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Stagnation 1971 - 1984
It was not until sixty-one years after the commencement of operations in 1900 that, for the first time, the undertaking generated 50 million units in a single year. It took only ten more years to 1971 to add another 100 million. But such was the effect of the two oil shocks, of 1973 and 1979, that fifteen more years elapsed before, in 1986, an additional 50 million units were generated and the milestone of 200 million units was reached.
During these thirteen years of stagnation the number of units generated in any year never exceeded the 184 million generated in 1979/80. These thirteen years comprised three distinct phases. During the first phase, 1971 to 1974, the price of oil and the Retail Price Index (RPI) both rose steadily until at the end of the period war broke out between Israel and the Arab States. Supplies of oil were curtailed and the OPEC marker price was raised nearly fourfold. There followed the second phase, 1974 to 1978 during which the price of oil again rose steadily, whilst the annual rate of increase in the RPI climbed to a peak of 22%. The third phase lasted from 1978 to 1984. During this time there was another huge increase in the price of oil, followed by several years of smaller increases bringing the marker price to US$34 per barrel. In October 1973 it had been US$3.50. The effect of all of this on the island was reduced activity in the commercial and industrial sectors and, at its peak in January 1981, 1200 people unemployed, some 4.5% of the working population.
It is the practice for the international oil industry to measure large quantities of oil in terms of 'barrels'. The content of a 'barrel' varies widely depending on the commodity being measured. Crude oil is measured in US barrels, each of which nominally contains 42 US gallons, 35 Imperial gallons or approximately 159 litres. One barrel per day equals roughly 50 tonnes per year.
At the beginning of 1971 the movements in the oil price outlined above were not foreseeable and priority was being given to solving the problem that had dominated the scene for some twenty years, the race to install sufficient plant to meet the ever-growing demand. The maximum demand had reached 41 MW whilst the plant available was 47 MW. During the winter of 1971/72 the maximum demand rose to 44 MW, but the difficulties caused by the narrowing gap between plant and demand, was worse than at first appears due to the series of problems encountered with the Mirrlees KV Major generating sets. These problems resulted, in 1972, in the manufacturers recommending that the number of hours run between overhauls should be reduced from 6,000 to 5,000, effectively increasing the number of annual overhauls to fifteen.
The forecasts made in August 1972, well before the first massive oil price rise and the curtailment of supplies, assumed that the maximum demand would continue to grow over the next few years, at the rate of about five or six MW a year. This would lead to an increase in the maximum demand to nearly 70 MW by 1976/7. Mr Peter Guldberg, the Board's consultant expressed the opinion that the number of medium speed generating sets installed had reached the limit, and that if more were installed operational difficulties would become severe. At this time there were no tried and tested medium speed Diesel generators, with an output above four MW, operating in an electricity supply undertaking. Under these circumstances consideration was given to the installation of either a steam turbine set or a gas turbine.
The running costs of a gas turbine were considered to be too high for one to be used for the purpose of meeting the base load, therefore attention turned towards installing a steam turbine set with an output of 20 to 25 MW. This would allow for some of the older plant to be decommissioned. In October 1972, to meet the load in the years before a steam generating set could be commissioned, the Board ordered a packaged gas turbine set, with an output of 13 MW at 10.5 kV, from Stal-Laval of Sweden. The set was commissioned in July 1973 and connected to the station 11kV bus bar via two"back-to-back" 15MVA transformers. Over the years, wear on the turbine blades reduced the output of this machine to a maximum of 11 megawatts.
A few months later, in October 1973, the scene changed when OPEC announced its first massive increase in the marker price of oil, and imposed restrictions on the quantity of oil to be exported from member countries. In November, the UK Department of Trade and Industry instructed the oil companies, to restrict supplies to 90% of the previous year's consumption. In Guernsey, the States established an Emergency Fuel Conservation Advisory Committee. This committee required the Electricity Board and the Gas Company to submit weekly reports of sales, and placed restrictions on the use of electricity for some less essential purposes. These included heating swimming pools, Christmas Festive lighting and the hours during which streetlights were switched on.
The increase in the marker price of oil announced by OPEC in October 1973 was followed in December by a further increase. Together they raised the price by 230% to US$11.65 per barrel causing the fuel cost per unit generated to go up from 0.32p in 1973/4 to 0.89p in the following year. The tariff, being inadequate to meet the new costs, was adjusted from April 1st 1974. From that date units charged at the block tariff secondary rates were increased from 1.0p to 1.7p and those charged at the flat rate heating from 1.8p to 2.0p. Off peak units went up from 0.55p to 1.25p each.
These increases, along with apprehension as to the future of the economy brought on by the tension in the Middle East, the conservation measures and growing signs of depression caused sales of electricity to fall for the first time since the occupation. The number of units generated in the year to March 31st 1974 fell by four million to 160 million and the maximum demand fell by four megawatts to forty. It was generally accepted that growth would return, but when considering plant replacement the big question was, when would it return and by how much?
During the course of 1973 a comprehensive review of the generation and distribution safety rules was undertaken, leading, in the following year, to the publication of a new set of safety rules. These introduced a more positive health and safety policy and included new regulations governing the operation of switchgear.
The year 1974 brought continuing problems with the Mirrlees sets. Exhaust valves on the KV Majors continued to fracture and in March an eight-ton crankshaft on one set became bent and was not replaced until December. Finally a suspected inertial cracking in the lower areas of the connecting rods caused the manufacturers to recommend that all rods should be replaced after 30,000 running hours. To add to these problems the inter-turn insulation of the stator windings of some of the 6.6kV alternators broke down as a result of excessive oil mist and the salt laden atmosphere in the 'A' engine hall. Two alternators were rewound in 1974 and the rest in the summer of 1975. In the following year the gas turbine developed electrical troubles that caused it to shut down on load. Investigations by the manufacturers in Sweden, resulted in major repairs that kept the machine out of action for several months through the winter period.
The decision not to install more plant, with a low output per piston, left the"B" engine hall, which had been built to accommodate six sets, with only four sets whilst the old engine hall had two relatively new sets in an old environment. The position was rationalised during the years 1974 and 1975 when the two Mirrlees KV Majors were moved from the old area to"B" engine hall. The two Mirrlees HFS8 generating sets, commissioned in 1950 and 1951, were dismantled and sold in 1974 and the three English Electric sets, commissioned in the years 1949 to 1953, were dismantled in the following year.
The use of other fuels for generating electricity was considered during the survey of future generating plant requirements, which took place after the first oil shock. The importation of natural gas was not a viable proposition, and the space and handling difficulties associated with coal fired plant, made steam plant unattractive. Alternative energy sources had not been developed to the stage at which any one of them could be relied upon in an island situation. Furthermore the forecasts indicated that the position would not be changed by the year 2000. JEC had surplus capacity and in May 1972 a meeting had taken place, attended by engineers from JEC and Guernsey States Electricity Board, at which consideration was given to a submarine cable link between the islands. The discussions concluded that such a project was feasible but the question of the price that Guernsey would pay for electricity was left for further consideration. In March 1975 a further study of the viability of a cable link with JEC reached the conclusion that the project, as proposed, would still not bring benefit to Guernsey. However, long-term, because of the diversity of fuels used for the generation of electricity on the mainland of Europe, a direct link with France could prove beneficial. In the meantime the only viable solution appeared to be to continue with Diesel sets, medium or slow speed.
In other departments of the organisation plans for development were less complicated. In the first years of its operation the viability of the computer bureau was judged by comparing the net cost of the new unit, with the cost of doing the work using alternative equipment. The cost of the latter being hypothetical, the results were not definitive, but it was concluded that the position was not unsatisfactory. Income came from the hire of time for running programs for clients, some of which were written by the clients themselves. By 1973 the workload had expanded to the point at which comparison with alternative systems was no longer relevant as many of the applications could not have been carried out without a computer. Initially these were accounting systems, but in 1973 the work of the section included the calculation of fault levels, load flow and voltage levels for the electrical engineering department. The configuration had been enhanced in 1972 with the addition of key to disc data entry facilities, but in 1974 the need to include remote visual display units (VDU) in the system led to an order being placed for a new computer, this time an ICL 1901T.
During the years 1971 and 1972, before the oil shock the number of consumers of electricity increased by 1,200 to bring the total to 22,708. However the slowdown in economic activity caused the number of new connections to fall to 500 during the next two years. This respite provided the opportunity for the electrical engineering department to enhance the distribution network, which it strengthened by the addition of thirty substations in the four years to 1974. One of these, and one of the largest in the Island, was at the Belle Greve Sewage Treatment Plant.
The tariff that became effective from April 1st 1974 heralded the start of the second phase in this period of stagnation. As the year progressed, it became apparent that the sales lost during the restrictions of the preceding winter were not being recovered. During the four years 1974 to 1978 the number of units generated increased by only 2% per year. The annual average used by each domestic consumer remained surprisingly consistent throughout the whole of the stagnation period, only varying around the median of 4,500 units by amounts that could well be attributed to variations in the weather. The majority of the small increase in consumption came from newly built houses and from the commercial sector, although the latter was seriously affected by the recession and could not be relied on for sustained growth in the short term.
In September 1974 Ian Young, the general manager since 1950, retired. His successor was Eric Towner on promotion from the post of secretary and accountant. Other staff changes at this time included appointments to new posts of safety officer and personnel officer. The former was considered necessary as it was anticipated that the island would adopt parts of the new UK legislation, and also to ensure that there was a common policy on safety standards across the undertaking. A personnel officer was considered desirable to assist in promoting good industrial relations, and to develop a staff-training programme.
Considerable progress was made in this latter respect during the course of the following year. Trainee posts were established, to provide facilities for those working in the engineering departments to qualify for higher posts in the technical staff ranks. To this end, the courses provided by the College of Further Education were augmented by in-house lectures given by senior members of the staff. Four trainees attended a two-year block release course at Derby College of Art and Technology, others attended courses at Portsmouth Management Centre, the Central Electricity Generating Board's (CEGB) Training Centre at Buxton and the Electricity Council's Training College at Horsley Towers. Vocational courses were arranged in such subjects as computer appreciation, reliability engineering, jointing and refrigeration.
The budget and tariff proposals for the year 1974/75 were prepared before the December 1973 oil price rise was announced. In the event, from the beginning of 1974, oil prices rose by more than had been expected and during the ensuing three years to 1977, the price of oil continued on its upward spiral. This resulted in annual increases in the tariffs, until on April 1st 1977, the new tariff charged block secondary units at 3.5p each and off peak at 2.4p. Compared with the 1.0p and 0.55p charged, respectively, in 1973 these were massive increases. The chain, of oil price rises followed by tariff increases, was broken when, in October 1977, a new contract for the supply of fuel was negotiated with BP Ltd. This led to a reduction in the price so that, for the first time in several years, the tariffs were not adjusted in 1978.
Despite slow growth in sales at this time, the ageing generating sets were subjected to long hours of operation giving impetus to the search for suitable generating plant. In 1975, following the decision not to proceed with the proposed cable link with JEC, approval was sought from the British Government for discussions to be opened with both Electricite de France (EdF) and the Central Electricity Generating Board (CEGB) of the UK for the supply of power to the Island. The latter had a cross channel link with France and technically could therefore supply Guernsey, via the EdF network.
In 1976, when approval for these talks was still awaited, alternative sources of energy were again considered and discarded before attention returned to Diesel plant. During the course of the previous few years larger medium speed Diesel generators had been developed, but these had been used almost entirely in ships, and there was no information available as to there reliability in an island public supply situation. Nevertheless the study included them and in particular the Dutch Stork-Werkspoor TM620 and the French SEMT-Pielstick PC 4V 570 were considered. In September 1977, the alternatives having been closely studied and with the support of the consultant, the Board decided to turn to larger slow speed Diesel Generators.
A contract was awarded to Sulzer Bros. for the design, supervision, construction and commissioning of a new engine hall. The contract included the installation of one slow speed 9RNF 68M-type Diesel generator driving a GEC alternator with a nominal output of 12 MW, to be situated in a building adequate to accommodate two such machines. The UK firm, Kennedy and Donkin, was appointed consultants for the foundations of the building and the Guernsey firm, Gamble and Blair was approved as the contractor for the civil works. The plant also included a waste heat boiler that, when commissioned in late 1979, supplied heat to the offices and heavy oil fuel tanks, three of which were fitted with steam heating coils.
View of the crankshaft for Sulzer generator 1C in the new engine hall - March 1979
At the time of placing the order for the plant the Board was also interested in the Sulzer Engine Diagnostic System (SEDS). This had been developed for marine applications to continuously monitor engine-operating temperatures, pressures and alarms. However the Board decided that, because of the high cost of SEDS, it would only include the installation of the necessary sensor mounting points in the specification for the equipment. The facility would then be there to install a full monitoring system if and when required.
Meanwhile electronic plant monitoring was being studied as a separate issue. This led, in late 1977, to the installation of a small Bell and Howell computer based monitoring system in 'B' engine hall, which would continuously monitor the six engines and display the data on a visual display unit in the control room. Under the previous system staff took periodic readings of essential operating conditions. By replacing this arrangement with continuous monitoring, abnormalities in performance would be detected at an earlier stage so that defective plant could be shut down in an orderly manner before significant damage occurred.
The installation of the large slow speed generating set would replace the output from five of the old 12-cylinder sets in 'A' engine hall with that from a single 9-cylinder set. This would reduce the routine maintenance and the number of annual overhauls. At the same time the running hours would be reduced and this, along with the introduction of electronic monitoring systems, would eliminate many of the routine engine hall tasks and would lead to reduced manning levels. When the time came for the changes to be implemented some of the personnel in the affected areas filled vacancies that arose in other parts of the undertaking, whilst others opted for early retirement.
During the winter of 1977/78 the maximum demand rose to 47 MW, which after allowing for the largest unit, the gas turbine, to be out of action, was less than two MW below the nameplate rating of the generating plant available. This rise of three MW in the maximum demand in a single year, after a period of five years during which it had only risen by four MW, brought forward plans for the installation of more generating plant. The second Sulzer 9RNF 68M generating set was ordered in July 1978 for commissioning before the winter of 1980/81.
In 1976 the electrical engineering department undertook a review of the cable records of its distribution network. They were made up of a multiplicity of manually prepared documents created over the period from when the first cables were laid in 1899 to the current date. Putting together several records, to make a composite picture, was particularly difficult with this system. ICL in conjunction with the North Eastern Electricity Board had developed a system for the maintenance of cable records on a computer. This system, Computer Aided Recording of Distribution Systems (CARDS), provided records in a form that could be easily updated, and could quickly produce a seamless map containing details of the size of cables and their depth over any chosen area.
A digitising table, visual display unit, keyboard and pen plotter were installed in the drawing office and a data and control cable run through the office block to the ICL mainframe computer.
The digitising table in use
In preparation for recording the cable records a start was made on digitising the 1963 edition of the geographic map of the island. However, the completion of a further aerial survey in 1979 led to the work from the previous survey having to be revised. Once this was done a start was made on transferring the existing cable records to the digitised maps.
The Plessey rhythmatic control system that, since the mid-fifties, had been used to control the streetlights and off-peak heating, was obsolete and reaching the end of its useful life.
The Plessey Rhythmatic Control Panel
By 1976 the changing characteristics of the distribution system load had led to the malfunction of control relays due to excessive signal attenuation. The following year the position became worse when harmonic voltages, generated by colour TV sets that were being installed in increasing numbers, caused more malfunctions. There was an improved system available manufactured by the GEC at Stafford, England. This Cyclo-Control system employed a pulse transmitter, that generated a series of small short-circuit pulses which were impressed upon the mains voltage waveform, without interfering with its quality. The pulses could be arranged in unique sequences to form coded signals to activate relays tuned to recognise them. This system was introduced into Guernsey as the result of a contact with the Sark Electricity Company. The company had put out an enquiry to GEC who subsequently arranged a demonstration of the Cyclo-Control system for them. Although the system solved the problem in Guernsey, it was not installed in Sark due to the scale of the operation.
Initially, the transmitter that activated the relays was operated manually by control room staff. In 1979, a GEC PERM computer was installed in the control room to enable each tariff period to be programmed and automatically switched. The changeover of the injection equipment at the power station and the relays in streetlights and in those installations with off peak heaters was completed in September 1981.
The third phase of the period of stagnation came with the second oil shock at the end of 1978. At its meeting on December 16th OPEC announced that the marker price of oil would be increased progressively by 14½% during 1979. In the event political upheaval in Iran led to OPEC losing control of its member countries, some of which added surcharges to the marker price of as much as 50%. The result was that the price of crude oil on the spot market increased, pushing the cost of oil per unit generated up to 1.792p. This was double that reached in 1974/5 after the first oil shock, notwithstanding the improvement in the thermal efficiency of the generating plant.
The electricity tariff was adjusted three times during the year 1979, another rise was announced to become effective from April 1st 1980, with yet another from April 18th 1980. From that date all block tariff primary units and flat rate lighting units were charged at 7.0p each, whilst secondary units and flat rate heating units cost 5.6p each. The spot price of crude oil on the Rotterdam market continued to rise taking the oil cost per unit generated to 2.9p in 1983. During this two-years period, the tariffs were revised on five occasions until the last, introduced with effect from September 21st 1982, charged the block tariff primary units at the rate of 10.3p each and the secondary units at 6.7p. By this time non-OPEC sources of oil were becoming plentiful, in particular from the North Sea. Oil had been discovered on the Continental Shelf in 1969, and subsequent developments had produced sufficient output to create competition that weakened OPEC's influence for some years. However the oil reserves of the Arab countries far outweighed those of the North Sea, consequently the situation that existed in the nineteen eighties could not continue indefinitely. But for the time being there was a break in the price rise spiral that allowed the rates introduced in 1982 to remain unchanged until 1985.
The commissioning of the first slow speed generating set in 'C' engine hall, in September 1979, led to a project to upgrade the main 11kV switchboard at the power station from single to double bus-bar units. In this way the output from the generators could be divided, if necessary, between two separate distribution systems should the switch-gear fault levels exceed permissible values at times of peak output. The double bus bar also improved the security of the supply in the event of a breakdown of one or other of the bars. The whole changeover exercise was accomplished without the need to disconnect the supply to any customer.
The winter of 1978/9, the last before the first of the slow speed Diesel sets became available, was particularly difficult for the power station staff. The effects of the first oil shock were beginning to be absorbed, and the second major increase in the oil price came too late in the winter to influence the price of electricity before the spring. Also the rise in the RPI had fallen below 10% for the first time in six years. These factors encouraged an increase in the consumption of electricity. The maximum demand rose a further 3 MW to 50 MW in the winter of 1978/79. The small generating sets in the old part of the power station having been removed, the generating capacity was reduced to,
| 12 | KVSS12 sets rated at 26 MW |
| 6 | KV Major sets rated at 22 MW |
| 1 | Gas Turbine rated at 13 MW |
The
number of units generated during the year, 184 million, was the highest
to date a record that stood for a further six years. It was achieved
by running the gas turbine for 326 hours in support of the base load Diesel
sets that ran for a total of 71,000 hours.
An oil spill in St. Sampson's harbour in the autumn of 1979 was traced to the pipeline from numbers 1 and 2 berths to the Board's tank farm at the Hougue Jehannet. When there had been a similar occurrence, about two years earlier, it was found that the oil had leaked from a gasket. Investigations on this occasion revealed that the oil had leaked from a hole in the pipe, made over the years when contraction and expansion caused it to rub against granite rock as it was first heated for pumping fuel oil, and then allowed to cool down when pumping was finished. The pipeline had been installed in 1966 and pressure tests confirmed that leaks from similar causes could occur in the future. It was therefore decided to replace the entire pipeline with one with a larger bore. This would have the added advantage of allowing ships to be discharged during a single tide, instead of two, and so support a claim for a reduction in the price paid for oil. On this occasion not only was the new pipe laid in a protecting bed of sand, but as a further precaution cathodic protection was included by the addition of a sacrificial anode.
Following the decision, taken in 1978, to install the second Sulzer generating set the condition of the old plant was again reviewed. No new plant had been commissioned since 1970, which had led to the four-stroke Diesel sets being run for an excessive number of hours. It was generally considered that the life of these machines was 70,000 running hours, and it therefore would be false economy to prolong the life of the sets in 'A' engine hall. In addition to this the 'B' engine hall plant was ageing quickly. With these factors in mind, in the later months of 1979 an order was placed for the third Sulzer generating set, to be installed before the winter of 1982/83. This involved the construction of an extension to the 'C' engine hall. The contract for the civil engineering works was awarded to Miller and Baird. Work started in May 1980 and the entire project was completed in time for number 3 'C' Sulzer 9RNF68 generating set to be commissioned in July 1982. Meanwhile four KVSS 12 generating sets, installed in the years between 1955 and 1960, were decommissioned in 1981. Once the third slow speed generating set was operating, 'A' engine hall was completely decommissioned.
In the UK, Protective Multiple Earthing (PME) of the low voltage systems had been introduced on a limited scale in 1962. In 1974, the postmaster general having withdrawn his objections, it was given blanket approval. In Guernsey, earth leakage circuit breakers had continued to be used for the automatic disconnection of consumers' installations in the event of an earth fault. However, by 1974 improvements to the low voltage network and the imminent change by UK cable manufacturers to a new Combined Neutral and Earth (CNE) cable design led to consideration of PME in Guernsey. The CNE design would assist in the development of the PME system by introducing simpler jointing methods, and would be cheaper than the traditional 4-core cables. It had been made clear by the manufacturers that the production of conventional cables would gradually diminish due to a fall in demand, and therefore their cost would increase. By 1978 the undertaking was committed to change over to the PME system by mid 1985, and therefore the decision was taken to adopt the CNE cables as the standard. This also meant that the existing 4-core, Separate Neutral and Earth (SNE), system had to be modified to connect the neutral conductor to earth at appropriate points on the low voltage system. To assist in its introduction a comprehensive explanatory guide was made available to electricians and electrical contractors. The changes coincided with the adoption of the 15th Edition of the Institution of Electrical Engineers 'Regulations for Electrical Installations', that introduced new and more stringent procedures for the bonding and earthing of electrical installations.
In 1981 JEC had resolved to proceed with the installation of a power cable to EdF. In the same year the CEGB indicated that it was unable to supply Guernsey with electricity and suggested that the Board should pursue the matter with EdF. The UK Government having given its approval for discussions to take place between the Electricity Board and EdF, in 1980 and 1981 there were preliminary investigations into the feasibility of a cable link with France. These highlighted the differences in the likely advantages of connections between France and Jersey and between France and Guernsey. The greater distance from the mainland put Guernsey at a technical and financial disadvantage, which was increased by the fact that the thermal efficiency of the Diesel plant in Guernsey was higher than that of the steam plant in Jersey. The Board decided to keep in touch with the progress made by JEC and to generally keep the prospect under review.
During the following years there were no indications that the economics of a submarine link were any more favourable and the matter was allowed to rest with only periodic general reviews. In 1984, following a substantial reduction in the EdF bulk users tariff, there were several facts gathering visits by representatives of the SEB to EdF. They produced a better understanding of the EdF tariff philosophy and structure, and as a result there followed a period during which the concept of a submarine link was studied in more detail. At the same time, to cater for the immediate needs consideration was given to the installation of a fourth Sulzer Diesel set.
A further step towards the concentration of activities on one site had been taken in 1977 when the aged small generating sets in the old engine hall at St Sampson's were decommissioned. The building was no longer suitable for housing generating plant, and it was therefore decided to convert it into an office block, a scheme that was completed in March 1979. At that point the Albany building was vacated and the work carried out there was transferred to St. Sampson's, the Albany building being taken over by the Board of Administration for the use of States departments.
The next stage in the implementation of the concentration policy started in 1983. The twelve KVSS 12 generating sets in"A" station were finally decommissioned in that year when the last four were shipped to a purchaser in Indonesia. Once the area was cleared work started on a scheme to provide accommodation for the mains and contracting sections, which would be relocated from the Bouet. This would leave that site vacant and available for sale.
The extended use of electricity, in both the home and in the business place, had by 1973 made it an essential part of life. Consequently, the massive increases in the electricity tariffs after the first oil shock led to a not inconsiderable level of criticism. In view of the public concern, in July 1981 the Advisory and Finance Committee of the States arranged for an independent review of the way in which the undertaking was operated. Mr D. Simmons, a chartered engineer on the staff of the CEGB, was commissioned to carry out the study. His report found much on which to comment favourably and concluded that in general the undertaking utilised its resources efficiently. It made several suggestions for improvements, including a recommendation that the tariff structure should be modified. Instead of recovering the fixed costs of the undertaking through a higher charge for the first block of units, these costs should be recovered through a fixed quarterly charge payable by all consumers. The Simmons' report also recommended that a system of performance indicators should be developed with agreed targets and monitoring procedures.
The signs of growth, that raised the maximum demand to 50 MW in the first days of 1979, were killed by the second oil shock, which began to have its effect before the year was out. During the five years that followed, as the tariffs were increased, so both units generated and maximum demand slumped, and then stumbled along in a narrow range, that only recovered to 178 million units and 43 MW respectively, in the year to March 31st 1984. Six years earlier, in 1977/8, comparative figures had been 176 million units and 47 MW. The unforeseen absence of growth during these years, followed several years in which there had been considerable investment in new plant. Consequently, the failure to increase sales resulted in there being no extra income to meet the added interest and depreciation charges. This led to increased pressure for greater efficiency.
The cheaper HFO was used to fuel the new slow speed generators, and later the KV major medium speed engines were modified to use the same oil. The slow speed sets produced further savings arising from a higher thermal efficiency, producing 8% more units per litre of fuel than the medium speed generators. There was also a considerable saving from reduced maintenance. In the year ending March 31st 1982, with two of the larger sets in commission, the number of units generated was 5% fewer than in 1978/79, the last year before any slow speed set became available. However, there was a reduction of 60% in both plant running hours and in the number of overhauls.
Other steps to improve efficiency and cut costs that were taken at this time concentrated on the use of waste heat from the generating process. Most of the heat requirements on the site were met from this source, and a pipeline was laid across the Northside to the Marine and General property through which steam was supplied to heat the workshops. Despite a wide reaching survey, conducted at intervals over a period of years, the only other external viable scheme that could be found for the use of waste heat was that for water and space heating in the States Works Department, which was inaugurated in 1990.
The introduction of Heavy Fuel Oil for generation led to complaints of pollution of the atmosphere from the engine exhaust emissions. Initial investigations, with the assistance of the CEGB, concluded that they did not exceed the level approved under UK legislation. As the complaints continued further investigations took place in conjunction with officers from the Board of Health. After taking measurements over a period of time, with specially acquired instruments, the Medical Officer of Health reported that, whilst the emissions breached the EEC guidelines only intermittently, they could cause distress to persons with a respiratory disease. In the light of this advice, in the summer of 1982, a contract was awarded to Messrs. F.E. Beaumont of Wiltshire for the construction of a scheme designed to remedy the situation. This comprised the installation of equipment that would gather the emissions from the engine exhaust manifolds in each of "B" and"C" engine halls, and channel them into separate 55-metre chimneys. The work was completed early in 1983. Unfortunately the measures did not meet with the success expected and complaints continued to be registered over the next few years, despite a variety of further modifications.
From the late seventies it had been recognised that steps were needed to strengthen the supply to the West of the Island. It was the Board's policy to ensure that the supply to all consumers should not stray outside of the voltage limits applicable to the UK electricity supply industry. In this way electrical appliances that complied with UK requirements would operate satisfactorily in Guernsey. Readings at substations, taken during the winter of 1977/8, showed that the limits had been reached in some areas in the West, and any increase in the demand there could lead to problems for consumers. The voltage could be raised by either of two methods. A second generating station could be commissioned in the area, or a 33kV feeder could be laid from the power station to a suitable substation site. The former solution would present many problems. The only suitable type of unmanned plant would be a gas turbine, but the current cost of gas oil would make this very expensive to operate to meet the base load. The problem of delivering oil to the site by road tanker also presented the prospect of creating traffic disruptions. It was therefore decided to adopt the second alternative, which would have the added advantage of reducing transmission losses.
The project that evolved from the detailed studies was the establishment of a bulk supply substation at King's Mills with the capacity to supply 15 MW. A pair of 150 sq. mm. 3-core 33kV cables with associated pilot cables was laid, mainly under agricultural ground, some 7½ kilometres from the power station to King's Mills. The States Water Board offered the Electricity Board a disused pump house, popularly known as the 'Odeon', on their King's Mills pumping station site. The building was converted into a substation to accommodate two 15 MVA 33kV/11kV transformers, earthing transformers and an 11kV switchboard. Subsequently, a noise attenuation enclosure was fitted to each transformer to reduce noise levels. In the late summer of 1983 the last lengths of cable were laid in marshy ground allowing the project to be completed ready for commissioning early in 1984.
King's Mills Substation
The completion of this project allowed a considerable area of existing 11 kV network to be electrically isolated from the power station network, and supplied from the King's Mills substation.
At the power station a building was erected alongside"B" engine hall to house the 33kV switchgear that would be connected to the cables. The 33kV switchgear, manufactured by GEC, was the first generation of vacuum bottle switchgear at this voltage in Guernsey. This type of switchgear virtually eliminated the risk of fire in the event of a major breakdown since it dispensed with the use of highly combustible mineral oil.
At March 31st 1984 the distribution network included 291 substations, with a transforming capacity of 97 MVA. Although not a new addition, an innovative modification was made to the substation at Violet Villas, in the heart of St. Peter Port. This substation had been commissioned in 1963 on a property managed by the States Housing Authority, in a building that, by 1981, was becoming derelict and in a dangerous condition. The building was demolished and rebuilt to include two flats above the substation. The heat from the transformer was upgraded by a heat pump, to raise the water to a temperature adequate to provide space and water heating in the two one bed-room flats.
In March 1979, Conseiller Rex Bragg retired from the post of President of the Board, an office he had held since 1971. The States elected Deputy John A. C. de Garis to succeed him. In March 1982 there was a further change when John de Garis retired from the post and Deputy Henry B. Lancaster was elected by the States to fill the vacancy. A few months later in November the incumbent general manager, Eric Towner, retired and was succeeded by Mr. John H. Humphreys.
As this period of general economic stagnation drew to a close the prospect that growth would be resumed prompted the Board to begin a programme of land acquisition for the accommodation of more Diesel plant. The indications at that time were, that the only way in which there could be a diversification from oil as the fuel for the generation of electricity, was through a submarine cable link with EdF. However, this did not appear to offer any economic benefit, and therefore it was decided to purchase land to the east of the Hougue Jehannet.