Energy From Thorium Discussion Forum

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PostPosted: Jan 29, 2014 1:42 pm 
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Cyril R wrote:
KitemanSA wrote:
Cyril R wrote:
Very, very few people change the angle of their solar panels.
True, but immaterial.


Not at all immaterial. The common practice is what determines fleet output and performance.
True, but we were not discussing "common practice" but whether a single specific installation in a single specific location COULD have done that. So the "common practice" IS immaterial.

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PostPosted: Jan 29, 2014 2:51 pm 
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Cyril R wrote:
There are other factors involved as well of course, such as the correlation with demand. In high insolation areas with a modern living standard you see a lot of aircon that correlates reasonably well with solar output (could use a few hours ice storage to deal with afternoon aircon needs). There may be considerable capacity credit in such areas. A properly installed, maintained system in the desert can have a good capacity credit for aircon heavy grids nearby.

In Germany there is the problem that winter is peak demand not summer, and the daily peak doesn't occur at noon either. So you can actually state solar PV has negative capacity credit, it can be considered a drain. In a properly working market the Germans would be paying to get rid of solar panels in Germany, not subsidize more into being.


Air conditioning loads aren't just a problem in the desert. Here in Alberta (49°N to 60°N), it is the summer peaks that put maximum stress on the grid, even though the winter peaks are just as high or even slightly higher. The capacity of transmission lines and the maximum output of thermal powerplants is substantially higher when it is -30°C outside than when it is +30°C.

A large fraction of solar power is impractical without an as yet unknown means of large scale energy storage, but a GW or two of rooftop PV here could stop the rolling blackouts on hot July afternoons. Encouraging people to orient them a bit to the southwest instead of straight south would help shift the output peak closer to the demand peak without too much loss of total output.


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PostPosted: Jan 29, 2014 2:52 pm 
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In that case a high capacity factor on a sunny snowy day is still impossible. The atmosphere takes out so much radiation from the sun, when you're in winter at a northern location there's just too much atmosphere for the light to pass through. Winter noon will be like a summer sunset. Not much power to be had.


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PostPosted: Jan 29, 2014 2:58 pm 
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Quote:
The capacity of transmission lines and the maximum output of thermal powerplants is substantially higher when it is -30°C outside than when it is +30°C.


It makes only a few percent difference for wet cooled powerplants. Much smaller than the difference in aircon - zero at -30C (obviously) and very high at +30C, though it clearly is pushing things the wrong way. |A 10% solar PV contribution would be useful in those areas.

The difference is bigger with dry cooled powerplants but still not that drastic compared to aircon. Cold countries can make use of this, where there is a winter peak from heating, television and lights. PV would be useless, though nuclear could benefit from the colder heat sink.


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PostPosted: Jan 29, 2014 8:04 pm 
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Renewable power really matches with distributed generation rather than bigger grids. It requires storage back up. The gas back up should also be replaced by the 'renewable' bio-fuel powered fuel cell back up. It is still a niche use and has to be supported by coal/nuclear/piped gas base power for heavy use.
Management of used LWR fuel is a major worry in Europe. It has to be burnt in fast MSR to keep amounts in control. Perhaps the Czech republic in center of Europe is thinking on the right lines. The big nuclear power France should also take up fast MSR nuclear as there are worries about sodium fires in current fast reactors.


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PostPosted: Jan 29, 2014 8:22 pm 
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Despite what the greens like to claim the only storage capacity issue for LWR fuel in Europe exists in the minds of regulators and legislators.

AIUI the input wet stores at the La Hague plant are nowhere near full, let alone reactor sites.
And then we have to include stacking of dry casks...


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PostPosted: Jan 29, 2014 9:44 pm 
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In discussing spent fuel I think it is helpful to put numbers into scale. A typical plant generates less than 30 tonnes spent fuel per year and supplies around 1 million people. So we are talking about waste of 30 grams per person per year. Forty years worth of waste is about the size of an orange. Absolutely it must be handled with care but the scale of this problem is pretty small.

Recycling the plutonium into fast reactors or LFTRs and removing the uranium reduces the volume of spent fuel by 95% and removes the long term issues.


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PostPosted: Feb 06, 2014 10:33 pm 
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Don't discount the power of attaching battery storage to those solar PV systems.
This can be done as a latter upgrade.
Solar PV really make little sense in Germany, but in southern USA, southern Europe (and places closer to the equator) they will eventually allow for off grid electricity in parity with buying from the grid at retail. I expect that to happen before 2020.
Li-ion batteries are dropping in price about 8% per year.
It is already speculated (with sound logic) that Tesla is purchasing them at US$ 200 / kWh, so for US$ 200 million a large volume buyer could buy a 1 GWh worth of raw storage capacity. By 2020, this price should half, even without considering newer/cheaper chemistries.
Tesla is looking to building a new giga battery factory to double worldwide production of li-ion batteries. They need it to continue their explosive growth (current models use either 85kWh or 60kWh battery packs, with production projected to break through 100k cars/year in 2015 or 2016, they would need all current li-ion production to make that happen).
Guess what, Solar City (same major shareholder Elon Musk) will get access to those cheap battery packs too.

Don't get me wrong, I would prefer a Thorium/LFTR world, specially since I want to get rid of all fossil fuels (including process heat, either electric cars or synthetic fuels taking over petrol), but the math is compelling.

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PostPosted: Feb 06, 2014 11:06 pm 
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I would be surprised if the economics will work on a grid size battery system. Its not only the cost of the batteries but the replacement of them as well. The batteries age to fast especially when you cycle them every day.


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PostPosted: Feb 07, 2014 3:57 am 
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Tesla's battery pack costs about 50 thousand dollars. With mass manufacturing this is expected to drop into the 20-30 thousand dollar price range. But still very expensive for an offgrid home PV installation. It would mean 20 thousand dollars every 10-15 years or so. Even then there is still a possibility of several bad solar months in a row, it is called winter, the probability of such an event is 1 per year. Even in the Mojave desert the PV output in winter is much lower than in summer. Even with a 85 kWh battery system you risk blacking yourself out in fully offgrid.

This isn't going to happen. People that have a grid nearby will suck on that tit, and play pretend at being green with their battery-less solar PV system.


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PostPosted: Feb 07, 2014 5:59 am 
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The nature's energy storage system includes bio-mass. If you want renewable and have storage, you have to depend on it.
The biomass can be converted to methanol which can produce electricity through Direct or reformed Methanol Fuel Cell. Methanol could be stored and fuel the cells when back up is required. Germany could make use of this method. It would be better with smaller grids balancing their own generation with demand. It could be as unobtrusive as solar panels.
Bigger cities and industrial areas may still require coal, gas or nuclear power.


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PostPosted: Feb 07, 2014 7:09 am 
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There is nowhere near enough biomass to go around.


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PostPosted: Feb 07, 2014 8:11 am 
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Liquid synfuels can have two roles: vehicle propulsion and grid energy storage. Synfuels such as hydrogen, methanol, dimethyl ether, and ammonia can fill both these roles. R&D investment in this area can also solve the long-term problem of peak-cheap-oil.


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PostPosted: Feb 07, 2014 10:17 am 
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To me it is doubtful that chemical energy storage can prove economic for the grid for a very long time - if ever. Pumped hydro works, heat storage for shifting up to a couple of hours generation by 12 hours seems plausible. For seasonal variations schedule maintenance for low season. For many decades natural gas will fill in the rest. Eventually, we need to have the capital cost of nuclear low enough that we can afford to power ramp the reactors.

A long time into the future I could see using low electrical demand season to generate chemical fuels for high value applications like transportation and higher industrial heat than nuclear provides.

But these are problems for my kids to work out. Our focus needs to be replacing coal.


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PostPosted: Feb 07, 2014 12:27 pm 
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Lars wrote:
... For seasonal variations schedule maintenance for low season. For many decades natural gas will fill in the rest. Eventually, we need to have the capital cost of nuclear low enough that we can afford to power ramp the reactors...

For fossil gas producing countries, it will be very hard to economically replace peaking gas plants with anything. Same goes for home heating.

For fossil fuel importing countries, things may be different.

For most of the US, electrical demand in the summer and/or winter is much higher (around 50-100% higher) than in spring or fall. This is much higher than can be covered by taking nukes off-line for maintenance (typical spring-time capacity factor around 80%). So any zero-carbon grid will have low season curtailment (i.e. free electricity).

For a syn-fuel plant that costs $1 per input Watt, and runs on free off-peak electricity with a 25% capacity factor, returning 8% interest on capital, at 60% efficiency, would make syn-fuel for $2.31 per gallon of gasoline equivalent. Note that $1/W and 60% effic are realistic today for hydrogen, and plausible eventually for solid-state ammonia synthesis (neither requires a carbon source, ammonia is NH3).

Hydrogen can be stored seasonally today in locations with depleted (conventional, not tight/shale) gas reservoirs, and ammonia can be stored anywhere in huge refrigerated (non-pressurized) tanks. Like diesel and methanol, ammonia can be burned in internal combustion engines with 25% higher efficiency than gasoline (due to higher viable compression). Ammonia (at 200 psi) also has 25% better energy density than CNG at 3600 psi, and double that of 10,000 psi H2.

The amount of syn-fuel which could be produced with off-peak plants would be similar to the fuel needs of heavy duty trucks, trains, and stationary diesel (i.e. with professional operators), so we would not necessarily have to teach car owners to handle ammonia safely, but it is conceivable.

For China or India, a baseload syn-fuel plant including a nuke might cost $3/Watt, and make fuel for $1.82/gge. So nuclear has similar appeal for making fuel as it is for making electricity, and note a mixed fleet of old and new plants will deliver a lower average cost. Also, it still has major advantages compared to imported oil.

The US gets more energy from petroleum than it does from coal, so China can be expected to follow. If the environment community does not push hard on ammonia fuel, then methanol or other coal-based syn-fuels will eventually fill the roll in non-petroleum producing countries, at very high cost to the environment.

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Last edited by Nathan2go on Feb 07, 2014 4:11 pm, edited 5 times in total.

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