INAUGURAL ADDRESS

Waste not, want not

G.T. Shepherd, CBE, BSc(Eng), DSc, CEng, President

Indexing terms: Energy conversion and storage, Long-term planning, Engineering and society

Abstract: The paper reviews the effect of totalenergy schemes on the operations of the LondonElectricity Board (LEB) in the late 1960s and early1970s, and describes the proposed connection ofprivately owned generators to the LEB system.The introduction of combined heat and power(CHP) systems is then described, and the benefitsof the more efficient use of fuels in such systemsare explained. Reductions in heavy fuel oil priceshave helped the economics of CHP. The adoptionof CHP and district heating (DH) in the UK isencouraged, and is foreseen as being complemen-tary to conventional and nuclear power gener-ation.

1 Introduction

It was in 1982 that I gave the Chairman's Address to theIEE South Midlands Centre, and I would like to quotefrom that paper:

'The first nuclear power stations are now reaching theend of their design lives and they have been, on thewhole, a success, operating reliably and safely for upto twenty years.

'Later nuclear projects have not been so happy, andI wonder if this is primarily another example of thingsgetting too big. Both in nature and engineering, thingsseem to develop bigger and bigger until suddenly, cir-cumstances dictate a retreat to "small is beautiful". Itis not as though we always get the benefits of scale!Nuclear power stations are getting more and moreexpensive to build, both in time and money. Sizewell'B' is at present estimated to have a capital cost of£1,300 per kW, not to mention transmission linecosts—and we should not see any return for ten yearsor so. At the same time we are scrapping perfectly reli-able conventional power stations!

'I personally am in favour of nuclear power, butone cannot help but wonder if private industry wouldbe prepared to build such plants at today's costs, andsell the power to the Electricity Supply Industry. Onthe other hand, would it be wise to plan to rely exclu-sively, or even largely, on coal?

'Other options open to us are district heating (DH)and combined heat and power (CHP).'

How quickly situations can change in a few years!

It was 13 years earlier, in 1969, that I left the South ofScotland Electricity Board (a board involved in both gen-

Paper 4864A, delivered before the IEE on the 2nd October 1986

IEE PROCEEDINGS, Vol. 134, Pt. A, No. 1, JANUARY 1987

eration and distribution) to take up the post of DeputyChairman of the London Electricity Board.

2 Total energy schemes

There was no disguising the fact that the LEB had prob-lems, and perhaps the biggest of these was that inroadswere being made by so-called total energy schemes.

In essence these schemes operated in very large officeblocks and the like, and the idea was that private gener-ators, fuelled by gas or heavy fuel oil, would not onlyprovide the necessary lighting and small power require-ments such as for lifts etc., but also that the exhaust heatfrom the gas turbines, or other heat engines, wouldprovide the heating for offices etc.

So what could we do about this potentially significantloss of revenue? Not surprisingly, it soon became evidenton investigation that engines and generators did some-times fail, and standby plant was expensive.

Secondly, there was often a mismatch between thepower generation and heating requirements, and plantalso had to be designed to meet extremes of heat andcold. This operation was often inefficient. Despite thedesire of entrepreneurs to isolate themselves from thepublic power system, such a departure could be veryexpensive for the reasons given above.

The solution however appeared obvious, or partly soat least! If the privately owned generator were to be con-nected to the London Electricity Board (LEB) system,then substantial advantages would arise for both parties.

The entrepreneur would not need a standby generatoras far as power was concerned, since the LEB systemcould be available for back-up. The LEB system couldalso be used for peak lopping, enabling a cheaper andmore efficient generator to be installed.

At about this stage, we were approached by a largedevelopment organisation with a view to collaboratingwith the LEB in regard to a small but prestigious districtheating scheme on the South Bank, based on the aboveprinciples.

The CEGB was particularly helpful and allowed us toput our proposed plant on the Bankside power stationsite, using the existing power station chimney for engineexhausts. On the other hand, it literally took an Act ofParliament to enable us to open up one of the streets onthe South Bank in order to lay a pipeline from the powerstation to the proposed development site; but we did getthe necessary permission.

Unfortunately, or not, according to point of view,there was a change in the local government; and our newmasters were not in the least interested, and would notgive us the necessary go-ahead. So we had to call the

wLole thing off. Luckily the exercise was at little or nocost to LEB.

Combined heat and power (CHP)

atAt this point. .1 time two interesting things happenedleast from my point of view.

First, I v s appointed Chairman of the MidlandsElectricity I rd, which of course was, and is, a largemixed board, its business ranging from rural electrifica-tion to heav> lustrial involvement.

Secondly id a real stroke of luck! An MEB engi-neer had, sevt al years before, been responsible for plan-ning and exec >ting the introduction of gas turbines intothe South We tern Electricity Board (SWEB)—the first,and as far as 1 know, the only ones installed in any areaboard for many years. He was John Lycett, a name fam-iliar to many.

Like me, he was keen on combined heat and power(CHP), and so we formed a team to design, build andoperate industrial CHP schemes, which we believed to bevital to the wellbeing of industry.

In a sense, the electrical part of the problem wassimple, once one had accepted the need for intercon-nection with the area board network; there was nothingvery new about that!

However, although waste heat recovery from a primemover was commonplace in industry, it was not, as far asI know, usual to add fossil-fired boilers to the scheme soas to cover peak heat loads and possible engine failure.

These points seemed to us to be vital to the economicsuccess of combined heat and power. The basic require-ments were as follows:

(i) A suitable heat engine (e.g. a gas turbine, dieselengine or back-pressure steam turbine) drives an elec-tricity generator, and uses the engine exhaust to providethe necessary base load heat requirement for the plant. Inother words, the base load heat requirements of the plantdetermines the size and design of the engine (Fig. 1).

(ii) The generator is connected to the area boardnetwork, either exporting or importing power, dependingon the works demand.

(iii) A boiler (relatively cheap) is also installed whichcan meet peak heat loads, even without the heat enginerunning (Fig. 2).

Such a simple system can be very economical, producingsomething like twice the output of power and heat com-bined, compared with more conventional plant. It alsogives high reliability!

This is all fairly obvious and it is unfortunate that theUK has not been able to cash in, to any great extent, onsuch a simple principle.

One of the problems is the lack of a reasonable 'buy-back' price for surplus electricity. For example, the elec-tricity boards will only pay about 70% or so of thenormal price for surplus power exported to the Gridfrom a CHP scheme.

This is not only unreasonable, but is especially sowhen one realises that, in the general case, where a localgenerator is installed remote from a power station (unlikeperhaps 30 or 40 years or so ago), the transmission,transformer and distribution losses are reduced, if notcompletely saved. If the electricity boards were to pay thesame price for buying as for selling, then at least thiswould be some comfort and be more equitable to bothparties.

The seconu problem is that of profit. The electricity

supply industry makes a profit (as required byGovernment) of about 3% or so, and clearly no entrepre-neur would be satisfied with such a return. This in itselfdoes not kill CHP, because of the much greater efficiencyof CHP, but it does of course make it more difficult forthe private sector to compete. The 1983 Act has helped,but does not go far enough.

HEAT LOADM W (h)

STATION GUARANTEEDHEAT CAPACITY

WINTER

SPRING/AUTUMN

FULL LOAD HEAT OUTPUTFROM PRIME MOVER HEAT

RECOVERY SYSTEMS

0 1200 2400

TIME OF DAY

PERFORMANCE ON FULL LOAD BASED ON NET HEAT VALUE OF FUEL

THERMAL EFFICIENCY OF GENERATING SETS WITH HEAT RECOVERY 76%THERMAL EFFICIENCY OF OIL FIRED BOILERS 84%OVERALL THERMAL EFFICIENCY OF COMPLETE STATION 80%STATION AUXILIARY LOAD = 5% TOTAL OUTPUTOVERALL THERMAL EFFICIENCY OF STATION 76%

Fig. 1 The daily load cycle for the Hereford CHP Station

Because of the lack of interest shown by other parties,the Midlands Electricity Board has, in fact, pioneeredtwo such plants of the type referred to earlier. It was inAugust 1978 that the MEB, after several abortiveattempts elsewhere, started construction of the wellknown Hereford plant. The station commenced gener-ation with both units on the 2nd May 1980, a buildingtime of about 21 months.

It would be idle to pretend that all went well. Theoverall design of the plant was satisfactory. High pressuresteam and hot water were supplied to Bulmers and SunValley Poultry (M & S), (both large users of heat) atvarious take-off points and at differing specified pressuresand temperatures.

Apart from a lOmin stoppage in the first month ofoperation, the customers have been delighted. However,problems arose on some aspects of civil engineeringdesign which have only now been largely resolved.

Since the inception of the plant, two further customers,one a local government depot and office and the other asmall factory, have joined the 'club'.

The unfortunate part of the business was that heavyfuel oil prices really began to take off in 1980, shortlyafter the plant was commissioned. However, heavy fueloil prices have fallen dramatically in the past year (Fig.5), and I am glad to say that, as of today, Hereford isworking very profitably.

Encouraged by Hereford, the MEB decided to goahead with a more advanced plant at Fort Dunlop inBirmingham. This was a larger plant, of 24 MW output,compared with 15 MW at Hereford.

An unusual aspect of the Fort Dunlop requirementswas a relatively high process steam temperature, with theresult that, in addition to the two large diesel engines,two coal-fired boilers were installed in series with theengines. The plant took longer to build than wasexpected, but no serious problems were encounteredduring commissioning.

IEE PROCEEDINGS, Vol. 134, Pt. A, No. 1, JANUARY 1987

STEAM CONDITIONS 235°C

EXHAUSTSTACK

GENERATOR

HOT WATERSUPPLY 80°C

75°C

CONDENSATERETURN

FROMCUSTOMER

Fig. 2 Flow diagram for the Hereford CHP Station

Fig. 3 Aerial view of the Hereford CHP StationThe grey line encloses the CHP plant and its pipe runs

Fig. 4 External view of the Dunlop CHP Station

IEE PROCEEDINGS, Vol. 134, Pt. A, No. 1, JANUARY 1987

RAW WATER 10°C

It was unfortunate that the Dunlop site changedhands in respect of its tyre making; but luckily our finan-cial contract was with the holding company and theBoard's financial interests were fully protected.

Present indications are that a new company is pre-pared to take the necessary heat from the MEB, and theprospects are good. The plant is operating satisfactorilyand, like Hereford, is giving a good financial return.

There is, in fact, nothing new about CHP. There aresome CHP stations working in Britain, but they are fewand far between. For a technology that was first installedat a sugar factory in Clydebank, Scotland, in 1898, it hashad a remarkably unhealthy upbringing. (Nurse wasalways forbiddingly in the background!)

4 Heat from waste

While MEB engineers were scouring their area with aview to developing further CHP schemes, they proposeda potentially economical scheme for a waste-paper plantin the centre of Birmingham.

This plant, privately owned and constructed, has nowbeen operating successfully for well over a year, using asmall steam turbine, and utilising pass-out steam. Theoverall plant thermal efficiency is just over 77% and thecost of generating electricity is 1.8p/kWh.

A Government grant of £400000 towards the totalcapital cost of £1 600000 permitted savings of £450000 inthe first year of operation alone. There must be manymore situations as this.

The capital cost, even without the grant, amounted tono more than £500/kW, which is much the same as thesecond half of Drax Power Station in Yorkshire, but ofcourse with twice the thermal efficiency and, very impor-

tant, although small, it is in the middle of a conurbation,thus avoiding transmission and distribution losses. Thismust be the way ahead!

5 Steam and CHP

As a generalisation, steam tends to be a bit of a loser,mainly because steam is not at a very high temperature,even before it enters, say, a steam turbine. By the time thesteam has done its work there is not much heat left forany other purpose. The situation can, of course, beimproved by passing some of the steam out of the turbine(after it has done some work) at a higher point in theturbine than the condenser. It need hardly be pointed outthat the turbine itself is less efficient in these circum-stances.

Generally speaking, large steam turbines, such as areused in power stations, are relatively inefficient, as Table1 demonstrates. Small turbines can be another matter.

The motor car has a very low thermal efficiency, say10-15%, but it has other advantages (mainly ofconvenience), and we all love our cars!

The best candidates for CHP therefore are the hightemperature engines with relatively high temperatureexhausts, which are useful in almost any heat process.

Table 1 illustrates the point.

Table 1: Efficiencies of heat sources

Diesel enginePower stationGas turbineBack pressure steam turbine

Fuel

oilcoal,gas,coal.

oil,oiloil.

gas

gas

Efficiency,Electricity

40353020

Heat

30

5565

CHP

70358585

It will be seen that the economics of scale in the caseof large fossil-fuelled (or for that matter, nuclear) powerstations are somewhat diminished by comparison withthe very high efficiency of combined heat and powerunits.NET PENCE PER LITRE

20—I

I80

I84

I86

YEARS

Fig. 5 Heavy fuel oil prices

A further advantage of CHP is that it is rather likeyour neighbourhood friend. It is on a small scale and, ifCHP were to expand greatly, as some time it must, thenthe need for huge transmission lines would be consider-ably reduced.

The only need for high powered transmission in thefuture would then be in conjunction with nuclear powerstations, since the likelihood is that large fossil-fuelledpower stations will slowly give way to CHP. Inevitably,some conventional power stations (nuclear or otherwise)

will always be necessary. The one clear lesson is thatbusiness in the energy sector is not easy, but determi-nation linked with practical, sometimes novel, methodscan and does pay off!

Not only do the three Midlands plants operate reli-ably and profitably; they also produce power and heat atan overall efficiency of 70%, (as do several other plants inthe UK) compared with 35% from a large modern powerstation.

A matter that has been little considered in the Pressand elsewhere is the basic fact that, if it really is acid rainthat is causing so much concern, not only in the UK, butparticularly in Scandinavia, then CHP will be helpingenormously in reducing it. Simply of course by usingfossil fuels at twice the normal efficiency.

Although CHP schemes utilise basic fuels very effi-ciently, one cannot ignore the fact that electricity, ingeneral terms, is a 'refined' fuel and hence more valuablethan just as heat. Thus an engine transforming, say, 40%of its heat input into electricity is probably more eco-nomical than one transforming 35% of its heat input intoelectricity, even though the total heat output of the latterengine may be greater.

So much depends on circumstances, but as a gener-alisation, electricity is more valuable than other fuelsowing to its efficiency in use and its flexibility.

It may well appear to some that I have been leaningmuch more to combined heat and power than to districtheating. The main reasons are as follows:

(a) The Government is encouraging district heating ina big way, and I believe we can leave it safely in thatsetting.

{b) CHP is not, in the view of many, getting fair treat-ment. Nevertheless, despite the opposition of vested inter-ests, CHP can and will continue to succeed.

We all need to encourage the slow but increasing interestin our cause—a cause that has been accepted in manyother countries, but is stifled in the UK by the inwardlooking opposition of some large and powerful estab-lishments.

6 Conclusion

It is perhaps instructive, as in so many matters, to seewhat the other chap is doing, for example,

(i) I should like to quote from Malcolm Brinkworth'sbook, 'Tommorow's world—energy', where hesays:

'The development of smaller compact units hasalready been successful. In West Germany, forexample, over a hundred small CHP plants havebeen installed and results from the country'senergy research programme look very encour-aging. They show that it is possible to save 50% ofthe primary energy required for heating purposes

(ii) An extract from a submission to the Select Com-mittee on Energy by the Watt Committee

'We do not think it necessary today to make thecase for combined heat and power (CHP) in theUnited Kingdom since, as we stated in our writtencontribution to the Select Committee dated 15thFebruary 1982, this has been dealt with in con-siderable detail over the last three decades or so,and the energy savings possible have been thor-oughly documented in the reports EP26 and EP35

IEE PROCEEDINGS, Vol. 134, Pt. A, No. 1, JANUARY 1987

to the Secretary of State for Energy, produced bythe Combined Heat and Power Group of theDepartment of Energy. Seldom has there beensuch a unanimity of view on the advantages ofpursuing a particular technological solution to theproblem of achieving very substantial energysavings, departing in a major way, as does theCHP concept, from established practices in theproduction of electrical energy.'

(iii) Wolfgang Riidig, a Research Fellow at the Uni-versity of Edinburgh, has recently produced apaper in which he attempts an explanation of thevast differences between the countries of WesternEurope in the adoption of CHP and DH. The

author concludes that the overcentralisation of theelectricity supply industry is a major obstacle inthe widespread adoption of combined heat andpower and district heating, to which some of us atleast would say 'Amen'.

Why must we continue to be so inward looking, ratherthan adopt old concepts in a new role? Do our legisla-tors really not understand the necessity of using fuel eco-nomically and cleanly? Are we so wrapped up in ourcosy monopolies that every objection is raised to anysystem that encourages endeavour, initiative andeconomy? Do we really have to wait until the Govern-ment eventually, as it must, forces us to do what weought to be doing anyway? I hope not!

1EE PROCEEDINGS, Vol. 134, Pt. A, No. 1, JANUARY 1987