Intermittency Of Renewables? … Not So Much


By Zachary Shahan via CleanTechnica.

Below was a great summary comment (if a bit simplified in parts) from one of our readers on one of our posts last week. I thought it deserved a few more eyes. Also, I happened to go back to a roundtable discussion of utility CEOs today that supports the overall “the ‘intermittency’ of renewable energy issue is overhyped” argument. More on that below the reader comment.

Here’s the comment from Victor Provenzano (paragraph formatting and some links added):

To sum up the so-called “intermittency and storage” problem for renewables: Geothermal has no intermittency issues and experiences fewer ephemeral shut downs than coal, nuclear, and natural gas. Solar thermal — with molten salt as its storage medium — can be designed to have no intermittency issues. Offshore wind yields power more or less 24/7 with relatively limited intermittency compared with onshore wind. The two most common sources of renewable electricity, onshore wind and solar photovoltaics, are, of course, complementary: wind turbines (which, in the case of GE, already have built-in storage capacity) yield more power at night, while solar panels yield power during the day; hence, used in tandem, they can provide electricity 24/7 with “intermittency” being experienced only locally at each individual solar installation. The experience in Germany shows that the more wind and solar PV installations one has in the various regions of one’s country, the less the so-called intermittency problem is an issue because electricity is generated at varying wattages in the various locations more or less 24/7 and the actual total daily electric power levels become more and more stable and more and more foreseeable as the number of installations increases nationwide. At that point, the intermittency deficit is more easily and more predictably counterbalanced with reserve power (natural gas and hydro), storage (pumped hydro, compressed air, flywheels, grid storage batteries), and grid power from neighboring nations.

The European experience shows that the “intermittency” issue is being widely and very inaccurately exaggerated by America’s energy specialists. What is more, if one has a mix of renewable energy sources online that includes the non-intermittent forms of renewable energy (hydro, geothermal, and solar thermal with molten salt), the far less intermittent sources (offshore wind), and the complementary locally “intermittent” sources (solar PV and onshore wind with its own built-in storage capacity), then the limited remaining “intermittency problem” can be far more easily overcome.

Well summarized.

In a utility company CEO roundtable at Solar Power International 2011 (video here), the General Manager of Austin Energy through up the same sort of anti-solar lob that the commenter above was addressing. What was great to see was that a couple of other utility company CEOs stood up very strongly to the (intentional or unintentional) propaganda and explained why integrating renewable energy into the grid was not an issue. (To watch the responses quoted below, jump to 1:25:29 in the video.)

First, the then CEO and President of Florida Power & Light, Armando Olivera, chimed in. “I spent a lot of time in operations in our company. Of all the things that I worry about, regulating using solar, or renewables, really doesn’t worry me. I think you gotta be at a really huge scale of solar before that becomes an issue. And in the meantime, we’ve got a lot of enabling technology going into these grids… about half of the meters at FPL are already automated devices. We are learning a huge… we’re seeing benefits that we didn’t fully anticipate in terms of managing the grid. We’re also putting in a lot of smart technology that can adjust at a very local level whenever there’s a problem. So, you know, I think there’s a huge foundation that’s being laid out today that will facilitate all of these technologies….”

Doyle Beneby, President & CEO of CPS Energy, backed him up. ”Yeah, I would agree with Armando, I don’t worry about that at all…. Generally, if you’ve got automated meters, if you’ve got the means for a home area network, I think you can easily reduce demand to follow — I call it load-following — for solar. What we found, also, is that there are a very discreet set of customers out there who would volunteer to have their load reduced to follow the drop in output for solar…. So I think that’s a big opportunity out (there) for us. I really think concerns about the grid, so to speak, and even to a degree intermittency, should not at all impede the progress of solar.”

Robert Powers, President of AEP Utilities, also chimed in and said, “I agree with my colleague that near-term there’s no, no issue with grid stability with deploying solar.”

I thought that was all a great, serendipitous addendum to this reader comment. And I’m happy that after about two years I got around to transcribing that. I also transcribed much more back around the time of the conference and roundtable.

By the way, just following that discussion was some more fun discussion around the benefits of solar in protecting against cyber attacks, something two CEOs noted the military was well aware of that and already using solar and microgrids for security reasons. To watch to that section, jump to 1:27:53. And, if you want even more, a very interesting section on what these utility company CEOs and Presidents would wish for if they had one wish that could really help them ramp up solar started at 1:31:05. Or just watch the whole thing….

25 Responses to Intermittency Of Renewables? … Not So Much

  1. Zimzone says:

    In case you’re keeping score…

    Clean energy supporters = 1

    Clean energy deniers = 0

  2. wili says:

    In the first sentence of the first full paragraph of the indented, italicized quote, you have:

    “Manager of Austin Energy through up the same sort of anti-solar lob”

    Presumably you wanted ‘threw’ rather than ‘through’ but that would still leave you with the unfortunate collocation “threw up.”

    Maybe ‘tossed up’?? to keep your metaphor of a ‘lob’ that you make later in the sentence in tact?

    Anyway, great piece, as usual.

    My recollection is that the issue of “base load” first came up in the history of energy transmission as a problem to be solved, not an absolute necessity that must be provided.

    More on that later.

  3. Mike Roddy says:

    Lack of clean energy baseload was always a denier meme, just like low emitting natural gas, clean coal, safe nuclear etc.

    Fossil fuel company owners will do anything to discredit solar and wind, because they fear it. Burning fossilized carbon requires no brainpower- you dig it up or drill for it, and it turns into money. That’s something we have in our favor- they are dumb enough to make mistakes. If we can stop making them ourselves, we have a chance.

    High on this list would be demanding a responsible media. We are nowhere near achieving that goal.

  4. Paul Magnus says:

    Intermittency Of Renewables… so what.

    Its the end of the world otherwise.

  5. Mulga Mumblebrain says:

    ‘Throw up’ implies, in the common argot, an expulsion of emetic substances. Seems appropriate here. The tennis metaphor is inapt, however, as such eruptions are usually described as ‘projectile’. A projectile lob puts one in mind of the late, lamented, Mr McEnroe.

  6. Mulga Mumblebrain says:

    And never will be. The situation, as expected, is actually growing worse, as the destructocrats double-down their bets. For them it is ever ‘My way or no way at all’. The Rightwing MSM, being totally irredeemable, must be ignored and by-passed, by the Internet, before it, too, is brought under control.

  7. Leif says:

    The city of Palo Alto is expecting to be 48% renewable in 5 years. And Save money. A grid storage utilizing electric RR cars full of gravel run up a 8 degree incline and re-genitive breaking on the coast back down gives almost instant response to power fluctuations of renewable power at ~85% efficiency. Solutions abound, the will can use help. Many hands, (think jobs), make light work. Stop profits from the pollution of the commons. Power to the People, NOT the polluters.

  8. Henry says:

    Unfortunately, it’s not quite as simple as the article is suggesting. Recent developments in India underscore some of the problems that need to be overcome.
    As of this month, the Indian government is threatening fines for wind energy suppliers that can’t accurately predict their daily output. Bloombberg Business and others are reporting.

    These things are to be expected with newer technologies, and renewables have come a long way since their infancy, but there is still room for fine tuning it seems.


  9. Jonathan Byron says:

    Solar power is intermittent, but is correlated to peak demand in many places. In warmer climates, solar PV output is highest on the hottest days, when air conditioning is straining the grid. In such regions, solar has a stabilizing effect that is ignored in other statistics.

  10. A couple of important renewable energy sources that were not mentioned (I think?) in the article:

    Wave power is quite constant if well sited, and only really varies in amplitude. There are at least three companies around the world that already build working systems. There are two types: buoys with tall columns underwater that have suspended magnets (think giant shake flashlights!) and an array of ~66-70 buoys can produce 10MW. The other type is a floating series of horizontal tubes, that are hinged together – hydraulic pumps at the hinges build pressure in accumulators, and then this is used in hydraulic motors to spin generators. Each 500′ long (5 sections of 100′ each) produces ~0.75MW.

    Tidal power is very consistent and predictable; though obviously cyclical. Underwater turbines make a lot of power because of the immense torque provided by the flowing water. Again, there are several companies already making these.

    Methane gas can be made from sewage, and from farm waste (plant and animal) and this can be stored, and used in gas turbine peaker plants. After the methane is made, the resulting material makes a high quality fixed nitrogen fertilizer – which can replace synthetic fertilizer now made from natural gas. This avoids another very large source of greenhouse gas!


  11. That’s just it – renewables are *not* intermittent if we do them right – so we can limit climate change and stop polluting and fix our broken (factory) farming, as well.

    We have to switch to renewables, and we can.


  12. Dr.A.Jagadeesh says:

    Intermittency of Renewables is well known. That is why I always assert that Renewables can only Supplement Conventional power but cannot replace the latter. For that matter in many developing countries Grid without power for hours a day is common.
    Dr.A.Jagadeesh Nellore(AP),India

  13. Mulga Mumblebrain says:

    It’s Intermittency of Existence that worries me. Human beings and Rightwingers cannot stand more than a few minutes of ‘interruption of service’. PS Is ‘Mitt’, as in Mr Romney, short for ‘Intermittent?’.

  14. Mulga Mumblebrain says:

    That is bloody marvelous. If only the Powers of Darkness were removed from blocking the way, we could yet save ourselves.

  15. Robert Brecha says:

    Spending time in Germany is somewhat instructive on this count. Over the past few weeks of unusually sunny weather, the percentage of renewables in nationwide electricity generation has been reaching as much as 40% during the week and 60% on weekends during the day, with most of that being solar pv. At night, the percentage of renewables is “only” 15% or so.
    Meanwhile, the large penetration of renewables has driven down prices on the daily electricity market to the extent that operators of conventional power plants (coal, nuclear, gas) are threatening to pull their plants from the grid because they cannot make enough money.

    Links are unfortunately only in German

  16. Spike says:

    One interesting point that hadn’t occurred to me was the issue of direction of orientation of solar panels. In germany they have a large midday peak in production relating to high insolation on south facing roofs for maximal benefit.

    As panels become ever cheaper soon it will be as beneficial to orientate them SE, giving earlier peaks, and SW giving later peaks.When they are cheaper still E and W facing ones extend production throughout daylight.

    Another study in the UK showed that solar panels perform well even in a relatively cloudy country like the UK because light is scattered allowing 98% of panels to run as projected – “We would have expected more systems to be under-performing – but it seems that the UK weather, with its lack of direct sunshine, actually makes installations less sensitive to orientation than might be expected.”

    I have also read that peak wind occurs at nights, so the two complement one another fairly well. Add in the developments in storage and other renewables as outlined in the article and you see why there is so much antipathy from vested interest financial and political encampments.

  17. Ernest says:

    The intermittency problem is solvable. The question is at what cost? More transmission lines for geographic distribution and arbitraging won’t be cheap in the US, when it even hesitates to do other basic infrastructure maintenance.

    On the issue of intermittency, I put hydro and geothermal in its own class. Unfortunately, these solutions are not generalizable and are solution specific to certain locations.

    Hooray for Palo Alto, 48% renewables, using RR cars up an incline for storage. How ingenious. I’m sure there are other solutions for cheap electromechanical storage analogous to pumped hydro. (I thought about similar, like pushing a building up, or high density weights up inside some old abandoned buildings downtown, etc. Plenty of room for innovation on the issue of grid storage.)

  18. wili says:

    You are contradicting yourself.

    If you can run a society with a grid that has no power for a few hours a day, then intermittency of renewables is not a problem.

    Really, load management of various sorts, as well as storage, and having a variety of sources, takes care of most of these problems.

    So why the hard stance.

    We have to get to zero net carbon release as soon as possible, one way or the other.

    Relying on ff forever is not an option if we want a livable future (which may already be not in the cards).

  19. wili says:

    Here in Minnesota, everyone knows that if we have a very heavy snow or an extreme ice event, most businesses and schools will be closed for at least part of the day.

    If we can live with accommodating nature in that regard, why not just accept that in the rare instance when there is no wind and no sun for a long time and whatever reserves are tapped out, that we mostly just all take a break.

    What is so freaking horrendous about adjusting the rhythms of our economy just a little bit to the rhythms of nature for once?

  20. Jeff Howard says:

    through up –> threw up

  21. fj says:

    Pathologies of power and the fossil fuel house of cards

    Solar and human powers both necessary for life supplied freely by natural systems in extraordinary abundance are way undervalued, underutilized, and undeveloped.

  22. quokka says:

    The AEMO (Australian Energy Market Operator) was recently requested by the Australian Government to produce a study with scenarios of all Australian electricity supplied by renewables in 2030 and 2050. The report is one of the better, more competent and thorough of it’s type.

    The study goes out of it’s way to explain the significance of baseload generation and the scenarios it comes up with contain substantial amounts of baseload. And the baseload technologies – wood burning and geothermal because there were no other options.

    Australia *might* be able to grow enough trees to burn them, but that doesn’t make it a good idea at all. As for geothermal, in Australia it would have to be EGS (Enhanced Geothermal Systems) with 4km+ deep bores. It doesn’t exist as a commercial technology. There was a lot of hot air about EGS in Australia a few years ago. There was even a bit off a bubble in geo stocks on the ASX. So far nothing has been delivered. There were two main players – Petatherm who have just declared it all too hard and are moving into gas and Geodynamics who are many years behind schedule and recently been dumped by their project partner Origin.

    Oh, and AEMO declared all storage other than molten salt associated with CSP and existing hydro, to be prohibitively expensive.

    All this ridiculous nonsense just to avoid mentioning the “n” word.

    Anybody still wondering if baseload is still needed, need look no further than Germany which is projected to commission over 5GW of new coal capacity in 2013. Why not more PV and wind?

    Every electricity grid in the world relies on baseload to deliver reliable supply. That’s reality and it is not going away anytime soon. Pretending that anything other that high quality electricity supply will be politically acceptable is beyond fantasy. People will no go without – fossil fuels will be burned rather than that.

    Trying to pass off some of the nonsense here as energy debate is a joke. A bad joke because it will guarantee the continuance of fossil fuels. All to try to dodge around the need for nuclear power.

  23. Mulga Mumblebrain says:

    Gosh, Fukushima is going great, ain’t it? I’d like one of them just down the road, and I’m sure everybody else would too. Come to think of it, at the rate that Fukushima is leaching radio-activity into the Pacific, it looks like we’ll all be well and truly Fukushimaed soon.

Zachary Shahan is the director of CleanTechnica who focuses on solar energy, electric vehicles, bicycling, and wind energy. Reposted from CleanTechnica with permission.