New “Dry Heat” Geothermal System “Could Meet All NZ’s Power Needs”
July 2nd, 2008
Chris Mole, Associate Editor
• Tapping into dry heat underground.
• 50MW “possible within 3 years.”
• Interest from generation companies.
An Auckland businessman has developed a new method of generating electricity from underground geothermal heat, which he claims could provide all the power NZ will ever need. John Lehmann and a group of private investors have been working for seven years on the project, which is unique in the world.
Essentially it involves boring a hole about 350m deep to tap into geothermal heat, which is then transmitted up a 38cm-diameter pipe to drive a generator. Lehmann won’t disclose exactly how his technology works, for commercial sensitivity reasons. But he claims it can produce power for about 1c/kWh, which is a fraction of the price of any other method now available.
Lehmann says his company could have 50MW of generation feeding into the national grid within three years. He adds, “Ultimately, NZ could have more power than it knows what to do with.” A 10MW power station using his technology would be about 2.5m high and 5m wide. Thus its environmental impact would be minimal compared with any other form of generation. Such a power plant could cost as little as $250,000.
Lehmann stresses his system uses dry heat, unlike conventional geothermal power stations. The system can generate power once the temperature reaches 140°C but the ideal temperature is around 300°C. Lehmann had a small prototype of his system operating in Northland about five years ago, which he says worked “far better than we anticipated.”
Since then he has been “tinkering around” to get the technology to the point where it can be used commercially. He says, “We now know the thing works and we have done all our figures.” Lehmann and his backers are about to form a company to take the project forward. They are in talks with Todd Energy and two electricity generators, all of whom are interested in pursuing the idea further. Several overseas power generation companies have also shown interest. Lehmann says he has also had a positive response from Energy Minister David Parker, and the Green Party is particularly enthusiastic.
Lehmann says everyone he has explained the technology to has been astounded by its simplicity and the fact it has never been thought of before. He believes NZ is an ideal place for his system because there are geothermal hot spots all around the country.
Lehmann points out the geothermal resource is renewable and will last forever, “at least until the earth cools down.” He adds, “It’s the nearest thing to a perpetual motion machine.” He believes his system would be a golden opportunity for farmers whose land sits above geothermal hot spots.
Copyright © Media Information Ltd
NZ Energy & Environment Business Week
Amalgamated Dairies