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The nice thing about flow batteries is they have the potential to store energy for long periods while being relatively cost effective. All you need is larger t

The nice thing about flow batteries is they have the potential to store energy for long periods while being relatively cost effective. All you need is larger tanks for the electrolyte. With Li-Ion batteries, the number of batteries you need scales with the length of time you need to store energy for. So, at some point you reach a crossover point - if you need to store a month's energy, you're probably not going to do that with Li-Ion, but it's not inconceivable with flow batteries (at least assuming the electrolyte itself is relatively cheap and stable).

kumarvvr 8y ago
Exactly, if flow batteries can convert a solar power plant to a base load plant, that would be the ultimate savior of mankind's energy needs.
- dragontamer 8y ago
  Nothing can do that. The amount of energy storage needed is in the Terawatt-Hours. Lithium Ion / Flow Batteries are in the hundreds-of-Megawatt-hours area. Solar + Wind will get us pretty far however. Wind picks up at night, while Solar is best during the day. Natural Gas Peaker Plants seem to be required in any situation I foresee in the next 20 years, but minimizing the use of peaker plants should be the goal. Alternatively, we build higher base-load plants like nuclear. That would help a lot.
  - epistasis 8y ago
    A Terawatt hour is about a years production from 30 Tesla gigafactories. We're going to have that amount of production within a few decades. Probably before small modular nuclear reactors have gotten their first production reactor off the line. Building new nuclear is riskier than other existing technologies, as evidenced in South Carolina, Georgia, Hinckley, and others. Therefore it currently seems that building nuclear is less plausible than building many terawatt hours of storage. SMR may change that, but I have a feeling that current companies are not planning for the grid of tomorrow, and are stuck in the last century when it comes to the grid's needs.
  - kumarvvr 8y ago
    For a SPV plant to be a base load plant, it would have to store just a days worth of energy. Say we have a 100 MW plant. Use 50 MW to charge batteries and 50 MW to supply power during the day. Having a battery capacity of 50 MW * 12 h = 600 MWh, will convert this plant to a 50 MW base load plant. Tesla's recent 25/50 MWh battery cost 25 Million USD, so a 600 one would cost about $300 Million.
  - Robotbeat 8y ago
    Not quite true. If you over-build solar by a factor of 3 (above what you'd expect from an energy-only basis), then you can convert it into a 100% constant output baseload plant using about 50 hours of storage, based on a year of hourly sun data for a single site I found. You don't try to store seasonal energy, you over-size the solar panels so there's significant energy production even on cloudy winter days. Costs less than you might think, considering the spot price for solar cells is like 10 cents per Watt right now (20 cents for panels). Works in the continental US. Doesn't work in northern Europe because the winter days are too short (too high latitude).
Retric 8y ago
From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. More generation tends to be vastly cheaper then storage in such situations. Some reserve is very useful, but lithium ion batteries should not be fully discharged regularly which allows for deeper discharges at higher cost and thus some reserve capacity naturally follows. Flow batteries might work to replace backup generators, but the cost would need to fall much further.
- nradov 8y ago
  More generation tends to be vastly cheaper than storage in the absence of a carbon tax. If carbon emissions and other externalities were fully priced in then that would favor storage.
  - Retric 8y ago
    The daily min vs max power output variation for wind is huge, but the median daily power output over large areas vs the min daily power output is far less so. Even more so when combined with solar which again has a significant minimum output. If you look at 20% over capacity as adding 20% to the cost of wind and solar it’s still cheaper than coal. But the minimum is now 20% larger reducing the gap very significantly especially over several days. Hydro naturally provides long term storage, so you can generally over any remaining gaps before looking to multi day battery storage. Plus your dealing with that 20% over capacity so the next day is very likely to be a net gain.
- marcosdumay 8y ago
  > From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. It also means you can wait to charge at the cheapest possible times, and sell on the absolutely most expensive ones. And since it's cheaper to add further storage, it means that you can do both the faster cycle with low margins and the slower one with higher margins.
- robocat 8y ago
  In some places you could make money trucking electricity in tankers or shipping it. > From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. Only true if you are selling on the spot market. You can also get paid for grid security - your ability to potentially deliver power during extreme load or deliver power to constrained nodes. For example, you may be paid to install and maintain a whole power station that is only expected to be used rarely (or ideally not at all if designed for emergency loads!)

kumarvvr 8y ago

Exactly, if flow batteries can convert a solar power plant to a base load plant, that would be the ultimate savior of mankind's energy needs.

dragontamer 8y ago
Nothing can do that. The amount of energy storage needed is in the Terawatt-Hours. Lithium Ion / Flow Batteries are in the hundreds-of-Megawatt-hours area. Solar + Wind will get us pretty far however. Wind picks up at night, while Solar is best during the day. Natural Gas Peaker Plants seem to be required in any situation I foresee in the next 20 years, but minimizing the use of peaker plants should be the goal. Alternatively, we build higher base-load plants like nuclear. That would help a lot.
- epistasis 8y ago
  A Terawatt hour is about a years production from 30 Tesla gigafactories. We're going to have that amount of production within a few decades. Probably before small modular nuclear reactors have gotten their first production reactor off the line. Building new nuclear is riskier than other existing technologies, as evidenced in South Carolina, Georgia, Hinckley, and others. Therefore it currently seems that building nuclear is less plausible than building many terawatt hours of storage. SMR may change that, but I have a feeling that current companies are not planning for the grid of tomorrow, and are stuck in the last century when it comes to the grid's needs.
- kumarvvr 8y ago
  For a SPV plant to be a base load plant, it would have to store just a days worth of energy. Say we have a 100 MW plant. Use 50 MW to charge batteries and 50 MW to supply power during the day. Having a battery capacity of 50 MW * 12 h = 600 MWh, will convert this plant to a 50 MW base load plant. Tesla's recent 25/50 MWh battery cost 25 Million USD, so a 600 one would cost about $300 Million.
- Robotbeat 8y ago
  Not quite true. If you over-build solar by a factor of 3 (above what you'd expect from an energy-only basis), then you can convert it into a 100% constant output baseload plant using about 50 hours of storage, based on a year of hourly sun data for a single site I found. You don't try to store seasonal energy, you over-size the solar panels so there's significant energy production even on cloudy winter days. Costs less than you might think, considering the spot price for solar cells is like 10 cents per Watt right now (20 cents for panels). Works in the continental US. Doesn't work in northern Europe because the winter days are too short (too high latitude).

Retric 8y ago

From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. More generation tends to be vastly cheaper then storage in such situations. Some reserve is very useful, but lithium ion batteries should not be fully discharged regularly which allows for deeper discharges at higher cost and thus some reserve capacity naturally follows. Flow batteries might work to replace backup generators, but the cost would need to fall much further.

nradov 8y ago
More generation tends to be vastly cheaper than storage in the absence of a carbon tax. If carbon emissions and other externalities were fully priced in then that would favor storage.
- Retric 8y ago
  The daily min vs max power output variation for wind is huge, but the median daily power output over large areas vs the min daily power output is far less so. Even more so when combined with solar which again has a significant minimum output. If you look at 20% over capacity as adding 20% to the cost of wind and solar it’s still cheaper than coal. But the minimum is now 20% larger reducing the gap very significantly especially over several days. Hydro naturally provides long term storage, so you can generally over any remaining gaps before looking to multi day battery storage. Plus your dealing with that 20% over capacity so the next day is very likely to be a net gain.
marcosdumay 8y ago
> From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. It also means you can wait to charge at the cheapest possible times, and sell on the absolutely most expensive ones. And since it's cheaper to add further storage, it means that you can do both the faster cycle with low margins and the slower one with higher margins.
robocat 8y ago
In some places you could make money trucking electricity in tankers or shipping it. > From a grid storage standpoint longer energy storage just means you have fewer cycles to make up your investment. Only true if you are selling on the spot market. You can also get paid for grid security - your ability to potentially deliver power during extreme load or deliver power to constrained nodes. For example, you may be paid to install and maintain a whole power station that is only expected to be used rarely (or ideally not at all if designed for emergency loads!)