More than just light

In the early 1880s, there was not much one could use electricity for except lighting, and consequently expensive generating plants stood idle during the hours of daylight. The English engineer REB Crompton (Fig. 1), the subject of this paper, actively promoted other uses. Crompton studied the economics as well as the engineering of electricity supply systems. A paper he gave to the Institution of Electrical Engineers in 1888 was a detailed study of the costs of building and running generating stations and the associated supply networks. The paper makes fascinating reading today for what it reveals of the thinking behind the early supplies, as well as for the details it gives of equipment and staff. He did not expect everyone to want electricity, but he thought that about one household in three would actually take a supply if it were available, and that the typical generating station would have about 1000 customers. He estimated a total load of 10 000 lamps or about 600 kW, and a demand of 2100 kWh per day. He then calculated the costs for both ac and dc systems. The generating equipment cost more to buy and even more to run in the ac system than in the dc case because at least one generator had to be kept running 24 hours a day to maintain the supply. In the dc system the supply could be maintained by batteries when the demand was light, so the fuel costs and staff costs were less than in the ac case, but the batteries were expensive. Crompton’s calculations showed that the capital cost would be about £60 000 (sixty thousand pounds) whether ac or dc were used, but the cost of electricity would be 3.75 pence per kilowatt hour with the ac system and 2.7 pence per kilowatt hour with the dc one. An important conclusion to be drawn from Crompton’s calculations was that any increased demand for electricity during the day, when the lighting load was very small, could be met with only a small increase in running expenses. Electric traction for railways and trams was still in its infancy, but cooking and heating at home was a possible daytime load and had the further advantage that it would use the same distribution network. Cooking and heating by electricity, however, was easier said than done. There were technical problems in making suitable