The Implications of the Iceland Deep Drilling Project for Reducing Greenhouse Gas Emissions Worldwide
Wilfred A. ELDERS, Guðmundur Ó. FRIÐLEIFSSON, and Albert L. ALBERTSSON
[University of California, Riverside, USA]
To mitigate climate change, it is imperative to reduce emissions of greenhouse gases (GHG). Renewable resources should play a greater role in that endeavor by reducing use of hydrocarbons for electrical generation. Unlike intermittent resources like solar and wind, geothermal energy provides baseload power, that can be cost competitive with those intermittent resources. However geothermal power has higher capital costs and longer lead times to develop and furthermore generation using geothermal steam is not entirely GHG free, although emissions are only about a third of those from natural gas fired turbines. However, the GHG emissions produced by transportation far exceed those from electrical generation in California, for example, as in all industrial societies worldwide. This requires greater use of zero emission vehicles, powered by electricity or by hydrogen. Iceland is leading the way with the Iceland Deep Drilling Project (IDDP) which is exploring for and developing supercritical geothermal resources, The success of the well IDDP-2, a 4.5 km deep geothermal well at Reykjanes, in Iceland, that penetrated supercritical conditions, (bottom hole temperature of 500-600C) suggests new possibilities for both improving geothermal economics and reducing GHG emissions. Because of the higher enthalpy and more favorable flow characteristics of supercritical water, a supercritical geothermal well should produce an order of magnitude more power than is available from a conventional geothermal well. Producing much higher temperature working fluids creates other possibilities to improve geothermal economics by making downstream processes more efficient. Flexible downstream use of the high-temperature fluids produced, principally by making hydrogen, would make the resource even more valuable. This could be done by selling electricity when demand is high, and at times of lower demand using electricity to produce hydrogen by electrolysis of hot water. This is especially advantageous in markets like California where there is a risk of over generation due to large amounts of solar generation. Electrolysis is more efficient at high temperatures, but electrolytic cells require clean water, so heat exchangers and/or desalination would be necessary. Similarly, when the chemistry of geothermal brine is suitable, salable products such as lithium, base metals, and other mineral products could be extracted from the brines. Another project in Iceland is sequestering CO2 by injecting it into hot rocks in geothermal reservoirs, where it is fixed by forming carbonate minerals Development of supercritical and superhot geothermal generation would reduce emission of GHG’s by (1) replacing the use of the hydrocarbon fuels to produce electricity, (2) using electrolysis to produce hydrogen, as a transportation fuel or as a form of energy storage, (3) sequestration of CO2 in geothermal reservoirs, (4) producing lithium from geothermal brine (reducing the price of batteries used in zero emission vehicles), and (5) extracting metals like zinc, silver, lead, manganese, from geothermal brine without the GHG produced by smelting. These concepts are especially applicable in California,but could be used worldwide wherever suitable high temperature geothermal systems exist. Successful adoption of these technologies would not only contribute to the growing worldwide demand for energy, but at the same time lead to significant reductions in GHG emissions.
|        Topic: Sustainability and Climate Change||Paper Number: 05005|