5 ms·

The only problem is variability. I know that many places have fairly stable wind 99% if the time, but it's the absolute lowest you need to worry about. If we a

by mabbo 9y ago

The only problem is variability. I know that many places have fairly stable wind 99% if the time, but it's the absolute lowest you need to worry about. If we are to rely on wind as a power source, we either have to only rely on its lowest output or else rely on its typical output, but have a second source that can be easily scaled up and down. The problem is that the good sources of energy that can scale up and down well and cheaply are coal and natural gas. Nuclear, by contrast, works best when is outputting constant amounts of energy.

eru 9y ago
Some alternatives for quick scaling up and down: - finding some big consumers (like aluminium smelters) that can scale down. - batteries (both as scalable consumers and suppliers); widespread electric car usage might accidentally help her
- krrrh 9y ago
  > batteries (both as scalable consumers and suppliers); widespread electric car usage might accidentally help her I've been in a some jurisdictions that have periods of low water supply where you can't water your lawn or garden on certain days, or sometimes based on whether your house has an odd or even number. Imagine the same applied to fueling up your car. Not enough wind and sun this week, sorry you'll have to stretch out the capacity you put into your car last week. Obviously demand could be shaped with spot pricing, but it's interesting to imagine how rolling brownouts would affect mobility and transportation.
  - ZeroGravitas 9y ago
    Restrictions like these have been used on electricity for roughly as long as they have on water. They're slightly different in that with electricity it's often the peak usage that they care about rather than total usage, but some people are ordered or paid to reduce usage at certain times where this is considered cheaper/better than building a coal plant that's only used 1 day a year. Due to the nature of modern electricity generation, electric car batteries will help the grid rather than harm it, as they can be (and are) set to use off-peak power to avoid increasing the peaks, while getting best usage of the grid at other times.
    - eru 9y ago
      Yes, demand shaping is already done for some big consumers of electricity. It would be a new development to eg have my fridge defer its cooling for five minutes (or do some cooling earlier) in response to the spot market.
      - ZeroGravitas 9y ago
        That already happens for commercial fridges and freezers, farm water pumps and for home A/C and EV charging. As it becomes more widespread it can be done more cheaply and be extended to lower power devices like home refrigerators where there is less bang per buck. Microsoft is involved in a project called Watttime that provides an API for this for use by the IoT: https://api.watttime.org/ https://api.watttime.org/
  - usrusr 9y ago
    Rolling brownouts (or even/odd licence plate rules and the like) only encourage inefficient stockpiling. People buying the bigger battery option when purchasing an EV (which is dead weight when not needed), degrading their batteries faster than necessary by putting their Tesla on max range charge mode all the time, because what if, and so on. I'd say spot prices for everyone or a reliable fixed rate model, everything in between will turn into a negative-sum game. Exceptions only where discrete consumers are so big that their paid shutdown can be individually supervised and verified (aluminium smelters, ice storage cooling for datacenters and the like). You clearly would not want those to simply switch over to a fixed rate outlet behind your back in times of scarcity, they need to be verifiably off.
    - eru 9y ago
      > You clearly would not want those to simply switch over to a fixed rate outlet behind your back in times of scarcity, they need to be verifiably off. The fixed rate outlet would be quite expensive in that case, wouldn't it be?
- bluGill 9y ago
  The big consumers do scale down at times. When the price of electricity is high enough they send all their workers home with pay. However this is hard for them to do: the workers don't like it (they worry they might be told to not come back next time). Management has contracts to deliver that they cannot back down on, and this is in conflict with "just in time management".
bdamm 9y ago
Hydro scales quickly and cheaply (run-time, not capex.)
hwillis 9y ago
Coal isn't really any better than nuclear, and can take days to ramp up. Natural gas makes up virtually all fossil peaker plants and most load-following plants.
olau 9y ago
I think in many places, gas peakers are already available. In the long run, we're probably going to need to do something else, but who knows where storage tech is in twenty years? In Denmark, home of the biggest wind power companies, this is a frequent topic of discussion among people interested in energy, but the answer is really that there are many options on the table, including expanding the grid. While many options are too expensive to see much use today, that will probably change over years. New ideas are also coming up, e.g. this http://www.salon.com/2017/08/09/alphabet-turns-to-molten-salt-to-store-clean-energy_partner/ http://www.salon.com/2017/08/09/alphabet-turns-to-molten-sal... which might work except they should just store the heat in rocks instead of molten salt which is a PITA to work with. I know of at least two independent designs (both Danish) that store the heat in a huge repository of insulated rock/dirt and use a turbine to get electricity back out, at an efficiency about 40-45% IIRC. A prototype plant recently received funding. Not sure it has reached the international press yet. I don't think it has much future in Denmark, though, there's plenty of hydro in Scandinavia.
- biehl 9y ago
  This is a fun energy storage project - http://www.aresnorthamerica.com/ http://www.aresnorthamerica.com/
DenisM 9y ago
Powerwall can level the load. And making Powerwalls can turn out rather cheap: electric car batteries degrade towards low energy/weight ratio, but it hardly matters for a stationary installations. Two used li-ion car batteries - one happy household.
- hwillis 9y ago
  > electric car batteries degrade towards low energy/weight ratio And even then- barely. The Panasonic NCR18650B has a weight of 3.94 kg/kWh at the beginning of its life, and a weight of 4.92 kg/kWh after it's considered "dead". The average US household uses 30 kWh/day, which would require 117 kg of new batteries (in practice the pack will weigh double that) or an extra 29 kg if you use old batteries with 300k miles on them. That's an immaterial difference for almost any purpose. Used car batteries will be incredible. Salvaged Tesla modules are already starting to have impacts on hobbyists, but if used cells make it to market at even just a 25% discount it'll be incredibly awesome.
tbihl 9y ago
Your point about nuclear is interesting; do you know an approximate magnitude disadvantage of varying nuclear plant output? Presumably it's a concern of cool-down thermal stresses, or perhaps flux tilting/uneven fuel burnout. Or is it something else entirely?
- biehl 9y ago
  Fuel rod oxidation? https://www.euractiv.com/section/electricity/news/german-nuclear-damage-shows-atomic-and-renewable-power-are-unhappy-bedfellows/ https://www.euractiv.com/section/electricity/news/german-nuc...
- toomuchtodo 9y ago
  Xenon poisoning. Nuclear reactors are not meant to be throttled outside of a narrow operating band, and xenon poisoning can result from attempting to throttle down to very low power output configurations. Xenon poisoning takes ~7-9 hours to abate due to the half life of xenon-135. https://en.m.wikipedia.org/wiki/Xenon-135 https://en.m.wikipedia.org/wiki/Xenon-135
biehl 9y ago
If you really mean that "it's the absolute lowest you need to worry about.", then Nuclear plants working 99% of the time, but going off-line for maintenance must really worry you? Seems like a huge disadvantage for nuclear? Also the fact that nuclear works best when outputting constant amounts of energy doesn't really seem to be an advantage - https://www.euractiv.com/section/electricity/news/german-nuclear-damage-shows-atomic-and-renewable-power-are-unhappy-bedfellows/ https://www.euractiv.com/section/electricity/news/german-nuc... ?
- vlehto 9y ago
  It's advantage practically everywhere else except on a suddenly windy day in Germany. https://www.energy-charts.de/power.htm?source=all-sources&month=6&year=2017 https://www.energy-charts.de/power.htm?source=all-sources&mo... Consumption naturally spikes, when you add the natural volatility of wind power, you have greatly increased need for quick adjustment. Germany is using practically everything else than wind and solar to adjust. They also sometimes have to sell power with negative price. As a result even nuclear gets pushed into a role it's poorly suited to.
- mabbo 9y ago
  These are good points, but I think you may be falling into the Nirvana Fallacy. These problems will still exist for any power source (planned outages and following demand). Nuclear is no worse than wind power at these things, so why does it matter that it doesn't perfectly solve these issues as well? When there's a planned outage, you can schedule other sources to scale up as needed. Following demand is hard no matter where the power comes from, but for wind it's even harder as you can control neither supply nor demand. There's no ultimate, perfect solution. But I see Nuclear as a good option to be the major strength of our power systems.
crdoconnor 9y ago
>The only problem is variability. It's a way overemphasized problem with a multitude of solutions: * Spot pricing and time shifting demand * Scaling up/down large scale industrial demand (e.g. aluminum smelting) to accommodate * Hydro storage * Gas peakers * Overproducing and developing markets for electricity that's "almost free" at certain times It's not like variability is causing brownouts in countries that rely heavily upon wind either (e.g. Denmark/Germany).
- _Tev 9y ago
  Yeah, "no issue", they just produce half of their electricity from fossil fuels. (Denmark a bit less recently)
rsynnott 9y ago
Usually, gas is used to cover shortfall, yeah. Here are stats for the Irish national grid (see the monthly view): http://smartgriddashboard.eirgrid.com/#all/wind http://smartgriddashboard.eirgrid.com/#all/wind There are periods of almost no production for a few days; this is handled by spinning up gas turbines, mostly. In the future, storage may be more viable; here's an interesting project: https://arstechnica.com/information-technology/2017/07/german-energy-company-wants-to-build-flow-batteries-in-old-natural-gas-caverns/ https://arstechnica.com/information-technology/2017/07/germa...

by mabbo 9y ago

eru 9y ago

Some alternatives for quick scaling up and down: - finding some big consumers (like aluminium smelters) that can scale down. - batteries (both as scalable consumers and suppliers); widespread electric car usage might accidentally help her

krrrh 9y ago
> batteries (both as scalable consumers and suppliers); widespread electric car usage might accidentally help her I've been in a some jurisdictions that have periods of low water supply where you can't water your lawn or garden on certain days, or sometimes based on whether your house has an odd or even number. Imagine the same applied to fueling up your car. Not enough wind and sun this week, sorry you'll have to stretch out the capacity you put into your car last week. Obviously demand could be shaped with spot pricing, but it's interesting to imagine how rolling brownouts would affect mobility and transportation.
- ZeroGravitas 9y ago
  Restrictions like these have been used on electricity for roughly as long as they have on water. They're slightly different in that with electricity it's often the peak usage that they care about rather than total usage, but some people are ordered or paid to reduce usage at certain times where this is considered cheaper/better than building a coal plant that's only used 1 day a year. Due to the nature of modern electricity generation, electric car batteries will help the grid rather than harm it, as they can be (and are) set to use off-peak power to avoid increasing the peaks, while getting best usage of the grid at other times.
  - eru 9y ago
    Yes, demand shaping is already done for some big consumers of electricity. It would be a new development to eg have my fridge defer its cooling for five minutes (or do some cooling earlier) in response to the spot market.
    - ZeroGravitas 9y ago
      That already happens for commercial fridges and freezers, farm water pumps and for home A/C and EV charging. As it becomes more widespread it can be done more cheaply and be extended to lower power devices like home refrigerators where there is less bang per buck. Microsoft is involved in a project called Watttime that provides an API for this for use by the IoT: https://api.watttime.org/ https://api.watttime.org/
- usrusr 9y ago
  Rolling brownouts (or even/odd licence plate rules and the like) only encourage inefficient stockpiling. People buying the bigger battery option when purchasing an EV (which is dead weight when not needed), degrading their batteries faster than necessary by putting their Tesla on max range charge mode all the time, because what if, and so on. I'd say spot prices for everyone or a reliable fixed rate model, everything in between will turn into a negative-sum game. Exceptions only where discrete consumers are so big that their paid shutdown can be individually supervised and verified (aluminium smelters, ice storage cooling for datacenters and the like). You clearly would not want those to simply switch over to a fixed rate outlet behind your back in times of scarcity, they need to be verifiably off.
  - eru 9y ago
    > You clearly would not want those to simply switch over to a fixed rate outlet behind your back in times of scarcity, they need to be verifiably off. The fixed rate outlet would be quite expensive in that case, wouldn't it be?
bluGill 9y ago
The big consumers do scale down at times. When the price of electricity is high enough they send all their workers home with pay. However this is hard for them to do: the workers don't like it (they worry they might be told to not come back next time). Management has contracts to deliver that they cannot back down on, and this is in conflict with "just in time management".

bdamm 9y ago

Hydro scales quickly and cheaply (run-time, not capex.)

hwillis 9y ago

Coal isn't really any better than nuclear, and can take days to ramp up. Natural gas makes up virtually all fossil peaker plants and most load-following plants.

olau 9y ago

I think in many places, gas peakers are already available. In the long run, we're probably going to need to do something else, but who knows where storage tech is in twenty years? In Denmark, home of the biggest wind power companies, this is a frequent topic of discussion among people interested in energy, but the answer is really that there are many options on the table, including expanding the grid. While many options are too expensive to see much use today, that will probably change over years. New ideas are also coming up, e.g. this http://www.salon.com/2017/08/09/alphabet-turns-to-molten-salt-to-store-clean-energy_partner/ http://www.salon.com/2017/08/09/alphabet-turns-to-molten-sal... which might work except they should just store the heat in rocks instead of molten salt which is a PITA to work with. I know of at least two independent designs (both Danish) that store the heat in a huge repository of insulated rock/dirt and use a turbine to get electricity back out, at an efficiency about 40-45% IIRC. A prototype plant recently received funding. Not sure it has reached the international press yet. I don't think it has much future in Denmark, though, there's plenty of hydro in Scandinavia.

biehl 9y ago
This is a fun energy storage project - http://www.aresnorthamerica.com/ http://www.aresnorthamerica.com/

DenisM 9y ago

Powerwall can level the load. And making Powerwalls can turn out rather cheap: electric car batteries degrade towards low energy/weight ratio, but it hardly matters for a stationary installations. Two used li-ion car batteries - one happy household.

hwillis 9y ago
> electric car batteries degrade towards low energy/weight ratio And even then- barely. The Panasonic NCR18650B has a weight of 3.94 kg/kWh at the beginning of its life, and a weight of 4.92 kg/kWh after it's considered "dead". The average US household uses 30 kWh/day, which would require 117 kg of new batteries (in practice the pack will weigh double that) or an extra 29 kg if you use old batteries with 300k miles on them. That's an immaterial difference for almost any purpose. Used car batteries will be incredible. Salvaged Tesla modules are already starting to have impacts on hobbyists, but if used cells make it to market at even just a 25% discount it'll be incredibly awesome.

tbihl 9y ago

Your point about nuclear is interesting; do you know an approximate magnitude disadvantage of varying nuclear plant output? Presumably it's a concern of cool-down thermal stresses, or perhaps flux tilting/uneven fuel burnout. Or is it something else entirely?

biehl 9y ago
Fuel rod oxidation? https://www.euractiv.com/section/electricity/news/german-nuclear-damage-shows-atomic-and-renewable-power-are-unhappy-bedfellows/ https://www.euractiv.com/section/electricity/news/german-nuc...
toomuchtodo 9y ago
Xenon poisoning. Nuclear reactors are not meant to be throttled outside of a narrow operating band, and xenon poisoning can result from attempting to throttle down to very low power output configurations. Xenon poisoning takes ~7-9 hours to abate due to the half life of xenon-135. https://en.m.wikipedia.org/wiki/Xenon-135 https://en.m.wikipedia.org/wiki/Xenon-135

biehl 9y ago

If you really mean that "it's the absolute lowest you need to worry about.", then Nuclear plants working 99% of the time, but going off-line for maintenance must really worry you? Seems like a huge disadvantage for nuclear? Also the fact that nuclear works best when outputting constant amounts of energy doesn't really seem to be an advantage - https://www.euractiv.com/section/electricity/news/german-nuclear-damage-shows-atomic-and-renewable-power-are-unhappy-bedfellows/ https://www.euractiv.com/section/electricity/news/german-nuc... ?

vlehto 9y ago
It's advantage practically everywhere else except on a suddenly windy day in Germany. https://www.energy-charts.de/power.htm?source=all-sources&month=6&year=2017 https://www.energy-charts.de/power.htm?source=all-sources&mo... Consumption naturally spikes, when you add the natural volatility of wind power, you have greatly increased need for quick adjustment. Germany is using practically everything else than wind and solar to adjust. They also sometimes have to sell power with negative price. As a result even nuclear gets pushed into a role it's poorly suited to.
mabbo 9y ago
These are good points, but I think you may be falling into the Nirvana Fallacy. These problems will still exist for any power source (planned outages and following demand). Nuclear is no worse than wind power at these things, so why does it matter that it doesn't perfectly solve these issues as well? When there's a planned outage, you can schedule other sources to scale up as needed. Following demand is hard no matter where the power comes from, but for wind it's even harder as you can control neither supply nor demand. There's no ultimate, perfect solution. But I see Nuclear as a good option to be the major strength of our power systems.

crdoconnor 9y ago

>The only problem is variability. It's a way overemphasized problem with a multitude of solutions: * Spot pricing and time shifting demand * Scaling up/down large scale industrial demand (e.g. aluminum smelting) to accommodate * Hydro storage * Gas peakers * Overproducing and developing markets for electricity that's "almost free" at certain times It's not like variability is causing brownouts in countries that rely heavily upon wind either (e.g. Denmark/Germany).

_Tev 9y ago
Yeah, "no issue", they just produce half of their electricity from fossil fuels. (Denmark a bit less recently)

rsynnott 9y ago

Usually, gas is used to cover shortfall, yeah. Here are stats for the Irish national grid (see the monthly view): http://smartgriddashboard.eirgrid.com/#all/wind http://smartgriddashboard.eirgrid.com/#all/wind There are periods of almost no production for a few days; this is handled by spinning up gas turbines, mostly. In the future, storage may be more viable; here's an interesting project: https://arstechnica.com/information-technology/2017/07/german-energy-company-wants-to-build-flow-batteries-in-old-natural-gas-caverns/ https://arstechnica.com/information-technology/2017/07/germa...