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December 15, 2007

Comments

Harvey D

Wind Farms can effectively be used as base load when interconnected with Hydro Power.

Hydro water reservoirs are excellent for energy storage. Using hydro for peak loads has a significant side benefit because Hydro energy production is optimized when reservoirs are kept at very high level.

Jim from The Energy Blog

Harvy, Although what you say is true, all hydro in the U.S. is spoken for and only a very small amount could be added. In the developing world, what you say may apply, but hydro provides a very good baseload. Pumped storage is a better answer for use of our water resources in the energy mix, although it is quite expensive.

bigTom

There are often restrictions on how much, and how quickly many hydro plants are allowed to change output. Fishermen and environmentalists tend to get upset if the water creatures are left high and dry. Then there may be users downstream whose desires with respect to minimum and maximum flow rates must be respected. The dispatchability of hydro may not be nearly as large as you think.

eric

Extended drought could force some hydro projects to shut down due to low water levels. Consider Lake Powell, for example:

https://www.glencanyon.org/library/1104barjournal811.pdf

When it is full, the water level in Lake Powell reservoir is at 3700' above sea level. The water level currently sits at 3570' and continues to fall. Minimum power operating level, where the Glen Canyon Dam loses its capacity to generate electricity, is at 3490 feet. At 3371', the water would reach the bottom of the river outlets and the dam would not be able to release any water. At that level, Lake Powell would sit in a stagnant state known as deadpool. At deadpool, the riverbed of the Colorado could be dry through the Grand Canyon.

That article was written in 2005, and current water level is 3597, so levels have gone up a bit since that article was written.


Chanranshu Pandya

As very clearly indicated in this report,the day is not far when a combination of all types of renewables will be feeding the grid. Solar power will be better utilised in various decentralised systems. The large variety of parts, components and systems that can be made use of makes solar energy more useful in decentralised areas and for the development of hydrogen based power systems being planned on a maga scale to replace fossilfuel based power plants now in use in the world.

Prof C G Pandya
Ahmedabad, INDIA

DaveMart

Dunno about the hydrogen based power systems.
You loose energy at every stage in generating and transmitting the hydrogen:
https://entropyproduction.blogspot.com/2006/07/hydrogens-death-knell.html
the production of synthetic liquid fuels is a whole different ball-game, and much more practical IMHO

amazingdrx

https://gristmill.grist.org/story/2006/12/17/212637/60

This article claims 95% of baseload can come from wind with a small, affordable amount of storage. How so? That claim is based on a study of the output of 8 wind farms.

The more wind farms, the higher the baseload power percentage and the lower the amount of storage or backup needed.

And as amory Lovins pointed out, our vehicles have 7 times the power generation potential of our entire power grid. If only 10% of vehicles were plugin hybrid, vehicle to grid storage would more than take care of storage.

An internet enabled smart grid that used heating/cooling load timing (storing heat or cold in buildings and freezers for instance) letting them coast on stored heat/cold, would also be enough to fill in gaps in wind.

Another great backup power source is solid oxide fuel cell/turbines running on natural gas or biogas. These can be distributed around the grid in smaller units that the typical coal or nuclear power plants. The cogenerated heat used for heating, adding efficiency to the already 70% efficiency of the fuel cell/turbine.

Natural gas for this application can be diverted from heating buildings by switching to smart grid controlled geo heat exchange heating/cooling. Another big load of gas can come from biogas production from the waste stream, keeping high nitrogen run off from human waste, manure, and landfills from releasing methane (a 23 times worse GHG than CO2) from natural carbon sinks, like wetlands.

Finally as the ultimate natural gas/fuel cell/ cogeneration backup, coal, tar sands, and sour oil can be converted to natural gas underground with bacteria. Making coal obsolete.

With solid oxide fuel cell/turbines in the 20kw range as liquid fueled backup generators for plugin hybrids, vehicle to grid with the vehicle fuel cell plugged into natural gas when parked would supplement distributed fuel cell cogeneration backup. These fuel cell units are under development by Boeing, as backup generators for their aircraft and the power source for unmanned aerial vehicles. Mass produced for vehicles the cost would come down to compete with internal combustion engine powertrains.

An internet enabled smart grid, incorporating these devices, would be different from the old centralized power grid model. The old grid is designed to meet any load at anytime, necessitating huge capacity for peaks that sits idle or worse is kept in "spinning reserve' mode, consuming fuel but yielding no kwh. No matter how much capacity or power line buildout, it seems that this grid always falls short during peak air conditioning load, or ice storms, or lightning events.

A smart grid would adjust load during emergency peaks by shutting down non-essential load. Letting heating/cooling coast for instance. It would adjust to variability, becoming much more predictable, even as the grid itself becomes more variable.

A new paradigm for utility engineering is emerging. A renewable distributed generation, storage, and conservation grid, operating with smart grid technology, that will make GHG and fossil fuel use a minor part of our power system. A system that makes local, regional, and national grids autonom,ous in emergencies, but allows for distribution of power over the grid for added efficiency.

This system can pay it's own way in fuel and GHG saved, storm outage averted, trillions saved on centralized power grid and power plant upgrades, and economic revitalization with lower energy costs and a whole new manufacturing sector.

DaveMart

There are lots of nice ideas about.
It's turning them from ideas into engineering at some sort of reasonable price that is the difficult bit.

amazingdrx

Yep, lots of nice ideas. Combining the ones that have the lowest long range cost and the least environmental damage, that tend to work together better than they work separately; brings about an economical solution.

The economic growth that occurs, along with this energy revolution, pays back the capital investment many times over. Tax subsidies shifted from the old grid and energy industries, to the new paradigm.

Taking the huge tax on econmomic growth, represented by ever higher energy prices and ever worse climatic disasters, off of the world economy will raise the quality of life all around the globe.

RJMACHUTA

Why not combine wind with solar thermal when they are near each other. Use wind generated electricity to heat steam in the solar storage tanks. I know it is inefficient, but wind power at night is essentially free and wasted if not used.

Cheap energy at night will help hybrid and electric vehicles because they can use a power source that is interruptable like wind.

One final thought, massive windmill arrays on ridgelines would make wonderful fire breaks in Socal. The service access roads would help CDF a lot too.

amazingdrx

Payback periods and energy prices. Wind and solar installations have fairly low payback periods. Around 3 to 7 years for most.

As the payback is reached, energy prices will start to drop. That is a stabilizing economic force that fights basic inflation.

It reinforces the cultural investment we have made in the pusuit of happiness, a big part of that happiness, personal and national financial security. Based on a strong, stable currency backed by a strong, competitive, productive economy. We need to continue to lead in renewable technology to do that.

Yuy Joe

Interconnecting wind farms with transmission lines to reduce variability of power availability makes sense, and even those connecting lines can be windpower strings, where topography permits.

For info on wind energy and other green power stocks and mutual funds, check our Guide to Top Alternative Energy Investing Websites and Blogs

Peace from Canada,

Yuya Joe

Yuy Joe

Interconnecting wind farms with transmission lines to reduce variability of power availability makes sense, and even those connecting lines can be windpower strings, where topography permits.

For info on wind energy and other green power stocks and mutual funds, check our Guide to Top Alternative Energy Investing Websites and Blogs

Peace from Canada,

Yuya Joe

Harvey D

eric;

The ideal, for multiple dams river systems, is to keep water level at each reservoirs close to maximum, with regulated overflows during rainy seasons.

Modern turbines water flow can be adjusted to suit power demands (Ex: for peak demands) and/or for water management purposes. Overflow and/or bypass gates can also contribute.

Lately, most hydro systems are short of water. Low water level = lower water pressure = reduced production from turbines and associated generators. Interconnected Wind farms could take over some of the power demands and help to conserve falling water levels and even raise water to higher production levels. An extra 100 feet means a lot.

Hydro power sites can be over-equipped with extra turbines/generators to meet peak demands.

Charles Barton

I am not a big fan of Christopher Booker, but he is on target on the costs of British wind power plans:
https://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/12/16/nbook116.xml

We already had this discussion on the 11th. Curiously the argument for renewables has been that we are better off with decentralized production, yet we have a highly centralized plan that relies 19 generating facilities. The present centralized systems relies on over 1000 generating facilities. We have vanadium redox batteries offered for backup reliability. 8 GWh worth of vanadium redox battery backup is going to cost at least $2.8 billion, as much as a 1 gig nuclear plant that will produce power 24 hours a day. The plant can be located near an existing power grid, thus eliminating the need for new and extremely expensive infrastructure.

Wind is not less expensive than nuclear power, even French nuclear plants. A plan that involves one connecting point for 19 wind fields is highly vulnerable to terrorism. Basically it sets up a chock point at which the entire power grid can be shut down by a single attack. If there are two power lines, one running east of the chock point, the other to the west, you have another set of vulnerabilities. Long extremely high voltage power lines make really good terrorists targets. Good opportunities for copper theft too.

Jeff Eldon

The Stanford study did not really involve any new study or shed anything novel on the subject matter, it was essentially a rehashing of concepts and proven results from other studies done by others.

Many people keep thinking that integrating Wind Power into the nation's grid is this big, unsolved problem that if we only had the answer, we could really use more wind energy -- if only... And that "energy storage" is some kind of Holy Grail, that if we could have energy storage matched with wind power, then we could really make a difference and wind power could really....

Sound familiar ? Well, the reality is that there are a number of utilities and supporting organizations that have been studying this for several years and the studies and reports now show that wind power can readily be integrated into the existing power grid within massive changes that the Stanford study seems to imply, without adding large amounts of back-up generation, without the need for energy storage at all, and at very minimal cost to the operation of grids that are part of robust, liquid power markets operated by utilities and Regional Transmission Operators / Independent System Operators today.

Not only have the studies already been done, and shown that wind integration of increasing levels of wind power penetration are feasible, but it is happening today already. So everyone that thinks we need to have some huge technology breakthrough or thinks that energy storage is the panacea for renewable energy in general and wind power in particular -- think again.

Visit www.uwig.org to learn more - take a look at the studies there and take a look at the recent articles in a special magazine of the IEEE magazine linked there today. Wind integration into power grids across the U.S. is very well understood, very manageable in terms of the costs of doing so, able to be done with existing technology, and very well understoof.

Jeff Anthony
American Wind Energy Association

Charles Barton

Jeff Anthony, at present ERCOT considers that 8.7% of rated wind generating capacity to be base power. I have seen some electrical prices by Texas wind generated electrical consumers. They range from $0.14 to S0.18+ per KWh. Wind in Texas is not ready for prime time.

Ender

Charles Barton - "Curiously the argument for renewables has been that we are better off with decentralized production, yet we have a highly centralized plan that relies 19 generating facilities. The present centralized systems relies on over 1000 generating facilities. We have vanadium redox batteries offered for backup reliability. 8 GWh worth of vanadium redox battery backup is going to cost at least $2.8 billion, as much as a 1 gig nuclear plant that will produce power 24 hours a day. The plant can be located near an existing power grid, thus eliminating the need for new and extremely expensive infrastructure."

Except of course that the storage does not have to be centralised. Redox batteries are just as efficient at 100kW or 10kW as 1MW totally unlike nuclear plants. The storage can be local and if the large transmission lines do fail they can take over ensuring supply.

You of course completely fail to mention the extremely expensive infrastructure required to safely dispose of the waste from the nuclear reactors - 24 billion and counting at the moment.

BILL HANNAHAN

From the report;
But interconnecting wind farms with a transmission grid reduces the power swings caused by wind variability and makes a significant portion of it just as consistent a power source as a coal power plant…..This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power

Wow! Average wind capacity factor of 0.3 and one third is reliable, 10% of data plate rating. How is that as reliable as coal or nuclear? Actually it is not that good, during the 2006 U.S. heat wave wind output in California was down to 5%.

https://gristmill.grist.org/story/2007/3/12/63111/0928/#37

If every windmill in the U.S. was connected to a single grid, it would have been down 20% during the heat wave when demand was up 20%. I would love to see an hour by hour graph of total U.S. wind production. I suspect we could find times when it was well below 10%

No quantity of differential equations will change these facts.

Wind needs backup capacity, the cost is never included in wind cost estimates
.
The break even cost of wind power is the cost of the fuel not consumed, and the cost of nuclear fuel is about one half cent per kWh. Wind is an expensive fad. in the long run it will go away.

Ender

Bill - "If every windmill in the U.S. was connected to a single grid, it would have been down 20% during the heat wave when demand was up 20%. I would love to see an hour by hour graph of total U.S. wind production. I suspect we could find times when it was well below 10%"

Except of course that in the heat wave the output of the nuclear plants could well be down 20% due to the lack of cooling water so don't pick on wind. Look what happened in France. Lucky the nuclear was backed up with wind from Denmark.

Also in a heatwave all the solar assets will be at their peak output compensating for the lack of wind and the lack of nuclear and fossil fuel plants starved of water.

"Wind is an expensive fad. in the long run it will go away."

Nuclear is an expensive fad and for the sake of the planet and future generations let us hope and pray that if goes away.

Ender

Bill - "Wow! Average wind capacity factor of 0.3 and one third is reliable, 10% of data plate rating"

I cannot believe I have found so much crap in one post. No Bill the study found that interconnected wind farms can provide 30% firm not 10% as you insinuate.

"Wind needs backup capacity, the cost is never included in wind cost estimates"

Nuclear needs backup AND waste disposal facilites. Have you forgotten that nuclear is baseload and needs peaking power backup? Neither the correct costs for waste disposal or the required peaking power is added to the cost of nuclear.

"The break even cost of wind power is the cost of the fuel not consumed, and the cost of nuclear fuel is about one half cent per kWh."

You forgot to add "at the moment". As high grade ores become more exploited and the supply of recycled warheads comes to an end you might find that fuel costs start to bite. If someone FORCES you to dispose of the waste PROPERLY instead of ignoring it, which is happening at the moment, then the lifecycle costs of the fuel will also skyrocket.

Wind does not have any of these problems.

Ender

Bill - and finally as I have just thought of this the smart people that are using distributed renewable power in the heatwave will be drawing power from assets all over the country through efficient HVDC power lines. The power will be coming from the solar assets producing their maximum power and from other power stations not affected by the heatwave. And even if there are disruptions the local vanadium batteries and V2G cars will see most consumers through. Rooftop solar will be powering a lot of the extra demand.

However the dumb grid people with their nuclear reactor stuck in the heatwave will be suffering load shedding as the nuke desperately avoids cooking the animal life in its cooling water already depleted by drought from climate change. As the nuke are so expensive the HVDC lines did not get built so there is no real option to get power from the creaking overworked grid.

I guess if you are afraid of change and doing the same with a lot less energy waste then nuclear is your only option.

BILL HANNAHAN


"Wow! Average wind capacity factor of 0.3 and one third is reliable, 10% of data plate rating"
I cannot believe I have found so much crap in one post. No Bill the study found that interconnected wind farms can provide 30% firm not 10% as you insinuate.

Ender;
Typical wind capacity factor is 0.3 times data plate rating, so what is 30% of 0.3?

Nuclear needs backup AND waste disposal facilites. Have you forgotten that nuclear is baseload and needs peaking power backup? Neither the correct costs for waste disposal or the required peaking power is added to the cost of nuclear.

Nuclear plants pay .1 cent / kWh into a huge trust fund for waste, far more than enough. Peaking power to backup baseload is nonsensical.

You forgot to add "at the moment". As high grade ores become more exploited and the supply of recycled warheads comes to an end you might find that fuel costs start to bite.

We only need 0.7 pounds / year with our primitive 1st gen reactors, 0.3 pounds / lifetime with breeders. Uranium cost is a tiny fraction of what we pay for electricity, price spikes have little effect on our bill.

and finally as I have just thought of this the smart people that are using distributed renewable power in the heatwave will be drawing power from assets all over the country through efficient HVDC power lines. The power will be coming from the solar assets producing their maximum power and from other power stations not affected by the heatwave.

Now I understand, to replace one coal or nuclear plant we need about $5 billion worth of windmills, about $15 billion worth of solar cells, and throw in $3 billion for the super grid, $23 billion.

Ender

Bill - "Ender;
Typical wind capacity factor is 0.3 times data plate rating, so what is 30% of 0.3?"

Yes but when you hook them up together they form a system that can offer power at 30% firm. At times fossil fuel generators do not do as well as this. Perhaps you should read the paper properly.

"Nuclear plants pay .1 cent / kWh into a huge trust fund for waste, far more than enough. "

Which at the moment is far short of the cost of even a single facility that can hold 17 000 tons which is not large enough for the estimated 29 000 tons of high level waste that you need to store and is building up. So how many mountains will you have to drill out and how much will your taxpayers have to pay to make up the shortfall.
https://climate.weather.com/articles/yucca100507.html

" Peaking power to backup baseload is nonsensical."

So France does not need Swedish pumped hydro? You can be the one to tell them as you seem to have all the answers. Perhaps you can convince a nuke operator to operate as a load follower. That should have the investors flocking. So what does peaking power for baseload power stations? Or are you trying to say peaking plants don't exist?

"We only need 0.7 pounds / year with our primitive 1st gen reactors, 0.3 pounds / lifetime with breeders. Uranium cost is a tiny fraction of what we pay for electricity, price spikes have little effect on our bill."

But they have a huge effect on your profitability. If you are forced to sell cheap electricity and can only sell into baseload supply, the cheapest type possible, you need to reduce costs. Fuel costs will hurt as uranium rises in price. You can't do peaking or ancillary as nuclear is totally unsuited for this so you are stuck selling cheap power with rising costs. This is of course unless you want to join the socialised power of France where profit is unimportant.

"Now I understand, to replace one coal or nuclear plant we need about $5 billion worth of windmills, about $15 billion worth of solar cells, and throw in $3 billion for the super grid, $23 billion."

Which should be 2/3 the cost of Yucca Mountain by the time it is finished. At least the supergrid plus renewables will last for longer than you can keep countries sufficiently scared of you so they will sell you uranium. Wouldn't you rather be independent instead of your energy future decided in the Senate of Australia or Canada?


DaveMart

Ender, this is a non-sequitur - the costs referred to are the costs to replace one nuclear plant, and you compare that with the costs of Yucca mountain, which is supposed to deal with the waste from all the nuclear plants, so your comparison is not valid.
I find myself somewhere in the middle on these arguments.
The link to the Cambridge study given in the original article makes it pretty clear in my view that intermittancy can be dealt with at the level of penetration that is contemplated in the US.
However, the 'plans' recently released in the UK to generate 33GW name plate capacity with off-shore wind are straightforwardly insane, and more like some 5 year plan by a communist dictator than any rational project by a democratic government.
The link given to the Telegraph article shows the basic economics - or lack of them.

Charles Barton

Ender, anti-nuclear "Greens" engage in a form of crazy thinking. They raise the issues of nuclear waste, but then they object to any proposed solution to the supposed problem. My view is that there is very little in "spent reactor fuel" that is really waste. At least 97% of so called nuclear waste can be reused in reactors. Some of the remaining 3% quickly becomes looses its radioactivity, and thus no longer fits into the category of "nuclear waste." Some of the remaining radioisotopes have medical, industrial, and agricultural uses. Thus true "nuclear waste" is a small amount of radioisotopes with relatively long half-lives, which cannot be reused in reactors, and which lack other uses.

Any one of a number of plans for the disposal of the unusable radioactive byproducts of reactor operations would be satisfactory. For example encasing them in glass, and disposing them in abandoned Uranium mines. The French do dispose of their nuclear waste without a problem, so we could follow their example. But for the anti-nuclear greens to acknowledge that, would be to admit that their opposition to nuclear power is emotional and simply not rational.

Kit P

“Except of course that in the heat wave the output of the nuclear plants could well be down 20% due to the lack of cooling water so don't pick on wind.”

None of the eight reactors in the eight nuclear reactors in the western US are cooled by river water. They are designed to operate at 100% on hot days which is one of the reasons you may them producing 102% power on a cold day.

Charles Barton

Except of course that the storage does not have to be centralised. Redox batteries are just as efficient at 100kW or 10kW as 1MW totally unlike nuclear plants. The storage can be local and if the large transmission lines do fail they can take over ensuring supply. - Ender

Localized storage costs too. The consumers are going to have to pay for storage whether it is centralized or local. The question is whether it is the better deal for the power consumer? Part of the answer can be found in the question, How often will the batteries need to be replaced? Reportedly vanadium redox batteries have an expected life of 5 to 7 years. Considering that many conventional nuclear power plants have an expected lifetime of 60 years, and will produce power 24 hours a day, the power consumers would be getting a very much better deal from investments in nuclear power, rather than investments in vanadium redox batteries.

Charles Barton

“Except of course that in the heat wave the output of the nuclear plants could well be down 20% due to the lack of cooling water so don't pick on wind.” - Ender

There are engineering solutions solutions for reactor water problems due to heat waves or drought. There is no engineering solution for a lack of wind in a heat wave.

Kit P

Speaking of engineering solutions in arid climates:

https://www.panoramio.com/photo/2309290

Thomas Pedersen

Charles Barton wrote:

A plan that involves one connecting point for 19 wind fields is highly vulnerable to terrorism. Basically it sets up a chock point at which the entire power grid can be shut down by a single attack. If there are two power lines, one running east of the chock point, the other to the west, you have another set of vulnerabilities. Long extremely high voltage power lines make really good terrorists targets.

What?!? Terrorists hitting power lines? That's a first. I bet that will have us running down the streets in panic. Explain to me how cutting the wire to a wind farm is worse than to a "nucular" power plant, please?

Terrorism is about getting big headlines. The way to do that is by creating a massive bodycount in a spectacular event, like 9/11. Snapping a powerline is hardly worth a major headline, let alone two weeks of non-stop news broadcast as with 9/11 or the London/Madrid bombings.

Good opportunities for copper theft too.

I'd like to see someone steal copper from a 150 kV line. We all know that's a major issue with wind farms. LOL

I'd bet the coal lobby is having a good laugh from the comments in this post. Seeing wind and nuclear people snapping at each other is just what they want. It's even more sad when you consider that the market is more than big enough for both of them. Wind energy is really expensive right now because the manufacturers can sell all the turbines they can possibly build.

Charles Barton

What?!? Terrorists hitting power lines? That's a first. - Kit P.

Kit That is hardly a first, New Your City is currently installing a superconducting, allegedly terrorist proof power line under Manhattan:

https://www.reuters.com/article/domesticNews/idUSN2133617520070521

Roger Brown

Interconnecting wind farms is a good idea, but it does not solve all the economic problems associated with integrating wind into a 24/7 grid. For one thing it does not address the problem of peak loads where you need to have reliable, dispatchable power available. With natural gas prices set to sky rocket this problem is needs to be addressed sooner rather than later. Furthermore wind power varies seasonally. I know that in some climates electric load roughly follow wind power availability, but if we are going to fire wind power around a large geographic area using a HVDC super grid then this convenient variation will not be universally applicable. Solar might work better than wind for peak load since solar is available during the day, but because of cloudy weather a super grid for solar would probably be necessary as well. Although HVDC is cheaper and has lower losses than AC, such a grid will still be very expensive and will require long lead times and careful planning. I do not think that the super grid idea will work well for a free form growth economy. It will require the dreaded central planning and will work well only if we carefully anticipate electricity consumption over long periods of time and over large geographical areas. If we abandon the madness of the pursuit of everlasting growth in favor of producing a decent quality of life with a minimal consumption of resources then these large scale cooperative energy systems might be effective.

Clee

a supergrid for solar would probably be necessary as well.

I figured if we had a supergrid, electricity from all sources would run across it. Having a separate grid just for solar seems bizarre. Have wind supply power during the cold windy nights and solar during hot still days to help reduce the amount of power that natural gas plants have to produce to meet peak loads.

Roger Brown

I figured if we had a supergrid, electricity from all sources would run across it. Having a separate grid just for solar seems bizarre.

I did not mean truly separate. I just meant more total lenth of transmission lines.

Nucbuddy

Charles Barton,

Kit P. did not write: "What?!? Terrorists hitting power lines? That's a first."

Thomas Pedersen wrote it.

Cyril R.

There is no engineering solution for a lack of wind in a heat wave.

Yes there is. Heat wave -> more solar thermal production. Perhaps with oversized thermal storage to partially host other renewables, such as wind. Ausra brought this idea up. That could be some of the small need for backup and even some storage. There would also be surplus PV in a heat wave to compensate. Just pointing out the obvious.

A peaker nuke could also do it. If only they actually existed in the real world...


Nucbuddy

Cyril R. wrote: Heat wave -> more solar thermal production.

No. Heat wave -> less solar thermal production. As the outlet temperature rises, thermal powerplant efficiency drops. This is basic thermodynamics. You can read more about it here:
en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29

the maximum [...] efficiency any possible engine can obtain [...] solely depends on the difference between the hot and cold temperature reservoirs.


A solar-thermal powerplant is no different from any other thermal powerplant in the fact that its efficiency depends upon environmental temperature, and drops as environmental temperature rises. In other words, a solar-thermal powerplant does not run on environmental heat. It runs instead on something that it turns into heat. The colder the environment is, the more-efficient -- and therefore the more-powerful -- a solar-thermal powerplant will be.

To state again: solar-thermal powerplants are more efficient on cold days, and less efficient on hot days. Solar-thermal powerplants are more powerful on cold days, and less powerful on hot days.

Nucbuddy

Cyril R. wrote: There would also be surplus PV in a heat wave

Photovoltaic (PV) efficiency and output drop during heat waves. Solar PV is more-efficient and more-powerful on colder days.


Cyril R. wrote: Just pointing out the obvious.

In that case, please refrain from ever-again on the Energy Blog "pointing out" anything "obvious".


Cyril R. wrote: A peaker nuke could also do it. If only they actually existed in the real world...

Peaker nukes presently do not exist, because cheaper peaking-power alternatives such as hydro, natural gas, and diesel presently do exist.

Cyril R.

No, Nucbuddy, you are wrong. The keyword is concentration ratio. Little bit more powerful sun, mirrors focus this little bit to one point where it becomes significant.

The difference in environmental temperature however will be small, e.g. 20 degrees K, if that. The stronger sun only heats the environment under a one sun concentration while the mirrors concentrate it many times, causing any increment in solar radiation to be multiplied many times, yielding so much more heat that it easily negates the higher environmental temperature effect. Thus, yielding more energy.

Still, the idea of using solar thermal plants in cold extremely arid parts of Canada etc. might have some potential.

Cyril R.

Photovoltaic (PV) efficiency and output drop during heat waves. Solar PV is more-efficient and more-powerful on colder days.

Again wrong my friend. Rooftop CPV would be more efficient due to concentration reasons outlined in my previous post. There are other technologies, such as certain thinfilms, which suffer less from hot temperatures. And again, even under one sun, with the correct passive cooling technologies, the temperature would not increase so much as to negate the increase in solar energy received and thus, converted.

In that case, please refrain from ever-again on the Energy Blog "pointing out" anything "obvious".

Sheesh, what's wrong with you, did your cat die or something? There's no need to get all riled up my friend.

Peaker nukes presently do not exist, because cheaper peaking-power alternatives such as hydro, natural gas, and diesel presently do exist.

Natural gas and diesel emit CO2. Plus they don't do much for energy independence. Hydro cannot expand significantly in the US.

Nucbuddy

Cyril R.,

You are fallaciously equivocating between local insolation and local temperature. In fact, these are two different things. There is not a 100% correlation between local insolation and local temperature. Heat-waves and cool-waves occur in the summer, largely-regardless of what summer insolation does. Insolation is not temperature.

Therefore, ceteris peribus, I was correct when I stated above:

Heat wave -> less solar thermal production. [...] A solar-thermal powerplant is no different from any other thermal powerplant in the fact that its efficiency depends upon environmental temperature, and drops as environmental temperature rises.
Cyril R.

There is not a 100% correlation between local insolation and local temperature.

Yes, but in the desert the correlation is extremely high (high enough to make my argument valid at least), and in the desert is where solar thermal plants would be. These could have their thermal storage deal with intra day variations as well.

And for PV the correlation is usually reasonably high enough to help a bit in most US climates, as it can utilize diffuse light.

Heat-waves and cool-waves occur in the summer, largely-regardless of what summer insolation does.

The most severe heat-waves occur simultaneously with periods of high insolation. But there is one other important thing you've forgotten about:

Local conditions (eg heat waves) will be less relevant if a large nationwide interconnected grid is established, with all the solar, wind etc. and nuclear plugged in.

Nucbuddy

Cyril R. wrote: in the desert the correlation [between local insolation and local temperature] is extremely high

Please point to some data relevant to that.


Cyril R. wrote: solar thermal plants [...] could have their thermal storage deal with intra day variations as well.

Why would one store the thermal power from a solar thermal powerplant, instead of storing cheaper thermal power such as that from a nuclear powerplant?

Cyril R.

Cyril R. wrote: in the desert the correlation [between local insolation and local temperature] is extremely high

Please point to some data relevant to that.

Well just a quick google led me to this reference. The measurements were done on clear days. Deserts have many clear days, and are pretty far from the ocean. It's not too good a reference, so if you feel like googling some more please be my guest. Since you brought it up, maybe you could provide me a reference that supports your assertion? Really, I feel like you are you asking me to point out the obvious...

Why would one store the thermal power from a solar thermal powerplant, instead of storing cheaper thermal power such as that from a nuclear powerplant?

Thermal storage, if cheap enough, can actually lower the price per kWh for solar thermal plants as they can have less turbine and BOP per kWh. Relatively that is. Solar thermal has much potential for cost reductions now and in the future. So does nuclear. Storing large amounts of heat for a nuclear plant is something I'd definately like to see. But it disappoints me that no one appears to be seriously working on peaker nukes of any design. Do you know of any companies that do?

More nuclear powerplants is fine with me. In fact, we should build them right now. I don't see any compelling reason not to investigate solar thermal with thermal storage though. Apparently you do.

Kit P

Jeff Anthony, thanks for the links, it took me a while to get through all the info. It nice to read what what is latest from EE and ME experienced with the how to integrate wind unto the grid.

bigTom

The change in solar thermal output due to ambient temperature changes should only be a few percent. Wind on the other hand may be anti-correlated with local heat waves.

Kit P

“But it disappoints me that no one appears to be seriously working on peaker nukes of any design. Do you know of any companies that do?” They all do. No extra charge. You can also buy an expensive car and take a cab if it 'disappoints' to drive it.

The US Navy to start with. You might be surprise how fast the reactor power change when the ship it is in needs to be someplace else. I would assume that the barge mounted reactors that the Russian are building for China would have the same abilities.

There is no reason to store the thermal energy of a nuclear reactor because the energy cab produced on demand.

Ender

Charles - "At least 97% of so called nuclear waste can be reused in reactors."

So why isn't it? Let me guess, no-one wants plutonium travelling about the country in ton lots for the terrorists you think might hit power lines to get. Consider the relative impacts 1. a cut power line 2. a dirty plutonium bomb.

KitP - "None of the eight reactors in the eight nuclear reactors in the western US are cooled by river water. They are designed to operate at 100% on hot days which is one of the reasons you may them producing 102% power on a cold day.'

I am sure they aren't however how do the other 100 odd cool themselves?

Cyrus

A weakness with this paper is that is takes the variability of output at existing wind farms, and scales it up to enough wind farms to make up a sizeable portion of the grid, without addressing that the those units that have already been installed are likely sited in very good locations for wind generation, whereas wind conditions at the 100,000th site may not be so favorable.

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