7 ms·

One thing that might go overlooked: Load shifting could, in theory, lower electric bills such that there's ROI without solar panels. --- Edit for why: On-dema

One thing that might go overlooked: Load shifting could, in theory, lower electric bills such that there's ROI without solar panels. --- Edit for why: On-demand power is expensive. "Spinning up" additional power during the day is more expensive than having certain types of power generation running all the time. In theory, pumping power into a battery at night during non-peak hours will cost less than consuming directly off the grid during the day. I'm forgetting all the details of energy economics, but IIRC there would also be far less emissions by having consistent load on the grid all day long. Something about the ones we "spin up" also being the worst for the environment.

kmod 11y ago
If what you say is true, then with better economies of scale and longer investment horizons, utilities would quickly erase any peak-vs-non-peak arbitrage opportunities.
- epistasis 11y ago
  Different entities have different risk profiles, and utilities are extremely conservative. It will probably be profitable to load shift for several years before utilities start to do it on their own. And even then, it may take quite some time before there's enough battery capacity for all the fluctuations to even out.
  - gutnor 11y ago
    Utilities with electricity production are more conservative because they have technical limitation due to the infrastructure they run. However, there is a bunch of companies that buy and sell electricity on the open market, so they have a direct financial interest to play with this arbitrage. In the UK, another reader has calculated the best case scenario was profitability in about 10 years. (his numbers ring true to me, I calculated recently that there was no reason to take an economy 7 contract for my electricity usage using similar data) That's a lot of time even in the utility market. So if batteries not attached to solar panel are going to be profitable (in the UK), that would be a future generation.
- toomuchtodo 11y ago
  > utilities would quickly erase any peak-vs-non-peak arbitrage opportunities. Probably right around the same time they're no longer necessary, as the cost of distribute solar continues to plummet. Its actually truly amazing how quickly the price continues to drop for panels each year.
  - eru 11y ago
    Depends on country. I doubt you could ever run, say, Germany or Britain on locally produced solar power.
    - maccam94 11y ago
      Relevant: http://en.wikipedia.org/wiki/Renewable_energy_in_Germany http://en.wikipedia.org/wiki/Renewable_energy_in_Germany
    - matt4077 11y ago
      There also wind... But solar already provides quite a substantial contribution in Germany. See this live chart: https://www.energy-charts.de/power.htm https://www.energy-charts.de/power.htm. Considering the rate at which solar power is getting cheaper, I'd say a solar power based economy is within reach.
      - kamikrazy 11y ago
        Great link. It's also amazing how Solar power generation falls significantly in the winter months. For instance, December output is less than 10% of June! Chart here: Check out monthly/weekly energy production for 2014 https://www.energy-charts.de/energy.htm https://www.energy-charts.de/energy.htm
      - eru 11y ago
        Sure, wind, geothermal, nuclear etc.
    - toomuchtodo 11y ago
      But you could run it on a combination of onshore wind, offshore wind, distributed solar, utility solar, and energy storage (ie Tesla's Utility Storage solution).
- colinsidoti 11y ago
  It's hard to wrap your head around all the challenges in energy. If you're REALLY good at it you can find some incredible arbitrage opportunities...see Enron. Consider the power output characteristics of some common energy sources: Gas, Nuclear, Hydro, Wind, Solar Our "sustainable" sources of power - hydro, wind, and solar - are also the ones with the most irregular and unpredictable power output. This creates a problem, because even if there was enough cumulative power output from sustainable sources today, it most likely wouldn't align with our usage schedule. So there are two solutions: 1) find a way to map the sustainable power output to our usage 2) find a way to store energy Today, our most readily available form of energy storage is gas. We just put it in a container and burn it when we need to. "Spin it up," if you will. An alternative to gas is a crazy network of Powerwalls. The hope is that, eventually, instead of spinning up gas turbines during peak demand, we can just draw from our Powerwall. There was another alternative on HN recently. Basically a super-deep hole in the ground with super heavy object falling into it, but suspended by a rope. You run a motor to lift the object during off-peak hours, then let it fall and spin a generator during peak hours. I can't find it right now but I remember thinking they had a great name. --- That said, power output is only part of the problem. If you're looking to factor the potential disappearance of arbitrage opportunities into your buying decision, you also need to consider the time until regulatory changes allow for perfect pricing, and the time until these Powerwalls have precise enough information to decide exactly when to draw from the grid versus the battery. tl;dr: "quickly" is probably optimistic. We're a long ways away from economies of scale.
  - jimmcslim 11y ago
    > There was another alternative on HN recently. Basically a super-deep hole in the ground with super heavy object falling into it, but suspended by a rope. Or a train going up and down a hill... http://www.aresnorthamerica.com/ http://www.aresnorthamerica.com/ Both are basically the same concept as pumped hydro which has been in use for a long time... pump water up a hill when energy is cheap, let it fall down and turn a turbine when energy is expensive. And hey, if it rains, free energy! The rail/hole in the ground approach have the advantage of taking up less land I suppose, but I suspect are less efficient.
  - TheLoneWolfling 11y ago
URSpider94 11y ago
I could do this today. With my current time-of-use electric rate, I pay an average of $0.25/kWh more for peak power than I do for off-peak [the differential is larger in the summer, smaller in the winter]. If I shift 8kWh per day, then I would generate positive ROI in less than five years. Your edit is spot-on. Utilities typically use natural gas "peaker" plants to meet mid-day spikes in demand, while nuclear plants are better suited to running at a steady state.
- mrfusion 11y ago
  And you'd get a free backup power system too. That's worth something.
- bryondowd 11y ago
  Is 8kWh/day realistic? I'm curious, honestly wouldn't know. Seems like that would be charging and discharging 80% of the 10kWh battery's capacity every day. Would that affect lifespan? Also, it would seem to render the device less useful as a battery backup system during most of the day, since it would be mostly depleted.
  - URSpider94 11y ago
    My home uses about 1000 kWh per month, so shifting 8kWh per day of my in-house demand is feasible. However, there's really no correlation with my usage, since I can just push and pull that power from the grid, as if I had a solar or wind generator. Lithium batteries are fairly tolerant of deep discharge, but yes, I would expect that the pack would be worn out after max 7-10 years if used like this. Yes, using the pack like this would make it much less useful for battery back-up, but where I live (SF Bay Area), I haven't had an outage that lasted longer than 2 hours since we moved into our house, and this would cover the basics (probably everything but A/C) for that time. You could always split the difference, for example using 4 kWh per day -- this would pay still give you 6kWh+ of backup power and let you get the battery at half off or better.
hackerboos 11y ago
Economy 7 power is significantly cheaper in the UK than peak power. Charging overnight in the E7 period could save money long term depending on the lifetime of the battery.
- IanCal 11y ago
  I did a quick bit of calculation on this. Assuming you use 10KWh per day and a perfect battery: Economy 7 KWh cost : 8.4p (Best deal I saw was 9.4 for me, but this was a figure on MSE) Standard tariff KWh cost : 14.5p (Best deal I saw was ~12 for me, but this was a figure on MSE) That'd be a £306/year cost on economy 7 and £530 on a standard, taking some more extreme figures. A $3500 (~£2300) battery would then have a payoff time of about 10 years. Using the other figures (9.4 and 12) gives a £95/year saving or a ~25 year payoff. That's also assuming the batter is perfect, no extra costs in installation and you use exactly 10KWh per day. Economy 7 tariffs are about 22p/unit during the day so any overrun would quickly eat into savings. I do think this is all very interesting, but with current offers in the UK it doesn't look too beneficial. However, if someone were to offer cheaper rates on a more granular level (rather than always midnight-7am) then this could work out better. Perhaps an energy company owned battery would be a good idea, they offer a flat rate back to you knowing they can smooth things out.
  - aidos 11y ago
    Oh interesting, I hadn't considered the aspect of charging overnight while it's cheaper. Of course, the moment it starts to get popular the energy companies will be eating that particular cake too, I'm sure. Sounds like right now there's not a huge margin anyway. I guess the energy companies have a financial incentive to run a more consistent supply if it could reduce the peak load. Just reminded me of a brilliant BBC documentary from a while back - The Secret Life of the National Grid. I think you probably have to piece it together from clips on youtube these days.
  - CHY872 11y ago
    If you get 90% charge/discharge efficiency, you're multiplying the economy 7 tariff by 1/0.81 = 1.23456790 (so close) so it's more like 12.5 years, and a bit less compelling.
eatmyshorts 11y ago
Yep. This is targeted at ERCOT as much as it is targeted at the home consumer. http://www.greentechmedia.com/articles/read/Bring-on-the-energy-storage http://www.greentechmedia.com/articles/read/Bring-on-the-ene...
amass 11y ago
Doesn't this ignore completely the efficiency of the batteries? These batteries aren't ideal, you won't get out 100% of the energy that is put in. I don't know the efficiency rating, and I haven't done the math, but I suspect that the losses will cut into the savings significantly.
- ZeroGravitas 11y ago
  The page says >92% round trip efficiency. Since they also claim that they're selling them to utilities for exactly this purpose I'd guess it's theoretically possible and probably comes down to the pricing structure offered to consumers in your local area to buy and sell to the grid.
ZeroGravitas 11y ago
Can grid arbitrage and time-shifting solar co-exist? Some clever software might be able to predict your energy demand (e.g. based on seasons and past usage patterns) and your likely solar output (this time based on seasons and weather forecasts) and make the maximum use out of the battery. I'm also wondering if the same software is going to be rolled out to Tesla's cars so that they act like Tesla Energy when plugged in overnight.
tootie 11y ago
Big cities are prone to brown outs on hot days in the summer due to air conditioners. The 2003 European heat wave killed thousands1. I could imagine mayors mandating use of this kind of technology in apartment buildings. Let them charge overnight to offset peak usage. You'd cover 100 or more people at a time. [1] https://en.wikipedia.org/wiki/2003_European_heat_wave https://en.wikipedia.org/wiki/2003_European_heat_wave
- TillE 11y ago
  Normal homes in Europe simply do not have air conditioners, not even in southern Europe. So the electricity is irrelevant.
  - _delirium 11y ago
    That's no longer really true. A/C units are in the past 10 years getting quite common in the hot parts of Europe now. In the '90s fewer than 10% of households had them in Italy or Spain, but that has jumped to nearly 50% now. People do use it a lot less, though: they are typically individual units, not central A/C, and only used for short periods on very hot days, not run continuously with a thermostat setting.

kmod 11y ago

If what you say is true, then with better economies of scale and longer investment horizons, utilities would quickly erase any peak-vs-non-peak arbitrage opportunities.

epistasis 11y ago
Different entities have different risk profiles, and utilities are extremely conservative. It will probably be profitable to load shift for several years before utilities start to do it on their own. And even then, it may take quite some time before there's enough battery capacity for all the fluctuations to even out.
- gutnor 11y ago
  Utilities with electricity production are more conservative because they have technical limitation due to the infrastructure they run. However, there is a bunch of companies that buy and sell electricity on the open market, so they have a direct financial interest to play with this arbitrage. In the UK, another reader has calculated the best case scenario was profitability in about 10 years. (his numbers ring true to me, I calculated recently that there was no reason to take an economy 7 contract for my electricity usage using similar data) That's a lot of time even in the utility market. So if batteries not attached to solar panel are going to be profitable (in the UK), that would be a future generation.
toomuchtodo 11y ago
> utilities would quickly erase any peak-vs-non-peak arbitrage opportunities. Probably right around the same time they're no longer necessary, as the cost of distribute solar continues to plummet. Its actually truly amazing how quickly the price continues to drop for panels each year.
- eru 11y ago
  Depends on country. I doubt you could ever run, say, Germany or Britain on locally produced solar power.
  - maccam94 11y ago
    Relevant: http://en.wikipedia.org/wiki/Renewable_energy_in_Germany http://en.wikipedia.org/wiki/Renewable_energy_in_Germany
  - matt4077 11y ago
    There also wind... But solar already provides quite a substantial contribution in Germany. See this live chart: https://www.energy-charts.de/power.htm https://www.energy-charts.de/power.htm. Considering the rate at which solar power is getting cheaper, I'd say a solar power based economy is within reach.
    - kamikrazy 11y ago
      Great link. It's also amazing how Solar power generation falls significantly in the winter months. For instance, December output is less than 10% of June! Chart here: Check out monthly/weekly energy production for 2014 https://www.energy-charts.de/energy.htm https://www.energy-charts.de/energy.htm
    - eru 11y ago
      Sure, wind, geothermal, nuclear etc.
  - toomuchtodo 11y ago
    But you could run it on a combination of onshore wind, offshore wind, distributed solar, utility solar, and energy storage (ie Tesla's Utility Storage solution).
colinsidoti 11y ago
It's hard to wrap your head around all the challenges in energy. If you're REALLY good at it you can find some incredible arbitrage opportunities...see Enron. Consider the power output characteristics of some common energy sources: Gas, Nuclear, Hydro, Wind, Solar Our "sustainable" sources of power - hydro, wind, and solar - are also the ones with the most irregular and unpredictable power output. This creates a problem, because even if there was enough cumulative power output from sustainable sources today, it most likely wouldn't align with our usage schedule. So there are two solutions: 1) find a way to map the sustainable power output to our usage 2) find a way to store energy Today, our most readily available form of energy storage is gas. We just put it in a container and burn it when we need to. "Spin it up," if you will. An alternative to gas is a crazy network of Powerwalls. The hope is that, eventually, instead of spinning up gas turbines during peak demand, we can just draw from our Powerwall. There was another alternative on HN recently. Basically a super-deep hole in the ground with super heavy object falling into it, but suspended by a rope. You run a motor to lift the object during off-peak hours, then let it fall and spin a generator during peak hours. I can't find it right now but I remember thinking they had a great name. --- That said, power output is only part of the problem. If you're looking to factor the potential disappearance of arbitrage opportunities into your buying decision, you also need to consider the time until regulatory changes allow for perfect pricing, and the time until these Powerwalls have precise enough information to decide exactly when to draw from the grid versus the battery. tl;dr: "quickly" is probably optimistic. We're a long ways away from economies of scale.
- jimmcslim 11y ago
  > There was another alternative on HN recently. Basically a super-deep hole in the ground with super heavy object falling into it, but suspended by a rope. Or a train going up and down a hill... http://www.aresnorthamerica.com/ http://www.aresnorthamerica.com/ Both are basically the same concept as pumped hydro which has been in use for a long time... pump water up a hill when energy is cheap, let it fall down and turn a turbine when energy is expensive. And hey, if it rains, free energy! The rail/hole in the ground approach have the advantage of taking up less land I suppose, but I suspect are less efficient.
- TheLoneWolfling 11y ago

URSpider94 11y ago

I could do this today. With my current time-of-use electric rate, I pay an average of $0.25/kWh more for peak power than I do for off-peak [the differential is larger in the summer, smaller in the winter]. If I shift 8kWh per day, then I would generate positive ROI in less than five years. Your edit is spot-on. Utilities typically use natural gas "peaker" plants to meet mid-day spikes in demand, while nuclear plants are better suited to running at a steady state.

mrfusion 11y ago
And you'd get a free backup power system too. That's worth something.
bryondowd 11y ago
Is 8kWh/day realistic? I'm curious, honestly wouldn't know. Seems like that would be charging and discharging 80% of the 10kWh battery's capacity every day. Would that affect lifespan? Also, it would seem to render the device less useful as a battery backup system during most of the day, since it would be mostly depleted.
- URSpider94 11y ago
  My home uses about 1000 kWh per month, so shifting 8kWh per day of my in-house demand is feasible. However, there's really no correlation with my usage, since I can just push and pull that power from the grid, as if I had a solar or wind generator. Lithium batteries are fairly tolerant of deep discharge, but yes, I would expect that the pack would be worn out after max 7-10 years if used like this. Yes, using the pack like this would make it much less useful for battery back-up, but where I live (SF Bay Area), I haven't had an outage that lasted longer than 2 hours since we moved into our house, and this would cover the basics (probably everything but A/C) for that time. You could always split the difference, for example using 4 kWh per day -- this would pay still give you 6kWh+ of backup power and let you get the battery at half off or better.

hackerboos 11y ago

Economy 7 power is significantly cheaper in the UK than peak power. Charging overnight in the E7 period could save money long term depending on the lifetime of the battery.

IanCal 11y ago
I did a quick bit of calculation on this. Assuming you use 10KWh per day and a perfect battery: Economy 7 KWh cost : 8.4p (Best deal I saw was 9.4 for me, but this was a figure on MSE) Standard tariff KWh cost : 14.5p (Best deal I saw was ~12 for me, but this was a figure on MSE) That'd be a £306/year cost on economy 7 and £530 on a standard, taking some more extreme figures. A $3500 (~£2300) battery would then have a payoff time of about 10 years. Using the other figures (9.4 and 12) gives a £95/year saving or a ~25 year payoff. That's also assuming the batter is perfect, no extra costs in installation and you use exactly 10KWh per day. Economy 7 tariffs are about 22p/unit during the day so any overrun would quickly eat into savings. I do think this is all very interesting, but with current offers in the UK it doesn't look too beneficial. However, if someone were to offer cheaper rates on a more granular level (rather than always midnight-7am) then this could work out better. Perhaps an energy company owned battery would be a good idea, they offer a flat rate back to you knowing they can smooth things out.
- aidos 11y ago
  Oh interesting, I hadn't considered the aspect of charging overnight while it's cheaper. Of course, the moment it starts to get popular the energy companies will be eating that particular cake too, I'm sure. Sounds like right now there's not a huge margin anyway. I guess the energy companies have a financial incentive to run a more consistent supply if it could reduce the peak load. Just reminded me of a brilliant BBC documentary from a while back - The Secret Life of the National Grid. I think you probably have to piece it together from clips on youtube these days.
- CHY872 11y ago
  If you get 90% charge/discharge efficiency, you're multiplying the economy 7 tariff by 1/0.81 = 1.23456790 (so close) so it's more like 12.5 years, and a bit less compelling.

eatmyshorts 11y ago

Yep. This is targeted at ERCOT as much as it is targeted at the home consumer. http://www.greentechmedia.com/articles/read/Bring-on-the-energy-storage http://www.greentechmedia.com/articles/read/Bring-on-the-ene...

amass 11y ago

Doesn't this ignore completely the efficiency of the batteries? These batteries aren't ideal, you won't get out 100% of the energy that is put in. I don't know the efficiency rating, and I haven't done the math, but I suspect that the losses will cut into the savings significantly.

ZeroGravitas 11y ago
The page says >92% round trip efficiency. Since they also claim that they're selling them to utilities for exactly this purpose I'd guess it's theoretically possible and probably comes down to the pricing structure offered to consumers in your local area to buy and sell to the grid.

ZeroGravitas 11y ago

Can grid arbitrage and time-shifting solar co-exist? Some clever software might be able to predict your energy demand (e.g. based on seasons and past usage patterns) and your likely solar output (this time based on seasons and weather forecasts) and make the maximum use out of the battery. I'm also wondering if the same software is going to be rolled out to Tesla's cars so that they act like Tesla Energy when plugged in overnight.

tootie 11y ago

Big cities are prone to brown outs on hot days in the summer due to air conditioners. The 2003 European heat wave killed thousands1. I could imagine mayors mandating use of this kind of technology in apartment buildings. Let them charge overnight to offset peak usage. You'd cover 100 or more people at a time. [1] https://en.wikipedia.org/wiki/2003_European_heat_wave https://en.wikipedia.org/wiki/2003_European_heat_wave

TillE 11y ago
Normal homes in Europe simply do not have air conditioners, not even in southern Europe. So the electricity is irrelevant.
- _delirium 11y ago
  That's no longer really true. A/C units are in the past 10 years getting quite common in the hot parts of Europe now. In the '90s fewer than 10% of households had them in Italy or Spain, but that has jumped to nearly 50% now. People do use it a lot less, though: they are typically individual units, not central A/C, and only used for short periods on very hot days, not run continuously with a thermostat setting.