Good things go­ing for hot frac­tured rock

Cre­at­ing en­ergy from the earth’s heat is an un­der­utilised science, even in New Zealand and Ice­land, writes Robin Bromby

The Weekend Australian - Review - - Clean Energy -

PRO­PO­NENTS of hot frac­tured rock en­ergy ar­gue they have three things go­ing for them: the tech­nol­ogy needs no fuel, pro­duces no emis­sions and there is no waste at the end of the cy­cle.

They could also men­tion a fourth fac­tor — that is, that Aus­tralia might not have too many op­tions apart from geo­ther­mal when it comes to meet­ing fu­ture growth in de­mand for elec­tric­ity. As this was be­ing writ­ten, there were warn­ings be­ing sounded of ‘‘ brownouts’’, the eu­phemism for power cuts, in east­ern Aus­tralia dur­ing 2008 if the drought does not end soon.

The Snowy Moun­tain hy­dro scheme’s wa­ter flow is in a par­lous state and there is even a threat to coal- fired gen­er­a­tion in Vic­to­ria and NSW where, af­ter coal, wa­ter is the other key com­po­nent.

So, with all that and the grow­ing tide of pub­lic opin­ion against more coal- fired power sta­tions and the emis­sions that come with them, it starts to pose a chal­lenge as to how Aus­tralia is to get the ex­tra 25,000 megawatts the Aus­tralian Bureau of Agri­cul­ture and Re­source Eco­nomics es­ti­mates we will need by 2030. This is a task that re­quires in­creas­ing present power gen­er­a­tion ca­pac­ity by an­other 50 per cent.

South Aus­tralia has its own par­tic­u­lar prob­lem in that the Leigh Creek coal field, which sup­plies the 400MW Port Au­gusta power sta­tion, has at most 15 years’ life re­main­ing.

Barry Gold­stein, di­rec­tor of pe­tro­leum and geo­ther­mal with the De­part­ment of Pri­mary In­dus­try and Re­sources of South Aus­tralia ( PIRSA), told a re­cent con­fer­ence in Ade­laide he ex­pected spend­ing on hot rock geo­ther­mal — ex­plo­ration, fea­si­bil­ity stud­ies and demon­stra­tion plants — to to­tal more than $ 500 mil­lion by 2012.

Given the level of ac­tiv­ity now, that will prob­a­bly turn out to a con­ser­va­tive pro­jec­tion.

Frac­tur­ing hot rock is one form of geo­ther­mal — ex­ist­ing schemes over­seas usu­ally in­volve ex­tract­ing wa­ter that is al­ready hot and pass­ing that through a heat ex­changer. With the hot rock method an ar­ti­fi­cial un­der­ground heat ex­changer is cre­ated by frac­tur­ing deep hot rocks; cold wa­ter is then pumped from the sur­face, heat­ing up as it passes through the frac­tured rock and comes back to the sur­face as su­per- heated wa­ter. The heat ex­tracted from the wa­ter in turn heats a low boil­ing- point liq­uid, which when brought to the boil, pro­duces high- pres­sure steam used to drive elec­tric­ity tur­bines.

In South Aus­tralia, where most of the hot rock ac­tion is tak­ing place and rock tem­per­a­tures at depth can be be­tween 250C and 300C, 12 com­pa­nies have al­ready ap­plied for 116 ar­eas. Gold­stein es­ti­mated that Aus­tralia by 2030 would be get­ting nearly 7 per cent of its elec­tric­ity from hot rock power sta­tions.

One of the more re­cent en­trants is Chris Matthews at Tor­rens En­ergy, who be­lieves his com­pany has one big plus — its South Aus­tralian li­cence ar­eas are all lo­cated on the state’s power grid, one run­ning along the edge of Lake Tor­rens just north of Port Au­gusta, an­other in the Barossa and a third be­gin­ning at the north­ern­most sub­urbs of Ade­laide.

In April, Tor­rens added two ex­plo­ration per­mits just north of Melbourne. But Matthews sees South Aus­tralia as the ideal place to be. It has the coun­try’s best po­ten­tial hot rock re­sources, and peak power sup­ply in the state looks like be­ing out­stripped by de­mand within two to five years, so there is plenty of room for all those try­ing to get projects go­ing.

‘‘ We don’t see other geo­ther­mal com­pa­nies as com­peti­tors — we’re in a state of dire en­ergy short­age,’’ he said. The en­vi­ron­men­tally friendly ap­peal of hot rock geo­ther­mal would make it the en­ergy of the fu­ture.

‘‘ The world is not go­ing to ac­cept a non­sus­tain­able fu­ture — nor a dirty en­ergy fu­ture. ‘‘ There’s a very bright fu­ture for us.’’ Geo­science Aus­tralia has es­ti­mated this coun­try’s geo­ther­mal en­ergy re­source at about 1.2 bil­lion peta­joules; to put that into con­text, Aus­tralia’s to­tal proven and prob­a­ble gas re­serves amount to 140,000PJ.

The whole idea of hot rock en­ergy has, in­evitably, been viewed with con­sid­er­able scep­ti­cism by some — but the fact that sev­eral com­pa­nies have man­aged to get ini­tial pub­lic of­fer­ings away sug­gests that there is now grow­ing be­lief that this could all work.

More­over, there is some se­ri­ous money also in­volved. Wood­side Pe­tro­leum and Ori­gin En­ergy hold shares in Geo­dy­nam­ics, the first hot rock player out of the blocks and most ad­vanced in its ex­plo­ration.

Geo­dy­nam­ics plans to have a 40MW plant in op­er­a­tion by 2010. But that is only the be­gin­ning. By 2015 this com­pany has set its sights on hav­ing 500MW in gen­er­at­ing ca­pac­ity, com­pa­ra­ble to the out­put of the Snowy Moun­tains scheme.

It has been ex­plor­ing the Cooper Basin, the oil and gas rich struc­ture that stretches from the north- east of South Aus­tralia into the south- west of Queens­land.

Geo­dy­nam­ics be­lieves its main ten­e­ments could con­tain more than 390,000PJ of high grade ther­mal en­ergy — enough, it says, to sup­port power plants to­talling 10,000MW in ca­pac­ity.

Pe­tratherm, the other big name in geo­ther­mal, has $ 30 mil­lion from Beach Pe­tro­leum rid­ing on its hot rock plans and in­tends to sell power to the nearby Bev­er­ley ura­nium mine as its first step into rev­enue earn­ing.

It also re­cently started its sec­ond project in Spain, ap­ply­ing for ar­eas just north of Barcelona look­ing for both con­ven­tional and hot rock geo­ther­mal re­sources.

The oth­ers in­clude Green Rock En­ergy, which has prospects close to the Olympic Dam mine and is work­ing with a Hun­gar­ian oil com­pany and an Ice­landic geo­ther­mal spe­cial- ist to de­velop a power project in the east­ern Euro­pean state, but that in­volves tap­ping hot geo­ther­mal wa­ter rather than in­ject­ing wa­ter into hot rock. Geo­ther­mal Re­sources is tar­get­ing a sec­tion of South Aus­tralia just across the border from Bro­ken Hill, and Eden En­ergy which also has targest in South Aus­tralia.

The new­est lo­cal player is tar­get­ing not South Aus­tralia, but Tas­ma­nia. Nickel pro­ducer Al­le­giance Min­ing has ap­plied for a 3000sq km spe­cial ex­plo­ration li­cence in the west­ern part of the is­land to look for hot gran­ite rock.

Hot rock en­ergy is be­ing taken se­ri­ously else­where. A small power plant is be­ing de­vel­oped in France, but Ice­land has very big plans in­deed. The Ice­landic Na­tional En­ergy Author­ity is work­ing with Ger­many’s En­ergie Baden- Wurt­tem­burg to tap hot rocks on the vol­canic is­land state and lay a 1930km cable on the seafloor which would link to the Bri­tish and Ger­man na­tional grids.

This cable would en­able Europe to har­ness Ice­land’s clean en­ergy — not only the hot rock po­ten­tial, but all the hy­dro- elec­tric ca­pac­ity that has been left un­touched be­cause of Ice­land’s tiny power needs.

New Zealand has been a big geo­ther­mal player, but its op­er­a­tions in­volve draw­ing al­ready heated wa­ter out of the earth. The first of its geo­ther­mal sta­tions, Wairakei, was com­mis­sioned in 1958 af­ter the New Zealan­ders had stud­ied the world’s first such in­stal­la­tion at Larderello in Italy.

New Zealand now has seven geo­ther­mal power sta­tions. Ear­lier this year, one of that coun­try’s large power gen­er­a­tion com­pa­nies, Con­tact En­ergy, out­lined plans for an­other 260MW of geo­ther­mal ca­pac­ity in­volv­ing two new sta­tions near Taupo in the cen­tral North Is­land and up­grad­ing Wairakei.

In to­tal, geo­ther­mal tech­nol­ogy now ac­counts for close to 9000MW in elec­tric­ity gen­er­at­ing ca­pac­ity across the globe. Geo­ther­mal may now be a pin­prick on the world elec­tric­ity scene, but Chris Matthews and the other geo­ther­mal be­liev­ers in­tend to change that.

Hot stuff: Con­tact En­ergy’s plant is among New Zealand’s seven geo­ther­mal plants

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