Never been on this index before,but finally found something that I'm not a Noob at.
I get to play "Guru"
I wonder how those evacuated tube solar hot water collectors would do in place of the geothermal? You would need quiet a few of them for a 280kw generator obviously but it could be a closed loop system with no waste. I guess it's a matter of doing a cost comparison this system and photovoltaic panels.
Geo blows everything away here.The size and amount of solar to match geo would be really prohibative and high maintenance.If you are already where there are hot springs like Iceland there's not much to recovering hot water from a hot well.But then you have to worry about seismic activity and vulcanism.
The diagram is a pretty basic computer animation too.What they are not showing is very expensive instrumentation for control valving and pressure relief systems.How are they controlling their electrical load.Would work fine if they could just dump whatever they produce in excess of their own electric demand into the local power grid and let the utility company worry about trimming and balancing the load.
Very interesting. I can readily see the advantage to such a system, particularly if the well water is contaminated by sulfur or mineral salts. Keeping that side under pressure would reduce the buildup through the heat exchanger, however there could be longer-term maintenance required. The intermediate fluid that steams could alcohol-based, or possibly a non-toxic refrigerant derivative. Not cheap, but then if yer in the boondocks and have ready access to these sorts of resources – I’d go for it. It’s just a lot of capital up front and a long-payback on investment. I wonder where they get the cooling water, and how they handle the “waste” well water.
1) High mineral content in the well water will scale up,no matter what requiring regular descaling of HX's.Pressure will only make it worse and involve more costs for pressure control and pumping cost.You're less efficient pumping against head of pressure.Also, what do you do when descaling?Go off line?If not an option will require redundant standbye and back-up units.So even higher cost.
2)Alcohol based feed fluid is flammable and toxic.Makes it extremely dangerous in case of a leak which is inevitable eventually.Non-toxic refridgerants,although not "poisonous",they are an affixiant and so will displace oxigen (alcohol is also).Elaborate continuous gas montoring and emerg ventilation equipment is required in case of leakage.
3)Cooling water is recirculated water cooled by cooling towers.This requires ongoing sampling and responsive water treatment with chemicals to stop algae and bugs from growing in system including the condeser.
4)Waste water just goes back to hot well to reheat or is dumped downstream in the hot spring stream depending on the original topography.
5)You are right on the money when you said a lot of capital investment up front with long term payback.That's why most of these are used in remote plants far from the power grid,totally government subsidized plants (eg Iceland),or real high end resorts on some remote vulcanic island or location.Some are used for waste heat recovery from other primary operations like steel plants in areas where local government agencies consider hot waste steams to be an environmental concern.
Other than that it's a cool idea.