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Bloomberg News reports[1] that David Keith, a Harvard professor of applied physics and public policy, used to be a solar power skeptic but has reexamined the ec

Bloomberg News reports[1] that David Keith, a Harvard professor of applied physics and public policy, used to be a solar power skeptic but has reexamined the economics of current solar power and now expects solar power to be important because the economics have changed. Professor Keith's recent essay on solar power, "Cheap Solar Power,"[2] shows the facts and calculations to explain why solar power now beats several other sources of primary electricity for many applications. It is very likely that many industries will move to places where solar power is especially abundant and inexpensive. [1] http://www.bloomberg.com/news/articles/2016-05-04/harvard-scientist-a-former-solar-skeptic-now-sees-the-light http://www.bloomberg.com/news/articles/2016-05-04/harvard-sc... [2] http://www.keith.seas.harvard.edu/blog-1/cheapsolarpower http://www.keith.seas.harvard.edu/blog-1/cheapsolarpower

epistasis 10y ago
Thanks for this pointer, it's very interesting! It's hard to argue with numbers that are already there in front of you. A lot of the cost changes have been driven precisely because there was investment and the industry grew, his prognostications about it never being affordable were an attempt at a self-fulfilling prophecy in that by increasing skepticism about the tech curve, it never gets explored. I'd be skeptical of his views of the future, though. For example, he mentions gas peaking plants, but grid-scale lithium ion batteries are already cheaper than natural gas peakers for many situations; lithium ion is getting cheaper but natural gas is not. The only advantage of natural gas is lower capex, but in this financial environment that's not a huge advantage. By the time that solar is displacing lots of other energy, lithium ion will be displacing all those natural gas peaker plants. Once he sees those numbers, he'll probably change his mind again.
- Brakenshire 10y ago
  Lithium ion can't store electricity across seasons, though, which is important anywhere outside equatorial areas. Gas can be left idle during the Summer, and used during the Winter. If the cost of solar power went below the marginal cost for burning gas (i.e. lower than the per unit fuel costs for gas generation), the most cost-effective solution might actually be to use solar during the Summer, and maintain a fleet of gas stations solely for the Winter months.
  - usrusr 10y ago
    Outside equatorial areas, lack of sun coincides with demand for heating. Combined cycle (correction: I meant cogeneration) heating plants are that winter months fleet.
    - Brakenshire 10y ago
      Yes, if you could combine gas generation with district heating, that + solar generation really would fit together neatly. Also, there are projects to do the thermodynamic equivalent of district heating over a single home! i.e. you burn gas to produce electricity, and use the waste heat to heat your house or office. A year or two back British Gas was doing a pilot using a gas boiler with a Stirling Engine to generate electricity (called the Ecogen IIRC). It seems to have been difficult/expensive to maintain, but it's an exciting principle. If you had battery storage for solar during the Summer, you could use that equally to buffer that kind of gas generation in the Winter. It seems to me sufficient solar and battery cost reductions effectively solve electricity generation for everywhere close to the equator. Add in that kind of waste heat boiler, generating electricity at a reasonable cost, and you have a solution for almost the whole planet.
  - Terribledactyl 10y ago
    You could store the electricity through H2O electrolysis, directly burn for heat or reclaim through a fuel cell for electricity.
    - peregrine 10y ago
      Could also use the Hydrogen and CO2 to make methane and utilize existing infrastructure.
    - jbpetersen 10y ago
      Better yet, those fuel cells can be "charged" wherever energy is plentiful then shipped as needed. Sneakergrid anyone?
      - 10y ago
- hughw 10y ago
  The Graduate, 2016: "I just want to say one word to you. Flywheels."
  - epistasis 10y ago
    I can't really see widespread use of flywheels. They are good for high power, low total amount of energy situations, namely frequency regulation. Bearings and motors/generators are very well understood, unlike lithium ion batteries, so I don't see them getting much cheaper as a flywheel industry expands. Currently, the most expensive lithium ion battery is cheaper than the cheapest flywheel: https://www.lazard.com/media/2391/lazards-levelized-cost-of-storage-analysis-10.pdf https://www.lazard.com/media/2391/lazards-levelized-cost-of-...
  - jcoffland 10y ago
    Flywheels are really cool. Especially when they explode sending out high velocity shrapnel and/or leaving a molten mass. Still a flywheel powered car using three flywheels set at opposing angles (so their gyroscopic effects cancel) composed of tightly wrapped layers (so they cannot explode) would be awesome.
    - ridgeguy 10y ago
      It isn't the shrapnel from flywheel failure that's hard to deal with. Frag containment, particularly of composite rotors that have high volume fractions of fiber and low volume fractions of binder, is actually pretty easy. What's really hard to deal with is the angular momentum. Regardless of how the rotor fragments, angular momentum is conserved. What this means is that the failing rotor will produce amazingly high torques as it encounters stationary surroundings. For typical rotor failures, you can figure that most of the angular momentum will get dumped into the environment in a few seconds as the fragments dig into whatever they hit and come to rest. So as a napkin exercise, if your flywheel spins up to full charge over a period of an hour, and then dumps all that momentum during ten seconds when it fails, you can kind of approximate the torque drama by multiplying the charging torque times the ratio of the charge duration to the failure duration. (I know the torque varies with the flywheel speed, etc. - this is just a disaster estimation exercise.) The practical effect is that you have to secure the containment really well to make sure it doesn't break loose and roll through your facility on its way out into the street. The only two ways I've seen of dealing with the angular momentum problem are (1) have two adjacent counter-rotating wheels that jam into each other when there's a failure or (2) have a containment shell that is free to rotate on one-time use mechanical bearings so it can take the failed rotor momentum and dissipate it over a reasonable time with a braking mechanism. Neither solution is cheap.
Brakenshire 10y ago
> It is very likely that many industries will move to places where solar power is especially abundant and inexpensive. I suspect over time the cost of producing solar electricity will become negligible against the cost of storage. The key thing will be not so much the lower levels of sun which you get in temperate latitudes, but the variation you get between Summer and Winter levels of insolation, which means you have to maintain backup generation. Variation within a day you can deal with, variation from season to season will be much more difficult. But as you say that is going to drive some interesting changes in geopolitics.
- deleted 10y ago
  [deleted]
- beat 10y ago
  Sufficient storage to handle local load + variation should be pretty well predictable in the future. The interesting difference to me is, since storage will probably cost substantially more than generation, what the ratio will mean for cost of energy in various locations. I have no doubt that at some point, the solar generation + storage formula will be broadly cheaper than fossil fuel.
  - Retric 10y ago
    Very large scale storage is fairly cheap as long as it's used every day. The issue is when your pumped storage power plant is only needed 1 month out of the year. However, with solar the daily demand for storage is fairly fixed as excess capacity is all generated at the same time of day.
    - beat 10y ago
      That's just an overcapacity problem (in this case, overcapacity on generation, not storage). In another post here, I proposed that we build a smart grid that supports pricing arbitrage on generation/storage in order to maximize generation utilization, and then let the market sort out storage requirements with a more distributed, fine-grained storage model - car batteries, for example.
wjnc 10y ago
This is the best quote imho: "If we can get CO2 from the air at 125 $/t-CO2 then the idea of making fuels at prices of order 1 $/L looks plausible over the next few decades." It's uplifting to me, both for the high value on a ton of CO2 and the (still) low resulting price of fuel. Solar beats fusion (chance * impact)!
- ThrustVectoring 10y ago
  Yeah, with cheap enough electricity you can run the chemistry of burning transportation fuels backwards, and wind up making our current cars carbon-neutral.
- patrickg_zill 10y ago
  Solar is fusion-at-a-distance, though...
- arikrak 10y ago
  Also with a really large number of solar plants, maybe the earth would cool slightly?
jcoffland 10y ago
Dubai has both oil and solar in abundance. They are bound to continue to be one of the richest countries in the world along with the entire UAE. Political considerations allowing.
- ericd 10y ago
  Abundant sunlight is much less rare than abundant oil...
- Mvandenbergh 10y ago
  Dubai has almost no oil, there's a few small gas wells, that's it.
rsync 10y ago
"Bloomberg News reports[1] that David Keith, a Harvard professor of applied physics and public policy, used to be a solar power skeptic but has reexamined the economics of current solar power and now expects solar power to be important because the economics have changed." I don't follow solar/power/coal news much, so forgive me ... Is all of this ex-subsidies ? That is, if we remove the subsidies that coal gets and the tax credits / subsidies that solar gets, does the math still pencil out in the way that still makes David Keith no longer a skeptic ?
- toomuchtodo 10y ago
  Yes, solar and wind are both below the cost of coal, natural gas, and nuclear, without subsidies (doesn't take capacity factor into account though). I'm always reposting that data here, so I won't dump a full page of citations here, but if you response with contact info, I'd be happy to send detailed information.
- Gibbon1 10y ago
  > Is all of this ex-subsidies? Also ask what price point would be needed to scale back CO2 emissions to something sustainable. Then run the economic analyses.

epistasis 10y ago

Thanks for this pointer, it's very interesting! It's hard to argue with numbers that are already there in front of you. A lot of the cost changes have been driven precisely because there was investment and the industry grew, his prognostications about it never being affordable were an attempt at a self-fulfilling prophecy in that by increasing skepticism about the tech curve, it never gets explored. I'd be skeptical of his views of the future, though. For example, he mentions gas peaking plants, but grid-scale lithium ion batteries are already cheaper than natural gas peakers for many situations; lithium ion is getting cheaper but natural gas is not. The only advantage of natural gas is lower capex, but in this financial environment that's not a huge advantage. By the time that solar is displacing lots of other energy, lithium ion will be displacing all those natural gas peaker plants. Once he sees those numbers, he'll probably change his mind again.

Brakenshire 10y ago
Lithium ion can't store electricity across seasons, though, which is important anywhere outside equatorial areas. Gas can be left idle during the Summer, and used during the Winter. If the cost of solar power went below the marginal cost for burning gas (i.e. lower than the per unit fuel costs for gas generation), the most cost-effective solution might actually be to use solar during the Summer, and maintain a fleet of gas stations solely for the Winter months.
- usrusr 10y ago
  Outside equatorial areas, lack of sun coincides with demand for heating. Combined cycle (correction: I meant cogeneration) heating plants are that winter months fleet.
  - Brakenshire 10y ago
    Yes, if you could combine gas generation with district heating, that + solar generation really would fit together neatly. Also, there are projects to do the thermodynamic equivalent of district heating over a single home! i.e. you burn gas to produce electricity, and use the waste heat to heat your house or office. A year or two back British Gas was doing a pilot using a gas boiler with a Stirling Engine to generate electricity (called the Ecogen IIRC). It seems to have been difficult/expensive to maintain, but it's an exciting principle. If you had battery storage for solar during the Summer, you could use that equally to buffer that kind of gas generation in the Winter. It seems to me sufficient solar and battery cost reductions effectively solve electricity generation for everywhere close to the equator. Add in that kind of waste heat boiler, generating electricity at a reasonable cost, and you have a solution for almost the whole planet.
- Terribledactyl 10y ago
  You could store the electricity through H2O electrolysis, directly burn for heat or reclaim through a fuel cell for electricity.
  - peregrine 10y ago
    Could also use the Hydrogen and CO2 to make methane and utilize existing infrastructure.
  - jbpetersen 10y ago
    Better yet, those fuel cells can be "charged" wherever energy is plentiful then shipped as needed. Sneakergrid anyone?
    - 10y ago
hughw 10y ago
The Graduate, 2016: "I just want to say one word to you. Flywheels."
- epistasis 10y ago
  I can't really see widespread use of flywheels. They are good for high power, low total amount of energy situations, namely frequency regulation. Bearings and motors/generators are very well understood, unlike lithium ion batteries, so I don't see them getting much cheaper as a flywheel industry expands. Currently, the most expensive lithium ion battery is cheaper than the cheapest flywheel: https://www.lazard.com/media/2391/lazards-levelized-cost-of-storage-analysis-10.pdf https://www.lazard.com/media/2391/lazards-levelized-cost-of-...
- jcoffland 10y ago
  Flywheels are really cool. Especially when they explode sending out high velocity shrapnel and/or leaving a molten mass. Still a flywheel powered car using three flywheels set at opposing angles (so their gyroscopic effects cancel) composed of tightly wrapped layers (so they cannot explode) would be awesome.
  - ridgeguy 10y ago
    It isn't the shrapnel from flywheel failure that's hard to deal with. Frag containment, particularly of composite rotors that have high volume fractions of fiber and low volume fractions of binder, is actually pretty easy. What's really hard to deal with is the angular momentum. Regardless of how the rotor fragments, angular momentum is conserved. What this means is that the failing rotor will produce amazingly high torques as it encounters stationary surroundings. For typical rotor failures, you can figure that most of the angular momentum will get dumped into the environment in a few seconds as the fragments dig into whatever they hit and come to rest. So as a napkin exercise, if your flywheel spins up to full charge over a period of an hour, and then dumps all that momentum during ten seconds when it fails, you can kind of approximate the torque drama by multiplying the charging torque times the ratio of the charge duration to the failure duration. (I know the torque varies with the flywheel speed, etc. - this is just a disaster estimation exercise.) The practical effect is that you have to secure the containment really well to make sure it doesn't break loose and roll through your facility on its way out into the street. The only two ways I've seen of dealing with the angular momentum problem are (1) have two adjacent counter-rotating wheels that jam into each other when there's a failure or (2) have a containment shell that is free to rotate on one-time use mechanical bearings so it can take the failed rotor momentum and dissipate it over a reasonable time with a braking mechanism. Neither solution is cheap.

Brakenshire 10y ago

> It is very likely that many industries will move to places where solar power is especially abundant and inexpensive. I suspect over time the cost of producing solar electricity will become negligible against the cost of storage. The key thing will be not so much the lower levels of sun which you get in temperate latitudes, but the variation you get between Summer and Winter levels of insolation, which means you have to maintain backup generation. Variation within a day you can deal with, variation from season to season will be much more difficult. But as you say that is going to drive some interesting changes in geopolitics.

deleted 10y ago
[deleted]
beat 10y ago
Sufficient storage to handle local load + variation should be pretty well predictable in the future. The interesting difference to me is, since storage will probably cost substantially more than generation, what the ratio will mean for cost of energy in various locations. I have no doubt that at some point, the solar generation + storage formula will be broadly cheaper than fossil fuel.
- Retric 10y ago
  Very large scale storage is fairly cheap as long as it's used every day. The issue is when your pumped storage power plant is only needed 1 month out of the year. However, with solar the daily demand for storage is fairly fixed as excess capacity is all generated at the same time of day.
  - beat 10y ago
    That's just an overcapacity problem (in this case, overcapacity on generation, not storage). In another post here, I proposed that we build a smart grid that supports pricing arbitrage on generation/storage in order to maximize generation utilization, and then let the market sort out storage requirements with a more distributed, fine-grained storage model - car batteries, for example.

wjnc 10y ago

This is the best quote imho: "If we can get CO2 from the air at 125 $/t-CO2 then the idea of making fuels at prices of order 1 $/L looks plausible over the next few decades." It's uplifting to me, both for the high value on a ton of CO2 and the (still) low resulting price of fuel. Solar beats fusion (chance * impact)!

ThrustVectoring 10y ago
Yeah, with cheap enough electricity you can run the chemistry of burning transportation fuels backwards, and wind up making our current cars carbon-neutral.
patrickg_zill 10y ago
Solar is fusion-at-a-distance, though...
arikrak 10y ago
Also with a really large number of solar plants, maybe the earth would cool slightly?

jcoffland 10y ago

Dubai has both oil and solar in abundance. They are bound to continue to be one of the richest countries in the world along with the entire UAE. Political considerations allowing.

ericd 10y ago
Abundant sunlight is much less rare than abundant oil...
Mvandenbergh 10y ago
Dubai has almost no oil, there's a few small gas wells, that's it.

rsync 10y ago

"Bloomberg News reports[1] that David Keith, a Harvard professor of applied physics and public policy, used to be a solar power skeptic but has reexamined the economics of current solar power and now expects solar power to be important because the economics have changed." I don't follow solar/power/coal news much, so forgive me ... Is all of this ex-subsidies ? That is, if we remove the subsidies that coal gets and the tax credits / subsidies that solar gets, does the math still pencil out in the way that still makes David Keith no longer a skeptic ?

toomuchtodo 10y ago
Yes, solar and wind are both below the cost of coal, natural gas, and nuclear, without subsidies (doesn't take capacity factor into account though). I'm always reposting that data here, so I won't dump a full page of citations here, but if you response with contact info, I'd be happy to send detailed information.
Gibbon1 10y ago
> Is all of this ex-subsidies? Also ask what price point would be needed to scale back CO2 emissions to something sustainable. Then run the economic analyses.