Baltimore study emphasizes the potential of bleeding edge geothermal technology
The potential geothermal resource beneath Baltimore, Maryland is at a depth >4.5 kilometers, making development feasible only with up-and-coming drilling technologies.
A study done by Dr. Saman Karimi PhD and Dr. Prof. Bruce Marsh PhD from the Johns Hopkins University and published by the Abell Foundation looks at the potential of developing geothermal resources in the city of Baltimore in the state of Maryland.
Their findings indicate that temperatures sufficient for electricity production can be found only at depths greater than 4.5 kilometers. This makes any potential geothermal project prohibitively expensive. However, new EGS and drilling technologies may make the project more economically feasible in the future.
Surface studies have shown that there are no major hot springs in Maryland. A well drilled in the Baltimore city area to a depth of 282 meters yielded a basal temperature of only 16.4 degrees Celsius. Numerous previous works have indicated that the average background heat flow in the Coastal Plain and Piedmont Plateau was only 48 mW/sq.m. – much lower than the global average of 67 mW/sq.m.
Based on estimates of subsurface temperatures, geothermal water that is sufficiently hot to produce electricity can be accessed at a minimum depth of 4.5 kilometers, with shallower resources sufficient for direct use. This is based on a thermal conductivity of 1.5 W/mK, a low estimate for the sedimentary, volcanic, and metamorphic rocks beneath Baltimore and adjacent areas.
Numerical modeling indicates that a geothermal power plant would be economical for at least six to seven years, after which the temperature of the extracted water will drop below the threshold value of 150 degrees Celsius. It can then be possible for the system to be repurposed for direct use. This conceptual model is based on the most favorable geophysical conditions which in reality might not be available.
Financial analyses indicates that a geothermal system for direct use will cost around USD 23 million and a geothermal power plant will cost around USD 52.41 million. This makes a potential geothermal project non-competitive compared to a coal or gas power plant, both of which are significantly cheaper.
The economic outlook has potential to change in the coming years. Financial studies predict that gas prices will rise 5 to 10 times in the next decade or so. Moreover, bleeding edge technologies such as the millimeter-wave drilling by Quaise Energy may make very deep geothermal resources accessible.
Source: Abell Foundation