Geothermal Energy Amongst the World¥s Energy Sources

Abstract

The world primary energy consumption is about 400 EJ/a. It is mostly provided by fossil fuels (80%). The renewables collectively provide 14% of the primary energy, mostly in the form of traditional biomass (9%) and much less by large (>10MW) hydropower stations (2%) and the "new renewables" (2%). Nuclear energy provides 7% of the world primary energy. The World Energy Council expects the world primary energy consumption to have grown by 50-275% in 2050 depending on different scenarios. The renewable energy sources are expected to provide 20-40% of the primary energy in 2050. The technical potential of renewable energy sources is estimated 7600 EJ/a, and thus certainly sufficiently large to meet future world energy requirements. The question is how large a part of the technical potential can be harnessed in an economical, environmentally and socially acceptable way.
Of the total electricity production from renewables of 2968 TWh in 2001, 91% came from hydropower, 5.7% from biomass, 1.8% from geothermal and 1.4% from wind. Solar electricity contributed 0.06% and tidal 0.02%. A comparison of the renewable energy sources (data from the UN World Energy Assessment Report update, 2004) shows the current electrical energy cost to be 2-10 UScents/kWh for geothermal and hydro, 4-8 UScents/kWh for wind, 3-12 UScents/kWh for biomass, 25-160 UScents/kWh for solar photovoltaic and 12-34 UScents/kWh for solar thermal electricity. Heat from renewables is commercially competitive with conventional energy sources. The current cost of direct heat from biomass is 1-6 UScents/kWh, geothermal 0.5-5 UScents/kWh, and solar heating 2-25 UScents/kWh.
The significant fluctuations in oil prices caused by political unrest in key oil producing regions should encourage governments to focus more on indigenous energy sources to meet their basic energy requirements. Since 1973, five major disruptions in world oil supplies (>4 million barrels/day supply loss) have occurred and caused significant escalations of oil prices. Recent developments in the deregulation of the electricity markets and integration of the electricity networks in Europe have unstabilised electricity prices to consumers. This makes e.g. ground source heat pumps a favourable alternative as base load heat source in countries where electrical heating is common.