Page 12 of 12

Re: Geothermal Empire

Unread postPosted: Wed 03 Feb 2016, 13:09:59
by shortonoil
"By our calculations the ERoEI of geothermal power is now at least as good as petroleum; which is now 8.7 :1." Unfortunately there is no EROEI of "geothermal" just as there is no EROEI of "oil wells".

Fortunately, a hundred and fifty years of Thermodynamic investigation says you are dead wrong. If you haven't heard about it yet, you are running a little late. Ignorance is no excuse for avoiding the law; in this case, the Laws of Physics.

We have even plotted the correlated between the ERoEI of petroleum (API 37.5° in this case) to its price over the last half century.

Your comment reminds me of the aborigine who believes that airplanes fly because the gods wish it to be so. Bernoulli was a wizard that used powerful incantations.

Re: Geothermal Empire

Unread postPosted: Wed 03 Feb 2016, 18:13:20
by hvacman
Together, these projects provide approximately 20 million gallons of reclaimed water per day for injection into The Geysers reservoir.

RM - Actually re-injection of the water from Santa Rosa and the city of Clear Lake helped resolve a giant problem they both had - what to do with their treated sewage waste water. Santa Rosa only had the Russian River to dump it into, which was a problem in the summer when the River becomes more of a mud puddle. The state had placed all sorts of restrictions on them. The City of Clear Lake had the lake to dump it in, which already is suffering from eutrophication from too much "stuff" flowing in. Again, state water quality board was clamping down.The water wasn't clean enough for most other uses, so when this re-injection idea came up, it looked pretty good.

You have schooled us well on the oil patch and one thing you always remind us of is the PITA and expense that produced water and frack-waste water is to get rid of. Wouldn't you like to have a geothermal reinjection well nearby that would take your produced or frac water for free? That's how Santa Rosa and Clear Lake felt when the opportunity arose. And the Geyers could get their power output back up and stay in business. Win-win from all the players' perspective.

Re: Geothermal Empire

Unread postPosted: Wed 03 Feb 2016, 18:31:22
by hvacman
IMO part of the problem is people insist on using plain distilled water as their working fluid on these systems. Way back in 1982 I remember reading about a off the grid system running in south Texas. The owner had built a circulating system of pipes suspended about a foot above the bottom of his largest cattle watering pond. The water was a pretty constant temperature around 70 degrees even in the spring and fall because of the local climate. However he didn't use water as his exchange medium, he used Butane. The pressurized liquid would flow out through underground pipes to the pond, pick up heat, be allowed to vaporize in a fluid separator and spin a turbine to generate electricity. The vapor was then cooled by a cold water bath and compressed back into a cold liquid state for reuse. From time to time I have wondered if this guy was the inventor of the ground source heat pumps that seem to have sprung up all over Texas, but I was never able to confirm it.

If only the steam driving the geothermal turbines were from distilled water. The steam coming out of the Geyers is anything but distilled. it has so much mineral, etc. in it that they have to use all kinds of special turbine materials to keep them from being destroyed. The other option is to use a "binary" system that doesn't use the geothermal steam directly, but generates clean steam (with distilled water) through a heat exchanger/boiler. At high temperatures/pressures, water is still the fluid of choice for Rankine cycle power plants.

The butane type generation system you are describing is called an "Organic Rankine Cycle" (ORC) system. Usually uses either a hydrocarbon, CFC, or other organic fluid as the working fluid. Very popular for systems that have relatively low temperature differentials between the heat source and sink, as the organics have boiling and condensing pressure-temperature relationship more conducive for lower temperature operation than water. One big application is for power from low-temperature geothermal sources that aren't hot enough to make high pressure steam naturally.

Re: Geothermal Empire

Unread postPosted: Wed 03 Feb 2016, 18:34:18
by pstarr
That was a pond source heat pump.

Re: Geothermal Empire

Unread postPosted: Wed 03 Feb 2016, 22:54:43
by Shaved Monkey
The Birdsville geo thermal plant that runs of hot water from the aquifer runs a third of the towns supply it used to run more but demand outstripped supply.
It started as a pure hydro plant in the 60s the demand out grew the supply
then got converted into a geo thermal plant in the 90s. and demand outgrew supply
They want to upgrade the capacity of the motor to cover demand.
Until Jevons paradox kicks in again.
The hot water gets cooled down,filtered and used for domestic supply.
Its the only geothermal plant using the artesian water in Australia. ... ochure.pdf

Re: Geothermal Empire

Unread postPosted: Thu 04 Feb 2016, 11:23:02
by efarmer
Of course the energy in petroleum and natural gas is sunlight produced plant matter.
My point is that the fraction that ends up protected from merely oxidizing needs heat
and pressure to morph into something worth drilling for. This heat is geothermal and
not solar in origin. I also agree that the special geologic sites that are prime for geothermal
are also prime for volcanic cataclysm.

We all seem to converge on the point that there isn't an easy way out that scales
to replace the big hydrocarbon burn that powered the last couple of centuries.

Re: Geothermal Technology

Unread postPosted: Thu 08 Feb 2018, 08:49:18
by Tanada
Scientists in China report the first successful well drilled into hot dry rock in the northwestern part of China. With temperatures at a 236°C, this could provide sufficient for an EGS geothermal project development.

As reported locally, scientists from China are reporting a temperature of 236 degrees Celsius from a well drilled in the Gonghe basin in the northwestern province of Qinghai in China. Drilled to the depth of of 3,705 meters the well is the first drilled in efforts to explore the geothermal hot dry rock potential in China. The recovery of energy from these rock formations can be done through engineered or enhanced geothermal systems (EGS).

Considered as a key potential energy source for the future, this hot dry rock project and its drilling results present a breakthrough in exploration efforts.

It is estimated that China holds 856 trillion tons of hot dry rock, similar to the same resources reported from the United States, according to a spokesperson for the Geological Survey of China’s Ministry of Land and Resources. Scientists estimate that about two percent, or 17 trillion tons are recoverable as energy source.

The nation’s southeast coastal areas, Songliao Plain in the northeast, North China Plain and the Qinghai-Tibet Plateau region are key potential areas for exploration and development. The southern plateau, in particular, is said to hold resources of the largest in volume and highest in temperature.

Hot dry rock at a depth of 3,000 to 10,000 meters, is a dense, impermeable, high temperature rock without water or steam.

With technology available today, engineered geothermal systems in those hot dry rocks, could recover energy a temperatures above 150 degrees Celsius, which could be utilised both for power generation and heating.

Energy contained in hot dry rock is considered recoverable, and equivalent to tens of times the energy of the world’s oil, natural gas and coal combined, preliminary calculations suggest.

Hot Dry Rock

Re: Geothermal Technology

Unread postPosted: Thu 08 Feb 2018, 09:11:30
by diemos

Re: Geothermal Technology

Unread postPosted: Thu 08 Feb 2018, 12:44:20
d - Excellent reference explaining why dry rock geothermal has very little chance of working. OTOH I've seen examples of very shallow (several 100') low temp (less then 100F) with significant economic potential to provide small scale commercial applications.

Re: Geothermal Power Technology

Unread postPosted: Tue 27 Feb 2018, 02:49:35
by kiwichick
236 degrees C would seem quite useful to mentioned in the comments the deeper you drill the hotter it gets......the planets core is molten afterall