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By Robert Rapier on May 17, 2012 with 44 responses

The Most Important Problem in Renewable Energy — R-Squared Energy TV Ep. 22

In this week’s episode of R-Squared Energy TV, I answer a question about the artificial leaf being worked on by Daniel Nocera at MIT. I discuss the strengths and weaknesses of various storage schemes, and explain why I believe storage is the most important problem in renewable energy.

In the video I discuss the low energy density of batteries relative to liquid fuels. Below is a graphic I pulled off of the Wikipedia entry for Energy Density that illustrates this:

Readers who have specific questions can send them to ask [at] consumerenergyreport [dot] com or leave the question after this post (at the original source). Consider subscribing to our YouTube channel where you’ll be able to view past and future videos.

Link to Original Article: The Most Important Problem in Renewable Energy — R-Squared Energy TV Ep. 22

By Robert Rapier

  1. By Jerry Unruh on May 18, 2012 at 9:54 am

    If PV efficiency is 15% (this is improving), water electrolysis can get to about 10% including compression  [e.g. Norsk Hydro at plant efficiency of 73% (NREL/MP-560-36734, Sept, 2004)].  Ignoring, for the moment the problems of hydrogen storage, do you think artificial photosynthesis will beat this?  Both improving PV and electrolysis will improve this number.  I chose the Norsk unit because it uses stainless steel/nickel electrodes not platinum.  Of course this is still better than biomass efficiency but I’m ignoring economics for this question.

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    • By Robert Rapier on May 18, 2012 at 2:22 pm

      Ignoring, for the moment the problems of hydrogen storage, do you think artificial photosynthesis will beat this?

      Jerry, I don’t know. It’s just an interesting concept to me. I like what photosynthesis does in nature, and always thought (even before I heard of Daniel Nocera) that it would be interesting to somehow be able to harvest that. Whether they can do it economically is another matter.

      By the way, I wonder why they don’t do electrolysis (or this process) under pressure, avoiding compression? I assume if I did electrolysis in a closed cell the pressure would build (i.e., automatic compression). Any ideas of whether that is feasible?

      RR

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      • By Jerry Unruh on May 18, 2012 at 4:53 pm

        Robert:

         

        My understanding is that there are units that run under pressure and are approaching 90+% efficiency.  I chose the Norsk unit because they have been business more than 80 years and aren’t using Pt electrodes.  Clearly there is room for improvement in both PV (or wind) and electrolysis.  BTW the 73% efficiency includes everything; the electrolysis efficiency is about 85% (and I think is based on HHV)

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  2. By Edward Kerr on May 18, 2012 at 10:33 am

    Robert,

    If the goal of “energy storage” is to provide a fully charged and harmonized electrical grid then I ‘m a bit confused concerning the point that you are trying to make. (?)  With the advent of “molten salt CS” being able to produce base load power 24-7 (with a single caveat) and wind providing energy “whenever” and PV providing energy when stimulated I think that energy storage is a red herring.

    As to liquid fuels (and I’ve harped at you on this issue before) it’s clear to me that oil produced by algae through photosynthesis will provide all of the liquid fuels (energy dense and stored) that we need to continue powering our civilization in a manner to which it has become accustomed.

    In the search of a sane energy paradigm,

    Ed

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    • By Robert Rapier on May 18, 2012 at 2:25 pm

      I think that energy storage is a red herring.

      Energy storage has to be cost effective. There are all sorts of schemes we could envision; few of them would be practical and cost effective. We could also say “With available battery technology, energy storage is a red herring.” Sure, you could just put enormous battery banks on every wind and solar farm. But why don’t they? Cost.

      it’s clear to me that oil produced by algae through photosynthesis…

      That’s not at all clear to me. In fact, many of the algae companies are going off in search of higher margin products because they can’t make fuel cost effectively. 

      RR

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  3. By Ed on May 18, 2012 at 5:59 pm

    Please remember that a CSP system with storage (ignoring in and out and storage period losses) must collect ~4 times the energy during the collection period (~6 hours/day) that it will deliver to the load on a 24/7 basis. Therefore, while the cost of the electric output might be $”x”/MWh for “source of opportunity” power, available when it is available, the cost of 24/7 power from a CSP plant with storage would be ~$5″x”/MWh, assuming that the cost of the storage system to store approximately 75% of the daily output of the plant for an average of 9 hours per day were equal to ~25% of the installed cost of the collector system. That is not a trivial issue.

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    • By Ed on May 18, 2012 at 6:09 pm

      CLARIFICATION: The system must collect ~4 times the energy EACH HOUR during the collection period that it will deliver EACH HOUR on a 24/7 basis.

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      • By Tom G. on May 19, 2012 at 9:08 am

        Hi Ed – Good Posting

        Only have a couple of minutes before going out the door this morning.  Two minor points.  

        If the plant is designed to run 24/7 which I think is quite unwise for Concentrated Solar Power [CSP]; shouldn’t the collected excess power be approximately 3:1?  I guess that could be 4:1 depending on how you look at it.  

        From what I read many CSP plants are being designed to generate electricity only during peak periods to reduce cost.  We have lots of other evening generation capabilities.  Therefor the amount of storage needed would be somewhat limited since the power would only be needed between say 5 pm and 9 pm.  I don’t think 24/7 CSP is cost competitive yet with some of the other available sources.       

        Have a great day 

         

         

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        • By Ed Reid on May 19, 2012 at 1:25 pm

          Tom,

          Thanks. I was replying to the Edward Kerr comment above, though it didn’t post that way. I worked from his premise of CSP 24/7 making storage a red herring, though obviously CSP 24/7 relies on a lot of storage.

          I’ll grant that we don’t need CSP 24/7 today. However, the folks who advocate for all renewables all the time would do well to analyze the power cost implications of renewables as reliable, dispatchable power, rather than “source of opportunity” power. A factor of 5 multiplier makes the economics look rather daunting.

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      • By Robert Rapier on May 20, 2012 at 3:07 pm

        The system must collect ~4 times the energy EACH HOUR during the collection period that it will deliver EACH HOUR on a 24/7 basis.

        And that was the point I was trying to make. Just because solar thermal can in theory provide energy 24/7 does not mean it can do it in a cost effective manner. The round-the-clock output will be a fraction of the potential daytime output.

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  4. By Russ Finley on May 19, 2012 at 11:00 am

    Cost effective storage would also allow nuclear (and unfortunately coal as well ) to cost effectively provide peaking and load following for intermittent sources like wind and solar. Storage would compete mostly with natural gas which is now used for peaking power.

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    • By Herm on May 19, 2012 at 12:34 pm

      Thats the problem with storage.. the essentially free natural gas that is available in the US will kill any storage potential for the next decade, perhaps longer.

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    • By Robert Rapier on May 20, 2012 at 3:05 pm

      Cost effective storage would also allow nuclear (and unfortunately coal as well ) to cost effectively provide peaking and load following for intermittent sources like wind and solar.

      I meant to make that point in the video. I did mention it in my presentation at Santa Barbara. It would allow for more efficient operation of fossil fuel plants though by allowing them to run at more stable rates. 

      RR

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  5. By notKit P on May 19, 2012 at 2:48 pm

    The basic problem with renewable energy is that the people who produce power are so good at providing when an where people need it, the impractical uses of renewable energy are not needed When renewable energy is available, we make use of it very effectively. Hydroelectric is used in the US to its practical extent. Same with geothermal and biomass.

     

    As society needed more power, fossil and then nuclear were used. When we have an adequate reserve margin, we stop building power plants. So what happens to wind farms when the power is not needed. You idle them just like you do coal plants in the spring and fall when the power is not needed.

     

    The real problem with renewable energy is that it is not a better environmental choice. Renewable energy has environmental impact just like any source of power. We are required to minimize the environmental impact so that the net result is that the impact is insignificant compared to the impact our customers have on the environment. The Seattle are has a big environmental impact. Making its power does not.

     

    ‘Clean energy’ is base on the fallacy that there is ‘dirty’ energy. All the promoters of ‘clean energy’ talk about some futuristic without noticing it is already here.

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  6. By Jim Takchess on May 19, 2012 at 8:57 pm

    I’ll pose the storage question in a different quirky way. 

    Is there a business, process or a form of work that could be connected to a intermittent variable power supply like solar or wind that would be profitable using only that input ?  

    The ideal process would fit this criteria:

    * A process that had low fixed costs whose costs are mainly variable based on energy input.

    * could take advantage of all the energy provided when it was provided (little waste) 

    * would have low or no cost when not being provided with energy  

    * could be performed near the energy source with little energy  loss.

     I find this to be an interesting question. Any thoughts?

     

     

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    • By robert on May 19, 2012 at 11:17 pm

      Is there a business, process or a form of work that could be connected to a intermittent variable power supply like solar or wind that would be profitable using only that input ?  

       

      Pumping water uphill.  Let’s take the example of Little House on the Prairie with a windmill and a well.  Perhaps irrigation.  Pumping water into a holding tank need only occur when the wind blow.

      The central arizona project pumps water uphill to Tucson where we inject it into the ground in case we need it a generaton from now.  It takes like an entire coal burning plant to do this.  There isn’t much wind in Arizona and solar is still kind of expensive but it seems like something that could be done at night or whenever there is cheap time of use rates.

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    • By Robert Rapier on May 20, 2012 at 3:09 pm

      Is there a business, process or a form of work that could be connected to a intermittent variable power supply like solar or wind that would be profitable using only that input? 

      That’s an interesting way to think about it. One I have heard discussed is refrigeration. If you kept a large thermal mass at somewhat less than was required for the particular purpose, when the power isn’t producing you could just let the temperature rise somewhat. You would have to be connected to a backup power source though in case you were without the intermittent power for an extended period.

      RR

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      • By Ed Reid on May 20, 2012 at 5:21 pm

        Ice storage equipment is commercially available. http://www.calmac.com/products/icebank.asp

        It is typically used to take advantage of lower night electric rates, as well as the lower night temperatures of the condensing environment. It could certainly be used to store “coolth” produced using  intermittent power sources, especially wind. Profitability is another question.

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  7. By Jim Takchess on May 20, 2012 at 10:25 am

    It would be interesting if there was a desalinization process that could be run entirely by tidal power  or a storage system that would pump salt water into a tower then have it desalt itself while extracting energy from it. Two benefits for the price of one. 

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  8. By Optimist on May 21, 2012 at 8:58 pm

    As to liquid fuels (and I’ve harped at you on this issue before) it’s clear to me that oil produced by algae through photosynthesis will provide all of the liquid fuels (energy dense and stored) that we need to continue powering our civilization in a manner to which it has become accustomed.

     Makes no sense to go growing new biomass, when we are dumping so much of it in our landfills. Start with the landfills. The biggest single component is paper (and that’s after all that much ballyhooed recycling).

    Harvesting only the lipid fraction from algae is sure way to FAIL: the yields aren’t high enough. High density is of little use. As is demonstrated by the continuing failure of algae to take the market by storm.

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  9. By Warren Stephens on May 23, 2012 at 11:42 am

    The best storage technology that I’ve found so far that could potentially scale up is the Carnegie Mellon University spinoff company Aquion Energy. 

    They have a battery that uses only cheap materials that are available in abundance, can be made in a factory without “clean room” type of equipment, and is environmentally benign (“edible” someone wrote).

    Aquion obtained $30m of (high profile) venture capital funding and is building their first commercial scale plant now.

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  10. By mac on May 25, 2012 at 12:16 am

    Warren,

    Here is  link to a TED talk given by Jay Whitacre, one of the engineers at Aquion Energy,  a materials scientist who used to work for NASA on the Mars Rover program. 

    Very funny presentation.  Worth watching just for the chuckles.  He explains why Aquion chose the materials they did and how they got the battery to market so quickly < 4 years.

    http://www.youtube.com/watch?v=vaMuxB4s5qI

    ————————————————————————————————————

    Also, I see in today’s ‘ news that they are planning to try to bring Donald Saldoway’s MIT molten metal battery to market, also made out of relatively inexpensive materials.

    http://www.masshightech.com/stories/2012/05/21/daily41-Gates-backed-Liquid-Metal-Battery-secures-15M.html

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    • By Warren Stephens on May 25, 2012 at 1:44 pm

      Thanks for that one on Whitacre.  I hadn’t seen it.

      Also, I have to confess that I’ve seen Sadoway present his idea, but have not actually figured out how why it should work.

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  11. By mac on May 25, 2012 at 4:56 pm

    Warren,

    Here’s a link to  a TED talk that Sadoway gave.  Like Whitacre’s talk, I found it quite amusing.

    Sadoway doesn’t go in depth into the actual formulas for the electro-chemical reactions but discusses mostly how the battery was conceived, developed, etc.  If you haven’t seen it. you might get a kick out of it.

    The Sadoway video on the MIT Technology Review website is a bit hard to follow and not nearly as funny as this one where Sadowy goes to the chalkboard.

    http://www.youtube.com/watch?v=Sddb0Khx0yA

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    • By Warren Stephens on May 29, 2012 at 11:13 am

      That is a good talk. 

      Some time ago I had seen Sadoway (in person) do a serious talk.  And I, like others, tuned out after hearing that the storage runs at high temperature.  That isn’t a reason to kill the idea, but I still don’t know exactly why.

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  12. By drunyon on June 10, 2012 at 10:39 am

    RR: have you seen any details from Solar Fuel (http://www.solar-fuel.net/en/the-challenge)?  They are pushing conversion of extra electricity from Solar/Wind to hydrogen, then to methane.   Supposedly, Alpha plant in production with beta plant “Currently being planned”.  They claim 60% effieicncy.

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    • By Robert Rapier on June 10, 2012 at 3:04 pm

      RR: have you seen any details from Solar Fuel (http://www.solar-fuel.net/en/the-challenge)?

      I have seen a number of schemes like that on paper — some to produce ammonia — but don’t know that anyone has pulled it off at any sort of scale. Their biggest challenge for that route is that methane is dirt cheap and likely to remain so for a while.

      RR

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  13. By Russ Finley on June 10, 2012 at 1:04 pm

    There is always somebody looking for funding for any given energy scheme. In one place they say:

    “The attainable level of efficiency is over 60 percent.”

    In another place they say:

    “The efficiency of the SolarFuel power-to-gas method is about 60%.”

    And by that they are only referring to the conversion of hydrogen into methane. Unlike fossil fuel power plants, solar and wind typically send electricity directly into the grid without any efficiency loss (100% efficiency) at the power plant (all sources suffer line losses on the way to an outlet). This is a major factor in their economics–no fuel burn losses. If you are going to use solar and wind generated electricity to make a fuel, it would be deceptive to not account for the losses associated with turning fuel back into electricity.

    Not to mention, part of the appeal of hydrogen is that it emits no emissions (converts hydrogen and oxygen back into water). Although the promoters are careful not to say it, combustion of this source of methane creates more CO2 than was used to make it which defeats the main reason many environmentalists support solar and wind. From Wikipedia:  

    Combustion

    In the combustion of methane, several steps are involved. An early intermediate is formaldehyde (HCHO or H2CO). Oxidation of formaldehyde gives the formyl radical (HCO), which then give carbon monoxide (CO):

    CH4 + O2 → CO + H2 + H2O

    The resulting H2 oxidizes to H2O, releasing heat. This reaction occurs very quickly, usually in significantly less than a millisecond.

    2 H2 + O2 → 2 H2O

    Finally, the CO oxidizes, forming CO2 and releasing more heat. This process is generally slower than the other chemical steps, and typically requires a few to several milliseconds to occur.

    2 CO + O2 → 2 CO2

    The result of the above is the following total equation:

    CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −891 kJ/mol (at standard conditions))

    This hydrogen to methane idea requires burning the fuel in an internal combustion engine of some sort. Conversion of fossil fuels into useable electricity typically throws away roughly 60-70% of the energy in the fossil fuel. Assuming they really are 60% efficient (which is unlikely) their conversion process throws away an additional 40% of of that  30-40% left after burning a fossil fuel for a total efficiency of about 18-24% compared to the original electricity efficiency of 100% I mentioned earlier.

    The only advantage of this idea is to trade the cost of storing hydrogen for the cost of converting it into methane (which can be stored in the existing natural gas infrastructure). However, whether you create and burn hydrogen or methane, the combustion process imparts a huge energy loss compared to sending electrical power straight into the grid without any conversion losses.

    Assuming cost is directly proportional to efficiency, this idea would increase the already high cost of electricity generated by wind and solar about 100-24 = 76 to 100-18 = 82 percent (neglecting the cost of building hydrogen-to-methane refineries and other complexities).

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    • By JonathanMaddox on June 17, 2014 at 3:01 am

      The round-trip efficiency of power storage doesn’t have to matter very much when the spot price for off-peak power is close to or less than zero (some markets permit, and frequently observe, negative prices) and peak prices are tens of times greater than the average. Similarly, consumers pay far more for a unit of energy in the form of liquid fuel we can put in our road vehicles and aircraft than we do for the same amount of energy in the form of on-demand electricity. Storage is arbitrage between energy forms or time with very different monetary value.

      Storage technology (at least today) is capital-intensive and so at least initially it makes more economic sense to overbuild low-cost generation capital and curtail when it would generate power in excess of demand, just as we do with dispatchable generators. This is already a commonplace scenario: wind generation, despite its very low variable cost, is curtailed when inflexible baseload generators bid very low or even negative prices into the spot market to avoid their own curtailment; rooftop solar PV inverters cease grid feed-in or inefficiently shut down altogether when the local connection is over-voltage.

      Therefore in the scenario where a combination of intermittent generation and storage is intended to displace fossil-fuel generation altogether, it makes sense to start out by overbuilding intermittent generation such that it can meet 100% of demand for an ever-increasing fraction of the time, gradually relegating fossil-fuel generation to peaking duty only. Storage to replace that fossil capacity is only required for exactly the same peaking duty, perhaps just a few hundred hours per year. But in such a scenario the amount of excess energy potentially available at very low cost from the intermittent generators over the course of a year would be very much greater than the amount of energy needed to be delivered from storage.

      Loss of energy when it is inevitably available far in excess of instantaneous demand is nothing to weep over :-)

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      • By Forrest on June 17, 2014 at 12:53 pm

        Per your scenario of over building generation….I could see that if the excess capacity could be utilized for hydrogen production and storage for use upon peak load demand or low capacity via fuel cell. That would tidy up the unattractive habit of green energy being unreliable and hard to schedule. Tie that thought in with the automotive predictions of utilizing fuel cell for transportation needs. Hyundai just produced first production model. Reviews are very positive. Double the MPGE, adequate power, range, and refueling. The FCV probably could be utilized as stand by power source for home use. Low pressure hydrogen can be piped much like natural gas.

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      • By Russ Finley on June 21, 2014 at 1:11 am

        …it makes sense to start out by overbuilding intermittent generation
        such that it can meet 100% of demand for an ever-increasing fraction of
        the time,

        Until you reach the limit of what is economically viable. Can’t go without power on windless nights and cloudy days. Even the NREL doesn’t believe renewables can do it all. It’s a question of how much.

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        • By JonathanMaddox on June 21, 2014 at 9:59 am

          You don’t need to go without power on windless nights and cloudy days if you keep the old dispatchable fossil plant around.

          Intermittent generation can put daytime peaking power stations out of business but it can’t replace all dispatchable power capacity on its own. Storage can, to some extent.

          As much as 50% of demand might be able to be met directly by intermittent generation, curtailing the fossil power as required but with minimal curtailment of the clean power. Extending that to 70 or 80% would lead to a lot of excess (wrong-time) intermittent power, however curtailment of wind or solar power is pretty much without costs. There’s no reason to expect the equipment not to keep getting ever-cheaper as more is deployed and new techniques and economies of scale are explored, so continuing expansion will still be viable beyond 50% penetration despite curtailment. At 80% penetration, 100% of demand would be met by intermittent generation for many hours of the year, maybe as many as half.

          The last 20-30% of annual electric energy demand — unless you’re very lucky with dispersed, statistically independent wind resources — *needs* to be met with dispatchable capacity up to quite a large fraction of maximum demand. That can comfortably remain mostly fossil capacity (charging high spot prices to remain economically viable) until storage is cost-effective. Which it may be, quite soon.

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          • By Russ Finley on June 21, 2014 at 11:41 am

            …curtailment of wind or solar power is pretty much without costs.

            You pay for maintenance, staffing, and interest on your loans whether they make power or not. A powerplant not producing energy isn’t paying for itself. I think we’re counting angels on the head of a pin. Ubiquitous cost-effective storage, like cellulosic ethanol, does not exist.

            Wind and solar without cost-effective storage are best viewed as devices that can make gas fired powerplants more efficient by reducing fuel bills when the wind blows and the sun shines. The cost effectiveness of these devices largely depends on the price of natural gas. They may increase profitability or decrease it.

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            • By JonathanMaddox on June 21, 2014 at 11:06 pm

              Well, okay, the gross cost of curtailing wind is not *zero*, but the marginal cost is near enough. Of course you still have the fixed costs.

              As for those fixed costs, do bear in mind that even a traditional power system with all-dispatchable generation has overbuilt capacity for the sake of reliability, well above peak load, and frequently to more than double average load (2.4 times in the case of the USA, subtracting existing intermittent generation), meaning gross capacity is five or six times the “baseload” minimum demand. At all times, some of the dispatchable capacity available on the network is “not paying for itself”. Most of the time, half of it isn’t. Frequently, 80% of it isn’t. Are these angels on pinheads? Redundancy is part of the cost of having a reliable system. Overbuilding intermittent generation and curtailing excess production is just more of the same. Wind and solar are not, in this regard, special.

              You wrote, “Ubiquitous cost-effective storage, like cellulosic ethanol, does not exist.” I’d beg to differ. As far as I’m concerned, fossil fuels *are* cost-effective storage, and should be treated as such. Yet cost-effective storage from electrical sources, even at busbar costs, *does* exist in the form of pumped hydro, and ignoring the developments in the power storage industry (some of which, like distributed PV, need compete only at retail costs, not busbar) would seem extremely foolish to me.

              Batteries are obviously not cost-competitive with fossil fuels yet, but they are getting cheaper. Electrolysis and fuel synthesis is a ready-made dispatchable load for long-term storage and carbon-neutral displacement of fossil fuels in non-electric applications such as aviation and road transport where fuels command much higher prices than equivalent energy in the form of electric power. Non-hydro, non-electrochemical storage techniques such as adiabatic compressed air storage (Lightsail, RWE’s Project Adele), reversible heat-pump or cryogenic storage (Isentropic, Highview) are compact, mostly independent of geography, and inherently cheaper than electrochemical techniques in terms of material and capital costs.

              Even *without* storage, curtailment of excess wind and solar power is easy and cheap.

              http://www.powermag.com/study-wind-power-curtailment-more-cost-efficient-than-storage/

              In legacy systems which still require baseload generation for transmission grid stability, wind is curtailed in preference to that baseload, with minimal inconvenience or cost. In a modern regime where grid stability can be assured by power electronics even where the power is entirely sourced from distributed sources, and where there are penalties for CO₂ emissions from fossil-fuelled power stations, gas and coal are curtailed first, wind later, nuclear last if present. Wind curtailment is simple, cheap and convenient — and even in a gas-dominated system, it can work out cheaper for capacity additions than consuming additional gas.

              http://reneweconomy.com.au/2013/us-utility-chooses-wind-and-solar-cheaper-and-more-reliable-79876

              Curtailing rooftop solar PV feeding into the local distribution grid is entirely automatic — if the local line is over-voltage, the inverter doesn’t feed. Zero marginal cost of curtailment. Some inverters actually shut down altogether when the line is over-voltage (forcing the premises to take power from the over-voltage line, which is good for grid management but bad for the individual customer), but more sophisticated ones continue to permit self-consumption of rooftop generation behind the meter while curtailing only the grid feed.

              Wind is not just displacing flexible gas power. Even in the US, it is displacing coal-fired generation even locally. Most countries do not have gas-dominated power systems, and the US has only reached that point in very recent years thanks to the shale gas boom.

              In most of the world, wind does not compete with gas-fired generation on price but with coal, which is by far the cheaper fuel. In the eastern states of Australia and in China, for instance, wind displaces coal (the SA and WA power supplies are gas-dominated).

              http://reneweconomy.com.au/2013/ipa-concedes-wind-farms-successful-in-displacing-coal-53517

              This is increasingly the case in Europe too, of course.

              http://reneweconomy.com.au/2013/graph-of-the-day-how-wind-displaced-coal-in-spain-47008

              Distributed rooftop solar PV doesn’t compete with coal or gas busbar costs, but with the consumer price after distribution, markup and taxes.

              http://cleantechnica.com/2013/05/26/solar-grid-parity-in-102-countries-map/

              Germany has recently made a massive fuel-shift from imported gas to locally-mined brown coal as a result of painfully high gas prices. There is a higher penalty for carbon emissions for the dirtier fuel, but it is nowhere near high enough to counter the difference in the prices of the fuels themselves. Gas now provides only slightly more of the nation’s gross power generation than wind does (less than wind and PV combined) — and it is coal-fired power stations which are the ones to ramp down when strong intermittent generation is anticipated. Modest amounts of wind curtailment are used to smooth the shoulders too. Gas-fired generation still fills some of the gaps when very rapid ramping is required (eg. for the early morning and early evening demand peaks, the midday peak having been eaten by solar PV), and many premises still rely on gas for heating, but those are the main uses for gas now. It certainly isn’t providing the bulk of electric power demand.

              Note that the day-ahead-price of wholesale power in Germany only goes below zero when nuclear power stations (not built for ramping at all) are among the candidates for curtailment. It’s clear that most of the day-to-day variation in dispatched generation comes from black coal these days, and the utilisation factors of gas-fired power stations are generally around 25% and rarely above 50%. Gas is at most providing intra-day ramping (dominated by the predictable diurnal curves of solar PV and commercial demand) rather than compensating for the gross variations in intermittent power availability based on changing weather from one day to the next. See the chart on page 10 of the following PDF :

              http://www.ise.fraunhofer.de/en/downloads-englisch/pdf-files-englisch/data-nivc-/electricity-spot-prices-and-production-data-in-germany-2014.pdf

              Note also that quite a few of the “conventional” (ie. dispatchable) power stations in Germany run wholly or in part on renewable fuels. Biomass, biogas and waste incineration (considered partly renewable because most of the energy content of the waste is from biomass, though it takes some fossil gas, and some of the incinerated waste is fossil-derived) provide about as much electric power as solar PV does.

              You write, “Wind and solar without cost-effective storage are best viewed as devices that can make gas fired powerplants more efficient by reducing fuel bills”. I look at the same basic facts and think, “Gas-fired powerplants are best viewed as appliances for withdrawing energy from stable chemical storage in the form of light hydrocarbons.” Fossil fuels *are* cost-effective storage!

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            • By Russ Finley on June 22, 2014 at 11:39 am

              I think your point can be summarized as; It would be cheaper to build more wind and solar than to try to provide storage for them using today’s non-fossil fuel storage technology. I suspect you are right.

              But that is not a novel argument nor does it mean that it would be cost effective to do so. Most realistic predictions I’ve seen over the years show that we could afford to increase wind and solar input to some point but eventually, further penetration creates escalating costs.

              If we resist reading our respective crystal balls and stick to the present, the German experiment has to-date validated predictions of higher costs and GHG emissions. We can choose to predict a rosier future or not but I’d rather wait to see the outcome of the experiment than waste time and words making predictions and counter-predictions about it.

              Synonyms of the word prediction: guess , indicator , prognosis , prophecy , augury , cast , conjecture , divination , dope , foresight , foretelling , horoscope , hunch , omen , palmistry , presage , prevision , prognostication soothsaying , tip , vaticination , zodiac , crystal gazing , fortune-telling , of event anticipation , surmising , Antonyms for prediction.”

              Antonyms: proof, reality, truth.

              The recent mega-study done by the National Renewable Energy Lab (as you would suspect from an organization that exists solely to promote renewable energy, it is highly optimistic and biased in favor of renewable energy) “predicts” that a massive expansion of renewable energy (predominantly hydro and biomass with solar being a small component.) along with a massive expansion of non-fossil fuel storage could fulfill about a third of our total energy use by 2050. The technical feasibility of doing that is one part of the prediction, the cost of doing it is the other.

              The graphic below is a recent real world cost to install solar panels in two disparate locations in the U.S. from real solar installers looking for business.

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            • By JonathanMaddox on June 22, 2014 at 9:00 pm

              ” the German experiment has to-date validated predictions of higher costs and GHG emissions.”

              False. The German experiment has not been an independent one in replacing fossil fuels with renewable energy. In addition to adopting large amounts of renewable energy (dispatchable and intermittent both), the German experiment has been accompanied by the alarmist (but democratic) decision to close down nuclear electricity production in that country, and by a massive increase in the price of imported gas, causing a fuel shift towards domestic brown coal which is the highest-carbon fossil fuel available. Carbon-neutral nuclear and low-carbon gas generation have been displaced by a combination of very high-carbon coal and carbon-neutral renewables.

              Yet gross CO₂ emissions have increased only very slightly in the last two years of the fuel shift away from gas. They did not increase at all in the year of the fastest part of the nuclear shutdown.

              Solar PV costs have been falling dramatically and continue to fall dramatically. Present-day installation costs for those very large commercial-scale systems are not necessarily very relevant to future installations.

              http://www.businessinsider.com.au/elon-musk-just-made-the-same-huge-bet-on-solarcity-that-hes-making-with-tesla-2014-6

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            • By Forrest on June 23, 2014 at 7:58 am

              Germany a history lesson on how not to employ green power. A 100 billion euro investment and increasing emissions. The biggest factor to their reductions in CO2, a recession and obsoleting arcane communist production plants. Their green energy enthusiasm blinded their common sense and set them upon a course to be exploited by Russian natural gas price. When Germans realized the dilemma, they quickly returned to old friend coal, pollution be dammed. I’ve read a few Wall Street cost analysis of German wind investments, while lauded by environmentalist…the international investors scratched head, and awestruck on the government incentives. I do laugh at environmentalist whom claim wind energy cheaper than coal and notice they “forget” the federal incentive cost, infrastructure cost, back up power cost and pollution. Wind and solar compete upon power market as a result of regulations that minimize competition and throw maximum advantage to wind and solar. The rules are extremely bias and lack real world accountability. Environmentalist quickly offer solutions (excuses) to wind power limitations, with demands to spend ever more taxpayer and consumer money. I notice my utility bill steadily increase and read warnings from utility that rates will rise rapidly. I thought wind energy was free? Why are we not concerned with the huge economy killing federal deficit unsustainable rate of growth? Were often reminded of the rate of solar cost plummeting, but never enlighten by the fact that cheap inferior Chinese production being dumped at below cost to eliminate competition. The low cost may just be temporary marketing plan?

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            • By JonathanMaddox on June 24, 2014 at 1:29 am

              Forgive me. I did think that I was having a conversation with a human being interested in current transformations of the energy market. I didn’t realise until now that I was feeding a troll. Ignore everything I said and carry on as before.

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  14. By JonathanMaddox on June 21, 2014 at 10:17 am
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