Gar -- Excellent post, let me see if I understand you correctly, because I think some of the technical aspects got past me.

Rooftop PV could all by itself replace coal.

The heat that comes from the PV solar cell s(cogeneration) could provide much of the heating and cooling.  85% of commercial heating and cooling could come from this, with the other 15% from geothermal  -- assuming that you are using storage that is fairly cheap, such as phase change materials (PCM).  PCM, according to wikipedia, changes a solid to a liquid when it is heated, and when it moves back from liquid to solid, it gives back some of the heat.

This heat, in residential housing, could provide about 40% of heating -- but not cooling as in commercial establishments, because converting heat to cold involves large machinery that only makes sense in large buildings (although this could work in apartment buildings, no?).  For residences, the other 60% might come from geothermal.

The geothermal could be powered by some of the PV energy, stored in PCM -- at least, I think that's what you were saying -- can the PCM be used to generate electricity for the geothermal heat pumps?

I'm not sure what you were getting at in the paragraph about quads -- are you saying that some of the PV could be sent back onto the grid, as a way to store it?  Or were you saying that the industrial processes below 700 degrees could be run via PV as well?

One other thing -- I think with any kind of decent building density, you would send the geothermal pipes down at least 100 feet, which would be a better long-term solution than just 5 feet, if I understand the technology.

I think that this is the direction we should be going -- thinking about using buildings in addition to the grid to generate most of our energy needs.

I think if we rebuild the national grid, including with HVDC, to capture the huge Southwest solar potential and Great Plains wind potential, then if every metropolitan area has their own set of wind/solar farms, and we make the buildings as self-reliant as possible, we'll be able to easily generate all electricity renewably (and maybe some neighborhood projects in there as well).

and just to be clear, the 4000 watt gizmo would have a 12-foot diameter?

I wonder what would there be any synergistic benefits of hybridizing solar PV and solar water heating?

Would a "heatsink" on the solar panels increase their efficiency significantly?

Just a mirror on a pole on a concrete post, or roof if engineered for additional loads.  Over a load bearing wall is preferred.

Didn't you and I both predict this?  Hehey.

It was in one of your earlier articles, one of the best threads ever!  Great job once again.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

Gar.  Hehey, Jon's article was a foreshadowing of this event.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

...if research bucks went into fuel cells for buildings as opposed to fuel cells for cars, we'd be in much better shape.  Extra PV-generated electricity could create the hydrogen for use when it was dark, and you wouldn't have to worry about recharge times or the things smashing into something at 60mph, as you do with cars.  In addition, you could make them fairly big and bulky.

Of integrated solar/PV congeneration, geo heat exchange, heat pump, phase change heat/cold storage, battery storage, grid connected, biogas fuel cell backup complete buiding energy/utility core.

It will look like a furnace and connect to solar panels, plumbing, heating, electric outlets, power grid.  The builder will just put it in and hook it up.

Buy "Alamagamated Renewable Hotcakes Prefferred" (what Vonnegut might call it?) now, sell into the boom.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

>The geothermal could be powered by some of the PV energy, stored in PCM -- at least, I think that's what you were saying -- can the PCM be used to generate electricity for the geothermal heat pumps?

No stored in the PCM as heat or cold.

> I'm not sure what you were getting at in the paragraph about quads -- are you saying that some of the PV could be sent back onto the grid, as a way to store it?  Or were you saying that the industrial processes below 700 degrees could be run via PV as well?

The latter. Industrial processes under 700 F, ideally under 212 F could  use PV electricity to generate that low temp heat, and store the heat into Phase Change Materials until needed (within 16 to 24 hours, not long term). The reason 212 F is preferable is that as the temperature you store rises, it gets more expensive to store the heat.

The point is that if you want to use variable electricity without electric storage, then you have to be store the product, and the product has to be something that is cheap to store and that makes thermodynamic sense to use electricity for. Cheap to store pretty much means low temperature heat or cool. Using expensive electricity for direct resistance heating is thermodynamically wasteful, cause you are turning high quality power into equal amounts of low quality power. So if you need to use thermal storage to store electricity, the only way it makes sense is if you use that electricity to run a heat pump so that you can back multiple units of heat or cold for each unit of elecricity input. This is call a co-efficient of power or COP. But the higher or lower the temperature rises the lower that COP is. So for heat pumps to gain you much you want the temperature you are storing to range from not too much below the freezing point of water to somewhere to well below the boiling point of water. Industrial demand in that range is very low, but after domestic and commercial space heating, space cooling, and hot water are considered, industrial low temp uses probably could make use of enough heat and cold in low temp ranges to absorb the remaining variable electricity. I think a couple of percent of industrial energy goes to compressed air, which could be another part of the "store the product" game.  But remember, this is with only half our electricity coming from variable sources. Much past that and we need to start storing some of the electricity itself.

If we start increasing industrial efficiency greatly and then substituting electricity for most of remaining demand then you are going to increase the need for dispatchable, not variable electricity.  (Note that electrifying indusry is done not by direct substition of electricity for fuel, buy by substituting process that can be efficiencly driven by electricity for those that depend upon high temperature heat.)

I have a humongous spreadsheet where I've put together actual scenarios and costs - that is how much it would cost to get off of fossil fuels with no technical improvements and with varying degrees of breakthroughs under various efficiency scenarios. The rest of the week is going to be dead for me as far as Grist goes, cause I've got some deadlines, but I'll try to clean up the spreadsheet so it that it plays well with others and put a narrative in front of it sometime next week

Bear in mind that is post outlines a maximum from rooftops. I was able to apply a few filters to cut out some obvious no-gos, but there are all sorts of gotchas it did not deal with.  This should not be looked upon as feasible proposal, but as a limit on rooftop power. A realistic estimate of what we could gather from rooftops will be much lower. But you could take these numbers, add some realistic constraints and come up with the real potential.

>still need some (maybe small) amount of batteries because the heat pumps need to run at night, sounds to me.

Well ultimately we will need more than a little. But in this context, if this is all we do, no. Because we are phasing out coal. It does not yet phase out natural gas powered electricity. It phases out most peak and load following, with some reduction in baseload, but not all that much. So, say one half of coal baseload is directly replaced. The rest gets replaced by using the natural gas we save to replace that baseload. (We have two source for this. A lot of the natural gas we currently use for peak and load following will be available to run base loads instead. And of course 100% of the natural gas we use to run space heat and hot water will be available to run baseload electricity.

30% of natural gas is for residential and commercial heating; natural gas as a percentage of electricity generation actually goes up to something like 50% if coal plants are shut down under these building-self-reliance scenarios.  So the next goal, it seems to me, is replacing the natural gas, because you certainly don't want to remain in its thrall.

Absolutely, why you can't depend on rooftops, even though they have a role.

for plug-ins, electric vehicles, more transit...So, big wind/solar farms over an HVDC grid for transportation and the 33% of electricity for industrial, or for industrial you can't do on-site...then maybe local wind/solar to make up the rest of commercial and residential...

The heat pumps or diect circyulation cooling pumps need only run when the sun is shining, then the heat/cold is stored in building mass, augmented with phase change heat storage if necessary.

Natural gas would be freed up by geo heat exchange heating.  And by solar furnace industrial process heat.  Biogas from waste could act as backup for the grid, run through distributed generators, that could be mainly (much more efficient and less costly) solid oxide fuel cell/turbines eventually.

Baseload power from coal and nuclear will fade into the grimey past.

Battery storage in buildings and plugin cars can give emergency resilience to a distributed smart grid.  if you are not careful you can fall into the baseload, centralized always cover the maxiumum possible load, 100% dispatchable fallacy.

This just isn't what the grid will need to be as it transitions to full renewable distributed generation and storage.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

The many obvious false assumptions in MacKay's presentation put the burden on his defenders to back up his figures.

Every assumption needs to have a link to a scientific survey.  Starting with roof area.  Why would roof area per person be an accurate measure?  

The huge mall of america in Minnesota has no furnaces, body heat from vistors and solar coming through the windows and waste heat and heat storage in building mass heats it all winter.  How mant people would a building that size house?

In an apartment building the heating/cooling load is less per person.  And in a taller building the south facing wall space tends to be larger.  Why can't geo heat exchange go down deeper into the ground or cover larger areas not used for housing?  

Geo heat exchange freezing the ground?  That was one of MacKay's unsupported statements.  Where did he get his heat flow figures?  For fuel free heating/cooling it would be well worth it to install extra underground heat exchange outside cities if necessary.

Figures don't exagerate, but exagerators figure.  MacKay and fans have a negative POV on renewables so they exagerate to make it look impractical.  That makes their favored option, central nuclear power, seem necessary.  It's the old false dilemna fallacy.  

Disguised as a math problem to distract from the false assumptions.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

According to the EIA, in 2006 the residential sector of the US consumed 1,351,520,036 megawatt hours, which is 1,351,520,036,000 kilowatt hours.  Divide that by 300,000,000, and you get 4505 kwh per person per year, divide that by 365 days, you get about 12 1/3 kwh per person per day, which sounds more like it.

according to your 15 kwh per person per day figure.  by the way, residences use about 35% of all electricity.

"Average American energy requirement is 300 KWH per person per day."

Good eye Jon!  You must be wearing sunglasses.  That one blinded me.  

$33 per day per person for electricity?  4000 bucks per month for a family of four?

Exagerators figuring.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

It's true, Colin, that geothermal heat pumps are sort of a poor cousin to wind and solar, and it has not been adequately researched -- but then solar and wind are poor cousins  to oil and coal and nuclear!, but anyway, a friend once claimed that geothermal heat pumps become useless after 5 years because of the problem you were looking at -- but there are one million geothermal heat pump units in the US, and I've never heard of the problem.

I think it may be the case that economies of scale are at work, because when you have a large building, or a large set of buildings, it becomes more practical to drill down 100 feet or so, which I think is probably a much better depth than the 5 feet figure I've seen for single family homes.  For instance, there is a development of dozens of townhouses here in Evanston using geothermal heat pumps, I assume they went pretty far down.

I had a confusion with the 300 KWH per person per day quoted by MacKay. It refers to the energy use, not the electricity use. Further, the figure you have given me is residential electricity, which is a portion of the total electricity consumption.

I agree that 15 KWH per person per day is an achievable target for solar PV roof tops. Being larger and sunnier, USA should go for it !

300 KWH is an obscene number which just tells us how wasteful of energy USA currently is. MacKay estimates that 125 KWH is a more reasonable number (this includes all forms of energy+food+gadgets etc in an energy efficient world). If solar PV rooftops make up for 15/125=12% in a futuristic energy plan, we still need to figure out about the remaining 88%.

The answer is that we will use wind and solar farms to fill up the gaps.

But if the gaps don't get filled up, it means that we will still be burning coal, sweet coal. This for industrial electricity generation.. for coal liquification plants to obtain gasolene.. and for coal based electricity generation in plug-in vehicles.

This is why I think it is irresponsible to make claims such as "solar roof tops will replace coal".

@Gar

Thanks for clarifying the mismatch of 23% coal usage in USA, and the actual electricity produced.

@amazingdrx

I don't believe that MacKay is a pronuker. He debunks a lot of anti-solar propaganda in his book. He even suggests a few purely solar plans.

I am a pronuker, btw. I just love to get converted to solar, but I am not yet convinced of its potential. I think MacKay should be congratulated for his efforts. Sustainable energy is a big mystery for the general public, due to the lack of common units for comparison. MacKay made a good start by explaining with the unit of KWH-per person-per day.

We need to improve on this obviously, and I hope that a common language will evolve to discuss the issues of energy and environment.

Also Americans need to think of all the cheap Chinese gadgets that they are importing, and claim responsibility for their production.

25% of electricity usage in China is apparently for exports. And most of this electricity comes from burning coal.

China is the most prolific coal consumer in the world (more than the USA). And coal is getting burnt there at an ever increasing pace.

Replacing coal will not be that easy..

Is it reasonable to think of, at least, solar thermal, which is pretty reasonably priced?  An idea rolling around in my head:  What if the government just build pure silicon factories, the kind that is the bottleneck for getting out a lot of solar PV -- isn't India very blessed with sunshine?

By the way, I suppose 300 kwh is all energy -- although all electric energy is only about 3 times the 12 kwh per person per day I was using, I don't think oil is much more than electricity, and natural gas either -- but the main point I want to make is that the worlds of electricity and oil, at least in the US, are pretty much completely distinct (I realize that in much of the world oil generates much more than the 1% of electricity in the US).  In particular, the US transportation system is almost completely oil-based.  And talk about waste, I'm sure we are the champions of transportation waste, with 3 thousand billion vehicle passenger miles in the US per year.  

Now, I wish we had India's rail network, which I was informed by an Indian fellow on a rail trip I recently took, is the world's largest.  If we did, and if we made much of it high-speed, and added light rail (and this could happen before pigs learned to fly), then I think we could drastically reduce our oil dependence.  I hope India doesn't make the same transportation mistakes as the US.

another route to replace coal quicker is to convert it to natural gas underground.  natural bacteria farmed in the coal seam would do it.  miners could work on drill rigs instead of in mines or mountain top removal.

And all the distributed fuel cell/turbine generators would be compatible with natural gas/biogas.  Allowing natural gas to be phased out eventually as biogas takes over.

Some day soon maybe portable truck and train mounted solid oxide fuel cell/turbine backup generators, that can run on bioga/natural gas  will be mass produced for trucks, tractors, and trains.  Replacing internal combustion.

Converting diesel engines to run on natural gas is a good way to transition to an all renewable electric transportation energy system, backed up by biogas.  We have 20 years to go 100% renewable, it can be done.  And create wealth at the same time, that will give families financial security, and fight inflation.  

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

>irresponsible to make claims such as "solar roof tops will replace coal".

No, the claim is that solar roof tops "could" replace coal. The post is about physical potential, makes it clear that is about physical potential and is accurate.

that I put solar panels on my roof. It must have been that I was tired of paying electric bills......

Victory in Pattani

and I would also point out that India is way ahead of the US in that most of the Indian rail system is electrified -- about 10 or 20 years ago, an engineer I know estimated that it might take 100 to 200 billion dollars to electrify the US rail system, but of course since then nothing has been done.  Here in Chicago there is one urban line to another city that is the last electric interurban line in the country.

I think that the rich countries -- US, Europe,Japan -- should help India and China jump start their solar and wind industries -- although I believe India has one of the larger wind companies, I believe they just bought one of the German ones.  You're right, it's one planet, and the rich countries have contributed much more than their share of carbon to the atmosphere, time to clean it up!

..rough numbers, a 13 m2 dish would cost $700 materials, $600 labor, and require <200 cm2 type III-V 40% efficient cells at something like $10/cm2 ~ $2000.  $3300 for about 4,000 Watts(e) installed system at scale without margin plus inverter and cooling.  Type III-V cells are used on the Mars rovers.

A new inverter would add about $800 would it not? With concentrators cutting the number of solar cells you need, it makes sense that inverter cos

So $4,100 for 4,000 watts.  Add cost of either a cooling system with no added value or a more expensive cooling system that produces hot water and maybe some of your space heating as well. Still this damn close to the $1 a watt range, certainly well under the $1.50 a watt range.

So am I right Turnkey with inverter and cooling (and no hot watt water or space heating) well under $1.50 a watt. A more exensive system that uses the waste heat for hot water and space heating would double the effective output without doubling the price, so with solar CHP $.75 per watt (with a about half that power being thermal rather than electrical).

Add 50 cents per watt for margin. Could you deliver turnkey systems for that price? Because even if you lack the capital for mass production, there are a lot of people out there in our part of Washington State who probably be happy to pay $2.00 per watt for a turnkey solar electric system, or $1.25 per watt for a solar CHP system. (counting the thermal as though it were electric). Probably the pure electric would be more popular, cause of the lower upfront cost and the lack of need to change plumbing. Even though the pure thermal is the best buy, it would probably be least popular because you don't have the glamor of "look I'm running solar electric".)  

Also is $600 labor for the whole - turnkey?

One's personal solar roof is sexy, industrial solar somewhat grimy.  The objective beyond personal reproduction is community survival.  

The objective of cost effective solar energy is to rapidly scale the displacement of fossil fuels.  Industrial inertia to scale is mitigated by a gold rush of profits with minimum requirements of growth capital -- scale without tooling.

That gold rush will be chasing the lowest hanging fruit first, heavy energy users of oil and gas for low grade heat -- users surrounded by empty low-cost land under a sunny sky.  An example is a meat packing plant in Yuma Arizona cleaning equipment with hot water, or a brewery in Fort Collins Colorado surrounded by alfalfa.  This is very simple profitable solar, a $100 billion market in the US alone, and installs the profitable base for growth.

A niche market of solar thermal hotels, schools, farms, and homes will emerge and grow, followed by concentrator photovoltaics, concentrator thermal electric, and finally base-load solar power with region-wide district heating/cooling and seasonal heat storage.

More on hope.  Concentrator pv can be done at 1000 suns with future cells at 50% efficiency so future solar power will cost much less.  The one thing I've noticed is that solar always becomes less expensive with time while fossil fuels become more expensive with time.  Join the green rush.

the premise of the "solar farms" and "wind farms" you are "pushing back against" is that they are "renewable," but they AREN'T.  the hundreds of millions of acres of flat, open ecosystems and the hundreds of billions of gallons of groundwater each year that would be required to "farm" out current energy usage in the US, never mind international exports, are a TOTALLY UNACCEPTABLE price to pay, when there are billions of developed parcels sitting there using power and not producing any.

all the energy models other than point-of-use renewables externalize huge costs onto the planet, the economy, homeowners and ratepayers while privatizing profits in Big Energy (yes, including Big Solar and Big Wind).  

conservation has been an afterthought in 99% of buildings so far, ergo the incredible waste and consumption we are currently facing.  unless and until ALL costs are accurately borne by energy producers, consumers and sellers (including all costs related to reduced reliability from lengthy transmission, which fails on a regular basis), local, point of use residential/ commercial PV, thermal and wind don't appear to make sense, but once the REAL costs of lost ecosystems, lower reliability, lost water, lost job opportunities, lost income streams to homeowners/ business owners, lost homes to Big Powerlines and pricing/supply manipulations are accounted for, there is only one solution.

the greenest energy is that which you needn't ever produce.

that rich anymore. They are having a very difficult time maintaining their economic well beings. Standards of living are already starting to slip into decline. World-wide you see inflation striking everywhere.

The days of the US being able to pull off a Marshal Plan are about to come to an abrupt end. The increasing cost of oil is going to be devastating to the global economy.

Victory in Pattani

I'm still skeptical about homeowner solar as a broad solution.  Yes, it is great when a dedicated greenie buys in, places the panels carefully, monitors their output, cleans them as soon as needed, etc.

But the average homeowner?  My gut says a managed corporate solar farm will beat them every time.

Just to give you the chance to convince me though, tell me what fraction of US home rooftops are actually suitable for solar: either flat, or south facing.  Does anyone have a study?

I see your quoted text there:

Two previous estimates of the total available roof space for PV in the United States are 6 and 10 billion square meters, even after eliminating 35% to 80% of the total roof space due to shading and inappropriate orientation [6,7]. The lower value also does not include certain industrial and agricultural buildings. While fairly rough estimates, these values provide some idea of the potential resource base. Assuming a typical PV system performance of 100 watts per square meter (W/m2) (equivalent to an average insolation of 1000 W/m2 and a 10% AC system efficiency), this rooftop area represents a potential installed capacity of 600 to 1000 GW. At an average capacity factor of 17%, this installed capacity could provide 900-1500 terawatt-hours (TWh) annually. This represents about 25% to 40% of the total U.S. electricity consumption in 2004.

My comment:

25% to 40% is respectable, but not a firm number rivaling coal.  From a quick stop at the EIA I learn "Based on primary energy source, coal-fired capacity represented 43 percent (260,990 megawatts) of the Nation's existing capacity (Figure 1).[2004]"

Very nice that you were there earlier with the numbers.

>25% to 40% is respectable, but not a firm number rivaling coal.

You forgot, I was taking into consideration the use of concentrating solar, which lets you use more expensive more efficient cells because you need fewer of them. At double the cell efficiency 25%-40% turns into 50% to 80% which does indeed rival coal. But again, I am NOT saying this is feasible. I'm pointing out this as an upper limit on power from rooftops. In practice you never get close to maximum from anything (except sometimes harm).

I can't believe I was too subtle. I was pointing out there was no way rooftop power could ever provide all or most of our energy - by showing the what happens if you make the most optimistic reasonable assumptions.

Remember when the AWEA said 20% of grid power could come from wind, with no intermittentcy problems?

I thought that was way to mild, but then when it seemed possible that conservation could cut energy use in half, that was about right for wind.  40% of the new lower energy demand.

If you look at the estimate from the study Jon linked to, rooftop solar PV/heat cogeneration could supply the rest.  Add in CSP on factory roofs and large buildings excluded from the study too.  Those are roofs, south facing walls count too.  

That is with various storage methods like building mass heat/cold storage, water pressure storage for plumbing systems, high temperature CDP storage, emergency battery storage in buildings, and backup power sources like biogas/natural gas.

Skeptics you are on the ropes.  You don't have a factual argument to stand on.  Just repitition, which Colbert points out, does create truthiness.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

will increase, not decrease. Therefore, new power grids should be designed with this expectation in mind.

For sure, some technologies will improve energy efficiencies. But others (like wide screen TVs) use a lot more energy than those they replaced.

So for planning purposes, planners should assume and increase, not a decrease, in demand and plan accordingly.

Now, if the price of power, based on supply availability, increases, that will force a decrease in consumption. No question there. But an increase in energy cost will have an inflationary impact across the board that will hurt every sector of economic growth. That has to be considered when discussing any energy planning.

Environmentalist have a single objective in mind - the environment. But energy planners have to look at not only the environment but also other requirements, especially economic impacts.

In my view, if attacked aggressively, the environment could actually be a great engine to spur economic growth. Within the United States Federal dollars could be directed towards environmentally friendly, sustainable energy sources. Once money is in the game, all kinds of smart people will be in the hunt to get it. People like money - this should be exploited, not spurned.

Victory in Pattani

I'm looking at this as a dynamic transition.  As a nation we get less than 1% of our grid electricity from solar power.  (That's what my SCE stub says, and I assume we are at the high end.)  We'd like that to be much higher.

The energy folks like to draw changes like this as wedges, with contribution from A (solar) growing while the contribution from B (coal) falls.

We want to achieve this this solar transition with maximum speed and return on investment.

Speaking as someone in Southern California, I think the best way to do that is with large scale installations, and professional operation.  PV on large buildings might work, but I think we should be mainly looking out here at desert solar farms.  The desert is only 100 miles away.  Heh, it qualifies for a "100 mile energy diet."

I'm pushing back Gar not because I think home solar is bad (especially when it is homeowner funded), but because I think it is a shallower curve.

Dollar for dollar, year spent for year spent, I think it will give us less energy ... a shallower wedge.

And I really think the rational answer has an  uphill battle ... because rooftop solar has so many irrational pulls for the population.  "It's right there." "You can see it."  "It's a house of the future."

But for every $ invested will it give you the best 10 or 20 year production?

I hadn't thought of that before, people can actually see it, be proud of it, etc., just like a house or a car.  I don't know if I'd go so far as to say that it would be a status symbol, but on a more optimistic note, it might be worth the added expense just because of the "tactile", personal aspect.  Nothing like direct experience, and it would get people involved in a way that putting up a desert CSP plant never would.

Mad Mac -- I think that what should be argued is that after the wind/solar electrical system, nation-wide, has been installed, electricity will be cheaper than it is now and also much more reliable (because the grid will have been rebuilt, and much of the solar/wind will be decentralized).  So you should be able to sell it on economic grounds.

The problem is constructing it in the first place, which is why Federal and local governments should provide easy financing.

Low information voters provide some good rhetorical exersize.  Now where is the latest extrapolation of roof mounted solar PV/heat cogeneration cost?

Since it isn't in mass production yet, those costs are guesstimates.

Low information voters are better than disinformation voters.  The 27% bush faithful disinformation voters only produce frustration and spread limboob propaganda.

As Jon points out, this is a gradual transition (that won't even start unless/until america is mcbushless), as mass production and installation takes over and commodity fuel prices soar, wind and solar drops and fossil energy gets ever more expensive.

In order to take the best course in terms of GHG and the economy, extrapolation is necessary.  The old saw, "let the 'free' market decide", is obsolete without an actual free market.

Only direct subsidies to consumers who purchase solar panels and geo heat exchange heating/cooling systems and other GHG saving technology will free up markets.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

But I think there is reason to push for most efficient use of every dollar granted in this less-than-free market.

I'm also skeptical about how many we'll get ;-)

I'm going to be publishing this week some looks at the question you are asking as to what the optimum path is. Among other points it will make is that smart grid or no we will need baseline power, something rooftops can't provide.  Where I do think rooftops make sense is in hot water, and in a certain amount of space heating and cooling.  There is of course no one answer, and what I'm going to be posting is a range of scenarios, sticking strictly to renewables and efficiency and with very little use of biofuels.

the government, as amazin' comments, should come in -- I would say like a ton of bricks. in fact, if I ran the zoo, I'd just take a pile of money out of the Pentagon and put PV on every roof, for free -- now that would be a good campaign slogan, no, "Free electricity!"

So, whatever makes it work, make it work.  It's worth it to get away from coal.

As to whether the money -- actually, think resources, factories, labor -- would be better spent on, say, CSP, that's easy, do both!  To come back to reality a little more, at this point, I think it makes sense to try every possible permutation, and see what actually works, that is, push for pv on roofs, CSP, wind, geothermal, see what you get money for.

"I'm going to be publishing this week some looks at the question you are asking"

Bad ol' me, I'm flying to Alaska tomorrow.  To arrive at the Ted Stevens Anchorage International Airport galls me no end, but I have been to carbonfund.org

I'll look it up when I get back.

That should come from battery storage in cars and homes and boigas/natural gas backup generation.

If it is defined as emergency power that is there no matter how much renewable energy is available.

Keeping factories and homes running as they are now, before conservation or geo heat exchange and heat/cold storage, is a job for coal and nuclear power.

A transition to a new pardigm, a renewable distributed generation and storage smart grid, will allow the centralized 100% dispatchable sources to be shut down.  

High energy demand factories, like foundries and glass and metal recycling, will have to time their operations to the grid, instead of the reverse.  Most could be shifted to use solar furnace CSP and molten salt storage.  In less sunny areas factories could import electric power from the nearest wind farm along a high voltage DC transmission system.

And anyway, those old natural gas turbine generators and even old piston engines will always be around for ultimate emergencies, if we convert coal (sour oil, tar too) to natural gas undergound, with natural bacteria.  Natural gas doesn't wear the generators out very fast.

Talk all you want about replacing our centralized 100% dispatchable (until a summer air conditioning high load blackout, hehey) grid with a 100% dispatchable renewable power grid.  But it will never be cost effective.  Adjusting only the supply side of energy is problematic, even with fossil/nuclear power, the demand side must be adjustable too.

If homes and buildings need to go to emergency battery/natural gas cogeneration backup for hours or even days with inadequate wind, sun, water, and biogas power.  So be it.  

Shut high energy factories down for a few days, as happens anyway with storm and summer heat grid overload, and run everything on emergency backup natural gas.

What if volcanic winter sets in for a few years?  No solar, but adequate wind.  What if wind storms knock out most of the wind power?

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

That's what RMI says.

A 20 to 50 hp backup generator in each plugin hybrid vehicle made in flex fuel version to run on natural gas/biogas or liquid fuel, would be close enough to match the total grid generation capacity we have now.

Plug in the vehicles to a gas line and let the smart grid start and stop them as necessary.  There's an ultimate emergency distributed backup plan.

Mass produced solid oxide fuel cell/turbine generators (maybe 10 years away) for cars and trucks, would even make this 70% efficient.  

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

>A 20 to 50 hp backup generator in each plugin hybrid vehicle made in flex fuel version to run on natural gas/biogas or liquid fuel, would be close enough to match the total grid generation capacity we have

If they are running on fossil fuel or biomass, not better environmentally that centralized power. The fetishism of distributed power over low carbon power. If they are running on hydrogen from electrolysis, NOT a least cost path, or a second or third least cost path.

Yeah we need everything, but there physical limits and practical limits.

That's my first choice.  The car plugged into a biogas/natural gas line and the grid.  At home or business the waste heat could be collected too.   If biogas runs low, then natural gas takes over until the wind blows and sun shines again.  

Nano storage developments make portable tanks very small and safe too, to replace backup liquid fuel.

To answer bio-d's critique of serial hybrids, the backup generator could connect directly to the drive train through an (speed sensing) electric clutch, for economy cruising after plugin in battery power is exhausted.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

In fact the recent 230x atmospheric pressure nano storage material development makes natural gas/biogas a perfect replacement for gasoline or diesel.

The hope is it won't impell a big natural gas guzzller economy with big trucks and SUVs burning gas instead of oil.

It is 1 dollar per gallon equivalent to a gallon of diesel.  That could push a big conversion industry starting in long haul trucking.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

The real issue of course is that RMI keeps talking about distributed generation primary as natural gas cogen units.

The problem with distributed Solar is that it doesn't provide reliable power, and it doesn't provide night-time power.

CSP in deserts is both reliable, (Hardly any cloudy days a year), and can provide night-time power (Thermal Heat Storage)

And it can do all that for less than it costs to build new coal fired power plants.

Either solar or wind (or in some rare cases even hydro) that is home funded for the home owner is a great solution for the individual. We should not depend on government to fix all of our problems. This is why I went with solar on my roof. Of course, I am in the very fortunate position to be living in a place with a LOT of intense sunlight - very favorable for solar power.

But clearly when invested at the corporate and government level, massive wind farms in areas with consistently good wind, and massive solar power stations in areas with good, consistent sunlight, are the way to go. In the long run, if we can combine this with nuclear power,we can end up with energy that perhaps is even cheaper than what we have today. Of course that won't be true in the short or medium term, but might well prove true down the road.

Victory in Pattani

Actually a 50% increase would put it around 20% for most existing PV cells.  

10 sun PV concentration has reached 38% already, according to NREL tests.  And the cooling isn't really a drawback, it is a plus, producing cogenerated heat.  

IBM had a breakthrough with cooling recently, getting the same power from one tenth of the PV cells with 10 sun concentration.  Where was the NREL 38% efficiency in the IBM test?  Not sure.  30 times the power per cell area of regular flat panel PV should be possible.  

This still looks good for converting glass to solar PV concentrating collectors.  There's a lot of solar power hitting those skyscrapers!

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

"That may allow the efficiency of the solar cell to reach 40-50% using the conventional, expensive multi-junction cells."

 in that post should be

"That may allow the efficiency of the solar cell to reach 40-50% without using the conventional, expensive multi-junction cells."

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