Solar has won.

[EdEarl]

 

theguardian.com

 

Last week, for the first time in memory, the wholesale price of electricity in Queensland fell into negative territory – in the middle of the day.

 

For several days the price, normally around $40-$50 a megawatt hour, hovered in and around zero. Prices were deflated throughout the week, largely because of the influence of one of the newest, biggest power stations in the state – rooftop solar.

In the nick of time, or too late?

[Sensei]

Couple months ago I even wrote letter to our government showing that their idea to start up new atomic power station for $7bn (10 MW) is simply silly.

For the same money they could buy at detail price solar panels enough for 2 million apartments and make them independent from power stations.

But instead I suggested them to buy/create whole company producing solar panels, which would decrease costs even more..

[John Cuthber]

"For the same money they could buy at detail price solar panels enough for 2 million apartments and make them independent from power stations"

until sunset.

[StringJunky]

I wonder what the ratio of land area required for nuclear and solar plants respectively is for producing equivalent output.

[swansont]

I wonder what the ratio of land area required for nuclear and solar plants respectively is for producing equivalent output.

 

I expect nuclear has a smaller footprint. But the comparison is skewed. Solar can be put on rooftops and on land unsuitable for other purposes (e.g. desert land, which is pretty much ideal for solar generation). Nuclear needs a water source, so they tend to be on rivers or lakes.

[Sensei]

I wonder what the ratio of land area required for nuclear and solar plants respectively is for producing equivalent output.

 

Each m^2 of Earth is receiving average 1360 W, but part of energy is absorbed by atmosphere, which gives max 1050 W per m^2.

Solar panel typical efficiency is 15%, so from 1050 W there is remaining 160 W/m^2.

Then you have to take care of that Sun shines just between 4-20 at summer, or between 8-16 (or so) at winter, and max output is varying depending on hour.

For mine latitude I have calculated that I need 18 m^2 to cover all mine needs 460 J/s (which is 330 kWh per month), regardless of season and hour. During day there must be enough gathered for all night.

So if nuclear power station have 1000 MW it's giving energy to ~2.2 mln houses like mine. And it's equivalent to 39 mln m^2 of solar panels.

Edited July 9, 2014 by Sensei

[swansont]

10 MW for a nuclear plant seems low by at least an order of magnitude. Where was this to be built?

[Sensei]

Sorry I meant 1000 MW. Thanks for spotting it.

Edited July 9, 2014 by Sensei

[Danijel Gorupec]

For mine latitude I have calculated that I need 18 m^2 to cover all mine needs 460 J/s (which is 330 kWh per month), regardless of season and hour. During day there must be enough gathered for all night.

Hi Sensei... can you tell me more... Did you calculate with sun-tracking panels or fixed ones? Is this 330kWh/month with or without home heating/cooling? Did you also compute the storage battery capacity that you might need to live, say, 90% of the time off grid?

[Sensei]

Hi Sensei... can you tell me more... Did you calculate with sun-tracking panels or fixed ones?

Fixed.

 

I was calculating from perspective somebody with solar panels at hand at any time from nearest shop selling them.

Exact model. 1600x800 mm size, with area =1.28 m^2, giving 190 W (15% efficiency), for 315 usd with tax each. 36.6 V and 5.2 A according to shop specification.

I was simply interested "what quantity of them do I need to cover all mine needs".

14 such solar panels (for $4410) = 18 m^2, and it should give me all what needed, including winter time.

 

Time (whole year) would tell whether it's correct quantity...

 

Is this 330kWh/month with or without home heating/cooling?

Without. It's what I am personally spending (the most of it is server running 24h/d)

 

Did you also compute the storage battery capacity that you might need to live, say, 90% of the time off grid?

Nope.

Edited July 9, 2014 by Sensei

[EdEarl]

There are vast differences in energy needs for a house. The best need no additional heating or cooling, and the worst are leaky and uninsulated. Each house must be evaluated to determine its solar PV needs.

[overtone]

 

 

I wonder what the ratio of land area required for nuclear and solar plants respectively is for producing equivalent output.

.

 

Photovoltaic panels are very expensive and inefficient compared with thermal collectors of various kinds.

 

Using Stirling cycle thermal collectors with either onsite storage (molten salt, pumped water, pressurized air, flywheel, whatever) or distributed storage (pump the water back over the Hoover Dam, charge fuel cells or batteries on location, etc) a back of the envelope calculation shows we would need a patch of Southwest high altitude desert 100 miles on a side - 10,000 square miles - to supply all the energy used within the borders of the United States.

 

To provide merely the electrical energy would of course take much less room.

 

That's feasible.

[iNow]

Thermal collectors are rather problematic at times... Like winter. At least with photovoltaics, you just need incoming light (and not even very much as evidenced by Germany). Panel costs are decreasing and projections show that trend will continue, too.

 

 

http://futurist.typepad.com/.shared/image.html?/photos/uncategorized/2007/08/19/solar_3.jpg

[overtone]

Thermal collectors are rather problematic at times... Like winter.

Winter makes little difference to the common heat engine collectors, such as the Stirling cycle mentioned - the power comes from the difference between the hot and cold, not the absolute values. There are maintenance issues - but compared with handling waste and effluent and security and supply issues with other tech, nothing serious.

 

Southwestern US high altitude desert, 100 miles squared, current efficiencies and storage tech, replaces the entire energy supply of the US. In theory. The rest is ordinary engineering (not theoretical breakthrough) and politics.

 

The solar panels in Germany work OK, and could quite likely replace fossil fuels and such at a net gain, but they are expensive and fragile and inefficient, especially compared with other solar tech for large scale and centralized power production. The opponents of solar sometimes try to limit the fuel comparisons to PV panel generation, for that reason.

Edited July 10, 2014 by overtone

[swansont]

Winter makes little difference to the common heat engine collectors, such as the Stirling cycle mentioned - the power comes from the difference between the hot and cold, not the absolute values. There are maintenance issues - but compared with handling waste and effluent and security and supply issues with other tech, nothing serious.

 

Southwestern US high altitude desert, 100 miles squared, current efficiencies and storage tech, replaces the entire energy supply of the US. In theory. The rest is ordinary engineering (not theoretical breakthrough) and politics.

 

The solar panels in Germany work OK, and could quite likely replace fossil fuels and such at a net gain, but they are expensive and fragile and inefficient, especially compared with other solar tech for large scale and centralized power production. The opponents of solar sometimes try to limit the fuel comparisons to PV panel generation, for that reason.

 

Heat engines run of of a temperature difference, as you say. What is the cold reservoir for such a system?

 

A big advantage of solar PV is that it is a passive, scalable system. You can put it on your rooftop, and you can build it in utility-sized systems. Distributed generation means less stress on the grid.

[kristalris]

I guess if you combine solar panels with small rooftop windmills then the combination would provide a more steady power supply. In the Netherlands when the sun doesn't shine we often do have wind. I would be in favor of copying the Danes who have made themselves independent of the rest of the world for power. And I guess that copying the Germans in having the possibility to get payed properly for the energy given to the net would also help in getting sustainable power supply and having people invest in their own power supply..

 

Small rooftop windmills I'm told are very quiet. Yet I'm not quite certain as to the life cycle and maintenance cost.

[overtone]

 

 

Heat engines run of of a temperature difference, as you say. What is the cold reservoir for such a system?

Varies. Everything from phase change in liquid nitrogen to simple passive air cooling has been used (the nitrogen dump ones can be jacked up over 90% efficiency, but that's probably not viable mass market tech).

 

 

 

A big advantage of solar PV is that it is a passive, scalable system.

There's no intrinsic reason that heat engine solar could not be scaled, but the engineering challenges - mostly to keep the cost down, and fit installation to existing structures as well as output to existing grids - haven't been met AFAIK. Here's a good start: http://www.bsrsolar.com/sv/produkte3_e.html

 

Note the lifespan - 30 years projcted, with no power degradation expected over time until failure, and then repairable. Heat engines can be set up very simply, with few moving parts - they are intrinsically more rugged than PV panels, as well as environmentally more benign. PV systems do not normally last half that long, they degrade over time, and they are environmentally tricky to manufacture and discard.

 

I've not seen a good explanation for the overwhelming focus on PV panels in the public discourse - I suspect some of the motive and policy influence lies in the desire of well-connected military and satellite contractors to turn a buck with what they already have on the shelf.

[swansont]

 

I've not seen a good explanation for the overwhelming focus on PV panels in the public discourse - I suspect some of the motive and policy influence lies in the desire of well-connected military and satellite contractors to turn a buck with what they already have on the shelf.

 

 

Can you name a single PV manufacturer that is a well-connected military or satellite contractor?

 

There's no intrinsic reason that heat engine solar could not be scaled, but the engineering challenges - mostly to keep the cost down, and fit installation to existing structures as well as output to existing grids - haven't been met AFAIK. Here's a good start: http://www.bsrsolar.com/sv/produkte3_e.html

 

 

IOW this is less mature than solar PV. "Tested in over 1000 hours of operation, including at the Solar Test­field of Tamera, Portugal" means they've tested it for a couple of months.

[timo]

I suspect some of the motive and policy influence lies in the desire of well-connected military and satellite contractors to turn a buck with what they already have on the shelf.

To my knowledge the largest share of PV modules comes from China. That may be satellite contractors (not sure how many million satellites China has in space), but I doubt they have a large influence on German or US politics. In my experience, westerns companies mostly provide the AC/DC converters for the installations. An AC/DC converter, however, is not exactly the first piece of hardware I would expect in satellites or military equipment associated with PV.

 

@Tom: Siemens

Distributed generation means less stress on the grid.

At least in a physicist's world in which a power grid is a set of connected lines with a certain length and resistivity, some power sources and sinks at which some of the lines end, and some magic that controls the flow at the nodes. With a universal language spoken by all nodes, of course. And a well-defined optimization problem to solve. And perhaps even with correlations discarded for simplicity. A bit more than two years ago I was still in physics, too. And I would have said the same. Then I switched into a field called "distributed energy management", and supposed tautologies start to be a bit more tricky when it comes to details.

 

Examples: In reality, there is a strong hierarchical structure in the nodes. The magic that controls the power flow at the nodes is devices built by engineers who knew that power flow is always from the central production to the distributed consumption. So no need to build an engine that supports power flow in the other direction. On the ICT side a lack of common communication protocols is an issue. As is the lack of common goals. On the business level, the whole thing is much more complicated than "I buy electricity from the shop who sends it via line", and there is a whole lot of different parties involved. And correlations of random production on different scales may even create new problems for the already-existing grid. Wind power may look distributed. But in Germany on a country-wide level most wind is in the north, requiring large new grid lines to be build from the north to the south. So on that scale wind power production is more centralized than coal or nuclear power, which you can spread evenly (or even better: put where the demand is). To put it back into the physicist's perspective: Even if large amounts of PV production were a good idea a phase transition into a new grid state may be required (grid in this case meaning the whole of physical grid, protocols, laws, parties, ...) which is likely to be associated with a phase transition barrier that must be crossed (or catalyzed),

 

Derailing the thread even a bit more: The problems mentioned in the previous paragraph are problems that can probably be solved somehow. What is left is the archenemy of distributed generation: Captain Corporate Capitalism with his mighty hammer "local jobs may be endangered". Big companies that can afford to build large power plants, with little competition because not many others can afford it, are not interested in people putting solar panels on their roof and producing their own energy (and neither in having a lot of competitors if they went into that market, themselves). Smaller companies cannot afford to support an army of lobbyists and PR agents.

Edited July 12, 2014 by timo

[swansont]

To my knowledge the largest share of PV modules comes from China. That may be satellite contractors (not sure how many million satellites China has in space), but I doubt they have a large influence on German or US politics. In my experience, westerns companies mostly provide the AC/DC converters for the installations. An AC/DC converter, however, is not exactly the first piece of hardware I would expect in satellites or military equipment associated with PV.

 

@Tom: Siemens

 

Siemens doesn't do PV panel systems, AFAICT. According to their site they do solar thermal and concentrated, utility-scale systems.

[EdEarl]

Heat engines run of of a temperature difference, as you say. What is the cold reservoir for such a system?

It is possible to radiate heat a clear night sky very effectively, because it is about 3K. Thus, systems built in areas where clouds are less common (e.g., deserts) usually have a very good heat sink at night. Thermal storage could store solar heat in the day and loose heat at night (storing cold).

 

A big advantage of solar PV is that it is a passive, scalable system. You can put it on your rooftop, and you can build it in utility-sized systems. Distributed generation means less stress on the grid.

A single cylinder(i.e., engine-alternator) Sterling engine-alternator might reliable enough to compete with solar PV--especially if the displacer is moved magnetically; thus, eliminating the crankshaft, seals, bearings, etc.

[overtone]

 

 

IOW this is less mature than solar PV

The entire field of thermal solaris less "mature" than PV solar, in the sense that it has not had the same advantage of concentrated attention and research money from military and satellite and other government contractors.

 

That adds to the interest of it, actually: the large advantages it already possesses (approximately double the conversion efficiency already, easier storage arrangements for continuous power, greater reliability and longer lifespan, much smaller environmental issues in manufacture and disposal, probably much cheaper prorated power cost, etc etc etc) are not from more mature development - there's substantial upside potential.

 

But it's not raw, rookie tech: there are large thermal solar plants in operation, the basic heat engine design is well understood, and so forth. Needs some attention, mostly - odd it gets left out of the public discussion.

[swansont]

The entire field of thermal solaris less "mature" than PV solar, in the sense that it has not had the same advantage of concentrated attention and research money from military and satellite and other government contractors.

 

I take it this is a mirage?

http://gigaom.com/2014/02/13/the-hoover-dam-of-solar-is-now-live-in-the-desert-of-california-why-its-so-important/

 

And they only got $1.6 billion in U.S. government loan guarantees. I'd like to be ignored like that.

 

That adds to the interest of it, actually: the large advantages it already possesses (approximately double the conversion efficiency already, easier storage arrangements for continuous power, greater reliability and longer lifespan, much smaller environmental issues in manufacture and disposal, probably much cheaper prorated power cost, etc etc etc) are not from more mature development - there's substantial upside potential.

 

But it's not raw, rookie tech: there are large thermal solar plants in operation, the basic heat engine design is well understood, and so forth. Needs some attention, mostly - odd it gets left out of the public discussion.

 

Thermal systems need a heat exchanger, which usually means water for utility-scale projects, and not so plentiful in the desert (and especially in a drought).

 

While the efficiencies may be higher, they are also near to being as good as they will get, precisely because basic heat engine design is well understood, and so forth. Mirrors aren't going to get more reflective with more research, but PV cells will get more efficient.

[barfbag]

I think too many people do not even realize how cheap solar power has become. You can take a normal size home off the grid for about the same cost as a mid size car.

 

I'd like to point out though that thieves can target them because they are outside and accessible.

 

Extra insurance is also required. Not only theft, but poorly secured panels could fall and damage property or even kill. Fire damage is also possible when electrical installations are involved.

 

It still is cheaper than grid power for now.

Edited July 17, 2014 by barfbag

[overtone]

The entire field of thermal solaris less "mature" than PV solar, in the sense that it has not had the same advantage of concentrated attention and research money from military and satellite and other government contractors.

 

I take it this is a mirage?

I'd take it as an infrastructure investment using decades old technology - not a cutting edge research program into new stuff.

 

 

 

While the efficiencies may be higher, they are also near to being as good as they will get

The difference between the best lab setups and the best commercial ready setups is substantial yet. Advances in such aspects as cylinder materials (a really good and rugged ceramic capable of holding hydrogen and easily manufactured, say) or dish aiming gear (the recent invention of a glass structure that is opaque to anything except perpendicular light intrigues) would make significant differences. It's a bigger upside than realistic expectations allow for PV - and in the levelized cost, especially.

 

 

 

It {PV solar} still is cheaper than grid power for now.

Not around me, in the US. Are you in the US?

Edited July 17, 2014 by overtone