The Influence of Plant Capacity on the Economics of Geothermal Development

Abstract

The economic implications of development capacity are reviewed for the components of a geothermal power development. The major power plant components, such as turbines and alternators, show substantial economies of scale whereas well costs f o r example are typically neutral. Steam field development costs are particularly site- specific, although some general conclusions can be drawn from a typical field development layout. The greater pipeline distances o f a large development may be expected to incur higher unit costs than a small one, although these costs are more than compensated by the economies of large- scale separation plant. Other capital cost components show similar economies of scale as do operating costs. The earlier completion possible with small-scale plant, though significantly improving the economics, is not sufficient to overcome the penalty of higher specific cost. Providing sustainable reservoir capacity i s not exceeded there is no economic advantage to be gained from small-scale geothermal development. Analysis shows that power cost is relatively insensitive to well cost, operating cost and reservoir decline rate, moderately sensitive to capital cost