Geo­ther­mal en­ergy

The power un­der the ground could un­der­pin a clean en­ergy fu­ture for this na­tion, and give us a lead­ing role in a multi-bil­lion dol­lar global in­dus­try.

Element - - Primary Industry - By Andy Ken­wor­thy

Geo­ther­mal en­ergy cur­rently pro­duces about 13% of New Zealand’s elec­tric­ity sup­ply, about 750 megawatts of elec­tri­cal power. Most of it comes from the Taupo Vol­canic Zone, with an­other 25 megawatts in­stalled at Ngawha in North­land.

The first gen­er­a­tor was com­mis­sioned at Wairakei in 1958, mak­ing New Zealand only the sec­ond na­tion to be­gin com­mer­cial geo­ther­mal power pro­duc­tion. Part of the in­spi­ra­tion for this was se­vere elec­tric­ity short­ages in 1947, when two dry years re­stricted hy­dro-gen­er­a­tion, a sit­u­a­tion that re­turned in 2008.

The good news is that there is sig­nif­i­cant scope for ex­pan­sion of geo­ther­mal en­ergy in New Zealand. The lat­est es­ti­mate is that there is ap­prox­i­mately an­other 1,000 megawatts of geo­ther­mal po­ten­tial. There is also sig­nif­i­cant po­ten­tial for the di­rect use of geo­ther­mal heat. Be­cause most elec­tric­ity gen­er­a­tion re­quires high tem­per­a­ture re­sources, it is pos­si­ble to use the grad­u­ally-cool­ing geo­ther­mal fluid in a num­ber of other ap­pli­ca­tions as well, in­clud­ing green­houses, tim­berdry­ing, aqua­cul­ture or even di­rectly heat­ing homes. The cooled liq­uid can then be re-in­jected into the geo­ther­mal area to be re­heated.

Mighty River Power is one of the big play­ers in turn­ing that po­ten­tial into power, and it is ex­pand­ing rapidly. Over the past five years, the com­pany has in­vested $1 bil­lion into new geo­ther­mal de­vel­op­ments, in­clud­ing shelling out $466 mil­lion this year to con­struct the new Ngata­mariki geo­ther­mal plant near Taupo, which is due to be com­mis­sioned in 2013. Mighty River Power cur­rently op­er­ates more than 380 megawatts of geo­ther­mal gen­er­a­tion, with an­other 82MW cur­rently un­der con­struc­tion.

And the firm’s reach is spread­ing well be­yond these shores. Geo­ther­mal power presently sup­plies the world with 10,715 Megawatts of elec­tric­ity in 24 coun­tries on six con­ti­nents. But the po­ten­tial to use geo­ther­mal re­sources is much greater. With the tech­nol­ogy avail­able to­day and un­der de­vel­op­ment for the fu­ture, it is es­ti­mated that geo­ther­mal re­sources could sup­ply more than 300,000 Megawatts of power, while pro­duc­ing far fewer car­bon emis­sions than fos­sil fu­els.

Mighty River Power com­mit­ted US$250 mil­lion to in­ter­na­tional geo­ther­mal in­vest­ment through Geoglobal En­ergy in early 2010, which is pi­o­neer­ing the iden­ti­fi­ca­tion and de­vel­op­ment of new geo­ther­mal fields around the world. The firm cur­rently has in­ter­ests in a 50MW project in the Im­pe­rial Val­ley South­ern Cal­i­for­nia, due to be op­er­at­ing in the first half of 2012; is part­way through a drilling pro­gramme to con­firm the re­sources avail­able on the Tol­huaca geo­ther­mal field in Chile; and is well ad­vanced with de­vel­op­ment op­por­tu­ni­ties in Bavaria in Ger­many.

Doug Hef­fer­nan, chief ex­ec­u­tive, said: “Mighty River Power’s geo­ther­mal ex­pe­ri­ence is recog­nised around the world and this has opened up op­por­tu­ni­ties for us to make in­formed in­vest­ments in in­ter­na­tional geo­ther­mal projects.”

New Zealand’s con­sul­tants in this field have also be­come hot prop­erty as on geo­ther­mal projects. Geo­ther­mal boffins from global con­sul­tants Sin­clair Knight Merz have been in­volved in de­vel­op­ing more than 2,500MW of geo­ther­mal plants, about a quar­ter of the world’s in­stalled geo­ther­mal ca­pac­ity. Much of this is based on ex­per­tise gained in our own vol­canic land­scapes.

Geo­ther­mal power plant, Wairakei. Photo: Chris­tine Cor­nege.

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