News Energy independence for the US (or any other country)

[edpell]

What is the best way for the US (or any other country) to generate 50% of its energy from renewable (or at least source that will last for 500 years) source in the next 20 years?

My personal favorite is PV in the US Southwest with water->hydrogen as a storage medium for over night and for transportation.

I am also a long time fan of solar power satellites but I think ground based is cheaper.

I think the factor that is stopping the deployment is that both of the above are expensive. And for a country that can not even balance it's budget investing trillions of dollars in the future seems unlikely.

 

[drankin]

What is the best way for the US (or any other country) to generate 50% of its energy from renewable (or at least source that will last for 500 years) source in the next 20 years?

My personal favorite is PV in the US Southwest with water->hydrogen as a storage medium for over night and for transportation.

I am also a long time fan of solar power satellites but I think ground based is cheaper.

I think the factor that is stopping the deployment is that both of the above are expensive. And for a country that can not even balance it's budget investing trillions of dollar in the future seems unlikely.

Currently, we are not investing in the future, we are borrowing from it.

 

[edpell]

Currently, we are not investing in the future, we are borrowing from it.

Good point. So in order to get a new renewable energy system we will need to move to a net positive investment in the future. How much pain will there have to be for that to happen and what form will the pain take?

 

[Ivan Seeking]

Algae is probably our best hope
https://www.physicsforums.com/showthread.php?t=211274

Energy independence is worth [average over the long term] half a trillion dollars a year, or about 60% of our trade deficit, based on the cost and rate of importation of crude oil and other petro products. That is 10 million, $50K a year jobs. Currently, we might as well be burning that money. It is easy to justify a large effort to end our dependence on oil. Even an effort costing $5 trillion would pay back in about ten years.

For perspective: In the current economic crisis, we have lost something over 7 million jobs.

 

[edpell]

Algae is probably our best hope
https://www.physicsforums.com/showthread.php?t=211274

Energy independence is worth [average over the long term] half a trillion dollars a year, or about 60% of our trade deficit, based on the cost and rate of importation of crude oil and other petro products. That is 10 million, $50K a year jobs. Currently, we might as well be burning that money.

For perspective: In the current economic crisis, we have lost something over 7 million jobs.

Yes, I have been impressed by the gene engineering of Algaes it does seem hopeful in fact there is an upcoming conference on the topic in Walnut Creek California by the federal gene folks.

Thank God someone who understands the relation between energy independence and US jobs/standard of living.

 

[MotoH]

How much money would we save if we drilled for oil in northern Alaska? It has to be way cheaper than buying from the MEC.
(we won't be over our oil dependence any time soon)

I am a fan of the giant mirrors in the deserts and the geothermal steam energy plants. The Earth is going to be hot for a long time coming, and the sun will be there for also a very long time!

 

[Ivan Seeking]

Thank God someone who understands the relation between energy independence and US jobs/standard of living.

A bit of math makes it painfully clear. I can't think of a better reason for the political left and right to come together. One would think we could all agree on this one.

 

[Ivan Seeking]

How much money would we save if we drilled for oil in northern Alaska? It has to be way cheaper than buying from the MEC.
(we won't be over our oil dependence any time soon)

The arctic oil supply would barely make a dent.

What is the MEC?

 

[MotoH]

Middle Eastern Coalition. I just call the oil countries the "MEC" because its easier, and they are the big nosed fellows in Battlefield 2 Project Reality.

 

[edpell]

How much money would we save if we drilled for oil in northern Alaska? It has to be way cheaper than buying from the MEC.
(we won't be over our oil dependence any time soon)

I am a fan of the giant mirrors in the deserts and the geothermal steam energy plants. The Earth is going to be hot for a long time coming, and the sun will be there for also a very long time!

I like the mirror idea also.

On the Alaskan oil it is my understanding that there is something like 180 days of oil supply there to be drilled. Not sure if this is 180 of oil usage or 180 days of total energy use (in which case it might be more like 365 days of oil use). But either way it is not enough to make much difference. That is why I am in favor of drilling Alaskan oil at a deletion rate of 2% so it will last for 50 years. At that rate of extraction there should be very little environmental impact. At that rate, each year, we will get 3.6 days of supply from Alaska.

 

[Ivan Seeking]

You can go the the algae thread linked for pages and pages of discussion, but one critical difference between algae, and other options like concentrated solar, is that algae produces a fuel that can be burned in regular diesels. Solar energy produces electricity, but no fuel. To use it for something like H2 production is prohibitively inefficient.

Algae might also be used to produce H2.

 

[Argentum Vulpes]

What is the best way for the US (or any other country) to generate 50% of its energy from renewable (or at least source that will last for 500 years) source in the next 20 years?

My personal favorite is PV in the US Southwest with water->hydrogen as a storage medium for over night and for transportation.

I am also a long time fan of solar power satellites but I think ground based is cheaper.

I think the factor that is stopping the deployment is that both of the above are expensive. And for a country that can not even balance it's budget investing trillions of dollars in the future seems unlikely.

I'm sorry to say solar is just a good publicity form of power generation. Take Cal-ISO (California's largest electrical supplier). They have an average baseline load of 30000-31000 MW in the off season and 37000-38000 MW during the peak session. Also being able to supply a 45000 MW peak load.

The largest Solar generation field that I could find (Olmedilla Photovoltaic Park) only produces 60 MW and has a Capacity Factor of 0.16. I wasn't able to find out it's exact size but a smaller park (46 MW) using similar panels uses up 618 acres of land.

The Nellis Solar Power Plant project in the USA is the most efficient with a CF of 0.24 and producing 14.02 MW. It is using 140 acres of land.

From this point my simple math calculations were done using the size of the Nellis Solar Power Plant project and its numbers.

To provide the peak load to Cal-ISO would require about 450 kilo acres of land or about half of Rhode Island

The USA averaged 783 GW for a baseline load in 2008. Only 411 MW coming from solar systems. To get to that needed power production you would need 7.8 mega acres of land or about the size of Maryland.

Renewablies can not supply the needed power to run heavy industry. Switching over wind/solar will make this nation turn into a service economy. I still firmly believe that nuclear power is the way to produce safe, clean, and practical infinite power.

 

[russ_watters]

What is the best way for the US (or any other country) to generate 50% of its energy from renewable (or at least source that will last for 500 years) source in the next 20 years?

My personal favorite is PV in the US Southwest with water->hydrogen as a storage medium for over night and for transportation.

I am also a long time fan of solar power satellites but I think ground based is cheaper.

I think the factor that is stopping the deployment is that both of the above are expensive. And for a country that can not even balance it's budget investing trillions of dollars in the future seems unlikely.

The only thing that could possibly meet your criteria at a resonable price is nuclear power.

 

[WhoWee]

The only thing that could possibly meet your criteria at a resonable price is nuclear power.

Now, now Russ - it's not fair to go there.

Remember (refocus - deep breathing), it's perfectly fine and understandable for the Iranians to develop nuclear to satisfy their energy needs - even though they are an ideal solar candidate - but it's not good for us.

We have to develop alternative sources because it will create green jobs.

Let's also not mention that China and Russia are tapping every source they can get their energy seeking hands around.

 

[Skyhunter]

The only thing that could possibly meet your criteria at a resonable price is nuclear power.

"Only", is a very strong word. Why be so exclusive?

And let's be realistic, Our economic model of unrestrained growth is the problem. Building fourth generation nuclear plants is something I am in favor of, but to replace existing generation, not to maintain the growth curve.

PV is getting better and cheaper. Nanosolar is producing inexpensive, high voltage, thin film solar panels for commercial generation.

The problem with the mirrors is that they build them in the desert where there is no water.

Another great idea is to make carbon based fertilizer from coal plant exhaust. This way we can replace the carbon that has been depleted from the soil by industial farming.

And there is nothing wrong with putting Americans to work in green jobs. In fact, it is preferable to the alternatives.

 

[russ_watters]

"Only", is a very strong word. Why be so exclusive?

Because I'm assuming the OP isn't asking about fantasy or science fiction. If we want to discuss what can be done, nuclear power is the only possible solution that can do what the OP asks at a reasonable price (and that's generous: it may actually just plain be impossible any other way).

PV is getting better and cheaper. Nanosolar is producing inexpensive, high voltage, thin film solar panels for commercial generation.

The problem with the mirrors is that they build them in the desert where there is no water.

Another great idea is to make carbon based fertilizer from coal plant exhaust. This way we can replace the carbon that has been depleted from the soil by industial farming.

All of those are hypotheticals. They have not been proven to be viable yet. Nuclear has. Why bet our future on maybes when we have a can available?

And there is nothing wrong with putting Americans to work in green jobs. In fact, it is preferable to the alternatives.

I absolutely agree that green jobs are a good idea. So we should start immediately on hundreds of new nuclear plants. That would create hundreds of thousands of new green jobs.

And, I might add, with the heavy push right now for electric cars, a resurgence of nuclear power is becoming more important.

 

[edpell]

The only thing that could possibly meet your criteria at a resonable price is nuclear power.

I could live with nuclear but every time I look at the world supply of uranium it seems about as short lived as oil. We have discussed this in a thread within the last two months. I do not remember the exact numbers. How long do you calculate the world uranium supply will last?

 

[edpell]

The USA averaged 783 GW for a baseline load in 2008. Only 411 MW coming from solar systems. To get to that needed power production you would need 7.8 mega acres of land or about the size of Maryland.

I do not see this a a show stopper. Let's use Nevada.

 

[Argentum Vulpes]

I could live with nuclear but every time I look at the world supply of uranium it seems about as short lived as oil. We have discussed this in a thread within the last two months. I do not remember the exact numbers. How long do you calculate the world uranium supply will last?

The world supply of Uranium will last till the sun burns out, or a bit longer. Right now the large suppliers are Canada from about 5 mines. The stuff they pull out of the ground is almost at the point of enrichment that it can be stuck straight into the ground. Australia has a very large reserve of uranium but current economic and the political environment have them only operating two mines. The USA has several very large deposits of low grade uranium ore that is relative untouched because of cost. Also sea water has 3.3 ppb of uranium in it. Taking into account the massive amount of sea water on the world the reserves in the oceans are limitless.

Also given the use of breeder reactors and Integrated fast reactors thorium can be brought into the fuel cycle. Plus full burn up of all transuranics in the core of a nuclear power plant will allow for 20 years of operation before refueling, uranium will be around for a long time.

 

[edpell]

Also sea water has 3.3 ppb of uranium in it. Taking into account the massive amount of sea water on the world the reserves in the oceans are limitless.

What is the cost to extract uranium from sea water per kilogram of uranium?

 

[Argentum Vulpes]

I do not see this a a show stopper. Let's use Nevada.

So let's turn a very large part of the American South west into the equivalent of a parking lot? Well actually I can see the requirements for land needing to be larger. Because the entire power generation system has been centralized to get power into homes in Main at 120 VAC 60 Hz the losses of power over the HT lines would be massive. Costs of power on the east coast would become ridiculously high. Work on the Eastern states would be shut down till sun rise over the solar fields. Of coruse a field could become even larger to provide enoughs slack power to put it into storage for overnight loads, and overcast days. Then there is the fact that the most advanced and efficient solar generation field is only producing power 87.6 days a year or 2102.4 hours

So turning Nevada, Arizona, New Mexico, and Utah into a solar field is not only a show stopper but pure lunacy.

 

[Argentum Vulpes]

What is the cost to extract uranium from sea water per kilogram of uranium?

About 120 US dollars per lb. Working out the numbers that is equivalent to burning oil at 3 US dollars per barrel. The biggest cost is the need for high temperatures and electrical costs. However the usage of a nuclear power plant will nip both of those technical problems in the bud, and drive prices down.

As a byproduct of uranium separation from sea water you could get fresh water, hydrogen gas, and the necessary chemicals to produce fertilizers. Just think turning a very large swatch of the African desert into productive farmland.

 

[Skyhunter]

Because I'm assuming the OP isn't asking about fantasy or science fiction. If we want to discuss what can be done, nuclear power is the only possible solution that can do what the OP asks at a reasonable price (and that's generous: it may actually just plain be impossible any other way). All of those are hypotheticals. They have not been proven to be viable yet. Nuclear has. Why bet our future on maybes when we have a can available? I absolutely agree that green jobs are a good idea. So we should start immediately on hundreds of new nuclear plants. That would create hundreds of thousands of new green jobs.

And, I might add, with the heavy push right now for electric cars, a resurgence of nuclear power is becoming more important.

That is your opinion and you are entitled to it.

I personally think it is a bit absolutist, but then that is just my opinion. Let's not derail the thread.

Uranium is a limited resource. The nuclear plants of the future should be designed to burn the accumulated waste from older plants.

The Nanosolar started serial production of high efficiency, low cost thin film panels last year. They have two factories, one in San Jose and one in Germany. The one in Germany has a 640MW per year capacity.

Here is the http://www.nanosolar.com/sites/default/files/NanosolarCellWhitePaper.pdf"

A multi-faceted approach is IMO a better strategy.

 

[edpell]

About 120 US dollars per tonn. Working out the numbers that is equivalent to burning oil at 3 US dollars per barrel.

The current spot price for U_3O_8 is $98 per kilo in New York. How do you get your cost of $120 per kilo? Is it from a reference? Did you do the calculation your self? If so, can you please share the details. 3ppb is a lot of water and salt to sift through.

 

[edpell]

The one in Germany has a 640MW per year capacity.

It will be interesting to see who invest in solar (who buys).

The future belongs to those who invest in it.

 

[Argentum Vulpes]

The current spot price for U_3O_8 is $98 per kilo in New York. How do you get your cost of $120 per kilo? Is it from a reference? Did you do the calculation your self? If so, can you please share the details. 3ppb is a lot of water and salt to sift through.

It was from research put out by The President's Committee Of Advisors On Science And Technology in 1999. The report was wanting the USA to get into the international effort to get uranium out of sea water. Also it should of been 120 US dollars per lb not tonn. I just pulled up my research and saw I made a mistake

I was going off two year old research I did for an op-ed piece. Looking back into it Japanese researchers have developed a new system that is basically a large braid of specially treated fabric that is anchored to the sea bed like sea weed. Or it is placed in floating cages. It absorbs not only uranium but other useful heavy metals. Cost according to the paper is 96 US dollars per lb.

I couldn't find the paper I got my 120 dollar lb number, the URL is no longer valid, most likely archived in the White houses archive. However I do have the report from the Japanese researchers. http://physics.harvard.edu/~wilson/energypmp/2009_Tamada.pdf"

 

[Skyhunter]

It will be interesting to see who invest in solar (who buys).

The future belongs to those who invest in it.

Some very big energy players are invested in Nanosolar.

AES and EDF are some of the biggest in the world.

A 2MW plant requires ~10 acres, and with the high voltage panels they could plug right into the municipal grid. The installation can be designed so as to allow for multiple uses of the ground below. crops that require partial shade could be grown in sunny dry areas efficiently, since the shade will help the soil retain it's moisture.

 

[edpell]

About 120 US dollars per lb. Working out the numbers that is equivalent to burning oil at 3 US dollars per barrel.

With oil at 70 $/barrel what is stopping these folks from becoming rich? Or better yet you and I from becoming rich?

 

[Argentum Vulpes]

Some very big energy players are invested in Nanosolar.

AES and EDF are some of the biggest in the world.

A 2MW plant requires ~10 acres, and with the high voltage panels they could plug right into the municipal grid. The installation can be designed so as to allow for multiple uses of the ground below. crops that require partial shade could be grown in sunny dry areas efficiently, since the shade will help the soil retain it's moisture.

I'm confused, has this company found a way to produce an AC solar panel? My understanding was all solar panels produce DC, so you still need some very beefy inverters on site.

Also what is the CF of one of these new panels?

 

[edpell]

what does CF stand for?

To answer the question no. These are D.C. Yes, to drive an A.C. grid will require inverters.

 

[Argentum Vulpes]

With oil at 70 $/barrel what is stopping these folks from becoming rich? Or better yet you and I from becoming rich?

Simple economics of supply and demand. There are 453 reactors world wide needing 65.5 kilotons of raw uranium to refuel. Current mine output is 51.6 kilotons of raw uranium. However not all plants need to be refueled each year and average time that one rod spends in a reactor is six years.

Large supply + microscopic demand = not a lot of money

Start flooding the market with new sources of uranium and the market will crash. Just like it did in the 1950.

 

[Argentum Vulpes]

what does CF stand for?

To answer the question no. These are D.C. Yes, to drive an A.C. grid will require inverters.

CF stands for Capacity Factor. It is a measure of how efficient something is at generating power. It is determined by dividing actual output with maximum output.

 

[edpell]

So it looks like any industrial process that consumer large amounts of energy should be powered by nuclear to save cost. Since it does not matter where in the world the manufacture is done how about we move all energy intensive production to say Chad and use nuclear?

 

[Skyhunter]

I'm confused, has this company found a way to produce an AC solar panel? My understanding was all solar panels produce DC, so you still need some very beefy inverters on site.

Also what is the CF of one of these new panels?

No. The higher current and voltage eliminates the need for the extra cabling to the inverter. Since the panels themselves can carry the current, to the inverter. I didn't mean to imply that you could just plug it into a wall socket.

16.4% active area, 15.3 total area. That somehow (not sure how it is calculated) equals panel efficiency of ~11%. That is according to the NREL tests.

 

[Argentum Vulpes]

No. The higher current and voltage eliminates the need for the extra cabling to the inverter. Since the panels themselves can carry the current, to the inverter. I didn't mean to imply that you could just plug it into a wall socket.

16.4% active area, 15.3 total area. That somehow (not sure how it is calculated) equals panel efficiency of ~11%. That is according to the NREL tests.

So these panels will be useless 89% of the time that they are out in operation. That looks like a colossal waste of resources, considering US nuclear power plants have a CF of 0.92.

 

[Argentum Vulpes]

So it looks like any industrial process that consumer large amounts of energy should be powered by nuclear to save cost. Since it does not matter where in the world the manufacture is done how about we move all energy intensive production to say Chad and use nuclear?

So ship all of the worlds raw resources to Chad to be turned into products and then ship them back across the world? Need a skyscraper barge it back, need a bridge barge it back? If civilian nuclear power were used in the container ships then at least the current environmental impacts of current commercial shipping would be gone. But just think of the national security implications. Unless you are suggesting a one world government.

This is even more insane then using solar power centralized in the American south west as the power source for the USA.

 

[Skyhunter]

So these panels will be useless 89% of the time that they are out in operation. That looks like a colossal waste of resources, considering US nuclear power plants have a CF of 0.92.

I think we are talking about two different things.

And I am really not interested in derailing the thread with a debate about nuclear power.

 

[russ_watters]

That is your opinion and you are entitled to it.

I personally think it is a bit absolutist, but then that is just my opinion. Let's not derail the thread.

Well you are entitled to your opinion too, but the fact of the matter is that you didn't actually provide any proven solutions. You are hoping that the things you suggested could be viable, when we already know nuclear power is viable. Further, your ideas, at the very least, require time and money for research, mine does not and can be implimented now just by making the decision to do it. The French made that decision decades ago. The question that the OP asked is what can be done in the next 20 years and your idea simply could not be done in 20 years. Nuclear can.

Uranium is a limited resource. The nuclear plants of the future should be designed to burn the accumulated waste from older plants.

Certainly, it is limited, but it isn't as limited as most people think, partly due to the fraud that has been perpetrated on the American people when it comes to nuclear waste. For all intents and purposes, nuclear waste does not exist: http://online.wsj.com/article/SB123690627522614525.html

The Nanosolar started serial production of high efficiency, low cost thin film panels last year. They have two factories, one in San Jose and one in Germany. The one in Germany has a 640MW per year capacity.

Here is the http://www.nanosolar.com/sites/default/files/NanosolarCellWhitePaper.pdf"

That's nice but until it actually happens - until someone builds a commercial scale plant using their technology - it is still hypothetical.

A multi-faceted approach is IMO a better strategy.

Well I'm not saying we should get rid of hydro or stop building wind or even eliminate our natural gas. But I am of the opinion that a solution should be based on solutions. Since its inception, the environmentalist movement has always been based on hope and not reality. So for some four decades, while environmentalists have been wasting time hoping that this next big/new technology will have the ability to replace coal power, another country has already done it!

And now we have a President who'se primary campaign platform was "hope". So we've basically just formalized the policy of wasting time.

 

[Argentum Vulpes]

I think we are talking about two different things.

And I am really not interested in derailing the thread with a debate about nuclear power.

I do not see this as a derailing of the thread. The OP wanted to know what the best way to generate 50% of the USA or any other countries power from renewable sources. Even though it might be stretching the definition and conventional wisdom a bit about what classifies a renewable power source, nuclear power is a renewable power source. Or it is so darn close to one it might as well be one.

 

[russ_watters]

CF stands for Capacity Factor. It is a measure of how efficient something is at generating power. It is determined by dividing actual output with maximum output.

Efficiency isn't really the right word. It is more a measure of the fraction of time a plant is producing power at its nameplate capacity.

In other words (and I know you already know this part), a 1 MW nuclear plant with a 90% capacity factor produces 1*24*365*.9= 7884 MWh of energy per year while a 1 MW solar plant with an 11% capacity factor produces 1*24*365*.11= 964 MWh of energy a year.

In other words, assuming you can use the energy or store it, replacing 1 MW of capaicty from a high CF source like nuclear would require 8 MW of solar capacity.

 

[russ_watters]

No. The higher current and voltage eliminates the need for the extra cabling to the inverter. Since the panels themselves can carry the current, to the inverter. I didn't mean to imply that you could just plug it into a wall socket.

And this is something that really irritates me about a good fraction of the people in the "alternate energy" crowd. Ignorance of the technology helps drive the fantasy. Skyhunter, high voltage or not, a solar panel makes DC power, period. It requires an inverter to integrate it with the grid.

In addition, being "high voltage" is an irrelevancy because you can always just wire solar panels in series instead of parallel to get high voltage (or even do a combination of series and parallel to get whatever voltage you want).

 

[russ_watters]

I think we are talking about two different things.

And I am really not interested in derailing the thread with a debate about nuclear power.

Coal plants also operate on capacity factors of about 90%, so whether we talk about nuclear or not, you need to deal with the fact that replacing 1 MW of coal power capacity requires on the order of 8 MW of solar power. It's not a nuclear issue, it is a solar vs everything else (except wind...) issue.

 

[Skyhunter]

Like I said, we are talking about two different things.

I was referring to the panels conversion efficiency. CF would vary with location.

And it is interesting how you keep moving the goal post Russ. You used the same argument, different goal the last time I mentioned Nanosolar you used it to challenge the efficiency claim.

If everyone followed your advice there would be no progress because only the tried and true (according to personal judgement) would be acceptable.

I know this is hyperbolic... but you make such absolute statements I feel it necessary to use a little hyperbole.

I am not against using nuclear, and do not wish to divulge into an argument against it, but let's review a few facts. The capital costs of a nuclear plant are prohibitively expensive, $2.50/W to $5.00/W per so you are not being candid about the affordability. I don't know the exact cost of the utility panels, but the companies stated goal was to deliver a PV power plant for less than $1.00W.

I don't know if they met their goal, but the worlds leading producers and suppliers of electricity have bought up all there commercial production for the foreseeable future.

 

[Skyhunter]

And this is something that really irritates me about a good fraction of the people in the "alternate energy" crowd. Ignorance of the technology helps drive the fantasy. Skyhunter, high voltage or not, a solar panel makes DC power, period. It requires an inverter to integrate it with the grid.

In addition, being "high voltage" is an irrelevancy because you can always just wire solar panels in series instead of parallel to get high voltage (or even do a combination of series and parallel to get whatever voltage you want).

OK, I should have said higher current, not voltage. The higher voltage is however important for the higher current capacity and an overall benefit when designing a system.

Since the panels carry the current you don't need to wire the panels together to get the voltage you want. This amounts to a 75% reduction in cabling costs for both material and labor during installation.

And I should have said simpler to connect to the grid at municipal voltages. Of course one would need an inverter calibrated to the local grid.

I'll try and be more specific in the future to avoid irritating the mentors.

 

[mheslep]

Some very big energy players are invested in Nanosolar.

AES and EDF are some of the biggest in the world.

A 2MW plant requires ~10 acres,

In the US southwest for 15% panels it's more like 6MW over 10 acres, but only for ~five hours a day. Recall however that the OP asked about 50% renewables. Where then do we go for baseload power, i.e., something that works when the sun doesn't shine, and still get 50%? Without a storage mechanism that doesn't exist yet, 50% from solar is not possible.

 

[mheslep]

Commenting just on the nuclear vs solar cost:

...
The capital costs of a nuclear plant are prohibitively expensive, $2.50/W to $5.00/W per so you are not being candid about the affordability.

In the US, quotes for pending plants are more like $6/W. Shouldn't be, but apparently is. Even so ...

I don't know the exact cost of the utility panels, but the companies stated goal was to deliver a PV power plant for less than $1.00W...

If that becomes available, it is a cost per peak power figure, unlike the cost of nuclear which puts out rated power >90% of the time, the point of Russ's capacity factor post above. To replace ( or displace) an equivalent nuclear plant with solar PV compare all the costs:
1. To produce the same amount of energy in a day, multiply the PV figure by 6X in the southwest US, 8-10x in cloudier climates.
2. For the lower efficiency PV's like thin film, one needs a lot of land and a lot of installation. Maybe rooftops are free, or at least sunk costs. Certainly installation is not free. That $5/W for nuclear certainly includes 'installation'.
3. If its in the desert/ middle-of-nowhere add transmission costs, over and above nuclear transmission.
4. The overall cost has to include the 'other' energy source for nights/clouds, whatever it is. Maybe gas turbine electric.

Edit: the above reasoning changes if the if power is only needed for peak demand, like middle of the day air conditioning, and nothing more. However the OP wasn't looking for niche power, but 50% of the full time load.

 

[Skyhunter]

However the OP wasn't looking for niche power, but 50% of the full time load.

I think the OP was looking for 50% of energy coming from renewable energy. Since peak demand in during the hours when the Sun shines, solar can help fill that demand. With a smart grid, and using the batteries from electric vehicles, solar can be a significant contributor. Nuclear, especially fourth generation nuclear is a viable option, but not a magic bullet.

Solar at $1.00 a watt is economical enough to return a nice profit without subsidies. It can also be deployed in months instead of years, meaning that return on capital investment is much faster. A nuclear plant can take a decade or more to construct, tying up the investment capital during this period.

In the end, economics will determine what the makeup of our energy supply looks like. Solar power is fast becoming competitive with coal. Once these new panels hit the consumer market, look to see them on homes everywhere in the next decade.

 

[mheslep]

I think the OP was looking for 50% of energy coming from renewable energy.

Yes

Since peak demand in during the hours when the Sun shines, solar can help fill that demand.

Yes, help.

With a smart grid, and using the batteries from electric vehicles, solar can be a significant contributor.

Yes though I don't know what significant means here. I very much doubt 50% in the time frame of the OP.

Solar at $1.00 a watt is economical enough to return a nice profit without subsidies.

I see nothing here yet to support that assertion.

It can also be deployed in months instead of years, meaning that return on capital investment is much faster

I see this as one of the strongest points in favor of solar. Even transmission deployment disappears for rooftop installations.

A nuclear plant can take a decade or more to construct, tying up the investment capital during this period.

Yes, though that's a political consequence in the US, not something intrinsic to the technology.

In the end, economics will determine what the makeup of our energy supply looks like. Solar power is fast becoming competitive with coal.

Not true. In some scenarios, for peak power, solar PV is nearly competitive with peaking gas turbine plants, but not even close to coal without carbon taxes.

 

[mheslep]

Levelized cost of energy (not power) for multiple sources, before subsidies.

From http://www.newenergymatters.com/UserFiles/File/Presentations/NEF_2009-11-23_Guardian_Cleantech.pdf"
PV thin film 3-4X coal.

 

[edpell]

Levelized cost of energy (not power) for multiple sources, before subsidies.

From http://www.newenergymatters.com/UserFiles/File/Presentations/NEF_2009-11-23_Guardian_Cleantech.pdf"
PV thin film 3-4X coal.

Thank you for the reference. It is useful information.

Even at 4X I would think countries without coal deposits would be building.