these objectives, the arguments of this papersuggest that some of the essential elements of such a policyare as follows:

(i) Spend much more research and development effortand capital resources of fuel economy and alternative-energy sources such as refuse. This should apply to homeand industry with substantial tax or other incentives so asto make fuel savings as worthwhile as if fuel were alreadythree times as expensive as it is. It should also apply tovehicle fuel.

(ii) Start at once on a programme of converting all oldpower stations in or near towns or industry to combinedheat and power (CHP) with modernised coal-firingsystems. It would be necessary to introduce some partialSO2 removal from the flue gases, but the main reduction insulphur emission would come from the reduction in con-sumption due to the greatly increased overall efficiency.This would give plenty of work to the boiler makers andturbine manufacturers but above all it would give tremen-dous benefit to the construction industry in laying themains. In many towns it would be possible at the sametime to reconstruct the whole infrastructure before itfinally falls to pieces!

(iii) Gradually convert all oil-fired power stations tomodern coal firing, as well as CHP.

(iv) Do not build any new power stations for the fore-seeable future.

(v) For the sake of world peace, conduct research anddevelopment efforts in full cooperation with the Third

World to find appropriate ways of providing village powersystems of a few kilowatts from renewable resources withfull regard for the needs resources and customs of eacharea.

(vi) Spend more research and development effort onmethods of mining coal without men going undergroundthan on nuclear energy, because the potential benefits areso much greater. Ultimately such processes can more thandouble the amount of coal available in Britain andincrease it by an even bigger factor in other countries.

There are, of course, many other items in a completeenergy policy but these are the ones that must be urgentlyconsidered. They may be summarised by saying 'premiumfuels for premium purposes only, and maximum economywith both premium and nonpremium fuels'.

8 References

1 COLLINS, H.E.: 'The revitalised coal industries' (Colliery Guardian,1975)

2 KING HUBBERT, M.: 'Resources and man' (W.H. Freeman, 1969),p. 5 and p. 157

3 LORD ZUCKERMAN: 'Nuclear illusion and reality' (Collins, 1982)4 ROTBLAT, J. (Ed.): 'Scientists, the arms race and disarmament'.

UNESCO, Pugwash book5 GUTTERIDGE, W. (Ed.): 'European security, nuclear weapons and

public confidence' (Macmillan, 1982)6 SCHELL, JONATHAN: 'The fate of the earth' (Jonathan Cape,

1982)7 Nat. Acad. of Sciences: 'Energy in transition 1985-2010' (W.H.

Freeman, 1980), p. 1378 THRING, M.W.: 'The engineer's conscience' (Northgate, 1979),

p. 1289 BOLIN, B.: 'Energy climate' (Secretariat for future studies, Stock-

holm, 1975)10 THRING, M.W.: 'The virture of energy, its meaning and practical

significance', J. Inst. Fuel, 1944,17, pp. 116-12311 Proceedings of the Total Energy Conference, Institute of Fuel, Bright-

on, 197112 THRING, M.W.: 'Engineering for humanity' (James Clayton Lecture,

1982), Proc. l.Mech.E., 1982, 196, p. 17513 'Hillman Imp, careful owners, diesel-electric, three clutches, 100 mpg,

apply Queen Mary College', Petroleum Review, Sept. 1978, p. 3014 THRING, M.W., SHARPE, J.E., and LE SUEUR, P.K.: 'Steam on

efficient lines', Spectrum, 153, 1977, p. 315 THRING, M.W.: 'Mining without men going underground', ASME

paper 81-Pet-21, Jan. 198116 THRING, M.W., and CROOKES, R.J.: 'Farm straw as fuel for

power'. Presented at the International Conference on Biomass, 198017 THRING, M.W.: 'Solar distillation'. Presented at the Solar Energy

Conference, Reading University, 1976

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