What Is the Most Efficient and Safest Method to Generate Electricity?

[votingmachine]

It's not wasteful or efficient. It depends on capital investment and operating costs. Thus why nuclear is not feasible in most western nations. Even France is phasing out its percent of nuclear generated electricity. Germany, etc. are going to be replacing imported electricity with fossil fuels.

The majority of new capacity in the world will be what is being built now...as will be built in a decade...coal and natural gas generating stations. Solar, wind, etc. are feel good minor tinkering around the edges. The inefficiencies, capital costs, operating costs of alternative energy make them no more more than a footnote to energy needs.

Solar might be better than you are estimating. It was a year ago that news reports told us that HALF of German electricity was coming from solar power. As the higher capacity has grown, a lot from government incentivized demand, the economics of solar panels have gotten much better. With economies of scale, and better processes, solar panels are not that uneconomical. I think they are under 150% the cost of coal power electricity.

When I've looked at rooftop solar panels, they definitely pay for themselves in my sunny spot in Utah. But the lifetime used is generally 20 years. I believe that they are warrantied to be at 80% of the original capacity at 20 years.

The cost per watt keeps dropping on panels. My understanding is that a very large part of that is simply economies of scale as the factory infrastructure is built and operated at higher capacity. I don't think there is much further to drop, but the cost is fairly competitive now. A lot of the cost side has yet to be fully worked thru, as maintenance and true lifetime power curves are still changing.

 

[russ_watters]

Solar might be better than you are estimating. It was a year ago that news reports told us that HALF of German electricity was coming from solar power.

You misread. Coal is more than half of Germany's electricity production and like pretty much everywhere else, solar is an insignificant source of energy.

 

[zoobyshoe]

I think the "best" way is combined wind, solar, wave, hydro-electric, geo-thermal coupled with a push toward increasingly energy-efficient devices.

As Islands, the UK and Ireland have much more coastline than most countries and it would seem natural to take advantage of the usually windy conditions of coastal areas to take up as much slack as possible for their energy needs. According to Ryan_m_b, however, the British are psychologically resistant to the idea of having a lot of windmills on the landscape. The only thing that will dislodge them from that for certain is the eventual depletion of fossil fuels, but that's a long way away. In the meantime the only scenario that might give it a boost would be if some savagely aggressive, out-of-the-box-thinking person or group began to conceive of alternate energy as way to make money, to put the normal utilities out of business and set themselves up as the energy monarchs. Nice people working for a better environment, a better world, are never aggressive enough to change things. Technology only gets developed when businessmen get the idea they can make a lot of money off it. So, you'd need some kind of alternate energy pirate genius of the caliber of Steve Jobs to see a way it could make him rich, and who had the drive to get it done.

 

[votingmachine]

I think the news reports I read look like a snapshot, and it was misleading. They met half of demand with solar, but it was a low demand time. It is a bit difficult (apples to oranges) to compare power plant maximum capacities and what is being run. My impression is that Germany has been the leading installer of solar capacity, and once installed, Solar is used at full capacity available, and other plants are idled.

The yellow line for solar does show the story of increased installation. And you absolutely have to build capacity for peak demand, and the coal/nuclear plants will remain the main backstop for that peak. It looks like for the last decade, the only significant capacity they are adding is in Wind, Solar, and Other (hydroelectric?). The German goal is 80% of electricity from renewable sources. It may be that they will have a surplus coal plant capacity remaining idle.

I would say the electricity from solar in Germany is NOT insignificant. If you look at power capacity, it is still a very small fraction of the installed power production infrastructure. But it is used at 100% capacity available, which actually makes it more significant than you might otherwise expect.

The economics are definitely improved though. If given a purely economic choice between building a coal plant with 100 MW capacity, or solar installations at 100 MW capacity, the coal wins the business decision. But the gap has been getting smaller, as solar panel manufacture has moved to higher capacity, and has advanced technologically. THis curve shows some of the staggering progress in manufacturing costs of PV modules. And I think the drop has continue, and is now closer to $1 per Watt. Still higher than coal and natural gas, but surprisingly close.

 

[jim hardy]

I think the news reports I read look like a snapshot, and it was misleading. They met half of demand with solar, but it was a low demand time.

What ? The news was spun ?

Eternal vigilance is the price of truth.

Being generous
solar insolation might be 5 kwh/day.meter^2
http://www.nrel.gov/gis/images/eere_pv/national_photovoltaic_2012-01.jpg

5kwh is 17,060 BTU's
which is the heat co10 ntent of 1.7 pounds of coal - about one sockful.

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 ten square meters of solar cell (a twenty-three ten foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.Next time you have to wait at a railroad crossing for a coal train, think about it. Just to heat the water for 100 million morning showers is over a quarter mile of coal cars.

You can't beat steam. At Earth's population density we don't have a replacement for it.

I do like the idea of rooftop solar for heating water,
and whoever comes up with a solar airconditioner will sell zillions of them in our sunbelt.
That'd save a lot of coal and natural gas for our grandkids.

 

[votingmachine]

5kwh is 17,060 BTU's
which is the heat content of 1.7 pounds of coal - about one sockful.

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 square meters of solar cell (a twenty-three foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.

Next time you have to wait at a railroad crossing for a coal train, think about it. Just to heat the water for 100 million morning showers is over a quarter mile of coal cars.

You can't beat steam. At Earth's population density we don't have a replacement for it.

I do like the idea of rooftop solar for heating water,
and whoever comes up with a solar airconditioner will sell zillions of them in our sunbelt.
That'd save a lot of coal and natural gas for our grandkids.

PV efficiency is a little higher now ... more like 15%.

My rooftop in Utah can hold enough solar panels to equal my electric consumption total, using the grid and "net metering" as de facto storage. The hottest sunniest days are exactly when the air conditioner runs the most.

I don't really care about volumetric comparisons. I care about the economic comparison. Coal is much cheaper to build the equipment for ... but solar generally is almost ALL upfront costs, and then almost free to operate. Coal is very economical. Natural gas is very economical. Solar is one where the costs have been coming down so rapidly, that a lot of people don't realize the economics.

Solar has a huge disadvantage in that it doesn't work at all at night, and at lower power production as the energy of the sun is diminished. Current storage is too expensive ... although again, costs are improving.

My preference would be to use nuclear steam supply systems as the energy backstop, for peak handling and for when other sources are at lower capacity. Use solar, wind, geothermal, and hydroelectric at as high a capacity as possible, with the electric grid as backstop.

I see the economics of solar, living in Utah. I see solar panels going up on roofs all over, and I've attended some seminars for cost information. I have neighbors who put in panels and have a Nissan Leaf, that they drive completely charged by rooftop solar.

That 4¼ pounds of coal, maybe one shovel full, has immense value in portability. I don't want to move 50 square meters of panels around. But I have 3-4 times that as roof that gets good sun. To me it is strictly an economic proposition, with trade-offs for portability and infrastructure compatibility.

The news from Germany was not terribly misleading ... I was mistaken when I saw that Germany supplied half of the daily electric demand with solar, in generalizing that. They supplied half of one day, with low demand, and bright sunshine. That is still remarkable. It is also still true that the majority of electrical generating capacity in Germany is coal plants. They really are on track towards 80% of electric supply from renewables, with solar an important part of that.

I don't accept that you can't beat steam. It is an economic proposition. If the cost of photovoltaic modules drops enough, then they beat steam. Currently, the economics are great for homeowners who can replace buying kW-hrs with solar panels. They more than pay for themselves in sunny locations. Boiling water with fossil fuels is cheaper currently, but if it isn't in the future ... use the cheaper energy.

I think solar panels will play a growing role in energy production. Coal will continue to be important, as the infrastructure of coal fired power plants that exists is valuable and economically viable. I would say that the true cost of coal might be higher, if the impact of global warming is factored in.

 

[mheslep]

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 square meters of solar cell (a twenty-three foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.

10 sq m per 5kwh per day w 10% PV. 18% is common, with 20% available.

 

[jim hardy]

Well , i stand corrected on PV efficiency. In my day they were 2% and i'd heard of 25% panels for NASA.

Given the low consumption of LED lights and consumer electronics, a modest solar can provide that energy need.

It's my opinion electricity is just too convenient (hence precious) to be wasted heating water.. Those BTU's should be collected directly from sunshine. .
Hot water and refrigeration are the two biggest household loads . If they could be made non-electric it'd relieve much of the need for residential grid.
But Western lifestyle is energy centered , we expect to have as much of it as we want whenever we want it at the flip of a switch.
I don't really have to plan ahead to run my welder or air compressor, or even get the gas to drive 2500 miles across the country.

Look what we've done to the humble fishing skiff..

Gonna be some societal changes as we adapt to limited energy.

 

[rootone]

Strapping several outboards together like that (above pic) is I think likely to be very fuel inefficient.
Each propeller will have below optimum water flow over the blades due to interference of the flow caused by the adjacent propeller(s)
Maybe two spaced well apart might be good, but five?

 

[jim hardy]

Conspicuous consumption, that...
This plant uses solar collectors to preheat feedwater for its steam boiler saving around 10% fuel in good daylight..
The advantage is this plant still makes power at night, just a little less of it.
The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

 

[jim hardy]

10 sq m per 5kwh per day w 10% PV.

Oops - THANKS ! fixed it..

 

[mheslep]

All that solar for 10% ?

If that's the http://www.energydigital.com/renewables/2926/Worlds-First-Hybrid-Natural-Gas-Solar-Power-Plant-Premiers-in-Florida, the solar attachment supposedly will save http://weblogs.sun-sentinel.com/business/realestate/housekeys/blog/2011/01/fpls_estimates_on_solar_costs.html in fuel costs(30 yrs), and reduce emissions a bit. With regards to the gas share of infrastructure for the plant there's a lot we don't see in the photo (which solar doesn't need), including some hundreds of miles of gas pipeline, gas storage, and of course several of these below for just the one plant (I calculate 1882 - 100 Mcf/day gas wells for one 1150 MW plant @50% eff):

 

[zoobyshoe]

The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

"All that solar" just refers to some space taken up by the collectors. Show us the whole coal story: the pile of coal, the coal mines, the truck that haul it, the men that dig it, all that.

 

[jim hardy]

show us the whole coal story: the pile of coal, the coal mines, the truck that haul it, the men that dig it, all that.

well, in this case it'd be natural gas by pipeline.

 

[zoobyshoe]

well, in this case it'd be natural gas by pipeline.

Same problem, though. There's a whole natural gas infrastructure that isn't being shown in that pic compared to "all that solar."

 

[jim hardy]

Same problem, though. There's a whole natural gas infrastructure that isn't being shown in that pic compared to "all that solar."

quite so.

And solar doesn't replace that infrastructure or relieve its necessity if we're to have power outside the five hours per day of good sunshine.

 

[zoobyshoe]

And solar doesn't replace that infrastructure or relieve its necessity if we're to have power outside the five hours per day of good sunshine.

True, but 'solar doesn't work at night' is a different objection than "all that solar," by which you mean the large area required by solar collectors.

Fossil fuel is basically millions of years of stored solar energy, and there's no way we'll ever be able to compete with that once it's depleted. Eventually we'll have to collect solar directly as it hits the Earth as best we can. The more we do that now, the better we'll become at it and avoid a sharp, forced learning curve down the road.

 

[votingmachine]

Conspicuous consumption, that...
This plant uses solar collectors to preheat feedwater for its steam boiler saving around 10% fuel in good daylight..
The advantage is this plant still makes power at night, just a little less of it.
The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

View attachment 85665

I'm not sure why you keep harping on land use efficiency. It seems irrelevant. We all see that the most compact power source is nuclear, and solar can only harvest a portion of the solar constant (IIRC about 1.3 watts per square meter). In an area where the solar surface area is high priced, don't buy that surface area as an economic proposition.

Costs need to be considered. If they bought an acre of what looks like rural/agricultural land, and put a solar array on it, then you have to account for that opportunity cost.

You keep presenting power compactness as the definitive reason that fossil fuels are superior and that just doesn't matter as much as you portray it. Fossil fuels are cheaper. THAT matters. If solar gets cheaper, THAT matters.

As was pointed out, that solar field vs the power plant also ignores the amount of surface area dedicated to strip mining, or fossil fuel collection. There might be another photo with the collected areas of the fossil fuel collection ... that might be larger than the field where the solar sits.

There are cost-benefit analysis with every electric generating process. I think the cheapest in the US right now is natural gas. We should use the heck out of that. Cheaper is great. But it is important to notice that the PV module supply has been growing, getting cheaper, and while producing more efficient panels. The largest part of that economic improvement has been a result of German government subsidies for installations, which drove market demand, which drove producer investment. It was one of those chicken-and-egg situations, industrial investment in panels needed demand, and demand needed lower prices, and lower prices needed industrial investment, and so on. There is still an open question as to what the eventual price will drop to. Demand is now growing in ordinary consumer markets ... as I said, I am considering a home installation for economic reasons.

In that home installation, I will put roof surface area, ordinarily acting as environmental isolation of the home interior, to a second use. The surface area is basically free. Other than I am waiting to time solar installation after a new roof installation, as my roof is about 19 years old ... the economics have to include not throwing away 10% of roof life.

I think costs have to be evaluated and benefits have to be evaluated. If surface area is important, then it has to be considered. I tend to think it is an unimportant part in most cases. The picture you show does not really tell us the value of the land they used. Maybe the installation was purely a show, maybe the installation was a well reasoned economic investment.

 

[jim hardy]

True, but 'solar doesn't work at night' is a different objection than "all that solar," by which you mean the large area required by solar collectors.

Fossil fuel is basically millions of years of stored solar energy, and there's no way we'll ever be able to compete with that once it's depleted. Eventually we'll have to collect solar directly as it hits the Earth as best we can. The more we do that now, the better we'll become at it and avoid a sharp, forced learning curve down the road.

Good. Now we're in agreement. Extrapolating to the extreme mankind will someday have to get through every day on what energy he can eke out of the sun.

Utility scale solar and wind exist in US today only because of tax incentives.
In some quarters people gripe about corporate tax breaks , but you just explained why they exist - to get a technology or enterprise going. There's a premise that gov't will share in your development cost with anticipation of sharing in your future profits.

The question "What's the best way to generate electricity" has to be considered at two levels - utility scale and homeowner scale.

Utility scale i'd rank
1 Hydro, 2 Steam, followed by wind and solar where they're plentiful.

Homeowner scale i'd rank
1.Reduce consumption of electricity by direct solar heat collection for space and water heating, on premise not using electricity in the first place it is as good as making it..
2. Rooftop solar PV at latitudes where it makes sense, windmills where they make sense

If we're to keep our mechanized society and lifestyle i do not see the electric grid going away. Nuclear steam will replace fossil as carbon resources dwindle, buying a century or two to get fusion up and running.

 

[mheslep]

(I calculate 1882 - 100 Mcf/day gas wells for one 1150 MW plant @50% eff)...

Apparently ~7000 Mcf/day is more typical for a gas well brought online in the last few years, so 26 wells are enough for a 1150 MW plant at 50%.

 

[mheslep]

Fossil fuel ... no way we'll ever be able to compete with that once it's depleted.

Nuclear?

 

[mheslep]

1 Hydro, 2 Steam,

Jim - Don't need steam for gas fired electricity (Brayton cycle). More efficient and no large water supply required. US has 121 GW of such turbines (though only 3% of power as of 2012 - its rising).

 

[votingmachine]

At one point the Tennessee Valley Authority was looking at a storage idea where they used a mountain reservoir. Pump water up at low demand and then hydroelectric down when there is peak demand. I don't know if anything ever came of the idea, but I recall that there was one impressive claim of 90% efficiency of recovery.

It is only practical where there is an existing geographical feature to provide the elevation ... I would think building a supported tank would add to much cost. But if you could take advantage of natural geography, the pipes and pumps are pretty cheap. You might even be able to use the power turbines as pumps.

I agree that the inevitable backstop for the foreseeable future should shift to nuclear fission. Hydroelectric and geothermal are geography dependent, but make sense in places. I think nuclear should be much more cost efficient than it currently is. There should be much more standardization across nuclear plants. Standard, pre-approved designs would improve the construction economics considerably.

 

[jim hardy]

Jim - Don't need steam for gas fired electricity (Brayton cycle). More efficient and no large water supply required. US has 121 GW of such turbines (though only 3% of power as of 2012 - its rising).

Gas turbine powered generator?

My utility began installing them early 1970's when the nuke plant was late and they needed a few hundred megawatts online quickly.
Early ones had a terrible heat rate and there was a learning curve to stumble up, we were not jet engine mechanics.

They've come a long way but i spent hardly any time around them. When one recovers their exhaust heat by tacking a small boiler behind the gas turbine, their efficiency beats a conventional steam boiler/turbine.

Our system guys were ecstatic with heat rates of 6,000 BTU/KWH which is around 56% efficient.

http://www.energy.siemens.com/us/en/sustainable-energy/power-generation.htm?stc=usccc021878&s_kwcid=AL!462!3!44427756700!b!g!combined%20cycle%20power%20plants&ef_id=UpUo0gAABR99gZzO:20150708165315:s

It's the improvements in gas infrastructure that enabled them in Florida. When i started working there in 1969, we burned low grade oil brought in on huge barges.. 40,000 barrels a day of the gooey stuff. Our heat rate was around 9,000.

 

[mheslep]

they used a mountain reservoir. Pump water up at low demand and then hydroelectric down when there is peak demand. I don't know if anything ever came of the idea

See Pumped-storage hydro. Supposedly 128 GW of capacity worldwide, which runs on the order of hours. The largest facility in the world (by power output) is in Virginia.

https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

 

[jim hardy]

More efficient and no large water supply required. US has 121 GW of such turbines (though only 3% of power as of 2012 - its rising).

Interesting link.

It looks like the pure Brayton turbines are still expensive to run though , the article describes them used mostly for meeting peak demand. We called them "Peaking Units" .

Correspondingly, generation was highest when hourly http://www.iso-ne.com/nwsiss/grid_mkts/how_mkts_wrk/lmp/ (LMPs) averaged about $55 per megawatthour (MWh), and generation was much lower when real-time hourly LMPs were about $20/MWh. Natural gas combustion turbines are more expensive to operate than other types of power plants but can respond quickly when needed, so they tend to be used when they are needed to meet short-term increases in electricity demand related to ramping or when loads (and therefore prices) are higher.

We made a lot of nuclear electricity for under $20 a megawatt hour.

Our first Brayton turbines went in at a plant in Fort Lauderdale near the airport. When they were running, small planes on final approach got quite a lift as they crossed over the upward directed exhaust. A lot of heat was wasted. But the addition of heat recovery boilers and recent improved availability of gas fuel has really changed things for the utilities.

 

[EverGreen1231]

True, but 'solar doesn't work at night' is a different objection than "all that solar," by which you mean the large area required by solar collectors.

Fossil fuel is basically millions of years of stored solar energy, and there's no way we'll ever be able to compete with that once it's depleted. Eventually we'll have to collect solar directly as it hits the Earth as best we can. The more we do that now, the better we'll become at it and avoid a sharp, forced learning curve down the road.

The problem is, many real innovations come only at the precipice of need.

 

[EverGreen1231]

Good. Now we're in agreement. Extrapolating to the extreme mankind will someday have to get through every day on what energy he can eke out of the sun.

Utility scale solar and wind exist in US today only because of tax incentives.
In some quarters people gripe about corporate tax breaks , but you just explained why they exist - to get a technology or enterprise going. There's a premise that gov't will share in your development cost with anticipation of sharing in your future profits.

The question "What's the best way to generate electricity" has to be considered at two levels - utility scale and homeowner scale.

Utility scale i'd rank
1 Hydro, 2 Steam, followed by wind and solar where they're plentiful.

Homeowner scale i'd rank
1.Reduce consumption of electricity by direct solar heat collection for space and water heating, on premise not using electricity in the first place it is as good as making it..
2. Rooftop solar PV at latitudes where it makes sense, windmills where they make sense

If we're to keep our mechanized society and lifestyle i do not see the electric grid going away. Nuclear steam will replace fossil as carbon resources dwindle, buying a century or two to get fusion up and running.

Do you really think Fusion will ever become viable? Everything I've read seems to say a couple hundred years before anything significant can be produced.

 

[mheslep]

We made a lot of nuclear electricity for under $20 a megawatt hour.

Is that after the initial capital outlay was retired? For operating costs, nothing is cheaper than nuclear among dispatchable power sources aside from geothermal, if one can get it. The US government still estimates nuclear operating (fixed and variable O&M) costs at $24/MWh out to 2020. Problem is nuclear capital costs are $70/MWh (2020). China appears to be spending a third of that for their nuclear reactors (dozens of them).
http://www.eia.gov/forecasts/aeo/electricity_generation.cfm

 

[jim hardy]

Is that after the initial capital outlay was retired?

Nope. This was an early plant built for just ~120 million, a 10th what the next one cost us. (caveat - i was not in the financial side of the company. I don't know when they declared the plant paid off )
That was before steam generator replacement, though. I don't know what today's cost per mwh is.

 

[OmCheeto]

What is the best way to produce electricity?
Nuclear : people are afraid of leaks and waste storage problems.
Coal: People are afraid of smoke pollution, and it may run out soon.
Oil same as above.
Wind inefficient and to costly.
Wave renewable but again too costly
Solar: it takes up to much land.

What do you think?

All of the above?
There was a study done recently here in the states, where the authors determined the optimal combination of the above for each state.
The provided a cute little infographic web site, where we could go and see what combination is best for where we live.
I find it very promising that people are thinking this way.

And there are always novel new ideas popping up.
A local, a while back, decided that we should be making electricity every time we flush our toilets.
The first installation was done just about a mile from my house.
I just checked out the rivers of England, and it might behoove you to do a feasibility study of installing such devices on the larger streams that feed your rivers.

ps. Regarding the discussion of E.T. solar. I came up with a minimum cost of $500 trillion dollars, in another thread. I expect the cost to be more like $5 quadrillion. I just calculated that it would cost around $125 trillion for total Earth based solar electric.

pps. And if you don't like my response, start eating more pasties!

 

[zoobyshoe]

Nuclear?

You tell me.

I started googling to find some estimates on how long nuclear resources might last, but the sites that address this on the first page of results seemed to be pro-alternate energy sites. The notion they seem to purvey is that if we switched to all nuclear we'd use up those resources much faster than we're currently depleting them. Anyway, I couldn't get a good idea of how much time nuclear might buy us.

Also, there's the usual objections: storage of the waste, potential use of the waste as "dirty" weapons, all that.

 

[jim hardy]

The notion they seem to purvey is that if we switched to all nuclear we'd use up those resources much faster than we're currently depleting them. Anyway, I couldn't get a good idea of how much time nuclear might buy us.

Glasstone & Sessonske's 1960's textbook we used in Reactor Physics course said there's about the same amount of fissile fuel as fossil in the crust of the Earth . Add to that the near-fissile like Thorium that we can breed into reactor fuel and they estimated 400 years worth.
That's a fifty year old estimate.

You're right, i too find mostly pro-nuke produced info.

This one from a paper submitted by a Stanford student in an introductory nuke engineering course is readable, and he lists his references.
http://large.stanford.edu/courses/2011/ph241/engelsen1/

Mineable Uranium Resources
The most important Uranium reserves are found in Kazakhstan, Canada and Australia where Uranium is found in high enough concentrations to be commercially viable at current Uranium prices. Over half the World's yearly Uranium production originates in these three countries. [5] Uranium is found in the form of Uranium oxides and is usually extracted by open-pit mining. The Uranium ore is then purified, and in most cases enriched to obtain a higher percentage of U-235. The Uranium can then be used to manufacture fuel rods, which can finally generate electricity in nuclear reactors. The OECD estimates that there are 6.3 million tons of identified Uranium supplies recoverable at a rate less than $260/kg. At 2008 rates of Uranium consumption, these supplies would last about 100 years. If the projected discoveries are included as well, world supplies will last 220 years. [5] If Uranium consumption rates increase, as they are projected to, the supplies will last even shorter. A long-term energy solution can therefore not be based on minable Uranium in current reactor technology.

Technological Advances
The estimates given above only include mineable Uranium, and they also assume that there are no improvements in reactor technology. The most direct way of increasing nuclear fuel supplies would be to extract Uranium from sea water, where it is found in small concentrations. Pilot projects in Japan have estimated the price at 200-300$/kg. [12] The total amount of Uranium in the ocean is about 4.5 billion tons, but it remains to be seen whether it can be extracted on a large scale. Development of breeder reactors where fertile U-238 is transmuted to fissile Pu-239 in-situ such that more fissile material is produced than is consumed, would significantly prolong the lifetime of fissile fuel supplies. The use of the fertile material Thorium in a Thorium fuel cycle could allow us to use the Earth's Thorium supplies. Thorium is three to four times more abundant than Uranium and a Thorium fuel cycle may have significant advantages over the Uranium fuel cycle currently employed. However, significant technological and economic challenges remain before Thorium nuclear reactors are commercially viable and only India has a Thorium nuclear power program. [8] Reprocessing of spent fuel is a currently available technology increasing the efficiency of nuclear fuel by extracting the remaining fissile material in a spent fuel rod by the PUREX method. All major nuclear powers except the United States have a currently operating reprocessing program for spent fuel rods. [13] bold mine jh

 

[Enigman]

You tell me.

I started googling to find some estimates on how long nuclear resources might last, but the sites that address this on the first page of results seemed to be pro-alternate energy sites. The notion they seem to purvey is that if we switched to all nuclear we'd use up those resources much faster than we're currently depleting them. Anyway, I couldn't get a good idea of how much time nuclear might buy us.

Also, there's the usual objections: storage of the waste, potential use of the waste as "dirty" weapons, all that.

Here's what I got googling
Is Nuclear Power Globally Scalable?
Vol. 99, No. 10, October 2011 | Proceedings of the IEE

XVI. CONCLUSION
We have highlighted that there are fundamental engineering and re- source scaling limits that make the notion of a nuclear utopia somewhat impractical. There are fundamental limits imposed by embrittlement, accident rate, land resources, fuel re- source extraction rate, and mineral resources for making enough nuclear vessels. As the nuclear vessel is irradiated and not recyclable, we highlight that a rapid uptake of nuclear power would seriously limit elemental diversity and would drive up price volatility given there are other significant competing industrial uses of the required metals. Therein lies the rub. It can be argued that a nuclear nirvana supplemented by renewables may mitigate the need to reach 15 TW by nuclear power alone . Even a lesser goal of several terawatts of nuclear power would run into many of the outlined limitations.Therefore, the notion of a nuclear utopia is a false one. But there are two types of nuclear advocates: the nuclear utopian and the nuclear realist. A nuclear realist would only suggest that we need about 1 TW of nuclear power as part of our world energy mix. However, one only has to divide the results, in this paper, by 15 to see that 1 TW still stretches resources and risks considerably. One then has to count the cost, consider the safety, the complexity, and the issues surrounding governance of nuclear power. Also if the technology cannot be fundamentally scaled further than 1 TW, one has to ask if the same investment would have been better spent on a truly scalable technology. It has been suggested that for the same investment, solar thermal farms (with storage) would exceed the power output of nuclear stations and eliminate many of the problems. Solar thermal is also scalable as it has the capacity to deliver hundreds of terawatts should mankind require it in the future. The weakness of a scalable renew- able solution, however, is intermitten- cy. In the short term, this problem can be addressed via dual use of solar thermal with natural gas. Then, the natural gas can be phased out, as storage and grid balancing techniques come online to solve the intermittency problem.

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6021978

Shorter physorg summary of the analysis - http://phys.org/news/2011-05-nuclear-power-world-energy.html

Another thing I found worth mentioning was seawater extraction. Although, uranium extraction from seawater seems to show tremendous promise in future but is as of now terribly inefficient and will take a lot of research before it becomes economically viable let alone globally scalable.

Based on a cost analysis of uranium extracted from seawater, it is concluded that the world’s energy requirements for the next 5 billion years can be met by breeder reactors with no price increase due to fuel costs.(AIP)
Breeder reactors: A renewable energy source
Am. J. Phys. 51, 75 (1983);
http://scitation.aip.org/content/aapt/journal/ajp/51/1/10.1119/1.13440

Full paper: http://88.167.97.19/temp/Breeder_reactors_A_renewable_energy_source_pad11983cohen.pdf

http://webcache.googleusercontent.com/search?q=cache:F-uY83ty5UkJ:88.167.97.19/temp/Breeder_reactors_A_renewable_energy_source_pad11983cohen.pdf+&cd=1&hl=en&ct=clnk&gl=in

Further googling of seawater extraction gives -

The uranium concentration of sea water is low, approximately 3.3 parts per billion or 3.3 micrograms per liter of seawater.[12] But the quantity of this resource is gigantic and some scientists believe this resource is practically limitless with respect to world-wide demand. That is to say, if even a portion of the uranium in seawater could be used the entire world's nuclear power generation fuel could be provided over a long time period.[13] Some anti-nuclear proponents^[12][13][14] claim this statistic is exaggerated.^{[citation needed]} Although research and development for recovery of this low-concentration element by inorganic adsorbents such as titanium oxide compounds has occurred since the 1960s in the United Kingdom, France, Germany, and Japan, this research was halted due to low recovery efficiency.

At the Takasaki Radiation Chemistry Research Establishment of the Japan Atomic Energy Research Institute (JAERI Takasaki Research Establishment), research and development has continued culminating in the production of adsorbent by irradiation of polymer fiber. Adsorbents have been synthesized that have a functional group (amidoxime group) that selectively adsorbs heavy metals, and the performance of such adsorbents has been improved. Uranium adsorption capacity of the https://en.wikipedia.org/w/index.php?title=Polymer_fiber_adsorbent&action=edit&redlink=1 is high, approximately tenfold greater in comparison to the conventional titanium oxide adsorbent.

One method of extracting uranium from seawater is using a uranium-specific nonwoven fabric as an absorbent. The total amount of uranium recovered from three collection boxes containing 350 kg of fabric was >1 kg of yellowcake after 240 days of submersion in the ocean.^[15] According to the OECD, uranium may be extracted from seawater using this method for about $300/kg-U.[^16] The experiment by Seko et al. was repeated by Tamada et al. in 2006. They found that the cost varied from ¥15,000 to ¥88,000 (Yen) depending on assumptions and "The lowest cost attainable now is ¥25,000 with 4g-U/kg-adsorbent used in the sea area of Okinawa, with 18 repetitionuses [sic]." With the May, 2008 exchange rate, this was about $240/kg-U.^[17]

In 2012, ORNL^[18] researchers announced the successful development of a new absorbent material dubbed HiCap, which vastly outperforms previous best adsorbents, which perform surface retention of solid or gas molecules, atoms or ions. "We have shown that our adsorbents can extract five to seven times more uranium at uptake rates seven times faster than the world's best adsorbents," said Chris Janke, one of the inventors and a member of ORNL's Materials Science and Technology Division. HiCap also effectively removes toxic metals from water, according to results verified by researchers at Pacific Northwest National Laboratory.[^{18] 19][20]}

^wiki

 

[zoobyshoe]

Shorter physorg summary of the analysis - http://phys.org/news/2011-05-nuclear-power-world-energy.html

This has some damning figures:

Lifetime:Every nuclear power station needs to be decommissioned after 40-60 years of operation due to neutron embrittlement - cracks that develop on the metal surfaces due to radiation. If nuclear stations need to be replaced every 50 years on average, then with 15,000 nuclear power stations, one station would need to be built and another decommissioned somewhere in the world every day. Currently, it takes 6-12 years to build a nuclear station, and up to 20 years to decommission one, making this rate of replacement unrealistic.

and:

Accident rate:To date, there have been 11 nuclear accidents at the level of a full or partial core-melt. These accidents are not the minor accidents that can be avoided with improved safety technology; they are rare events that are not even possible to model in a system as complex as a nuclear station, and arise from unforeseen pathways and unpredictable circumstances (such as the Fukushima accident). Considering that these 11 accidents occurred during a cumulated total of 14,000 reactor-years of nuclear operations, scaling up to 15,000 reactors would mean we would have a major accident somewhere in the world every month.

The recovery of uranium from seawater was interesting. I have no doubt better ways of doing that would be invented down the road, but the above problems make it both unrealistic and undesirable to try to replace fossil with nuclear. Going from 440 nuclear plants to 15,000! I never realized it would have to be scaled up that much!