Drill Baby, Drill!

By Bill Moore

Posted: 04 May 2010

Sarah Palin wasn't wrong. She just has the energy resources confused.

Before the exploration drilling rig Deepwater Horizon went down 52 miles off the Mississippi Delta, it was costing British Petroleum between $500,000 and $1 million a day to operate. Using state-of-the-deep-drilling-art technology, the crew bored a test well down to at least 18,500 feet, which I am told was the depth they were permitted to drill. Rumor has it they drilled closer to 25,000 feet, while floating atop some 5,000 feet of water, making the total depth of the project nearly 30,000 feet (9 km). That's equivalent to where modern jetliners fly when they leave those white contrails high overhead.

The oil coming out of such depths is a scalding 275 degrees F at a metal cutting 17,400 psi. But the now-ruptured Macondo borehole isn't the deepest Gulf well drilled. That honor goes to the Tiber well at 35,000 feet, plus 4,100 feet of water. Prior to it, Thunder Horse held the record at 29,000 feet and 6,000 feet of water. By way of contrast, the deepest oil well of its time, the Daisy Bradford #3, struck oil at mere 3,593 ft in 1930.

As the Deepwater Horizon tragedy demonstrates, drilling for oil and gas offshore is expensive, risky and potentially disastrous; plus the resource is finite, at least on a human scale. Which begs the question, why bother? As the map below suggests, there is plenty of pollution-free energy to be had just below our feet… well, a bit deeper than that, around 6 km (about 20,000 feet), which,given today's drilling technology, should be a "piece of cake," though the reality is, it's a lot tougher than it appears.

US Deep Geothermal Resouces Map

Several years ago, the U.S. Energy Department did a study of America's geothermal resources and came up with this map, which shows that pretty much most of the United States has geothermal resources above the boiling point of water that could be used to produce steam for electric power generation and district heating. Living within 50 miles of one of the "orange" zones that covers nearly all of the state of Nebraska, I keep asking myself why our public utilities continue to burn mountains of dirty coal, when [theoretically] we could be taping that hot rock. And for that matter, check out Louisiana and east Texas. They too appear to have large swaths of their state sitting atop similarly hot rocks. As a general rule of thumb, the temperature of a borehole increases by 15F for every 1,000 feet, though some areas are hotter, some cooler depending, it appears, on the type of rock strata below.

So, why isn't BP looking beyond petroleum and hiring Transoceanic, Haliburton, or Schlumberger to use their expertise to tap this unlimited, pollution-free, dry land power source? Obviously, it isn't a matter of not having the equipment. If these firms can drill down into the mantle of the earth while floating on a heaving ocean a mile above the sea floor, boring to half that distance on stable ground would seem relatively easy.

Late last year, the British Department of Energy & Climate Change awarded three "deep heat" projects in Cornwall to the tune of some £4 million. Two of the projects are for exploratory boreholes and one is to upgrade and expand a existing "deep" geothermal project; "deep" being a relative term, since it's only about 1 km down.

In 2007, a U.S. Energy Department-funded panel, assembled by the Massachusetts Institute of Technology, produced the The Future of Geothermal Energy report, which concluded that for an investment of $1 billion over the course of the next 40 years, we could produce the electric power equivalent of 200 coal fired plants, 100 gigawatts of pollution-free energy.

As you'd expect, cost is a key factor holding back what is called EGS (engineered geothermal systems). Constructing a working EGS power system is capital intensive, both to find and exploit the resource, and then to operate it, which can include periodic drilling of new holes or stimulating existing resources. Taking east Texas as an example, since it's in the orange zone similar to that in Nebraska, MIT estimated that the well would have to be 7 km deep and produce a flow rate of 80kg/s to achieve power production costs of around 6¢/kWh. Rates at other sites from New Hampshire to Nampa, Idaho ranged from at high as 68¢/kWh to a low of 5.5¢/kWh depending on the depth of the boreholes (at least two are required as the illustration below indicates) and the flow rate of the heat transfer medium, likely water.

Considering, however, that, relatively speaking, the power is free and pretty much forever; and it has none of the waste disposal or pollution issues of either nuclear power or coal, EGS would appear to be one of the more promising "clean" technologies we should be seriously investigating.

Granted, there was one incident in Basel, Switzerland that appears to have triggered a 3.4 seismic event several years ago. The company doing the drilling, AltRocks, claims the project was built over a known geological fault line. Future projects would avoid making a similar mistake.

Other issues that confront EGS are finding an economical way to drill to depths where the hot rocks are, and then finding a way to safely fracture the rock so cold water can be injected and then extracted at working temperatures above 200?. Dr. Jefferson Tester, the lead author of the MIT report, has an excellent analysis of the costs associated with EGS on the Seeker Blog.

Considering the expected clean up costs of the Deepwater Horizon oil spill, which will easily exceed MIT's $1 billion EGS investment, not to mention the trillion dollars or more economic impact on the Gulf states fishing and tourism industries, drilling for hot rock instead of dirty oil, would seem a far wiser investment beyond petroleum.

Mrs. Palin, are you listening?

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