Key concepts for reliable, small-scale low-carbon energy grids

Recently, I published a guest post by Gene Preston on BNC, which examined the electricity cost comparison for remote solar PV vs small nuclear reactors. This generated considerable discussion (128 comments), much of which focused on whether this was a useful comparison in many circumstances; what if, for various reasons, the small-scale nuclear battery is not a viable option?

Gene has since done further work to consider the problem of how to design a reliable, small-scale, low-carbon energy generation system, which is economically competitive (though not necessarily lowest cost). He uses a case study approach to consider five crucial aspects:

1. System 1: A rooftop solar and wind 100% renewables powered microgrid concept.

2. System 2: Like (1), but the 10 kW rooftop solar is replaced with 5 kW of centralized solar.

3. Analysis 1: Three ways to improve the reliability of a (nearly) 100% renewables system.

4. Analysis 2: The cost of CCS carbon capture and sequestration makes coal power uneconomical.

5. Analysis 3: Small nuclear power provides reliability without needing a new transmission grid.

First, here is a summary of the five cases. Following this overview, the case studies are given in full (for the more dedicated reader — which is probably most BNC readers!). I find these type of empirical studies incredibly useful in understanding the options available to us. Great work Gene.

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In all the cases the microgrid has 150 homes. This number of houses was selected to best match the output of a 1.5 MW wind generator. Of course the size of the system could be scaled to any number of houses. The intent is to design each system to be as independent of the larger grid as possible. Each house has two PHEVs with 50 kWh batteries for a range of 100 miles of city driving for each fully charged vehicle. Each home is assumed to annually use about 12500 kWh plus another 12500 kWh for the PHEVs for a total of 25000 kWh per home annually. The PHEVs are assumed to be bi-directional power sources, being able to both receive power from the microgrid and deliver power to the microgrid in all cases. The microgrid consists of an undergound distribution system connecting the houses as well as the power sources local to the microgrid. All the costs for the distribution system, metering, etc that are the same for each of the above cases are not included in these calculations. The purpose of this analysis is to simply compare the cost and reliability of different types of power sources.

Here are the findings:

Case 1 has 10 kW of rooftop solar fixed panels at each house and a 1.5 MW wind generator for the whole neighborhood. The up front cost of the solar and wind per household is $90,000. This system will suffer occasional power deficiencies if operated as a standalone system. The interconnection costs for backup power from a larger grid were not estimated.

Case 2 replaces the rooftop solar panels with a centralized tracking solar system of size 750 kW.This saves each homeowner about $45,000 in up front costs and raises the question –- why are we installing rooftop solar when the centralized solar system is so much more cost effective? This system suffers the same problem as case 1 in that there will be occasional power deficiencies.

Case 3 looks at three ways to improve the reliability. #1 adds more battery storage and more renewable capacity to charge up those batteries and costs $100,000 more per household. However, this is still not a completely reliable system. #2 connects all microgrids in the US together with a massive investment in new transmission lines to gain reliability. The cost and environmental impacts are found to be impractical and the time to get approval and construct all the lines could take many years. #3 looks at installing backup generation at the microgrid instead of interconnecting. This is equivalent to firing up a put-put generator when solar andwind fail to produce enough power. The types of fuels discussed are oil, gas, coal, and nuclear. All of them are reliable, except they are deviations from our desire to be dependent only on 100% renewable power.

Case 4 looks at the cost of CCS carbon capture and sequestration and finds that it adds about 16 cents per kWh to the cost of coal generation, making coal unattractive as a base loaded source of power. Case 4 also shows that a 1 MW coal plant beside our subdivision eliminates the need forany solar or wind power at all and it would be the lowest cost if not for the CCS cost. With CCS coal looks no more economical than our 100% renewable plans, although the 100% coal is quitea bit more reliable than the 100% renewable plan, because the coal generator can run 24/7.

Case 5 looks at adding a small 300 kW nuclear plant beside the subdivision. It is air cooled and fits in a single homeowner lot. It silently runs for 30 years on a single fuel load and requires little maintenance. The wind generator is eliminated and the central solar is retained. Thesystem is reliable. The PHEV batteries are lightly used, allowing them to last longer. No new transmission lines are needed. This plan has a $45,000 up front cost to each homeowner.

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Designing a Rooftop Solar + Wind + PHEV 100% Renewables Microgrid.

Let’s consider a 100% renewables microgrid power system consisting of:

1) a single 1.5 MW wind generator located near a residential subdivision,

2) 10 kW of solar fixed rooftop panels on each home,

3) two PHEVs at each home with 50 kWh battery storage in each PHEV,

4) each home will use 25,000 kWh annually for electrical home use + transportation.

The wind generator costs about $2/watt or $3 million. The wind generator will be able to supply about 4000 MWh annually if the capacity factor is about 30%, which is typical. This microgrid might be able to operate independently from the larger grid if their location has enough wind and sunshine, such as Midland, Texas. Most customers will need to get their wind power from remote and windy locations that can produce energy at the lowest $/kWh cost.

The rooftop solar panels cost $7/watt or $70,000 per house and produce an amount of energy of (10 kW)(.77 DC-AC converter eff)(.15 annual capacity factor)(8760 hours/yr) = about 10,000kWh. The .77 is my EE friend’s new 4.4 kW system which produces 3.4 kW AC power.

The remainder of the energy must come from the wind generator, which is 15,000 kWh per home. In order to have some reserve, we should double the wind available energy as a part of the microgrid interconnection in which our renewables must also serve others so that we can draw power from other microgrids. Therefore, for estimating how many homes the 1.5 MW wind generator can serve, let’s be conservative and assume that each home will need 30,000kWh wind (double the 15,000). This means that our microgrid can serve a total of 4,000,000 kWh wind/30,000 kWh per home = 133 homes. Let’s round it off to 150 homes. The wind generator cost per home is therefore $3,000,000/150 = $20,000 which seems reasonable.

Each home will have two PHEVs in which most of the time one PHEV is active in driving locally and the other one remains parked in the garage most of the time. Each PHEV contains a50 kWh battery, which has a range of about 100 miles for city driving. Each PHEV charges at 220 or 240 VAC with a 10 kW load or 45 amps and can get a full charge in less than 5 hours andare charging when possible. These EVs are likely to cost about $40,000 each because of thelarge battery storage capacity and the battery cost of $10,000 for the electronics plus(0.4)(50,000) for the batteries = $30,000 total and then another $10,000 for the rest of the car.

The PHEVs are critical to storing energy for times when there is no wind and no solar, especially for an independent standalone microgrid system. The homeowner will need to be aware at all times of the charge state of the batteries and plan their daily activities around the power that is available from their batteries, their microgrid, and what’s available from the larger grid (if any).

The total homeowner cost of this system is $70k solar + $20k wind = $90,000 which should be affordable to most homeowners. The annual cost financed at 6% annual interest rate for 25 years is A = (90)(.06)(1.06^25)/(1.06^25-1) = $7040. The levelized energy cost is 704000 cents/yr /25000 kWh = 28 cents per kWh just for the wind and solar renewable power investment cost.

The 1500 MW wind generator is sized appropriately to simultaneously charge 150 PHEVs. Thesolar panel at each house is also sized appropriately to charge one PHEV at the house. A PHEVcould supply 1 kW power for up to 50 hours for backup power when there is no solar or wind.

Rooftop Solar Versus Centralized Utility Operated Solar

In the previous example, I had estimated that each home would need 10 kW of solar panels at an installed price of $7/watt and an annual capacity factor of 15%. The rooftop solar panels cost$70,000 per house and produces (10 kW)(.77 DC-AC converter eff)(.15 annual capacity factor)(8760 hours/yr) = about 10,000 kWh annually.

If we wanted to invest in utility-owned centralized solar and obtain the same amount of energy asour rooftop solar, how much would we need to spend?

The centralized solar cost is estimated to be $5/watt and have a 25% annual capacity factor. If 10 kW produces (10 kW)(.95 eff)(.25 annual CF)(8760 hr/yr) = 20000 kWh annually, we see that the centralized system produces twice as much energy as the roof top system. Therefore let usrequire only half the capacity or 5 kW per household to get 10,000 kWh annually for that home.

The cost per household is now (5000 watts)($5/watt) = $25000 versus $70000, which is a $45,000 savings per household. So why are we so interested in rooftop solar?

Three Ways to Improve the Reliability of a 100% Renewables System.

In the previous two case studies I used the batteries in PHEVs as the source of backup power when wind and solar power is not available, such as during a calm night. Windless nights will occur frequently. If we have too many windless nights and cloudy days in a row, our 150 homes willbe in trouble because the PHEV batteries will become run down and the lights will go out. And because the batteries are discharged, there will be no transportation either.

You might naively think that a simple connection to the larger grid will solve the problem. It won’t. I will discuss why below. Keep in mind Hawaii, which cannot connect to a larger grid.

#1 – The first possibility for improving the reliability of our 150 home microgrid would be to install more batteries. This will be an expensive addition because batteries are expensive. Doubling the size of the batteries in the PHEVs would cost another $60,000. To keep themcharged up will require increasing the size of solar and wind sources, possibly doubling them,which would cost each home owner another $20,000 for the second wind generator and $25,000 for doubling the size of the centralized solar farm (which is adjacent to the 150 home subdivision). We have spent an additional $100,000 to keep the lights on during extended calmand cloudy days. Our 150 home subdivision residents decide not to invest in additional solar andwind because the power supply is still not completely reliable, even with the additional battery,wind, and solar power additions. The additional storage idea is a bad idea.

#2 – The 150 homes may decide to connect to a larger system to provide backup power during the extended cloudy and calm days. However, the larger system is made up of thousands of microgrids just like ours, all hoping to draw on the larger grid for backup power, and hopefully not all at the same time. In this 100% renewables system, we have some microgrids that have extra power that can be used to supply energy to other microgrids that are short on energy. Each microgrid will need to install more wind and solar capacity than they need for their own system in order to have reserve power to assist their neighboring microgrid systems.

However, there is a severe shortcoming with this design of thousands of microgrids interconnected with each other. Because weather patterns cover large areas, we are likely to have times when large regions become deficient in power at the same time on cloudy calm days.This means that large transmission lines will be needed to cover the US, much like the interstatehighway system so that reserve power from one large area can be supplied to the other distant deficient area. These lines do not currently exist. They will be expensive and take many years to construct. There will be opposition to this plan due to its environmental impact and cost, so this plan may never be fully realized. Note that this interconnected system is not available toresidents in Hawaii. The building of all these lines connecting the eastern US to the western US to the Texas system (which are all currently isolated) is also a bad idea for improving reliability.

#3 – If the 150 homes microgrid wants a nearly 100% reliable source of backup power and does not want to connect to the larger grid, they could install a conventional generator that would onlybe run at times the renewables power is insufficient. There are four fuel types that could be usedto power the standby generators: a) fuel oil, b) natural gas, c) coal, and d) nuclear. Three emit CO2, except CO2 CCS (carbon capture and sequestration) might be used to capture the CO2. On Hawaii the backup fuel would probably be fuel oil rather than natural gas. The 150 homes might choose either a) or b) to keep initial costs low; however, these are not renewable sources.

The cost of CCS – Carbon Capture and Sequestration – Makes Coal Power Uneconomical.

In the previous example, #3c uses a coal generator to supply backup power to the 100% renewables microgrid system consisting of 150 homes. This would be a small generator of approximate size 150 times 5000 watts per house = 750 kW. Possibly a 1 MW sized coal plant would be a goodsize as a backup system. If the cost were $5/watt, then the cost of that backup system would be$25,000 per household. Because the capital cost of a coal plant is high, using it as a backup system does not make sense. That high a capital cost only makes sense if the coal plant were used as a base loaded generator. Interestingly, if the 1 MW coal plant were to run all the time, the solar and wind systems would not be needed and neither would the PHEV storage, except the battery storage can supply peaking power when the 1 MW generator cannot supply all the power demanded by the 150 homes, which would be rarely. Also, the PHEVs are going to be needed anyway to transition off the burning of oil and gasoline.

Ignoring the cost of coal fuel, the capital cost of the 1 MW base loaded coal would be a levelized annual cost of ($25000/home)(.06)(1.06^25)/(1.06^25-1) = $1956 per home. Then spreading that annual levelized cost over the energy consumed on average is 195600 cents/yr / 25000 kWh= 7.8 cents per kWh. Therefore, the base loaded coal plant supplying all the power is much lower in cost than the 100% wind-solar renewables system power cost, which was 28 cents/kWh.

But there is a problem with this design. The coal plant emits a lot of CO2. That CO2 will needto be captured and stuffed into the ground. Current estimates for CCS are about $100 per tonne (2204 lbs). A 1000 MW coal plant that is base loaded produces about 3 million lbs of CO2 per hour. However the CCS takes away 15% of the energy so that the 1000 MW coal plant is now 850 MW net electrical output. Considering that our coal plant is not 100% base loaded, but runs at an average power level of (150 homes)(25 MWh)/(8760 MWh) = 42.8% or 0.428 MW net electrical output, then our coal plant for the microgrid produces (0.428/850)(3,000,000) = 1511 lbs CO2 per hour on average or 0.6854 tonnes per hour.

The CCS cost is $68.54 per hour. On a cents per kWh basis the CCS adds 6854/(428 kWh) = 16 cents per kWh. Adding the CCS cost/kWh to the original coal plant investment cost/kWh we have coal costing 8+16 = 24 cents per kWh and that does not include the cost of coal fuel itself. Neither does it include the cost to pipe the CO2 to some remote injection point. The energy costof CO2 captured coal is nearly as expensive as our 100% renewables microgrid system. The only advantage of coal is that the power source is more reliable than the 100% renewables system, and that is why we were looking at coal in the first place.

Is there a better source of 24/7 power?

Small Nuclear Power Provides Reliability Without Needing a New Transmission Grid.

In this example, we instead use a nuclear generator to supply continuous power to the 100% renewables microgrid system consisting of 150 homes. This would be a small generator of approximate size 150 times 2000 watts per house = 300 kW that runs all the time. If the cost were $10/watt, then the cost of that backup system would be $20,000 per household. This provides a base load power source of sufficient energy to get past the cloudy calm days. Such a system would provide an annual energy of (300)(8760)/150 = 17000 kWh annually per home ormore than 50% of the annual energy needed. I will assume the nuclear generator actually provided 15,000 kWh annually to each homeowner. The wind generator could be eliminated from the mix of power sources saving the homeowner $20,000 in the cost of the wind turbine. The centralized solar farm could supply peaking power during the daytime and make up for the extra energy annually to get the annual 25,000 kWh annually.

The annual cost of the nuclear plant per homeowner would be (20000)(.06)(1.06^30)/(1.06^30-1)= $1453 annually and produce 15000 kWh. The energy cost is 145300/15000 = 9.7 cents per kWh. Nuclear also has an O&M cost that is about 1.6 cents/kWh bringing the total to about 11.3 cents per kWh for a small nuclear plant that costs 10,000 $/kW.

The cost of the centralized solar farm is $25,000 for 5000 watts per home, and produces 10,000 kWh annually. Its annual cost is (25,000)(.06)(1.06^25)/(1.06^25-1) = $1957 and the energy cost is 195700/10000 = 19.6 cents per kWh. Combining the solar and small nuclear plant costs produces an overall energy cost of (11.3)(15000)/(25000) + (19.6)(10000)/(25000) = 14.6 cents per kWh which is our lowest cost option yet. Note that we still have the PHEVs but the demand put on them to supply night time loads has been eliminated, thus extending the life of the batteries and saving a lot of money in transportation costs.

What about nuclear waste? The latest designs of small nuclear plants plan on using lower grade fuel and even burn what we would normally think of as nuclear waste as the main fuel of these plants. Therefore we create a new market for existing nuclear waste, and instead of throwing it away, we burn it further, getting much more energy out of the existing nuclear fuel, up to 100 times more energy. One example of a small nuclear plant is the Toshiba 4S plant.

There are several advantages of a small nuclear plant:

1) 24/7 reliable power nearly eliminates the need for transmission,

2) 24/7 hour base load operation makes wind power unnecessary,

3) the plant site is a small footprint,

4) the 4S plant is air cooled, not needing water,

5) the 4S plant is fueled once and runs for 30 years continuously,

6) solar and nuclear compliment each other in that nuclear provides base load and solardaytime peaking,

7) PHEVs have a continuous source of power by which to charge their batteries

8) the liquid sodium does not require a pressurized vessel,

9) there is enough fuel to power these reactors for hundreds of years using IFR technology.

10) once the fuel is spent, the entire reactor assembly is shipped back to the factory for refurbishing and another 30 year run,

11) the design is tamper proof eliminating the ability of terrorists to steal nuclear materials,

12) the design is operator error proof, i.e. the design is inherently meltdown proof.

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62 Comments

  1. Isn’t that a lot of concrete and a rather deep excavation for just $4 million? And operations and maintenance will cost only $42000 annually? No-one from the government regulatory agency permanently on-site, as is the case in the USA, then. Not even anyone frequently visiting.

    The concrete looks as if it might have the same volume as an 18-m sphere, so about 8000 tonnes.

    Thirty years, 263,000 hours times 300 kW(e) divided by 25 percent heat-to-electricity conversion efficiency makes 1.14 PJ. Per tonne, 142 GJ. Much better than any chemical fuel.

    The tonne-km of transport to bring in the concrete and rebar is actually rather small compared to the tonne-km of bringing people to and from the site during the for 30 years.

    (How fire can be domesticated)

  2. Perhaps a better approach than locating small nukes (assuming we go with the <300MW version) would be to make grid connections and distribution grid access completely zero: site these nukes at existing distribution substations and/or transmission substations.

    You get a much better benefit this way because many of these substations are staffed, and thus have a personnel infrastructure that can provide immediate response to any alarm, there is some security already in place which can be minimally upgrade and, it's easier to reverse generation direction for transmission of surplus, off-peak times if that is the choice.

    David

  3. A 300 kW power reactor is just absurd. Besides the outrageous technical difficulties (90% HEU core?), no justification is provided for the ~linear cost extrapolation, from commercial reactors 3-4 orders of magnitude larger. Where are the scaling economics?

    The (unsourced) CCS cost figures are odd. The claim is an additional 16c/kWhe levelized cost; an MIT study thinks it can be less than 2c/kWhe (from subcritical pulverized-fuel to IGCC+CCS). Obviously this is a crucial discrepancy. Perhaps the original “$100/t” figure (unsourced) referred to tons Carbon, but was conflated with tons CO2?

  4. Gene,

    I’m assuming any of the power systems in the scenarios could be managed externally by an energy services company and so the nuke’s systems would be remotely monitored and controlled and all this for a set or scaled management fee divided by the no of households per site?

    I’m also interested in the 12500 kWh for the households and PHEV you used. Do you have any sources for that sort of figure?

    One of your graphics has a listing of a micro grid control technology PC. In your scenario of say 150 houses would you envisage active power management such things like the CSIRO’s intelligent agents being an important part of managing such a system (e.g. telling fridges to turn off when they are not needed). Plus can the PHEVs be a method of importing power?

    Finally are you saying the exisiting US transmission grid cannot be considered in your base scenario because, if I undertand it correctly from what you are saying, it can’t supply when ten’s of thousands of microgrids suddenly descend on it both regionally and nationally given the differences across the US of time zones etc?

  5. Some of these ideas were demonstrated on a TV show last night about the Danish island of Samso Key differences were no PHEVs (but some biofuel), dependence on feed-in tariffs and district heating. Similarities were the short driving distances, a large amount of installed capital per person and the need for community co-operation. The island functions because the outside world can supply subsidies and hardware.

    I can’t see some of these ideas being easily implemented in the suburbs. I don’t think the public wants to see wind turbines everywhere nor new above-ground transmission. Solar PV and batteries need to come way down in price which may not happen. I think the current model of centralised generation and unplugged cars is really what the public prefers, assuming they have jobs to pay for it. Therefore I think the immediate course of action is to build large NPPs in secure areas and keep a lot of hydrocarbon transport based on natural gas or synfuel. Whether there is enough time left and low cost capital to achieve that is another issue.

  6. This whole concept of micro grids is insane! What is wrong with full nuclear powered well balanced grid by placing nuclear plants at suitable locations. If the environmentalists did not molest the nuclear power engineers 40 years ago such a grid would be a reality today. We could buy electricity for 5 cent per KWH and we would not have to bother with micro grids and other expensive schemes.
    $45,000 that it will now cost a homeowner to build nonsense micro grid would buy you your 12,500 yearly KWH for the next 72 years.
    This only further demonstrates how we got all screwed up by anti nuclear fanatics. As a result, expensive and environmentally damaging solutions are now jammed down our throats.

  7. The concrete looks as if it might have the same volume as an 18-m sphere, so about 8000 tonnes.

    The graphic actually shows the Toshiba 4S layout, which is a 10 MW design.

    A 300 kW power reactor is just absurd. Besides the outrageous technical difficulties (90% HEU core?), no justification is provided for the ~linear cost extrapolation, from commercial reactors 3-4 orders of magnitude larger. Where are the scaling economics?

    The Toshiba 4S 10 MW proposal is the smallest scale reactor I’m aware of being put forward for civilian power generation. I’ve heard of 100-500 kW reactors (real or proposed) for specialist purposes such as space exploration, but not for normal civilian power generation.

  8. I simply can’t see the benefits of mixing nuclear and renewable energy, since nuclear scales less expensively than wind or solar. Even if there was some reason for small grids they would be better serviced by small reactors rather than with a mix.

  9. Ultimately, I think the comments above reflect a broader consensus among us. One has to bend over backwards to the point of contortion requiring extensive chiropractic remediation, in order to get “100% renewable” microgrids to work — and even then they need a coal, gas or nuclear backup. There will obviously be call for microgrids in remote locations, but the expense of trying to do it as a community, in a city or large town, seems absurd, as Gene’s $$ figures point out.

    Regarding nuclear batteries, the smallest I’ve seen proffered for potential commercial application have been about 2 MW.

  10. I hope you guys are having a pleasant dream, because until we get Gen IV running commercially that is all the nuclear option will ever be. Folk just won’t accept it until the wate problem is solved (not swept under the carpet), and possibly not even then.

    Separately the 12,500 KWhr per house sounds excessive. I have been monitoring our usage for some years now and while we run most “conveniences” such as dishwashers, and have two people using computers during work hours we use 2600KWhr per year. The warm temperate climate helps but not that much. These sort of (mostly very useful) calculations would be much improved if they assumed we sorted out the gross inefficiency of our current homes before spending up big on infrastructure.

  11. Nearly everyone’s comments have some truth. Let me see if I can provide some additonal info. The nuclear cost was simply based on 10 cents per kWh which is a goal of small nuclear power developers. The 300 kW may be hypothetical, or possible with some additional engineering. Obviously a 150 home subdivision cannot go out and purchase a 300 kW nulear plant. I was just trying to show how such a plant could be used to supply base load power if it were available.

    The comment about small nukes at substations makes sense. I would think that an industrial company might be able to use a small nuclear plant at the substation feeding their plant. The reason we do not have small power plants today is because the larger plants have provided an economy of scale that resulted in lower energy costs than small plants that are on site. Maybe that is about to change.

    I agree about the insanity of microgrids. However it does provide a way to describe the costs to a small community what their energy costs and problems might be if they did try to power up using wind solar PHEVs and batteries and even small nuclear. If the micro grid could operate sustained, then the need for transmission is greatly reduced. Here is a small wind powered micro system: http://worldfocus.org/blog/2009/11/16/everyday-danes-profit-from-pioneering-wind-power/8431/

    Nuclear and solar and PHEVs integrate beautifully. The nuclear provides a low level of continuous power at night and even in the day. The solar tracks daytime increases in power usage and the batteries in PHEVs provide backup power when the load and solar and nuclear power are not enough to meet the peak demand. The PHEVs are acting like pumped hydro for energy storage. What is neat about nuclear is that on the coldest day when nearly every other source of power is kaput, nuclear is still quietly providing power. Its either that or freezing in the dark from time to time without nuclear power or enough battery storage. But battery storage is going to be more difficult and costly.

  12. Gene,

    In stead of the CCS option what about a gas turbine?

    As well would there be any mileage running the heat off the Nuke or other themal machines to the 150 homes for heating purposes in climates that need that?

  13. I have yet to see any justification for operating a mixed system with a NPP as the baseload provider. Nuclear scales inexpensively through a doubling of output in most cases, and nether solar or wind are particularly good at peaking. Any storage technology that would make them useful in this service, could just as well be applied to store off-peak power from a NPP.

    In other words I cannot see the point of this idea, or any benefit that would come from it.

    @Jeremy C – District heat is an established technology and probably the second most popular application of nuclear energy. Several manufactures that are developing small reactors for isolated communities expect this to be an important product of their plants.

  14. It’s not always about dollars and kilowatts. Home generated power may not make sense economically but you are less beholden to corporate spivs. Fortunately Australia hasn’t had anything to rival Enron Corp in the energy sector but with the ETS looming some large generators want to scam it. Apparently TRU Energy doesn’t want to be told to replace brown coal fired generation with renewables or gas fired baseload. I can understand that since renewables won’t be enough and long term Victoria will have to get gas from interstate. As we speak some kind of sweetheart deal is being worked out with the Federal govt.

    Compounding that I fear nuke ambivalent SA Premier Mike Rann will self destruct. His successor could be worse. Home PV might cost 30c per kwh but at least you own it.

  15. Small point. A PHEV (plugin Hybrid Electric Vehicle) with a 50 kwh battery pack?!? That’s a big battery pack for a BEV – battery electric vehicle. You would also probably limit DOD – Depth of Disharge to 80% to conserve battery life.

    So we are talking BEV, not PHEV, and a 50 kwh battery pack, 80% utiliized would be 40*4 miles/kwh = 160 miles range, city driving.

    You are still better off going with a home battery bank or a utility battery bank, than using BEV’s for energy storage since the High Power output batteries needed for EV’s are about twice the cost of regular storage batteries. For home storage applications a 40 kwh battery pack might have to put out a maximum of 25 kw, for a standard 100 amp, 240v service. Whereas in a EV, it will need to supply 80 to 200 kw maximum.

  16. Alastair Breingan, on November 23rd, 2009 at 10.17 Said:

    I hope you guys are having a pleasant dream, because until we get Gen IV running commercially that is all the nuclear option will ever be.

    What’s the definition of Generation IV?

    All the existing LMFBRs, MSRs, and HTGRs in the world are Generation IV reactors.

    The current Gen IV reactors operating are:

    – The French Phenix fast reactor.
    – The BN-600 sodium-cooled fast reactor in Russia.
    – The Monju fast breeder reactor in Japan (will be restarted soon)
    – The Russian Alfa-class naval lead-cooled fast reactors (Not on the grid, but generating nonetheless)

    The ones that were formerly generating energy on the grid:

    The Fort St. Vrain HTGR
    The Peach Bottom 1 HTGR
    The German AVR high-temperature, gas-cooled pebble-bed reactor.
    The German THTR high-temperature, gas-cooled thorium-fulled pebble-bed reactor.
    The Fast Breeder Test Reactor in India.
    EBR-II, which served as the first prototype for the Integral Fast Reactor.
    The Fermi I fast breeder reactor.
    The Dounreay Fast Reactor and the Prototype Fast Reactor at Dounreay.
    The Superphenix fast reactor in France.
    The French Rhapsodie fast reactor.
    The BN-350 in Kazakhstan (Notable for its use as an integrated desal plant.)

    Research reactors, prototypes or reactors under development, that didn’t or don’t generate electricity on the grid:

    The ORNL Molten-Salt Reactor Experiment
    The Aircraft Reactor Experiment(s)
    The Prototype Fast Breeder Reactor in India.
    The Clementine mercury-cooled fast reactor at Los Alamos
    The Ultra-High Temperature Reactor Experiment (UHTREX) at Los Alamos
    The SNR-300 in Germany. (completed power-generating reactor, never operated.)
    The High-Temperature Test Reactor (HTTR) in Japan.
    The Chinese HTR-10 small, modular pebble-bed reactor.

  17. “@Jeremy C – District heat is an established technology ”

    DV82XL,

    Thats why I brought it up though in Australia people aren’t aware of it.

    Overall, I think as the micro grid concept is still being developed I don’t think we can frame it and say, “this is what micro grids are”.

  18. Overall, I think as the micro grid concept is still being developed I don’t think we can frame it and say, “this is what micro grids are”.

    Then it’s not possible to propose them as energy solutions with any degree of confidence. Not as long as you have to concede that your concept cannot really be defined well enough to plug reliable numbers into it.

  19. Jeremy asks, what about a gas turbine? The short answer is that natural gas has a limited supply and we should be trying to use it more wisely than as a crutch for the failure of wind and solar to perform reliably.

  20. For DV82Xl I agree that nuclear base load and storage could be used for peaking. This is what I am proposing in my last small community scenario where solar gets some of the peaking load but batteries that have been charged up by both the excess solar and excess nuclear can also be used to serve the peaking power requirement, locally, for a homeower, and that would also reduce line loading, saving losses and allow more capacity on the distribution feeders.

  21. Warren Heath you are correct. Should have said BEV. However I think the cost of batteries will make homeowners skip installing battery banks. Use the cost of $1/w plus $0.4/wh and see what you get for the cost. I bet the homeowner will not want to spend something like $40,000 of batteries sitting there in their garage taking up space. However they have no choice but to buy the battery for their BEV. So if they already own the battery in the BEV, whey are more likely to use it. Shortening the battery life by over using it could be a problem with this concept.

  22. Warren Heath comment about CCS that costs $400 per tonne (2204 lbs) resulting in a 12 cent per kwh increased cost seems low to me on the cents per kwh estimate. I did not understand from your web page how you got the 12 cents per kWh. Here is my calculations on this.

    A 1000 MW coal plant produces about 3 million lbs per hour of CO2 http://www.powermag.com/environmental/Alstoms-chilled-ammonia-CO2-capture-process-advances-toward-commercialization_86_p4.html
    I checked this amount of CO2 based on carbon and oxygen weights and the 3 million lbs checks out.

    One tonne/hr is 2204 lbs per hour or a plant size of (1000 MW)(2204/3e6) = .735 MW. The CCS energy cost added would be 40000 cents / 735 kW = 54 cents per kwh, not 12 cents per kwh. Did I make a mistake in these calculations? 54 cents per kwh for ccs is not feasible.

  23. Luke, which nuclear technology is likely to be the best one? I have seen two liquid salts replacing liquid sodium being suggested lately. Makes me wonder what will be the winning technology. I must say that I am at a loss on this one. However simple energy considerations show that we will have a nuclear future of some sorts. I just wonder what it will be.

  24. @Gene Preston – Frankly I still don’t see the point of involving solar in any small grid/local power system.

    In the Canadian North and Far North there are may communities that get their power from local generation, mostly oil fueled, which is doubly expensive because it has to be hauled in from the nearest port or railhead that might be up to a thousand kilometers distant. These plants also often supply district heat for these towns. These are places with 150-300 residents, so they fall into the scale you are working with, so this sort of market is well understood here.

    In the 70’s AECL developed a small reactor, SLOWPOKE III to service these places when it looked like oil would not be available at any price. * The only role for auxiliary power in these designs, that would be supplied by the existing oil burner, was as back-up. Solar cannot even provide this service.

    To me this seems to be a case of a solution looking for a problem. I would like to know what advantage there would be to using solar, when a diesel back-up would be more practical if the reactor had to be powered down.

    * (oil prices collapsed of course, and the project was shelved.)

  25. DV82XL you are absolutely right about solar not being applicable when there is no sun. Now lets convince Scientific American and Jacobson that their non nuclear plans are not workable everywhere if they are workable at all. When I made up that solar example I was thinking about my local comminity which does have sunshine. Our city has gone nuts over solar so my thinking was influenced by the locals. Certainly in Seattle, Canada, England, and many places, rooftop solar is not feasible. In those examples there is just nuclear and wind. And the wind is difficult to operate and requires new transmission interconnections and is probably not realible regardless of how large the total wind geographic area is. That just leaves nuclear doesn’t it. Well there is hydro in some areas if you are lucky and are not concerned about the environmental effect of putting in dams.

  26. DV8 – I think it’s important to consider these scenarios, if for no other reason than many people will insist that they are realistic and cost effective (yet, these same people consistently fail to crunch the numbers). What Gene has shown here, by running the numbers, is that whilst a microgrid ‘solution’ that might be technically possible, it is not economically feasible, at least not when placed in competition with a centralised grid connecting to a reliable low-carbon alternative, like large-sized nuclear power (ranging from 300 MW modules through to 10 GW reactor clusters). So, I think microgrid concepts within large urban centres are a demonstrable nonsense — especially when system reliability is considered.

    But what about the remote communities of 150 to 300 people? Perhaps they must go for some system like Gene describes, whatever the cost. Or perhaps that is also unnecessary, if we really could get nuclear batteries working, economically in the range of 200 to 400 kW (which is what a 150 to 300 homes at 12 MWh/household/yr implies). If such small reactors are not feasible, what are we left with for these remote communities?

    Note: I see SLOWPOKE III was rated at 10 MW, yet the operating SLOWPOKE IIs are a mere 20 kW — did they consider the smaller-sized reactors to be uneconomic for non research purposes?

  27. Again the S-III was envisioned as supplying district heat as well as electricity and 10MW is the thermal output not the electrical. The size was also selected for the maximum size for the type of community it was expected to service. These were not just oversized S-II reactors, but had a redesigned core and different heat exchanges to provide a power pick off.

    The whole SLOWPOKE series are neat little reactors, the only ones ever type-approved internationally for unattended operation for up to sixteen hours. AECL however behaved like their usual idiot selves, and failed to market it with any vigor. The Chinese, that had bought a few, had no such inhibitions and promptly reversed engineered it and has been doing a brisk business selling them under the name Small Neutron Source for decades now.

  28. @Jeremy C – there were two patents held by AECL, one was for a Rankine cycle with Freon as the working fluid and the other was for a Stirling cycle. Nether were put into practice, although if I remember correctly some cadets at the Royal Military College of Canada. (which has a S-II) did a proof of concept for the Stirling, but I don’t have any details.

    BTW the Chinese SLOWPOKE knock-off is properly called the Miniature Neutron Source Reactor (MNSR). I misnamed in my previous comment.

  29. Gene Preston, my mistake on the CCS cost, I was using David Mackay’s 300 gm CO2 per kwh for Coal, but I thought that was kwhel, instead it is kwhth.

    EIA numbers are 963 gm CO2 per kwhel. The numbers that you calculated 3 million lbs CO2 per hr, for a 1000 MWe Coal Power plant, work out to 1360 gms CO2 per kwhel. So the discrepancy.

    Going with the EIA’s number, I get C$400 x .963kg -> C$0.39 per kwhel.

  30. Most people living off of grid use diesel or gasoline generators to charge batteries, and inverters to supply household power. Inverters are about $100 a kw and good storage batteries, about $300 per kwh. Decent automotive traction batteries are still upwards of $700 per kwh.

    Using expired automotive battery packs as home storage or utility batteries is a good option, which utilities are already considering.

    The requirements for an automotive battery pack are just way more severe than that of a household or utility battery pack, so I cannot see it will ever be economical to use an EV or PHEV battery for energy storage. Add to that the EV battery has a high probability of being unavailable for storage during daylight hours when energy demand is high.

    Normally a household battery pack, need only be about 15 to 20 kwh and 10 kw would suffice, if recharged daily at 5-8pm, by diesel generator.

  31. The biggest problem of using Wind, Nuclear or Hydro to supply Heat & Power in the North, is that Winter Peak demand (mostly heat) is up to 8X avg Summer energy demand. And Wind, Hydro & Solar are minimum in the Winter.

    So to supply Winter Heat Demand the Energy Source must be way oversized, which is no big deal for Oil Furnaces & Diesel Generators, due to their low capital cost. But it is a serious problem with high capital cost energy sources like Wind, Hydro & Nuclear.

    What we need is an automated Methanol production reactor. Using water & CO2 feed. Kinda like the Mars Society’s SP-100 Methane/O2 reactor. Then you could use surplus electricity to produce & store Methanol for winter heating needs.

    Another application for the small Nuclear Reactors is remote Mining Camps. They use Diesel Generators to supply power. Most of them capture waste heat for process & building heat, as well. 25 MWe is typical demand. I know of one Arctic Mining Camp that uses Diesel generators to supply Electric Heat! Again demand for heat will be much higher in winter than summer, although not as much a difference as for a residential supply.

  32. Warren – There is no good reason at all that a small NPP need be that expensive, and anyway in off-the-grid Northern communities electricity is now five or six times the price of power on the grid. The same holds true for heating which is why these places use a central system in the first place. This being the case nuclear becomes cost effective, even if HEU is not used in the core. 20% enrichment would have let an S-III run for two years before fresh fuel needed to be added.

    By the way, I’ve been asking a few people who were closer to this project than me, and it turns out there was a 1.5MWt core that was being developed as well as the 10MWt one to give a bit more range to the reactor.

    Ether way reactors of this sort can be dialed down with much less fuss that a reactor with pressurized cooling loops, (keep in mind that the SLOWPOKE class works at ambient pressure) so it could be idled in the Summer with no problem.

  33. … If such small reactors are not feasible, what are we left with for these remote communities?

    Enough aluminium to make eight kilotonnes — the mass I guessed for the small nuclear system — of oxide would, in making the oxide, provide 1.2 thermal megawatts for 3.3 years. Enough boron to make 8 kilotonnes B2O3 would be good for 3.6 years, but the mining cost of B2O3 will probably need to come down for that to work well (8 kt now costs $8-16 million).

    (How fire can be domesticated)

  34. DV82XL, actually no communities are on Central Heating in the North, that I have heard of. Only Mining Camps. The waste heat from Diesel Generation is discarded.

    So is small NPP’s viable in the North? Let’s work the numbers and see what we get.

    Typical household, 3000 liters per yr fuel oil for heat @ $1 per liter or $3,000 per yr. That’s worth $34k present value on a 17 yr, 5% bond. You would need to supply peak heat + power (mostly heat needed) of typically around 12 kw, so that’s C$2.8k per kwth peak plus the cost of the Heat & Power plants, maybe $300 per kw, which brings us to C$3.1k per kwth. With the Hyperion supposed to be C$457 per kwth, that sounds like a NO-BRAINER! It would be primarily be a problem of having a Reactor of the right size for the community. And some communities fuel oil is upwards of $2 per liter, when it has to be flown in. And winter delivery by Ice Road means large fuel storage tanks.

    Of course, you would have to add fuel & maintenance cost for the NPP, and the cost of supplying the district heating infrastructure. The actual avg power consumption would be about 5 kwth so the NPP would only use about 40% of its full load fuel consumption.

    Major problems: The irrational fear mongering of going Nuclear and the fierce opposition of Oil Vested Interests, including the Trucking Companies, for whom Oil deliveries are half of their long distance freight.

    Many communities in the 300 persons range, probable total peak load, including commercial & government, a little industrial, about 6 MWth. So a 10 MWth Slowpoke III, would be about an ideal size. So you would oversize above peak demand by 67%, bringing effective alternative fossil fuel cost down to C$2.1k per kwth comparative. I might also point out, that Hydro is proving to be a very difficult sell in the North – due to Native, Environmental & Cost issues. The latest plan to just supply Iqualuit with Hydro has been priced at $200M for 5 MW or $40k per kw & 6 yrs development, power only – no electric heating. So if AEC can sell Slowpoke III’s for about $1k per kwth – I want one – where can I buy it?

  35. @Warren Heath – I don’t know where you got the idea that there were no district heating systems in Canada’s North other than mining camps, because there are several communities that have them, at least to heat public buildings, although most of these use wood-pellet fuel now I see.

    A partial list includes: Burwash Landing, Yukon – 6 public buildings and 16 homes; Grassy Narrows, N. Ont – System services the commercial core, and approximately 30 percent of the residences; Oujé-Bougoumou N. Quebec – pop. 700, 100% of homes and buildings. There are ten more small systems in the Nunavut Territory, and several in the NWT, all of similar size.

    Also I did mention that the prices quoted for SLOWPOKE reactors were in 1979 US funds. To the best of my understanding AECL no longer offers this product in any form.

  36. Come on! This is egregious sloppiness.

    On your “source”: it is a completely inaccurate editorial in a tiny local paper. (Hanna Herald? Seriously?) The author got his “400/tCO2″ figure by erroneously dividing $2B by 5M tCO2. In fact the provincial governments’ relevant estimate was 5M tons per year (whereas $2B is a capital cost)!. Referring to the government’s press release (Alberta.ca):

    …the $2-billion fund will support CCS projects that are expected to reduce emissions by up to five million tonnes annually.

    And further — and everyone here well understands this — these are FOAK, pilot-project costs for extremely immature technology, and it is obviously meaningless to interpret them as commercial costs (they are not commercial), side-by-side with e.g. PWR costs.

    I’ll suggest again the MIT study I found, which attempts to predict future, commercial costs of CCS. Their estimate (table 3.5, and also appendix 3C + refs) is 6.52 c/kWh LCOE for IGCC with CCS (compared with 4.78 for conventional plants), or a marginal $24 t/CO2 cost (rel. to non-CCS IGCC). (Come to think of it, that’s not too far from your Alberta figure, assuming a >20-year plant lifespan…)

    Another study is the IPCC special report on the subject, which estimates (ch. 8) an extra 0.9-2.2 c/kWh for IGCC capture (slightly higher for PF coal and NG), and <1 c/kWh for CO2 transport+storage.

  37. “…it is a completely inaccurate editorial in a tiny local paper. (Hanna Herald?)…”

    Not true. The same numbers were published in a number of publications, including the CBC.

    Here, the illustrious Globe and Mail gives even worse numbers or $761 per tonne.

    http://www.theglobeandmail.com/news/opinions/on-a-cost-basis-carbon-capture-projects-are-madness/article1329825/

    Your source is ommitting the Federal contribution, and is very vague about what cost for how much. A more reliable statement is here:

    http://www.cbc.ca/money/story/2009/10/08/edmonton-money-announced-shell-quest-carbon-capture.html

    Which quotes one of the projects (the Shell upgrader) at $1.35B for 1.2M tonnes/yr. Which is $98 per tonne, financed at 5% over 17 yrs. or 9.5 cents/kwh. Does that include operating costs? I doubt it.

  38. DV82XL, I take district heating to mean supplying the heat to most town buildings through a central facility.

    What you’re talking about, I would call, CHP or Co-generation. Also I’m referring to NWT & Nunavut and all NCPC has declared is one site in Inuvik which heats the community centre with a Capstone NG turbine.

  39. @Warren Heath – those were all systems that supply heat to most town buildings from a central facility. They burn wood chips or pellets and have no co-gen capabilities. Perhaps you should read my comment again, I made it rather clear, I thought.

    I really don’t want to test the patience of the other readers of this thread detailing every one of the systems and providing links, but if you write me at dv82xl@gmail.com I will provide you with the appropriate references should you need them.

  40. G.R.L. Cowan, you’ll have to show us the numbers on that, in order to evaluate its viability. Capital Cost? Storage space? Round trip efficiency? Peak power output?

    Sorry, I don’t know the capital cost of the thing, or the few hundred things, that would burn the aluminum. Storage space for the 4234 tonnes of aluminum before it is burned is looking to be about 0.37 hectares, for a conical heap whose sides slope at 30°. The oxide will have more volume, so towards the end of the 3.3 years the storage would perhaps increase to 1 hectare.

    My point is that it makes more sense to try to develop aluminum burners, possibly single-household ones, and support millions of such burners from single multi-gigawatt nuclear aluminum deoxidation plants, than to try to develop village-scale fission power plants, or village-scale carbon-free power plants of any sort.

    For aluminum and its oxide, if the devices that turn the former into the latter can be scaled down to single households, the intra-village grid needn’t be a grid; it could be people walking with gallon pails.

    (How fire can be domesticated)

  41. Where theres smoke theres fire !

    Quite right. John Lott wants the world to burn and his folk are assiduously attempting to conjure a fire on non-combustible emails.

    It’s worth noting that where there is smoke, people find it hard to distinguish safety from danger. Little wonder Gordon, that you are so pleased at the smoke billowing from this in the more unhinged partys of the blogosphere.

  42. What I get on Aluminum Energy Storage. 16 kwh electricity to convert Al2O3 to 1 kg of Aluminum. 8 kwh back converting 1 kg Aluminum to Al2O3. Energy density of Aluminum, converting to oxide is 8 kwh/kg & 21.6 kg/liter compare with diesel 11.8 kwh/kg &10 kwh/liter. Although I imagine the Aluminum metal would be stored as a powder or a slurry, which would reduce the energy density.

    50% efficiency is not bad, comparable to H20 -> H2 & H20 + CO2 -> CH4OH (methanol production).

    Mars Society is claiming 96% efficiency converting CO2 + H2 -> CH4 + O2, with its nuclear powered reactor.

    “…. Dr. Robert Zubrin’s team created a unit that demonstrated efficiency rates as high as 94% within 3 months. Additional funding by JSC and NASA’s Jet Propulsion Laboratory allowed for further improvements, with a resulting unit that operated at 96% efficiency for 10 days straight with no outside intervention, generating 400 kilograms of propellant on 300 watts; ..”

    With a 100 kw Nuclear Reactor, and H2 transported from Earth, CO2 from the Martian atmosphere, they are claiming, in 10 months they can produce 24 tonnes CH4 plus 48 tonnes of O2, and an additional 36 tonnes of O2, by direct dissociation of CO2. That would be 290MWh of CH4 energy for 72 MWh of Nuclear electricity.

    So Aluminum certainly looks like an effective storage medium, for transportable energy. Certainly far superior to H2, as usual, it’s the devil-in-the-details. Is there enough Aluminum available to do the task?

    Still, unless the numbers are that much better, Methanol is a fuel easily made in huge quantities from NG, and it will burn in standard ICEngines, with improved efficiency & emissions and also existing NG turbines can readily be converted to Methanol burning. Also Methanol fuel cells. I suspect diesel or propane furnaces can also be easily converted to Methanol. And is easily transportable using existing pipelines & storage facilities. Not a severe task to convert over from a Diesel/Gasoline Fuel infrastructure to a Methanol one

  43. I think there’s a fair test to sort this out. Anyone who wishes to criticise the CRU scientists for these email exchanges (which to my mind simply reflect human nature), are welcome to, on one condition. The critic must first place the contents of their email archive for the last 10 years on a public FTP or HTTP repository, such that anyone has the opportunity to download and peruse it, if they so wish. Otherwise, any criticism levelled at the CRU folks is vapid and gutless, and deserves no further attention — people who live in glass houses…

  44. @ Warren I agree that meth..something may be the most practical hydrogen carrier. If the carbon is biomass derived and the hydrogen is from thermal splitting or electrolysis of water then perhaps it could be the hydrocarbon fuel of last resort (albeit expensive) on Earth. The combustion products will be recycled in the biosphere.

    Methane of course can be blended with natgas, coal seam gas and biomethane. I dislike methanol which I buy from dirt track racers. They use it in supercharged V8s but I use it in making biodiesel. If automotive fuel cells get cheap and durable enough methanol might be the fuel for them. Dimethyl ether can be handled as easily as LPG or propane and could be a future (Earth) fuel if scaled up and the price was affordable. Even at say $5/L it could be used in PHEV reserve tanks or aircraft. I think more research should go into bulk production of DME using water derived H2 and purer forms of biomass derived CO2.

    I like the idea that we stop using natgas (80% methane) for electrical generation and save it for a smooth transition to meth..something powered transport. Alas it looks like Australia’s convoluted ETS will see more gas going to the stationary sector.

  45. Well said Barry – can’t see Andrew Bolt or Nick Minchin complying with you request or any of the deniers boring us witless on the “Ian Plimer – Heaven and Earth” thread!

  46. Oh c’mon Barry. Thats a bit tough! The CRU hack has only used selected emails so if the denialists are going to follow your condtion shouldn’t they be allowed to upload selected emails e.g. “I believe in science and rationality”

  47. Jade the world is not going to burn!

    I watched an interesting program the other day about the discovery of a baby mammoth found intact in the frozen plains of Siberia. Turns out that 37,000 years ago the region was a temperate grassland. Methinks it will once again return to that state with or without human involvement.

    Fingers crossed Climategate will be the nail in Copenhagens coffin.

  48. The outgoing chairman of BHP Billiton acknowleges the need for carbon pricing and nuclear power
    http://www.news.com.au/adelaidenow/story/0,22606,26403740-5016955,00.html
    You’d think that some conservative politicians would listen to the world’s largest mining company.

    I wonder if this is setting the scene for a NPP/desal to enable the expansion of Olympic Dam. That is 120 ML/day of fresh water and 700 Mw or so additional power for various purposes.

  49. “So Aluminum certainly looks like an effective storage medium, for transportable energy. Certainly far superior to H2, as usual, it’s the devil-in-the-details. Is there enough Aluminum available to do the task?”

    Warren Heath; the Earth’s crust is 8% aluminium. High quality bauxite might have some limitations but lower quality ores are completely limitless.

    The problem is the gallium, which is rare and expensive.(why gallium? Aluminium forms an impenetrable oxide layer in air; the most succesful attempts to get around this have used aluminium alloys with a few percent gallium)

  50. Pingback: Learning the truth about energy « BraveNewClimate

  51. Soylent writes,

    The problem is the gallium, which is rare and expensive.(why gallium? Aluminium forms an impenetrable oxide layer in air; the most succesful attempts to get around this have used aluminium alloys with a few percent gallium)

    This is a misunderstanding of some recent talk about gallium as a component in an aluminum alloy that makes the aluminum react quickly with water:

    Al + 1½ H2O ---Ga---> ½ Al2O3 + 1½ H2

    This process yields the aluminum’s oxidation energy in two low-value forms — low-temperature heat and hydrogen — about half and half. Of course, to access the hydrogen-borne half of the energy, oxygen must be brought in in exactly the quantity that would have been required to oxidize the aluminum directly.

    Successful use of aluminum as fuel has always involved its combustion at high temperature, e.g. in solid rocket propellant such as that of the Space Shuttle’s two expendable boosters.

    These propellants typically contain oxygen in a dense but not strongly bound form such as ammonium perchlorate. So as combustion propagates through them, it first unbinds the oxygen at a relatively low temperature, and the main temperature rise follows as the high-pressure gaseous oxygen reacts with finely divided aluminum.

    (How fire can be domesticated)

  52. Gene, great post!

    You rhetorically asked, “So why are we so interested in rooftop solar?” The answer has at least 3 parts:

    1. the difference between retail energy prices and generating costs is about double. When I install rooftop solar with net metering, I get double the benefit as the centralized generator. I understand the net metering isn’t available everywhere, but that motivates a significant share of the current rooftop PV installations. It gets better because pricing is nonlinear, so I avoid the highest marginal rates with rooftop PV. Even with all this, my rooftop PV experiment is a financial disaster.

    2. Subsidy. Especially corporate rooftop PV is heavily subsidized. The resulting tax breaks occasionally make it financially reasonable to install PV panels upside down. I’ve seen the calculations for a large installation in Mountain View CA… It makes me ill because I know I’m the one paying for it.

    3. It just seems so right. Some people feel like they need to do something to reduce their carbon emissions. Buying rooftop PV is a modern form of buying an indulgence.

    Note that none of these are *good* reasons, but I think these are *the actual* reasons rooftop PV is such a powerful meme.

    Chris

  53. Concerning 1, the difference between retail and generation cost is about 2 to 1 is for the current fossil fueled system. This means that if a customer pays 10 cents per kwh currently, 5 cents per kwh is for gas and coal energy, and the other 5 cents per kwh is for T&D and admin costs, i.e. all other costs. Now if that production cost increased to 15 c/kwh with renewables, the customers bill would be 25% T&D and admin and 75% production. So the increasing cost of renewables changes cost components on your bill. RW Beck recently suggested to Austin Energy that a new rate is needed for customers with solar panels to capture the true cost of providing service to those folks. I.e. the benefit you describe Chris will go away if such a rate is adopted. If solar panels were a signifiant component of the power supply system, then the utilities would be forced to redo their rates so that the apparent low cost would no longer be available.

    Concerning 2, the heavy subsidies. That practice will have to end soon when its discovered how many billions the poor people are spenging on rich folk’s solar panels.

    Concerning 3, its an important concept that people spend their money the way they want to and to heck with detailed economics. Thats why they need to be given an opportinuty to spend about $10,000 US to buy all their future nuclear energy they will need fofr the rest of their lives, so that that their bills will drop from 10 cents per kwh to about 8 cents per kwh for the T&D and admin and nuclear O&M and nuclear fuel.. Over their lifetimes (60 years) that would save them about (13 c/kwh)(.01$/c)(60 y)(15000 kwh/y) = $117,000. Wouldn’t individuals want to invest $10,000 now to save $117,000 in renewables later? These are just back of the napkin calculations, incorrectly done, but the kind of thinking a typical customer might use. But they would spend that $10,000 to save the planet, and then wouldn’t even need any cost savings analysis at all.

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