Is Powerwall good for coal and nuclear?

No one seems to have spelt this point out, but there’s an obvious potential for Powerwall to be used in ways that benefit coal, nuclear and geothermal power, as well as renewables like wind and solar. Advocates of these technologies love to cite the fact that they are “baseload” supplies, but this is a misconception. Because they are costly to turn on and off (or even up and down), these technologies produce too much power at times of little demand (late night and early morning).

If owners of home solar systems, connected to grids with an off-peak excess supply, install battery storage on a large scale, it would make sense to run two cycles per day. The systems (most sensibly oriented west) would charge up from solar panels in the early afternoon, and supply power in the evening. Then they would recharge from the grid in the early morning, and supply power to meet the morning peak associated with getting ready for work, school etc.

What’s the net effect of this. First, obviously, it makes storage a more appealing economic choice for householders. Second, although it reduces costs for any kind of electricity that is not fully dispatchable, the benefits are bigger for renewables for two reasons. First, the variability of these sources is greater. Second, pricing systems, at least those in Australia, are already set up to encourage use of off-peak grid power, whereas current feed-in tariffs discourage solar PV.

From our current starting point, effect of adding more systems with a combination of solar PV and storage will be to reduce total demand for coal-fired power (and, where it exists, nuclear power), and to enable more efficient use of existing capital stock. So, it’s likely to discourage new investment in these sources. However, unless we have a carbon price, or other measures in place, it won’t necessarily accelerate the closure of existing coal-fired plants.

Update A note on the economics: Calculations I’ve seen on the web assumed that lithium batteries have a life of 1000 recharge-discharge cycles, but it appears this number can be improved drastically. These guys are claiming 20 000. More on this soon, I hope.

74 thoughts on “Is Powerwall good for coal and nuclear?

  1. For many years I’d tried to argue that nuclear needs storage as much as renewables in various places including Brave New Climate. If nuclear boosters wanted to avoid having to build their expensive plants to meet peak consumption, not the average, then they must also advocate storage. Of course, this advantages renewables (technically, politically and now cost-wise), so they couldn’t abide that.

    I don’t expect a change of attitude with Tesla’s product, because it has become the grid that is the ROI plaything for the dinosaur encumbents all around the world.

  2. John,
    I am shattered. Does this mean that during “Earth Hour” the base load supliers do not cycle down the output as the load reduces, thus achieving a reduction in CO2.
    All that “earth Hour” achieves is a warming of the supply wires.

  3. I suspect the power companies won’t like being arbitraged by home batteries and will devise new rules. EVs could be a different story. Stories are legion (not just Top Gear) about running out of battery miles from home and the public charging point is broken or incompatible. Maybe like dodgy public toilets they are best avoided. However with 300 km range which Nissan now say is the minimum acceptable owners can top up at night and have enough range to do an extended shopping trip around the city. If topped up they could power the house in a blackout.

    Australia has 18m cars suppose half went electric. Most EVs can get 4 km on 1 kwh of charge so for 40 km a day that’s 10 kwh. Times 9m cars that’s 90 Gwh on top of the present 680 Gwh a day we use. Few cars used for commuting will have daytime solar charging facilities. Flat dwellers and renters probably won’t have solar so charging at night is the go. Even casual workers seem to need cars so I think that’s where baseload finds a new niche.

  4. Anything which extends the profitable life of coal-fired power is counter-productive from the perspective of GHG emissions. The current trajectory of emissions is consistent with 4C of global warming, not 2C, and Professor James Hansen argues that even a 2C global warming target is insane.

    Instead of using powerwall to help existing power facilities to limp along, it would be much better to have a significant increase in RET to well above the previous 41TWh, and to encourage the developing market in higher efficiency solar PV for both household and for local area facilities as well.

    Brown coal burning has gone from decreasing to increasing again, and this is likely due to direct action policy settings. The LNP’s policy strategy for climate change is diametrically opposed to the direction we need to follow; in fact, I’d describe the current policies as utter lunacy.

    The ALP appear singed from their brush with climate change policy, but that struck me as more a failure of presentation to the electorate—coloured by the unusual step of changing prime ministers mid-term—than of resistance to having a meaningful policy. The ALP should campaign on really hard on a proper, scientifically justified, policy in this space, making them starkly different to the LNP. At the moment, there is only a few cigarette papers’ worth of gap between them, not enough to ensure the ALP would win at the next election. I don’t think the ALP can swing it withouth a strong policy vigorously pushed and competently defended.

  5. @Hermit

    So many assumptions, Hermit.

    “Few cars used for commuting will have daytime solar charging facilities.”

    Why not? Shopping centre car parks can be covered over with solar panels for shade and to charge cars. Just plug it in when you go in to shop. Each parking bay will have a plug-in point. Some car parks in Canada have plug-in points for all cars now (though there it is to keep engine blocks heated in winter while parked). Shopping centres will offer deals. The re-charge could be free if you buy $200 or more of groceries. Train station car parks can be covered with solar panels. Buy a monthly ticket and get the charging free.

    BTW, eventually electric cars will have 100% of the body, wind-screens and windows configured as solar power generators using thin film photovoltaic technology. Every car will be charging itself all day in the open while parked or travelling. The only drawback will be that your car will have to be black.

    Why won’t flat-dwellers and renters have solar power? Soon, the same technology will be applied that makes 100% of the roof, wall and window area of every dwelling and building a solar generator. Heck, we won’t even have to go that far. The over-supply of energy would be far too great.

    There are limits in this world but energy from solar power won’t be one of them unless we lack key materials for the build-out. It seems though that all necessary metals are in sufficient supply for the rest of this century at least. I see limits in other arenas but not (now) in energy. But the discussion of other limits will take us off-topic.

  6. Given that the Powerwall is ostensibly designed for home use and is subsidised by Tesla as a loss leader for the express purpose of enabling more sales of its profitable electric cars, I don’t think we’ll be seeing Powerwalls at power stations any time soon.

    However, if the Chinese get interested in this and bring the full force of their manufacturing sector to destroy the cost price of batteries through economies of scale like they have just done for solar PV cells, then… then, we might have something.

  7. Ikon you’re counting chickens that may not hatch. I agree we will need a vast overbuild of solar to get through rainy weeks and so that electricity will either be stored or curtailed in sunny weeks. Half a day’s storage is not enough. Meanwhile despite the enthusiasm for alternatives coal is still with us. I see from
    http://empowerme.org.au/market.html#
    that each of Qld, NSW and Vic were consuming 4 GW of coal power at 4 am this morning. That’s what has to be replaced.

  8. @Hermit

    The many synergistic possibilities have been explained to you over and over. You never absorb any of this. Your contsant statement is the “the job is big so it can’t be done.”

  9. I’m confused about how many cycles the 7kWhr Powerwall can do — daily cycling and a 10 year warranty imply 3500 — but what % of the original capacity will it be at the end?

    With peak power at 50 cents and off-peak at 10 cents it might already make economic sense for someone with no debt and no good low risk investment opportunities. (Ignoring the complication of shoulder pricing).

    With solar, it might even already make sense to save the 90 cents per day network fee, go off grid and buy a small petrol generator for periods of bad weather (that costs something like 96 cents/kWhr, not including the cost of the generator)

  10. @m0nty Is the Powerwall selling at a loss? Tesla already has the Powerpack which is/will be used by Southern California Edison. I don’t see the link between Powerwall and selling Tesla cars, except perhaps if economies of scale in battery manufacture allow the price of the cars to be reduced?

  11. Tom, if natural gas is available in the area of interest, use that and the fuel cost is more like 30c/kWhr. If you then use the waste heat to heat your hot water (observe that if you’ve got solar hot water heating bad weather is precisely when you’ll need backup for that) the effective cost goes down a little further.

    Small wind turbines might also be useful in some locations if there’s storage available.

  12. @Tom Davies

    Or even a genset that could run on biodiesel. That’s probably going to get a better return than a larger battery array.

  13. @Tom Davies , that’s precisely it. They’re building a gargantuan battery factory in Nevada, the “Gigafactory”; the economies of scale of selling these battery packs as well as fitting them to Tesla cars gives them a cost advantage.

    That said, while the first few of these might be loss leaders, I don’t think they will sell too many at a loss.

  14. @Ikonoclast
    “eventually electric cars will have 100% of the body, wind-screens and windows configured as solar power generators using thin film photovoltaic technology.”

    Your windows cannot be coated with thin film PV or they would be opaque. The active layer in thin film PV cells still absorb most of the light and the back contact is usually aluminium which is complete absorbing. So maybe the car body could have TFPV but not the windows.

  15. @Tom Davies Bluegen, the Australian company, are about to be wound up. Dunno about other domestic fuel cell companies but the fact that I don’t know suggests that they aren’t exactly setting the world on fire.

    Fuel cells are efficient but expensive to make, which makes them unsuited to a role in which they’re providing backup on an infrequent basis.

  16. The 7kWhr Powerwall can do a daily cycle for 10 years, so 3500 cycles for $3500, how convenient. But that also means $1/cycle, so $1/5 per kWh just for storage, or about 15 cents. Higher price if you don’t fully cycle it, the life doesn’t increase linearly as depth of discharge drops. So the best case, assuming free installation and no residual value (wanna bet that you’ll be able to get new cells in 10 years?), you need a price difference of 15c between input and output.

    Right now we pay Red Energy about 28c/kWh peak and 8c/kWh off peak for electricity and sell it to them for 5c/kWh. We are also an ideal household for battery because we use diddly squat of it, about 10kWh/day, and in summer our 3kW PV setup generates 10-15kWh/day (today it was 11kWh). More than half of that is hot water, but at 8c/kWh it’s very hard to make changing our crappy storage heater (payback on any expenditure when the max possible saving is 40c/day just doesn’t make sense).

    What kills it for us is the supply charge – the PowerWall is grid-dependent, and half our bill is the supply charge. With a PowerWall that would become all of our bill. So it makes much more sense for us to look at alternatives, and go off the grid entirely. Unfortunately until Tesla push battery costs in general down we can’t really do that. But with that goal, dumping the water heater for a heat pump unit (~$5k) and running that off the solar does make sense – why pay 8c/kWh when you can use electricity worth 5c/kWh instead?

  17. Also, we’re building a granny flat/ecohutch to live in with the goal of renting out the main house. That will only have us two in in, instead of 4 adults, and with a bit of work we’re expecting power use about 5kWh/day. At the point we need to pay $1000-odd to have the granny flat connected to the grid (in a year or so) we will be running the numbers very carefully to see whether off grid can be made to work. If we plan on backup charging via an extension cord to the house we can probably get away with 2-4 days storage, and even the pricey Tesla unit is probably $5k Australian. Two of those, some hacking (if we feed them from an off-grid inverter will they think they’re on-grid and work as advertised?). All up about $18k to go off grid, of which $6k we will spend anyway (the PV array). The alternative is $1000(ish) plus $1/day in supply charge. So $12k extra vs $1/day… not worth it right now. But I really, really want to do it.

  18. A new French government report on high-renewables scenarios backs large-scale P2G as the backup technology. They may be wrong, but the French élite is informed on technology, so this is a lot more than hot air. Germany has built pilot plants, so there is some experience to go on.

  19. @Tom Davies
    7kwh is the rated capacity, not the sum of the capacity of the batteries in the unit. The sum of cells is probably 10-12 kwh.

  20. Don Miller :
    @Tom Davies
    7kwh is the rated capacity, not the sum of the capacity of the batteries in the unit. The sum of cells is probably 10-12 kwh.

    Do you have a reference for that? It seems like a very unusual way to make a LiIon battery.

  21. For many years I’d tried to argue that nuclear needs storage as much as renewables in various places including Brave New Climate. If nuclear boosters wanted to avoid having to build their expensive plants to meet peak consumption, not the average, then they must also advocate storage.

    In a purely nuclear grid (assuming for simplicity) it seems unlikely that storage would have much to offer. A larger fleet of nuclear plants with load following capability would likely be cheaper to build and operate than a smaller fleet combined with storage. Of course it all hinges on the cost of storage but storage, other than reverse pump hydro, hasn’t shown itself to be cheap enough.

  22. @Moz of Yarramulla
    It’s a battery system, not a battery. Musk didn’t indicate the internal components. Consider that the 7kwh daily cycle and the 10kwh weekly cycle have the same spec for weight and size.

  23. Don Miller :
    @Moz of Yarramulla
    It’s a battery system, not a battery. Musk didn’t indicate the internal components. Consider that the 7kwh daily cycle and the 10kwh weekly cycle have the same spec for weight and size.

    The difference between a LiIon “battery system” and “battery” is very much in the mind of the beholder. It’s hard to buy even small LiIon cells without current limiting electronics, and even those almost always have a battery management system (if only a low voltage cutoff in the consuming device). Much as today we don’t talk about “household electric power system”, because the days when some people used steam or water for their home power system are long gone. Implicitly (and I suspect the ACCC would say explicitly), both should be rated under equivalent conditions. If not that had better be to the benefit of the purchaser 🙂

    That said, the weights being identical is very suggestive, and makes me wonder that justifies the price difference – I wonder if it is purely the cost of warranty on a deeper discharge? Or through the lower rate of discharge allowing them to have more parallel strings with fewer cells, thus suffering less from cell variation? I might have to read up, but then I’m not likely to buy one so maybe not.

  24. Someone tried some math: https://twitter.com/RF_HFC/status/594759852037173248

    If the spec sheet is right, Tesla is offering a 10 year warranty for systems that get daily discharges of 7 kWh (or very infrequent discharges of 10 kWh). So theoretically you’d get 3650 cycles of 7 kWh.

    If you are installing this for time-of-use arbitrage, the price goes up. There is no DC-AC inverter, which might be a thousand dollars or more. Also, it would reduce the efficiency of the system. It’s probably around 97% AC to DC, then 92% for the PowerWall, and then 97% to go back to AC for a round trip of 86.5%.

    These things will pair well with PV systems though – which generate DC. You’d want the PowerWall on the solar panel side of the inverter.

    One other thing to consider – continuous power rating is 2 kW (with 3.3 kW peak). Meaning if you do want to hook the solar up to it, you don’t want much more than 2 kW of panels per PowerWall.

  25. @TerjeP

    The Powerwall generates 2.0 kW continuous and 3.3 kW during peak usage. This means one Powerwall battery pack can boil your kettle. The thing is there are many renewable solutions to a house’s power needs. The issue is still price but that is coming down. Here are some of the solutions.

    (1) Have solar power and stay connected to the grid. Use the grid as your “giant battery”. While this makes financial sense stay connected. The grid itself benefits from being a network with large and small generation nodes.

    (2) Buy 2 Powerwalls if one won’t suffice. It’s still less money than many people waste on 5 years of depreciation on their brand new “prestige” car.

    For the future, I am planning to stay grid connected if the connection fee does not become excessive. With a 5.5 kWh (nameplate capacity) system, I generate enough power for 1.75 households llike mine with 4 people, all modcons, no real attempt to saver power. I also have solar hot water (evacuated tube solar heater).

    I am also planning to get battery storage when the economics of it are good. Then I can stay connected to the grid and juggle power sources to get best prices and have full backup for blackouts.

  26. @TerjeP

    Or to put it another way, WW2 battery technology propelled submarines underwater and you are worried that 2015 battery technology can’t boil an electric kettle! LOL.

  27. @Ikonoclast
    Terje is worried that the battery is insufficiently manly. Nuclear reactors, on the other hand, despite depending on big government in order to exist, are inherently manly, and therefore appealing. Remember, “libertarians” are essentially overgrown schoolboys. 😉

  28. @TerjeP

    That is missing the point. The grid uses mostly coal for energy at the moment. The idea is to supplement and eventually replace this with solar and wind power. The point being of course to reduce greenhouse emissions.

    These claims that renewable technology looks ugly are very amusing. I suppose Morwell Power station looks appealing? I mean especially when the brown coal pits are burning out of control as they did realtively recently. I supposed Chernobyl looks appealing too?

  29. Well, regardless of whether or not the Powerwall is good for coal and nuclear, or sufficiently manly, it does appear to be a good business proposition – Tesla has reported they have now sold out their production capacity until mid 2016. Musk is nothing if not a good businessman.

  30. @TerjeP

    I have a house which combines a modern architectural style with certain old Queenslander motifs (successfully IMHO). The solar panels look suited to it, again IMHO. I didn’t design it but I did commission it.

    But to actually drag out aesthetic considerations and claim that renewable installations are ugly while never raising a quibble about the (generally very ugly) appearance of coal power stations, coal pits and nuclear power stations just illustrates how desperate and bereft of real arguments anti-renewable opponents have become.

    In many domestic solar installations the panels, depending on house orientation and design, can be;

    (a) on the back roof;
    (b) on the front roof but still not visible from the road due to elevation;
    (c) integrated stylistically with modern architecture;
    (d) hidden by various roof design features which I can picture but do not know the architectural terms for;
    or
    (b) even now integrated into tiles, windows and roof sheets via solar thin film technology.

    There are so many design options that the argument “it looks ugly” is just about the weakest argument possible. As I say, it shows how desperate the anti-renewables lobby is getting.

  31. Nice to see the blossoming of aesthetes, first Joe Hockey and now TerjeP, although they do tend to be delicate little flowers. How long before they notice the fundamental ugliness of tar macadam?

  32. @zoot

    Yes, it’s funny how one never hears criticism from these people about how ugly power poles and wires are. On the other hand, in their book wind generators are extremely ugly (being tall, sleek and white) but smouldering, open cut brown coal pits emitting a brown haze that covers towns rate not a mention for ugliness or pollution. The entire infrastructure of fossil fuel capitalims is not criticised but woe betide the farmer who allows a wind generator on his hill or a suburbanite who puts solar panels on his roof. For they are the harbingers of ugliness and the apostates against King Carbon.

  33. Yes, it’s funny how one never hears criticism from these people about how ugly power poles and wires are.

    I love those giant 330kV power lines with their steel towers. They look majestic. The only consolation with those ugly wind farms is that they will necessitate even more majestic power lines.

    Solar panels are truly ugly because unlike wind farms, which are mostly in out of the way places, those ugly solar panels are on roof tops I have to look at. Heritage rules in my area mean I can’t paint my gutters a different colour without council permission but slap on a solar array to cover all those heritage tiles and it’s no problem at all.

  34. @TerjeP

    What is your solution to climate change then?

    Solar panels might look incongruous in a heritage area. It depends on the actual architecture in question. Again, I believe there are solutions to make the panels less noticeable.

    There is even the The Heritage Solar Slate was well as other solar tile solutions (in the UK at least). You are not looking for a solution because you don’t want a solution. You want to be able to complain and also to advocate unsustaibable, dirty and dangerous fission power for emotional and ideolgoical reasons. Your reasons cannot be logical for J.Q. and many others have demonstrated irrefutably with facts and calculations that the so-called nuclear renaissance has fizzled out and has close to zero chance (on grounds of costs and unsustainability) of ever reviveing.

  35. What is your solution to climate change then?

    Mostly adaptation. I think attempts to internalise costs (eg carbon tax) are theoretically okay but in practice they make no real sense unless applied pretty much everywhere and that defies real politic at the global level. So suck it up and adapt.

    Of course there are some interesting technologies coming along but none that should be mandated. And certainly not solar in the way we do today.

    The physicians motto is “first do no harm” and a lot of the measures people are pushing are harmful.

  36. p.s. There is also a risk that global warming will on balance be a good thing. In rushing to solve things you should not ignore that risk.

  37. @TerjeP

    This is a reply to both your posts above. I will play a straight bat and be sensible, serious and logical.

    1. Adaptation. We will have to adapt culturally, scientifically, economically and industrially (to name a few parameters). This is because a certain amount of warming, probably at least 1.5 to 2 degrees C is already in train in the system. The timespans are possibly too short for us to adapt biologically. I assume you know what biological adaptation means. Its means mass dieoffs of those who are biologically unfit for the new environment. Adaptation is “cure”. You know the old adage “prevention is better than cure” and it definitelty holds true in this case.

    2. “First do no harm” does not mean avoiding useful innoculation or vaccination measures nor does it mean avoiding interventionary surgery where it is competently assessed as most likely to aid or save life. You seem to be totally misunderstanding the concept of “first do no harm”. We need to do interventionary surgery on our economy and production system before it generates dangerous climate change. The science is in. The dangers are high and at well over 90% certainty rates.

    3. There is no credible scientific evidence that 2 degrees centigrade plus of warming will be a net benefit to man or or many other species we depend on for food or bio-services. The evidence is very much to the contrary. There is no credible evidence that a couple of metres sea level rise will not inundate urban and argricultural areas upon which 100s of millions of people (if not more) depend on.

  38. @TerjeP

    I love those giant 330kV power lines with their steel towers. They look majestic.

    Did you mean man-jestic? 😀

  39. @Ikonoclast

    2 degrees seems like a lot. But compared to the change since 20000 years ago it’s small beer. And biological systems adapted to that change. I’m sure 2 degrees more will be problematic for some species in some locations but claims of mass extinction due to 2 degrees of warming are an exaggeration. In some places some species will be better off including humans. And certainly humans themselves can deal with a much larger climatic range. Such warming would open up parts of Russia to agriculture.

    Richard Tol has done some interesting work attempting to add up the costs and benefits of a warmer world. There is a risk that it will be positive. Especially in the early stages. In which case we don’t want to go overboard with the mitigation attempts.

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