May 1996 The authors present simulation results on the benefits of alternative power tariffs for Nigeria and Indonesia, based on several closely related models of the firm. Nigeria is representative of developing countries where the public sector is inefficient and manufacturers provide their own electricity to compensate for that inefficiency. The use of private generators by Nigerian manufacturers is virtually ubiquitous, even though the government, to protect its monopoly, did not encourage that use in the 1980s. About 89 percent of a sample of Nigerian firms produced some of their power needs internally. But many large firms underused their power plants because of the substantial quantity discounts public power offered to large manufacturers. By contrast, in Indonesia, manufacturers were offered only slight quantity discounts for public power. Indonesia has encouraged manufacturers to produce their own power. About 61 percent of Indonesian manufacturers produced some power internally. Generally, in both countries firms purchase some power from the public sector at a quantity discount (slight in Indonesia, considerable in Nigeria) and also produce power internally at a declining marginal cost. The reliability of public power declines as the total quantity purchased increases, because transmission gets congested. Simulations confirm that an increasing block tariff is optimal in each country and produces savings in the cost of producing public power and in firms' operating costs (including the firm's cost of producing power internally). Under increasing block tariffs, firms that purchase more public power would be charged higher marginal prices than firms that purchase less. Large firms respond to the increasing block tariff by expanding their generating capacity and reducing their reliance on public power, while smaller firms contract their capacities and buy more from the public sector. When congestion in transmission persists, cost savings are higher as the increasing block tariff reduces total use of public power which in turn improves reliability. In Nigeria, where strong quantity discounts are offered, total costs savings (for NEPA and manufacturers) under 1989 conditions are about 4 percent without congestion and increase to 9 percent when there is some congestion. In Indonesia, where quantity discounts are mild, increasing the block tariff produces only slight cost savings.