[TrashMan]

IMHO, we should be doing our darnest to reduce power consumption.

America, I'm looking at you.

[Klaustrophobia]

why?  wasteful use is everywhere.

i'm one of those crazy guys who goes around turning off everything that's not in use.

[Kosh]

Also, if we are going to use pumped storage, I would suggest a liquid in an accumulator as we have much higher efficiency liquid pumps and turbines.

We could also put the fluid into a pipeline and join the wind farms together.  In fact I have heard suggestions of just doing away with the electric generators in the wind farm and just have the farms generate compressed fluid, which is then run to bigger electric generating plants.  This system to join them together would also average out the variations in generating capacity.  Admittedly, it is not quite as convenient to do in the ocean, but nevertheless, we know how to run pipelines under the ocean.

Isn't that going to dramatically increase the expense? All that tunneling isn't going to be cheap.

[perihelion]

Geothermal power was last addressed a couple pages back, but I don't think it should be so quickly dismissed.  Just because the produced fluids are corrosive isn't a show-stopper.  Most of the fluid produced in oil and gas wells is pretty corrosive as well.  I designed a completion system for one well that had upwards of 15% CO2 and 2% H2S, and the completion fluid had to be a CaBr2 salt-water brine just to be heavy enough to keep the formation under control, and the bottom hole temperature was in excess of 400°F.  That's just the nastiest well I personally dealt with.  I've heard of much worse.  I and the other engineers didn't just look at those wells and decide, "Well, I guess we're going to have to forgo these."  They are currently online and producing natural gas at a prolific rate, and the corrosives are being dealt with by surface separation equipment.

My point: we're quite capable of dealing with nasty corrosive fluids.  We are actually very good at it.  It gets expensive, and you can't go into it half-assed, but it can be done.  If we can find a hot enough formation to make it worth while, I'd be more than happy to get involved in a geothermal project.  Besides, any decent geothermal plant is going to be a binary loop anyway so the wellbore fluid will never come in direct contact with the turbine loop, just like the nasty radioactive coolant loop in a nuclear plant (almost) never comes in contact with the turbine loop.  The problem with geothermal has been a lack of funding and motivation.  Advanced research into HDR (hot dry rock) geothermal has been almost impossible to fund despite the fact that, if it works, it could support all our power needs just about forever.

[Klaustrophobia]

Besides, any decent geothermal plant is going to be a binary loop anyway so the wellbore fluid will never come in direct contact with the turbine loop, just like the nasty radioactive coolant loop in a nuclear plant (almost) never comes in contact with the turbine loop. 

that's only true of PWR designs.  BWRs boil the coolant directly in the reactor core and send that steam to the turbine.  the secondary (or tertiary in PWR i guess it's called) loop that supplies coolant for the condenser is segregated however.

[perihelion]

Is anyone still building those designs???  That technology is 60 years old!  Reactor design has gone 3 more generations past that.  I mean, I know there are still some of those old plants out there, but I had been under the impression that they were outnumbered by the pressurized water reactors with their triple-loop systems.

I actually got a chance to work at the Comanche Peak nuclear plant for one summer about ten years ago.  It was a neat and very worth-while experience.  No human being could possibly have convinced me at the time that I didn't want to go to work at a nuclear power plant.  If I hadn't had a chance to intern there, I probably would have continued to try like mad to get a permanent job at one.  That would have been... "unfortunate" to put it lightly.  Sheesh.  You have no idea what true boredom is.  The engineering team I was working for, their job was essentially to make sure nothing ever happened.  It was glorified maintenance.  Important, yes, absolutely, but there was zero room for creativity.  I'd love to get involved in the design of some of these monstrosities, but being an engineer at an operating power plant is boooooo-ring.

Still, I'm very grateful I had the chance to learn this first hand.  And she was a beauty, make no mistake.  The entire facility was a truly awe-inspiring piece of engineering.  It's a pity more people cannot see what I saw first hand.  No matter what side of the nuclear debate you fall on, walking where I walked, standing where I stood, you cannot help but be impressed.

[Klaustrophobia]

yes, they are still being made.  BWR/PWR are basic design concepts that will likely never go away.  they get refined and things like the safety systems get drastically changed, but the basic operating principles remain the same.  the ESBWR and AP1000 are the two leading generation III+ designs marketed and soon to be built today, which are a BWR and PWR design respectively.

[perihelion]

Hmm.  Well well.  I did not know that BWR's were still considered a viable approach in Gen 3 reactors.

Be that as it may, the point I was trying to make is that in geothermal applications, the highly corrosive produced fluid / gas need not come into direct contact with the turbine loop.  So, the fact that the fluid can be (not necessarily "will be") highly corrosive is not a show-stopper in and of itself.

[Kosh]

Personally I can't wait until we get nuclear lightbulb reactors working.

I'd love to get involved in the design of some of these monstrosities, but being an engineer at an operating power plant is boooooo-ring.

Then study nuclear physics. I do think the term "nuclear engineer" is something of a misnomer because it isn't really engineering.

[Klaustrophobia]

 


huh?  if designing a nuclear plant isn't engineering, i don't know what is.


as for the nuclear lightbulb, NCSU had one of those.  pulse power mode.  you get a nice bright flash of Cherenkov radiation by ejecting a control rod out.  the power spikes to like 2000% for a couple microseconds.  but they took it out of the licensing a while back because it doesn't do anything useful.  (btw, there's always a cherenkov glow when a reactor is at power).

[Kosh]

huh?  if designing a nuclear plant isn't engineering, i don't know what is.

Nuclear engineers don't actually design nuclear power plants, they just maintain them. The reactors are designed by nuclear physicists and the plants themselves are designed by mechanical and electrical engineers.

as for the nuclear lightbulb, NCSU had one of those.  pulse power mode.  you get a nice bright flash of Cherenkov radiation by ejecting a control rod out.  the power spikes to like 2000% for a couple microseconds.  but they took it out of the licensing a while back because it doesn't do anything useful.  (btw, there's always a cherenkov glow when a reactor is at power).

Gas core reactors (aka nuclear lightbulbs) operate at insanely high tempuratures, which allows for greater energy. Whats needed are more efficient ways of getting electricity out of the plasma generated by it as well as the radiation. So, with those no more heating water.

[Bobboau]

sort of like how train engineers don't design trains.

[Flipside]

GeoThermal is probably our best option for natural power sources at the moment, it's pretty constant compared to wind and solar power, and hydro-electric, at least my experience of the system in Wales relies heavily on economics, i.e., that using fossil/nuclear generated electricity at night to pump the water back uphill is cheaper than the cost of energy the dam produces during the day.

The down side to geothermal is that in countries that do not have access to open geothermal vents, it could be a serious engineering work to establish, and some places, like Yellowstone Park in the U.S. might be suitable, but I sure as hell wouldn't start mucking around there.

[Klaustrophobia]

nuclear engineers most certainly DO design reactors.  design is the definition of engineering for christ's sake.  nuclear physicists work in national labs doing research.

anywho, i've never heard them called "nuclear lightbulbs", but the reactor designs you are referring to are HTGC (high temperature gas cooled).  the problem with these designs is we don't have the material capability to build them to withstand those kinds of temperatures.  the high temperatures allow for better thermodynamic efficiency; the actual power output won't be drastically higher.  we're still limited by melting temperatures of the fuel.  and i can assure you that the gas coolant is NOT in a plasma state.  that requires millions of degrees.

[perihelion]

GeoThermal is probably our best option for natural power sources at the moment, it's pretty constant compared to wind and solar power, and hydro-electric, at least my experience of the system in Wales relies heavily on economics, i.e., that using fossil/nuclear generated electricity at night to pump the water back uphill is cheaper than the cost of energy the dam produces during the day.

The down side to geothermal is that in countries that do not have access to open geothermal vents, it could be a serious engineering work to establish, and some places, like Yellowstone Park in the U.S. might be suitable, but I sure as hell wouldn't start mucking around there.

Suitable schmutable.  Just drill deeper.   

Seriously, drill deep enough just about anywhere, even Antarctica, and you will hit a zone of hot rock eventually.  Up to this point, we've been relying exclusively on zones which are not only hot but also contain pressurized water, so all we have to do is drill the hole and crack open a valve, and boom, you have geothermal power.  Hot dry rock is a tougher nut to crack, but I'm convinced it can be done.  And once it is, that's technology that you can use ANYWHERE.  You just have to drill deep enough.

I swear, if even 1% of the R&D that is poured into going after hydrocarbons was invested in HDR geothermal wells, we would have it by now.

[Bobboau]

funny thing 'drill deeper' technology is extremely important to oil as well, so there is actually quite a lot of R&D going into it.

[Flipside]

GeoThermal is probably our best option for natural power sources at the moment, it's pretty constant compared to wind and solar power, and hydro-electric, at least my experience of the system in Wales relies heavily on economics, i.e., that using fossil/nuclear generated electricity at night to pump the water back uphill is cheaper than the cost of energy the dam produces during the day.

The down side to geothermal is that in countries that do not have access to open geothermal vents, it could be a serious engineering work to establish, and some places, like Yellowstone Park in the U.S. might be suitable, but I sure as hell wouldn't start mucking around there.

Suitable schmutable.  Just drill deeper.   

Seriously, drill deep enough just about anywhere, even Antarctica, and you will hit a zone of hot rock eventually.  Up to this point, we've been relying exclusively on zones which are not only hot but also contain pressurized water, so all we have to do is drill the hole and crack open a valve, and boom, you have geothermal power.  Hot dry rock is a tougher nut to crack, but I'm convinced it can be done.  And once it is, that's technology that you can use ANYWHERE.  You just have to drill deep enough.

I swear, if even 1% of the R&D that is poured into going after hydrocarbons was invested in HDR geothermal wells, we would have it by now.

From what I've heard, there are a few high-stress and highly heat-conductive materials that could be used to construct huge 'rods' that transfer heat up to the surface where it can be utilised. The problem is finding a material that is cheap to manufacture in the quantities desired.

The best thing about geothermal, if you have the drilling tech, is that, as you say, it doesn't matter where you are on the planet, dig a deep enough hole and you'll find an almost inexhaustable power source, you'd simply need a water tank which these rods would rise up into, heating the water and generating steam.

[Kosh]

GeoThermal is probably our best option for natural power sources at the moment, it's pretty constant compared to wind and solar power, and hydro-electric, at least my experience of the system in Wales relies heavily on economics, i.e., that using fossil/nuclear generated electricity at night to pump the water back uphill is cheaper than the cost of energy the dam produces during the day.

The down side to geothermal is that in countries that do not have access to open geothermal vents, it could be a serious engineering work to establish, and some places, like Yellowstone Park in the U.S. might be suitable, but I sure as hell wouldn't start mucking around there.

Drilling that deep is hugely expensive so no, it isn't our best bet.

[Flipside]

I didn't say bet, I said option, not all options are available in all situations, and, as I mentioned in the post, it could be problematic in areas where the geothermal energy is not easily accessible, but for pure power/investment ratio, and, as I also mentioned, if research that is currently taking place turns out to be productive, it is the most reliable and cost-effective option, maybe not for everywhere, but near crust-depth drilling is certainly an option that should, and, as Bobbau mentioned, is, being investigated.

[perihelion]

Honestly, it isn't the drilling that is the biggest issue.  We are capable of achieving depths today where we can reach rock with temperatures up in the 500°F range.  That's more than hot enough to run a geothermal plant.  It isn't easy or cheap to drill that far, and certainly you'd prefer to pick targets that are naturally hotter at a shallower depth.  But the reality is we've drilled wells in excess of 40,000 feet (12,000 meters) deep.  That technology is already adequate to the task of geothermal power, and it will only continue to improve.

The biggest issue I see is making it work with hot dry rock.  You could drop in some highly conductive material and essentially turn the well into a glorified radiator, but it won't take too long before you cool down the bottom of the well.  Part of the key to making geothermal work is drawing your heat from a fairly large area; just using the borehole itself isn't going to be enough for long-term use unless you are siphoning heat off at a really slow rate (slow enough to make the whole endeavor of questionable value).

To increase the area from which you are drawing heat, the old-school way is to just tap into an area that already has hot geofluid and produce that up the well.  In a dry rock application, you must supply the fluid yourself through (an) injector well(s), force it to meander through a large area of hot rock where it soaks up heat, and then force it into a production well from which it can be returned up to surface.  Then you have hot fluid on surface.  Most likely approach will be to run that hot fluid through a heat exchanger to heat water or some other fluid in a turbine loop.  The now-cooler produced fluid is pumped to the aforementioned injector wells, and the process repeats.  Unless you chose your formation very carefully (must have little-to-no natural porosity) and execute your hydraulic fracture of said formation perfectly, the amount of water that gets lost per cycle is going to be horrific.  That last bit is the biggest barrier at the moment to hot dry rock geothermal power.