A Thought on Geothermal Energy

[eclipsenow]

How much R&D money has it taken to give us solar? Let's start with the simple PN junction.

The major drawback to solar is storing the energy for night, and for cloudy days.

The major positive is that it's 1/4 the LCOE cost of nuclear. This means you can overbuild it for both winter seasonal variation and overbuild for the fact that it only works 1/3 the day. Overbuild + off-river pumped hydro storage = cheaper than fossil fuels if you count the health costs of coal, oil and gas.

 

[Tuur]

The major positive is that it's 1/4 the LCOE cost of nuclear. This means you can overbuild it for both winter seasonal variation and overbuild for the fact that it only works 1/3 the day. Overbuild + off-river pumped hydro storage = cheaper than fossil fuels if you count the health costs of coal, oil and gas.

Except the storage doesn't exist in sufficient quantity. That's why there needs to be energy storage built first.

 

[HARK!]

The major positive is that it's 1/4 the LCOE cost of nuclear. This means you can overbuild it for both winter seasonal variation and overbuild for the fact that it only works 1/3 the day. Overbuild + off-river pumped hydro storage = cheaper than fossil fuels if you count the health costs of coal, oil and gas.

Again this storage is not in place. It's inefficient, and costly to build. If it was that easy; it would have been done already. I didn't mention nuclear. There is a huge difference between fusion and fission.

 

[Tuur]

Again this storage is not in place. It's inefficient or costly to build. If it was that easy; it would have been done already. I didn't mention nuclear. There is a huge difference between fusion and fission.

Pumped hydro storage dates back maybe to at least the 1980s. But there was a case in Georgia where an energy producer built pumped hydro storage, and on the big day they demonstrated it for the public, there was a plum of red in the water. Turned out that the turbines had pureed fish from the upper reservoir, and right in front of reporters. Not good. Whether it was the bad press from that or something else, the power producer ended up selling another pumped hydro facility under construction. But to the best of my knowledge, neither has built any additional pumped hydro facilities.

 

[HARK!]

Pumped hydro storage dates back maybe to at least the 1980s.

I'm well aware of that. I had considered building such a system on my own property. It's just not practical.

 

[eclipsenow]

Again this storage is not in place. It's inefficient, and costly to build. If it was that easy; it would have been done already. I didn't mention nuclear. There is a huge difference between fusion and fission.

I was just showing the price structure. I do often mention nuclear - as I've been a nuclear fission fan for ages. I've only recently begun to rethink all my old concerns about VRE (Variable Renewable Energy) because the prices have come down so much.

However, who said storage must be built first? Sydney's population has grown by 2 million over the last few decades but the peak in demand on the electricity grid was 12 years ago - in mid 2010. Why? All that growth in solar power offset the growth in population and corresponding growth in electricity demand. Solar can have HUGE effects without demanding it be absolutely 100% of the grid straight away.

I'm getting solar soon - and will overbuild so I'm ready to hook up my next car. My next car will probably be an EV. (This is all hypothetical at the moment - I'm happy with my little car for now.) But when I get an EV, it will be like having an oil refinery on my roof!

But as VRE grows on our grids, we will of course need more storage. A medium sized off-river pumped hydro can be built in 3 years because you work on all parts of it at once and then fill it with water.
Maps show America has 100 times the potential for OFF-river. Pick the best 1% and you're done! ⁠100% Renewable Energy Group

 

[Tuur]

However, who said storage must be built first? Sydney's population has grown by 2 million over the last few decades but the peak in demand on the electricity grid was 12 years ago - in mid 2010. Why? All that growth in solar power offset the growth in population and corresponding growth in electricity demand. Solar can have HUGE effects without demanding it be absolutely 100% of the grid straight away.

Ah...if you're not putting them on rooftops, solar won't reduce peak demand. Demand per customer tends to drop due to increased energy efficiency, such as major appliances.

 

[eclipsenow]

Ah...if you're not putting them on rooftops, solar won't reduce peak demand.

Huh? It doesn't matter where you put them - rooftop or utility - the sun shines at the same time and the evening mealtime demand curve kicks in a bit after in some seasons. Location within the same state doesn't really impact this - storage does. Also Australia has off-rooftop schemes where renters and people in apartments can buy solar out in rural areas where the real estate is cheaper. They buy into this solar farm, own there solar panels, and for a small admin fee then get them supervised and their solar panel contribution refunded off their electricity bill - even if they're hundreds of miles away.

Demand per customer tends to drop due to increased energy efficiency, such as major appliances.

Um, still not sure what you're saying? Sure Solar Gardens or even utility scale solar is further away. But Utility solar comes in at HALF the cost of rooftop solar due to economies of scale. (Less inverters etc per panel.)

 

[Tuur]

Huh? It doesn't matter where you put them - rooftop or utility - the sun shines at the same time and the evening mealtime demand curve kicks in a bit after in some seasons. Location within the same state doesn't really impact this - storage does. Also Australia has off-rooftop schemes where renters and people in apartments can buy solar out in rural areas where the real estate is cheaper. They buy into this solar farm, own there solar panels, and for a small admin fee then get them supervised and their solar panel contribution refunded off their electricity bill - even if they're hundreds of miles away.


Um, still not sure what you're saying? Sure Solar Gardens or even utility scale solar is further away. But Utility solar comes in at HALF the cost of rooftop solar due to economies of scale. (Less inverters etc per panel.)

Peak demand is peak use of electricity on the electric grid. So let's say a power supplier installs hectares of solar panels and connects them to the grid. Nothing else changes. The peak demand remains the same, because customers are still using the same amount of electricity from the grid. The only thing that's changed is the source of the electricity.

Now: Let's say that customers also install solar panels on their roofs or backyards and tie it into their home. That reduces the amount of electricity each customers receives from the grid, which reduces peak demand. Now, if nothing else changes, if you measure the total consumption of electricity, the total amount used by each customers remains the same, just they use less from the grid. But since peak demand is the peak use of electricity from the grid, that reduces the peak.

The big take-away here is that any source of electricity tied directly to the grid doesn't reduce peak demand. But if another source of electricity is tied to the customer, that does reduce the peak demand.

It occurs to me that you might be using the term to indicate how much electricity the utility has to purchase from power suppliers. Have seen large diesel generators used to reduce costs during times of peak demand (diesel was much cheaper then), but from the utility's perspective, how much electricity used by their customers didn't change.

 

[eclipsenow]

That reduces the amount of electricity each customers receives from the grid, which reduces peak demand.

Yes I see what you mean. You're talking about Sydney's electricity demand not growing correspondingly to the population growth because of our amazing growth in ROOFTOP solar panels. I agree with the point you're making.

My point about pumped hydro is we can use solar power to store 'gravity energy' for after the sun has gone down. Hey - as the world moves to EV's and people charge at home or work even on cloudy days (works at 50%) - who knows how much we'll even have to store?

 

[Tuur]

My point about pumped hydro is we can use solar power to store 'gravity energy' for after the sun has gone down. Hey - as the world moves to EV's and people charge at home or work even on cloudy days (works at 50%) - who knows how much we'll even have to store?

How many are being built, though? That's my point there. The craze right now is solar panels and wind generation, and no one wants to focus on how to make them work like other generation.

 

[chilehed]

...off-river pumped hydro...

It's inefficient, and costly to build

Pumped hydro storage dates back maybe to at least the 1980s.

Large-scale pumped hydro storage isn't nearly as easy many people seem to think.

Let's assume a small-sized city of 10,000 homes, which would have a power requirement of about 100 megawatts, in a mountainous area like Colorado where we can put the storage reservoir way up a valley somewhere, let's say 500 meters. With an effective head of 500 meters and an overall turbine/generator efficiency of 0.8 you'd need 25 m^3/sec of water to run the plant. A 3 meter diameter concrete pipe that's 500m long would have a head loss of about 200 meters, so you'd have to put the reservoir up that much higher to offset that - now you're at 700 meters above the plant. To power the plant for twelve hours you'd need to store 25m^3/sec * 43,200 sec = 1,100,000 m^3 of water. That's about 890 acre-feet, so you have to find a place where you can put an 89 acre lake that averages ten feet deep. Note: that's enough water to supply the daily needs of about 12,200 households.

Then, assuming a pumping efficiency of 0.8, you need to build a 125 megawatt pumping station to get the water up there. To supply it you'd need either a sufficiently large river, or else another 890 acre-foot reservoir to store the water at the bottom of the hill for reuse (in which case you'd still need a river to supply makeup water as it evaporates).

Now you get to build the 125+ megawatt solar farm that will be used exclusively to pump the storage water uphill during the daytime.

So in order to build one 100MW hydro plant to use pumped-storage water, you need to actually build three plants that each handle 100MW or more of energy. This is a VERY expensive proposition.

What if you're not in Colorado and don't have a place 700 meters above you to put the reservoir? What if you only have... I dunno... 100 meters? Well, first off the reduced head will result in lower turbine efficiency, but let's ignore that for now. In that case the hydro plant would need 127 m^3/sec of water and a 12 hour supply of water would be 4,460 acre-feet, which is five times larger. And because that flow of water in a single 3m meter diameter and 200 meter long supply pipe would have a head loss of over 2,000 meters (which means you'd never get enough flow from a single pipe), you'd need to put in a bunch more of them to feed the turbines: twelve pipes would give a head loss of 16 meters. So now you better hope you really have a 116 meter tall spot and the political will to create at least one (and perhaps two if you really need to) ten-foot deep, 446 acre storage pond - enough for the daily use of over 60,000 households.

And again, this is for the needs of one small-sized city. Multiply appropriately for a place like Denver, LA or Chicago.

 

[eclipsenow]

How many are being built, though? That's my point there. The craze right now is solar panels and wind generation, and no one wants to focus on how to make them work like other generation.

They don't need to. Yet. Personally I think every nation could do with an energy tsar that would oversee national grids as a matter of national security. Imagine an enemy force has unloaded a bunch of tanks on your beaches, and you're watching it stream live. Someone in your living room says "Don't worry, the marketplace will deal with it." I mean, huh?
I know this is a rather extreme metaphor, but this is exactly what we've seen going on in Europe - a blithe handing over of energy supply to the cheapest supplier without any thought as to national security implications. I am of course talking about Russia buying gas off Germany - and how their former energy minister is now on a cushy million-euros-a-year salary with Gazprom. An energy tsar doesn't mean we have to nationalise energy - but they would oversee these matters and make sure that it didn't just work - but was secure. Home grown. Clean. And reliable.
This is the one area where (shudders at the next statement) I actually happen to agree with former President Trump. (I feel an OCD urge to wash my hands after typing that!) When confronting NATO (and I disagree with his general stance on NATO), he asked a very precise, intuitive question that has since come to smack the world in the face! Why should America continue to have bases in Europe to protect them from Russia while Germany and other European countries were buying so much gas off them? That's like asking beat cops for extra men to police your shopping district while on the side continuing to pay the mafia ever increasing fees for 'security'. They propped up the Russian military industrial complex - and are still pretty much paying for this war in Ukraine!
Energy matters. It's the backbone of the modern world. Every calorie we eat took 10 calories to grow that food - not including transport and cooking! Abundant reliable electricity is becoming even more important to our nations as we move into an era where we 'electrify everything.'

1. Do you agree?
2. Would you write to your local members of state and federal government to ask them to appoint an energy tsar to oversee these matters?
3. This is not an appeal to become a Communist - but that an energy tsar might for example note the need for more pumped hydro storage - and put out a market tender for applications to build the project and then select the best company.
4. Or if the market process was too slow, just downright call in the army engineers to rush-build the thing! Energy is THAT important!

 

[HARK!]

Every calorie we eat took 10 calories to grow that food - not including transport and cooking!

I read a report many years ago that it takes one pound of petroleum to get a pound of food onto your grocery market shelf.

This included the petroleum needed to till the soil, petroleum based fertilizers, petroleum based pesticides, the petroleum used to harvest the crops, and the petroleum to transport those crops.

 

[eclipsenow]

Large-scale pumped hydro storage isn't nearly as easy many people seem to think.

Let's assume a small-sized city of 10,000 homes, which would have a power requirement of about 100 megawatts, in a mountainous area like Colorado where we can put the storage reservoir way up a valley somewhere, let's say 500 meters. With an effective head of 500 meters and an overall turbine/generator efficiency of 0.8 you'd need 25 m^3/sec of water to run the plant. A 3 meter diameter concrete pipe that's 500m long would have a head loss of about 200 meters, so you'd have to put the reservoir up that much higher to offset that - now you're at 700 meters above the plant. To power the plant for twelve hours you'd need to store 25m^3/sec * 43,200 sec = 1,100,000 m^3 of water. That's about 890 acre-feet, so you have to find a place where you can put an 89 acre lake that averages ten feet deep. Note: that's enough water to supply the daily needs of about 12,200 households.

As far as I can tell - good math so far - although I'm just reading fast but you're using all the right terms. I don't do these calculations myself but just read the papers that pass peer-review - I'm a humanities geek myself.

Then, assuming a pumping efficiency of 0.8, you need to build a 125 megawatt pumping station to get the water up there. To supply it you'd need either a sufficiently large river, or else another 890 acre-foot reservoir to store the water at the bottom of the hill for reuse (in which case you'd still need a river to supply makeup water as it evaporates).

Yes - pumped hydro is only 80% efficient.

Now you get to build the 125+ megawatt solar farm that will be used exclusively to pump the storage water uphill during the daytime.

With you so far.

So in order to build one 100MW hydro plant to use pumped-storage water, you need to actually build three plants that each handle 100MW or more of energy. This is a VERY expensive proposition.

Now I'm lost - but I might be misunderstanding you?

You only need 1 lot of solar to push the water up that hill to get 80% of the energy back. That's true. This might just be semantics but it's how my brain sees this picture. (Again, I'm a humanities geek that sees things in stories and metaphors, not equations as much.)

Where I see the extra solar being required is that while your first solar farm is pumping the water up the hill, and 'only' going to get 80% back (which is the figure the Australian National University guys I'm reading give), then what's it not doing. It's not running your town.

So you need two "lots" of solar (of whatever required size.) No figures here - just broad concepts to illustrate what almost any geography would be dealing with (south of the Arctic circle at least).

Then we have to deal with the fact that winter has a lot less sunshine, and there are even Dunkelflautes (Dark Lulls) to deal with. So you overbuild your "lot" again (either in a local town grid, or a state or even national sense.)

Now you have roughly 3 lots of VRE (Variable renewable energy) to both run your town and pump all that water uphill. Every time there's a power excess - like peak solar output - your town grid 'breathes in' all that VRE and pumps water uphill. Then at night as there's only a little scattered wind around, your town 'breathes out' as all that water runs downhill, keeping your grid running.

BUT WAIT THERE's MORE! We still haven't talked about replacing OIL!
Converting transport to EV's and e-fuels (hydrogen, synfuels, etc) apparently takes us through to 6 TIMES today's electricity grids. But with solar at 1/4 the cost of nuclear, and wind even cheaper - the accumulative cost is still CHEAPER than today's grid. And that does not even include 'outsourced' expenses of fossil fuels like the health cost of coal and oil and gas particulates, which basically doubles your electricity bill. But you just pay it over in your healthcare sector! It's a stealth-cost.

So what did the Australian National University Blakers team model? This study was also accepted and published by our CSIRO. (Like your DARPA).

Blakers
PV and wind allow Australia to reach 100% renewable electricity rapidly at low cost.
Wide dispersion of wind and PV over 10–100 million hectares reduces cost.
Off-river pumped hydro energy storage is the cheapest form of mass storage.
There are effectively unlimited sites available in Australia.
LCOE from a 100% renewable Australian electricity system is US$70/MWh (2017 prices).
100% renewable electricity in Australia - ScienceDirect

That's the cost with 6 times overbuild! Clean skies, energy independence, and a cheaper health bill. Local jobs. Let alone not annoying other trading nations that take climate change seriously. What's not to love?

When counting off-river, Australia has 300 TIMES the POTENTIAL off-river pumped hydro storage required to take Australia 100% renewable. Other maps show America has 100 times. Pick the best 1% and you're done! ⁠100% Renewable Energy Group

 

[chilehed]

Now I'm lost - but I might be misunderstanding you?

You've got a 100MW hydro station. You need a 125MW pump station to pump the water uphill. And you need a 125+ MW solar farm to power the pump station.

EDIT: Okay, I see where I went off the rails. I was thinking of a Pelton wheel turbine, it's the optimal design for very high heads but it can't pump water so you'd need a separate pump to send the water uphill. If you use a Francis turbine you can use it to pump the water uphill, so you don't need a separate pumping station, but they lose a lot of efficiency running in reverse. My mistake.

Every time there's a power excess - like peak solar output - your town grid 'breathes in' all that VRE and pumps water uphill.

It sounds like you're assuming an unlimited reservoir capacity. Magical thinking.

 

[Tuur]

They don't need to. Yet.

We're already past the point we've needed to do so in some parts of the US. For a time this past summer, California had to ask people not to charge their electric vehicles at night because the solar panels don't work when the sun goes down, and there wasn't enough electricity to go around.

 

[eclipsenow]

EDIT: Okay, I see where I went off the rails. I was thinking of a Pelton wheel turbine, it's the optimal design for very high heads but it can't pump water so you'd need a separate pump to send the water uphill.

I'll take your word for it - I haven't got into the nomenclature of the different pump types yet! You're way ahead of me there.

If you use a Francis turbine you can use it to pump the water uphill, so you don't need a separate pumping station

Check Real Engineering - he has video footage of one of these in action in Ireland.

"It sounds like you're assuming an unlimited reservoir capacity. Magical thinking."

Yes, I guess I'm prone to hyperbole in the way I write. I said "Every time there's a power excess - like peak solar output - your town grid 'breathes in' all that VRE and pumps water uphill" when what I meant was 'breathes in' the required storage. It's not unlimited - in fact due to economic cost we're trying to limit how much storage we need in the first place. So again, the ANU Professors assume we'll overbuild Wind and Solar to meet as many electricity needs as we can in real time. We overbuild for a Dunkelflaute.

After studying Australian weather data for years and estimating various variable renewable energy scenarios involving Wind, Water (off-river-pumped hydro) and Solar, they decided to overbuild for the worst winter weeks to maximise renewables output and minimise storage costs. (Storage costs more than just building extra solar farms for winter and turning them off in summer.) This is what they found:-

“PV and wind allow Australia to reach 100% renewable electricity rapidly at low cost. Wide dispersion of wind and PV over 10–100 million hectares reduces cost. Off-river pumped hydro energy storage is the cheapest form of mass storage. There are effectively unlimited sites available in Australia. LCOE from a 100% renewable Australian electricity system is US$70/MWh (2017 prices).”

100% renewable electricity in Australia - ScienceDirect

Using satellite data they've found the world has vastly more potential off-river pumped hydro sites for all the storage we need. As Real Engineering shows above - this is a mature technology. It seems WWS really is enough!

 

[chilehed]

Yeah, yeah, I know about sizing solar farms to account for off-peak solar load, it's just not relevant to what I'm saying. You don't need to keep repeating yourself as if I don't understand the concept, because I do. And, TBH, I think it has an elegant simplicity that would appeal to my engineering sensibilities were it not for the significant system integration issues that will come into play if we try to scale it to a significant percentage of total energy capacity.

Check Real Engineering - he has video footage of one of these in action in Ireland.

Good video. The bit starting at 10:50 discusses the issues I've raised, and others that I thought of but didn't bring up. I get the feeling that you don't realize how significant they are.

Again, it's simple in concept, but it's far from easy to implement. People may nod their heads at the idea of flooding hundreds of thousands (millions) of acres to create power plants, but they'll scream bloody murder when it's planned to happen in their own back yard, even if they're not the ones whose land is taken under eminent domain. Count on it.

 

[eclipsenow]

system integration issues

What are they? Frequency control?

T

he bit starting at 10:50 discusses the issues I've raised, and others that I thought of but didn't bring up.

Siting and evaporation? Was there something else?
While I love the way he breaks down advanced engineering concepts for a lay person like myself, I get the feeling he hasn't studied the topology of Ireland as thoroughly as his assertions would claim.

The Blakers team drew up a world Atlas of potential sites based on algorithms on the following energy requirement assumptions.

How much storage is needed?
An approximate guide to storage requirements for 100% renewable electricity, based on analysis for Australia, is 1 Gigawatt (GW) of power per million people with 20 hours of storage, which amounts to 20 GWh per million people [2]. This is for a strongly-connected large-area grid (1 million km2) with good wind and solar resources in a high-energy-use country. Local analysis is required for an individual country. For example, Australia needs about 500 GWh (and has storage potential that is 300 times larger) and the USA needs about 7000 GWh (and has storage potential that is 200 times larger).
Terria Map​

Ireland has 5 million people * 20 GWh = 100 GWh storage. Now I'm no expert on using the Blakers Global Atlas of potential sites drawn up by algorithm - sites which of course would need environmental and cultural impact studies. But within a short period I found the following potential sites.

Two 50 GWh sites

These 15 GWh sites

These 5 GWh sites

but they'll scream bloody murder when it's planned to happen in their own back yard

Nimbyism really kicks in with ugly transmission lines that dominate the skyline, but these PHES are not up in the sky. Our Snowy 2.0 scheme is not the best site, and is quite an expensive government led program that many 100% renewable fans here in Australia are not that pleased with. But my point? It's being built in a national park because most of the tunnelling and power station is by definition underground, and the catchment reservoirs have been found not to be too destructive or visible.

And the money involved in rural wind and solar backed by local PHES could bring rural economies back to life.

I'm not against nuclear - far from it. In fact, unless countries high up towards the Arctic circle want to import most of their power as the sun gets low in the sky - what other option do they have? But I'm just saying wind and solar are deploying globally 3 TIMES faster than all other power sources combined. We've got a number of ways of stitching all this extra capacity together, be it via super-grids or smaller PHES grids. EG: Pumped hydro can also potentially be used to reduce transmission upgrade costs by buffering the transmission, for example a 100MW solar farm could be connected to the grid with 50MW transmission if there is a nearby pumped hydro facility by charging the pumped hydro facility with the remaining 50MW during the day and offloading the rest at night.