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PostPosted: Aug 16, 2016 10:59 am 
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E Ireland wrote:
Alex P wrote:
50 billion liters of MeOH per year corresponds to about 55 million tonn/year of CO2, that is a monstrous amount...


Well that is only a tenth of UK Carbon Dioxide emissions.


But an important fraction of UK transportation consumption, indeed. Anyway, again, the target of all this is NOT to cut emissions (that can be easily achieved through a deep electrification of the energy system, as I previously said), that is always a good thing, but to store high amounts of electricity in a sustanaible and cost effective way

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And Methanol has the advantage that it can be used as a highly energy dense feedstock for the production of animal feed protein from the bacterium Methylophilus methylotrophus - lots of research was done under the brand name of Pruteen by ICI in the 1980s.
It could replace things like soybean meal imports that run to something approaching a million tonnes a year, and would enable a major expansion in food production in the UK by drastically reducing animal fodder crop requirements. [cut]


If there are a lot of other uses of MeOH/DME than energy, it's always a good thing, even though these will obviously be a small fraction of the total uses


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PostPosted: Aug 16, 2016 11:06 am 
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Alex P wrote:
Interesting enough, even using that very inefficient way to get the CO2 (from limestone/lime) and the most inefficient reaction to produce methanol (and thus DME : CO2 + 3 H2 = MeOH + H2O) the energy cost to produce CO2 is only a quite tiny fraction (~ 20% of the total, if I don't get it wrong) than the energy to produce the hydrogen required (assuming high efficiency low temp electrolysis at 35-40 kWh per kg H as usual) - or, if we prefer, the energy cost of hydrogen production is overwhelmingly preponderant on all the rest. I've never guessed about that !


It is one of those that is not immediately obvious but eventually becomes apparent if you spend as much time studying electrification of random industrial processes as I do.
I originally settled upon it as simply as a limiting condition on carbon dioxide capture - make lime and dump it in the sea, and then realised it was nowhere near as hopelessly uneconomic as I believed it would be in the beginning.


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PostPosted: Aug 17, 2016 2:59 am 
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E Ireland wrote:

It is one of those that is not immediately obvious but eventually becomes apparent if you spend as much time studying electrification of random industrial processes as I do.


Interesting, I' ve always wondered how we can substitute high temperature heat in industrial process, if I remember correctly 80% of that heat in any industrilized country is at a temp > 400 °C (besides that part at a temp, say, > 1000 °C that is already electrified). A bit of that 50 billions liters per year of methanol we said, eventually converted to DME, can substitute some fuel (basically, natural gas) in high temp heat, but I guess that amount is not enough...


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PostPosted: Aug 18, 2016 6:43 pm 
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KitemanSA wrote:
Having water as a storage medium for nuclearpower is kind of silly.

I believe that thermal energy storage is silly.

The need for energy storage is based on the assumption that energy supply cannot match energy demand on time scales varying from minutes, hours, or seasons. Using energy sources like wind and solar this is true. With a nuclear reactor driving a steam turbine this is true, but this problem disappears with a gas turbine. The limiting factor is the steam not the reactor itself, even solid fuel reactors can load follow if somehow removed from the limitations of steam.

The need for energy storage, IMHO, sounds to me like a failure of proper planning of energy generation. Some energy storage systems do not seem terribly illogical though since they can serve purposes besides a failure to plan a proper electrical grid. I'm not completely opposed to pumped hydro storage since they can also serve the needs of irrigation, municipal water systems, and flood control. Using excess electrical capacity for liquid fuel synthesis sounds like a good idea to me since we will need liquid fuels for transportation and making that one of a number of dispatchable energy loads is sensible. I recall hearing about a nuclear power plant that would use the night time excess capacity to produce ice for commercial sale, which sounded to me like a very good idea. People want ice and the nuclear power is essentially a sunk cost, makes sense to use it where and when you can.

With natural gas being so cheap and plentiful it makes sense to use that as a dispatchable energy source. It does not sound like we are going to run out of natural gas any time soon. In the mean time we can work on getting LFTR and similar technologies working on commercial scales. Once we have LFTR we won't need energy storage except for what I've mentioned before, like ice production, liquid fuel synthesis, municipal water storage, and other means where energy storage is more of a secondary benefit.

If I'm missing an important detail then I invite anyone to enlighten me. I've read through this thread so far and I feel like this is an interesting discussion but I'm failing to see the need. We have natural gas now and, I expect, LFTR in the future that can provide load following electric generation.

That said, if I am to assume that energy storage is necessary then I'd like to see that US Navy seawater to jet fuel system used. We need liquid fuels at a nearly incredible rate, anything that can turn domestic sourced thorium into domestic hydrocarbon fuels makes me happy for many reasons.

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PostPosted: Aug 18, 2016 7:24 pm 
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Excellent points, Kurt, as usually. The rebuttal I suspect will be interesting.

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PostPosted: Aug 18, 2016 8:29 pm 
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Kurt Sellner wrote:
I believe that thermal energy storage is silly.

The need for energy storage is based on the assumption that energy supply cannot match energy demand on time scales varying from minutes, hours, or seasons. Using energy sources like wind and solar this is true. With a nuclear reactor driving a steam turbine this is true, but this problem disappears with a gas turbine. The limiting factor is the steam not the reactor itself, even solid fuel reactors can load follow if somehow removed from the limitations of steam.

You can easily load follow with a nuclear reactor this is true - but this does not change the fact that this is a terrible idea.
You have a power plant that is effectively charged by the kilowatt - with little to no operating costs that are actually dependent on the amount of electricity actually generated. It is pretty much only fuel and with some reactors even that is not dependent on the power generated as you will want to refuel in the off season for operational reasons - so you may potentially be forced to unload only partially burned fuel to avoid running out of EFPDs in mid-winter. [This was not a problem in the Magnox or AGR, and even in the SGHWR the refueling period was under 48 hours]
Since you have already paid for a plant that costs almost nothing to run if you have it - the levelised cost of electricity is effectively proportional to the inverse of the capacity factor.
Using 2kWe of plant half the time costs about twice as much as using 1kWe all the time.
Kurt Sellner wrote:
The need for energy storage, IMHO, sounds to me like a failure of proper planning of energy generation. Some energy storage systems do not seem terribly illogical though since they can serve purposes besides a failure to plan a proper electrical grid. I'm not completely opposed to pumped hydro storage since they can also serve the needs of irrigation, municipal water systems, and flood control. Using excess electrical capacity for liquid fuel synthesis sounds like a good idea to me since we will need liquid fuels for transportation and making that one of a number of dispatchable energy loads is sensible. I recall hearing about a nuclear power plant that would use the night time excess capacity to produce ice for commercial sale, which sounded to me like a very good idea. People want ice and the nuclear power is essentially a sunk cost, makes sense to use it where and when you can.

In this case, energy storage is proper planning of energy generation.
Why overbuild to cover peak power demand when you can use storage to allow fewer reactors to perform the same task of supplying demand - which is after all our objective. There is however a limitation to this caused by the economics of energy storage which is where the idea of disposing of excess electricity through interesting industrial processes comes from - after all most places do not have lakes the size of Hydro Quebec's to use as seasonal pumped storage.
Kurt Sellner wrote:
With natural gas being so cheap and plentiful it makes sense to use that as a dispatchable energy source. It does not sound like we are going to run out of natural gas any time soon. In the mean time we can work on getting LFTR and similar technologies working on commercial scales. Once we have LFTR we won't need energy storage except for what I've mentioned before, like ice production, liquid fuel synthesis, municipal water storage, and other means where energy storage is more of a secondary benefit.

Speak for yourself - my own country became a net importer of gas ten years ago and it appears that gas production has collapsed - the hoped for recovery crushed by shale gas.
And since I actually want a zero-net (or even negative-net) carbon dioxide release system I'm afraid natural gas is off the table.
And if carbon emissions are not a concern you share then I am afraid nuclear is dead. H-class CCGTs have killed them, as you say natural gas is really [globally] cheap and plentiful - so cheap and plentiful there is little reason to ever use anything else without global warming concerns. (Henry Hub prices stand around $2.60/million BTU, which in a ~60% efficient CCGT equals something like 1.5 US cents/kWh in fuel cost)

LFTR will not be able to escape the primary cost of a nuclear power plant - the cost of building them, infact the problem is even more acute than with a LWR because whilst a light water reactors fuel cost is small an LFTR's is well and truly negligible.
And LFTRs are not going to be able to compete with CCGTs on capital cost - despite what the ~$1500/kWe claimants would say [that is never going to happen].
Kurt Sellner wrote:
If I'm missing an important detail then I invite anyone to enlighten me. I've read through this thread so far and I feel like this is an interesting discussion but I'm failing to see the need. We have natural gas now and, I expect, LFTR in the future that can provide load following electric generation.

Load following with nuclear is literally setting banknotes on fire.
If you have the [nuclear] plant it will be generating [steam or electricity or similar] unless there is some technical reason why it can't.
Which generates very cheap off peak electricity and increases the effective price of peak electricity - producing the economic conditions for energy storage.
Kurt Sellner wrote:
That said, if I am to assume that energy storage is necessary then I'd like to see that US Navy seawater to jet fuel system used. We need liquid fuels at a nearly incredible rate, anything that can turn domestic sourced thorium into domestic hydrocarbon fuels makes me happy for many reasons.


I'm afraid the seawater scheme comes out considerably worse in economic terms than simply firing limestone, just too much pumping for too little product gas.


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PostPosted: Aug 18, 2016 9:36 pm 
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E Ireland wrote:
You can easily load follow with a nuclear reactor this is true - but this does not change the fact that this is a terrible idea.
...
Using 2kWe of plant half the time costs about twice as much as using 1kWe all the time..

I understand that there is a cost to not running a nuclear power plant at optimal capacity but there is also a cost to energy storage. This cost is not just monetary since, as many will agree here, there is a less tangible cost to the environment. Digging holes in the ground and filling them up with near boiling water is going to affect the local wildlife. I can see Mr. NIMBY and Ms. BANANA* holding up signs to protest the construction.

*For those unfamiliar with the term: BANANA = build absolutely nothing anywhere near anyone

E Ireland wrote:
In this case, energy storage is proper planning of energy generation.
...
after all most places do not have lakes the size of Hydro Quebec's to use as seasonal pumped storage.

Again I agree but then my concern is over using thermal energy storage when other more practical systems present themselves. Pumped hydro is nearly ideal when the geography allows for it. When pumped hydro is not available then I can see things like fuel synthesis, ice production/storage, and other dispatchable loads as feasible. These are not reliant on geography.

E Ireland wrote:
Speak for yourself - my own country became a net importer of gas ten years ago and it appears that gas production has collapsed - the hoped for recovery crushed by shale gas.
And since I actually want a zero-net (or even negative-net) carbon dioxide release system I'm afraid natural gas is off the table.
...
And LFTRs are not going to be able to compete with CCGTs on capital cost - despite what the ~$1500/kWe claimants would say [that is never going to happen].

Well I don't share the fears that many have over CO2 production. I'm content with natural gas for energy. If we assume that natural gas is bad, even though we get much more energy per CO2, and/or natural gas is simply not economically viable then LFTR will be able to compete. If there is no natural gas, or coal, then all that is left is nuclear. If in the short term we need some sort of energy storage to make up for the time between what is used now and when LFTR can come on line then perhaps thermal storage is optimal if only due to a lack of any other choice.

E Ireland wrote:
Load following with nuclear is literally setting banknotes on fire.
If you have the [nuclear] plant it will be generating [steam or electricity or similar] unless there is some technical reason why it can't.
Which generates very cheap off peak electricity and increases the effective price of peak electricity - producing the economic conditions for energy storage.

This gets back to my previous comment on the cost of the energy storage. So long as the storage system is cheap and efficient enough to make economic sense then I can understand it's use. I'm just not sure the economic case can ever be made when there are options to load shift through economic incentives, such as reduced rates for factories that run at night.

E Ireland wrote:
I'm afraid the seawater scheme comes out considerably worse in economic terms than simply firing limestone, just too much pumping for too little product gas.

I can get behind that. After the discussion over lime production with Prof. Siemer in another thread I can see the benefit. Lime is a very valuable agricultural and industrial feedstock which if it can be produced without burning more fossil fuels then we can put a good sized dent in the CO2 we produce.

I do believe that the economic case for synthesized hydrocarbons will be made at some near future date. It might not use seawater as the feedstock but we will continue to need hydrocarbons and we'll find a way to keep it flowing.

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PostPosted: Aug 19, 2016 4:49 pm 
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When you have a source who's cost is mainly capital, then you want to run it constantly to reduce the % of the product cost that is capital. So the simple question is, does it make economic sense to absorb the capital cost of NOT running it or should it be run and the product stored. Sometimes "just in time" makes sense. Sometimes a bit of warehousing makes sense.

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PostPosted: Aug 19, 2016 5:21 pm 
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Additionally for maintenance constraints and operational reasons mentioned before (shutting down your core may not actually save any fuel and spooling up and down tends to cause a large fraction of equipment breakage) you might chose to continue running your plant even though there is literally no market for the energy - if you have some method of dispersing it. For example some reactors might be provided with resistor grids.

An LFTR has this in spades since the cost of fuel is a few dollars per day at full power and the only other marginal cost is marginal graphite life - and since most of your reactors has mid life graphite changing that will likely be planned years in advance and there is thus little incentive to shut down and delay the change.


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PostPosted: Aug 22, 2016 8:08 am 
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E Ireland wrote:
Additionally for maintenance constraints and operational reasons mentioned before (shutting down your core may not actually save any fuel and spooling up and down tends to cause a large fraction of equipment breakage) you might chose to continue running your plant even though there is literally no market for the energy - if you have some method of dispersing it. For example some reactors might be provided with resistor grids.

An LFTR has this in spades since the cost of fuel is a few dollars per day at full power and the only other marginal cost is marginal graphite life - and since most of your reactors has mid life graphite changing that will likely be planned years in advance and there is thus little incentive to shut down and delay the change.


You could put the "resistor grid" offshore.

http://www.bbc.com/future/story/2015050 ... -the-ocean
https://en.wikipedia.org/wiki/Biorock
Quote:
Over three decades of practical experience with biorock have shown that one kilowatt hour of electricity will result in the accretion of about 0.4 to 1.5 kg (0.9 to 3.3 lb) of biorock, depending on various parameters such as depth, electric current, salinity and water temperature.


I think this is a good use of surplus electricity. Just build an artificial reef - say along the UK East Coast, and end all the issues of coastal erosion.

I recall working the figures and the energy is about the same as producing concrete - but this allows direct in-situ placement in the sea.

1TWh gives about 1 million tons of biorock.


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PostPosted: Aug 22, 2016 7:45 pm 
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KitemanSA wrote:
When you have a source who's cost is mainly capital, then you want to run it constantly to reduce the % of the product cost that is capital. So the simple question is, does it make economic sense to absorb the capital cost of NOT running it or should it be run and the product stored. Sometimes "just in time" makes sense. Sometimes a bit of warehousing makes sense.


I can certainly understand the desire to make the most of a large capital investment in order to increase profits and/or reduce time for payback. What storage technologies do is add an additional capital expense on the hope that it will make that money back by being able to buy electricity at low cost and sell it later at a higher price. These storage technologies must also compete with other means to shift load, so the capital expense and payback must look better on the balance sheets than this competition.

Having taken a course in college on electrical power distribution I know a few things about what these things are, how they work, and how much they cost. This class was some time ago so my memory is fuzzy on some of the details and I'm quite certain some new techniques and technologies have come up since. I don't know how much I should go into this since that might lead us off topic.

My point is that while estimating the costs of these storage technologies is an interesting exercise I believe that they are of limited utility unless there is a comparison to the costs of other techniques used to manage production and load. A widely used and certainly effective means to manage this is by on demand pricing. There are clearinghouses that price electricity on a minute by minute basis which manage production and load between the people that produce electricity, distribute electricity, and consume electricity.

I'd also like to just touch on the regulatory issues on this. In college I attended a conference for utilities to discuss matters on electricity production and distribution, there I learned a bit about the rules on those that buy and sell electricity. Again I'm not sure how much I want to go into this for fear of derailing the thread but that regulation is a cost that would need to be addressed in making a business case for electricity storage.

Because of what I know on this I am an advocate for the synthesis of hydrocarbons as energy storage. The business case is easier to make (people will no doubt buy hydrocarbons), it avoids the issues of introducing electricity back to the grid (let the utilities do that, just sell them the methane), and generally the math is simpler (the price of synthetic hydrocarbons vs. petroleum). There are other synthetic fuels that can also fall in this space, like hydrogen, ammonia, carbon monoxide, and some others that I know I missed.

Most, if not all, of these synthetic fuels also have non-fuel uses which also improves the business case. Thermal energy storage only has this flexibility if located very close to customers that are willing to buy this heat. Certainly not an insurmountable problem but also not trivial.

While the numbers for hot water storage of energy may be impressive at first glance I just don't know what to think about them without a frame of reference. I'm certain that anyone that is looking for an investment opportunity will have the same demands.

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PostPosted: Aug 22, 2016 8:50 pm 
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Kurt Sellner wrote:
KitemanSA wrote:
When you have a source who's cost is mainly capital, then you want to run it constantly to reduce the % of the product cost that is capital. So the simple question is, does it make economic sense to absorb the capital cost of NOT running it or should it be run and the product stored. Sometimes "just in time" makes sense. Sometimes a bit of warehousing makes sense.


I can certainly understand the desire to make the most of a large capital investment in order to increase profits and/or reduce time for payback. What storage technologies do is add an additional capital expense on the hope that it will make that money back by being able to buy electricity at low cost and sell it later at a higher price. These storage technologies must also compete with other means to shift load, so the capital expense and payback must look better on the balance sheets than this competition.
Well, for off site storage, maybe. But using thermal storage to turn a 1x24/7 power plant into a 2x12/7 power plant merely tries to make more electricity when it is wanted in the first place.

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PostPosted: Nov 28, 2016 4:41 pm 
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I have an alternative solution, based on new data.


The British Geological Survey turns out to have done an economic study on using underground mines at 300+m for aggregate production, in comparison with current surface quarries located more distantly from the demand hub. Using the South East of England as an exemplar.

Turns out the cost of production is something like ~£13/t as opposed to roughly ~£10 - with 13.5 million tonnes a year or more of potential demand.
Which means, using typical limestone as an example, the effective cost of large underground caverns is only about ~£7.50/cubic meter. Which is under $10/cubic metre.
Now by pressurising the cavern with compressed air to an appropriate pressure, you can use thin walled insulated tanks to store pressurised water at arbitrary pressures without exposing the cavern walls to problematic high temperatures.

This was studied in the 70s and using a triple-flash steam plant to convert the fluid into steam at varying pressures it can be used to generate electricity with at least ~21kWh(e) per cubic metre. A more modern steam plant or a supercritical carbon dioxide Rankine Cycle would be able to do much better in volumetric and energy efficiency terms.
It is likely that turnaround efficiency will be 75% or more and the cost per cubic metre of storage is something approaching ~$0.50/kWh.
And since we are storing pressurised water it can be pumped over large distances without enormous pumping losses.

This seems to certainly be a winner of a concept - and over time it could be developed to something appraoching the gigawatt-year level.

EDIT:
Found a report that suggests a supercritical carbon dioxide rankine cycle using brine at 250 celsius, and exhausting heat at 28 celsius carbon dioxide bottoming temperature can obtain approximately 20% efficiency. With a brine return temperature of 89 celsius.
That translates to something like 39kWh/tonne of water, or something like 31kWh per cubic metre.
Which is a lot, the price would depend on the supercritical carbon dioxide turbine etc. but that can benefit from recent work with the Allam cycle and its inherent compactness.
Even the condenser pressure is atleast several bar, potentially several MPa.


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