NZ Geothermal switching to binary systems, ramp-up forseen.

[skids]

http://www.scoop.co.nz/stories/BU0509/S00086.htm

There are many other geothermal fields in New Zealand that are currently untapped or underdeveloped, and that could potentially be developed assuming access and consenting is achieved. There is currently 450 MW of installed geothermal capacity in New Zealand, and geothermal stations supply 6 – 7% of our electricity demand.

[acmejack]

1. Very clever!

Have you seen a geothermal plant?

[Oerdin]

2. There isn't much to it.

In the traditional geothermal plant you inject water down there and have it come back up with steam then the steam powers a turbine. Pretty straight forward. The newer ones use a heat pump or a heat exchanger in order to be more efficent.

[jpak]

3. I've driven past some of these plants on the North Island (NZ)

Lots of steam (obviously) and a faint odor of hydrogen sulfide...

Hope to see (and smell) more of these in December...

:)

[NNadir]

7. Why is this not surprising?

One would have to know something about chemistry to know about the advisability of enjoying whiffs of hydrogen sulfide, wouldn't one?

Of course, if one knew no chemistry whatsoever, one wouldn't typically be troubled by the matter, would one?

Oh well, no loss really.

[Dead_Parrot]

9. To use a NNadir tactic...

...one wonders how the Icelandic government keeps all those H2S-related deaths quiet, since most of their power is geothermal. Oh wait, there aren't any.

Must be almost as safe as nuclear, then... :P

To be honest, I'd be more worried about a release of pentane (the chemical used in the second stage). At least you can smell H2S if you get swamped by it.

[skids]

10. Not to mention completely beside the point of the article.

The article, which apparently some folks didn't comprehend, explains how the trend is towards binary systems. Which recirculate the working fluid. Which means a closed system. Which means nothing gets out.

[skids]

4. A more in-depth article.

New technology and computer modelling techniques have started to make previously uneconomic exploration more viable, said a US researcher in geothermal drilling techniques, Stephen Bauer, on an earlier visit.

Drilling technologies were adapted from the much larger oil and gas exploration sector, he said.

The geothermal sector is too small to have much research and development done for its own specialised equipment.

Bauer's development of specialist electronic sensors has helped bring down the cost of drilling holes into hot, acidic and gaseous environments.

http://www.nzherald.co.nz/section/story.cfm?c_id=3&ObjectID=10349255

[Throckmorton]

5. There are many north of San Fransisco, I did start up on a few of them.

In the Geyser's Park near Cloverdale. They are all wet rock technology plants, and use a large part of there output for pollution control. The plant I worked on CCPA Coldwater Creek facility had to be closed as GEODEC, the steam field owner, could not supply enough steam to the plant economically to operate it.

The CCPA plant had a gross megawatt output of 180 Mw (90 per unit) but only had a net output of 130 Mw, over 40 Mw went to run the pollution abatement equipment, the an the other 10 Mw or so went to run the "Hotel" or House Total Electrical Load.

There primary pollutant what Hydrogen Sulfide, with is also know as sour gas. It is very toxic and corrosive. The plants were all built on hilltops, as the Hydrogen Sulfide was heavier than air and would spill away from the plant in a leak.

Incidentally, one of the two units was a pentane extractor and the out used isopropyl alcohol. In the system, the very dirty and high entropy steam heated the intermediate chemical, which spun the turbine blades.

[NNadir]

6. It doesn't sound particularly peachy.

The toxicity of hydrogen sulfide is roughly comparable to that of hydrogen cyanide, though happily one can detect hydrogen sulfide much more readily than one can detect cyanide.

[skids]

8. Good reason to switch to binary systems.

I guess the same kind of thinking that leads us to use fossil fuels can lead to problems with geothermal too. IMO if they are going to do it, they should do it right, with a closed system.