Geothermal hot springs like this one indicate the presence of molten magma relatively close to the surface. Such fields are ideal for use in the generation of geothermal-produced electricity.

Power Tube Promises - Part 2

An interview with Power Tube inventor, Doyle Brewington

By Bill Moore

"All geothermal plants today are one of a kind because none of them are alike," Doyle Brewington pointed out to EV World. "They are rated at approximately three million dollars an installed megawatt." According to Brewington, the inventor of the Power Tube, this makes them more expensive to build than conventional fossil fuel plants, which he estimates cost between $1.2 and $1.5 million per megawatt.

A megawatt is equivalent to 1,000 kilowatts. An average American home uses about one kilowatt of electricity per hour, occasionally peaking to 10kW/hr. A megawatt would therefore provide enough power, on average, for roughly 1000 homes.

By contrast, Brewington and his backers believe the eventual production model of their 10MW Power Tube can be installed for under $450,000 per megawatt, a dramatic cost reduction. This translates into electricity production at between 3.5 and 5 cents per kilowatt hour, depending on the type and location of the installation.

Up to this point in time, Doyle and his employer -- who is underwriting the initial development costs of the Power Tube -- have tested the individual components and run computer simulations of the system. The next phase of development will see the components assembled and tested at the J.J. Pickle Center at the University of Texas at Austin.. He estimates they are about 18-20 months away from actual field testing of the first three prototypes.

The first of the three prototypes will be tested in a simulated hot rock environment. Special rock is being imported from Mexico and will be assembled into two halves. These will be heated by a liquid propane gas burner system to simulate geothermal hot rocks. This is enable Power Tube developers to make on-going modifications.

The two subsequent prototypes are slated for testing in Hawaii and Costa Rica. Doyle added that the later is particularly anxious to begin testing the system.

But Costa Rica, with its rich geothermal resources, is only one of 39 countries around the world that could be powered entirely by geothermal energy, he observed. He also estimated that once the 50 megawatt Power Tube units that are on the drawing board reach production, he believes that he could provide up to one-third of US electric energy needs using geothermal power alone.

EV World asked Brewington if any independent testing entities have verified the feasibility of his concept. He responded that when they asked for such an entity to give them a idea of the cost of verifying the Power Tube concept, the cost was so prohibitively expensive that it simply made more sense to go ahead the build the prototype first.

"Everyone that has looked at it from the point of view of the technical side of it, including people who are interested in the investment side of it, have said that it is fantastic and why hasn't anybody thought of it before."

One of the reasons Brewington has designed the system to be module is so that it can be continually upgraded with new technology. He estimates the working life of each Power Tube to be 5 years, at the end of which, he expects the units will be ready to be upgraded with newer, more efficient technology. This is in sharp contrast to the normal central power plant that has a design life of 30-40 years, but cannot be easily upgraded or improved as technology advances.

One recent example is a brand new 36MW turbine developed by GE that can fit inside a 22 inch diameter enclosure. Brewington said he is working with GE to integrate this turbine into his design.

"New technology comes up very fast in five years. So we'll be able to pull those out and install the new technology. . . put one of the new ones in the ground in place of it, take this one back to the plant, install new technology and be able to install it elsewhere," he explained. "Our point is not to sell these. Our point is just to sell the energy, because by selling the energy and maintaining control over the unit, we're also responsible for its maintenance and reinstallation."

Brewington envisions three marketing models:

  1. Build, own and operate the geothermal electricity Power Tube installation, selling power to the grid.
  2. Subcontract the operation of the unit to a utility who sells the electricity to its customers.
  3. Leasing the units to organizations and businesses who want to set up their own utilities or distributed generation systems.

In looking at the international marketplace and the risks associated with going into under developed countries, Brewington reported that his firm has had conversations with the World Bank and others international risk underwriters and those discussions sound promising. "You're pretty much covered and as long as you're working in a country that has protocol with these organizations, you really don't have a risk."

Brewington explained that anyone interested in learning more about the Power Tube can talk directly to the company president, Dr. Patrick Hoskins or by calling (281) 351-4545 in Houston, Texas.

Times Article Viewed: 6468
Published: 14-Oct-2001


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