Provided drilling technology research is adequately funded, that technology will likely be developed enough in about seven years so it can access depths where the rock is hot enough to turn water into steam at such a rate it will generate about ten times the amount of electricity currently produced by geothermal systems, the head of a firm conducting geothermal research told The Driller.

Current geothermal technology heats water to produce steam that is at or below 200°C, according to Lev Ring, president of Sage Geosystems, Inc., which is developing energy storage and geothermal base-load technologies.

At commercial flow rates—which is about 50 to a 100 liters per second, or 20 to 40 barrels per minute—that amount of steam will produce 3 to 5 megawatts of electric energy, said Ring, who made a presentation on this subject on Oct. 2 at a workshop held by the Department of Energy’s Advanced Research Projects Agency-Energy.

Drilling to where the rock is 200°C is “not controversial.” But, if the rig drills to areas where the rock reaches 300°C, that temperature will generate “40 to 50 megawatts of electric energy” or “ten times more electric power than from the system that accesses heat of 200°C,” Ring said.

Because of the increase in steam produced by rock that is heated to 300°C, “the assumption is that if we can get water at ‘supercritical temperatures,’ which is 373°C, then we can get into even higher-power generation, which is true,” Ring said. He added the amount of power produced from steam created by rock that is heated beyond 300°C might not be worth the effort.

While accessing rock that is about 300°C produces steam that will generate ten times more electric power than the steam produced by rock that is 200°, when 300° is surpassed up to 400°C, “you get only another 20 percent increase in the power,” Ring said. “So from my perspective, it’s a fundamental difference to go from 200 to 300°, beyond that (300°C) is just incremental changes,” he said.

The impact on costs associated with electric power generated from steam produced by rock heated to 300°C is “unbelievable,” said Ring. Electricity generated from steam produced by rock that is 200°C would be “from five to six megawatts at levelized cost of energy (LCOE) of from 5 to 7 cents,” he said. Now “envision that you can produce ten times” the amount of electricity, “you can expect to have LCOE at unbelievable rates of between 2 and 3 cents,” he said.

Ring added there are several unique geological conditions on the Earth where this type of temperatures, from 300 to 400°C, can be reached at really shallow depths. An example is Iceland, where magma comes very close to the surface, and in the United States there is Salton Sea in California, Newberry Volcano in Oregon, and some of the Geysers. “The point being is while there are several more locations like this, they really depend on very special geology and they’re not scalable,” he said. “Everywhere else,” significant depths of from 8 to 10 kilometers (or 25,000 to 30,000 feet) have to be reached to access 300°C, Ring said.

Using a geothermal map of United States, Ring has identified the areas in which rock that is at 300°C is available at depths of 28,000 feet. Of those areas, national parks, mountains, and different areas that are not available for whatever reason are excluded. If only 20 percent of the land that remains is used, “that can potentially produce almost two terawatts of geothermal energy at those enormously low, amazingly low prices,” he said, adding “today U.S. total generation capacity is around 1.3 terawatts. So even at this depth you can cover everything.”

If drilling goes to 10 kilometers, the geothermal energy probably increases five times, according to Rink. “So if we can economically achieve access all this hot, dry rock, then we can produce all U.S. needs for electric power, including all the potential needs of data industry,” he said.

However, what is preventing the energy industry from accessing rock heated to 300°C is that existing rigs cannot drill to those depths because of the hook limitation on the load they can carry, Ring said. 

“I don't care what your drilling technology is, you can cut rock using lasers, using microwaves, using conventional drilling or something else,” because drillers “cannot drill to this depth because of the hook limitation on the load that they can carry,” he said.

In addition to the hook load, it is not yet known how to circulate cuttings because of the high temperature; there is no drilling mud that can survive; and it is not yet known how to run casing to those depths, Ring said. To solve those and other problems is going to take research and development, and “can be done, probably in five, to seven years,” he said. What is needed is funding and commitment. “It’s a lack of capital, not a lack of knowledge,” he said. “You need a very-focused effort to get it done and a lot of capital. This is capital intensive,” and will cost “from several hundred millions of dollars, to lower billions, depending how fast you want to deploy.”

However, the funding for research does not have to be “only government funding,” said Ring. Industry has funded research and development of other drilling technologies such as deepwater. He added that when examined, “the scale of technical challenges, they’re very similar [to deepwater].”