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Musings of an Energy Nerd

Can We Build An Electricity Grid Based on 100% Renewable Energy?

I visit El Hierro to find out

The peak capacity of these five wind turbines on the island of El Hierro exceeds the peak electricity load of the island. When the turbines produce more power than needed, the extra electricity is used to pump water to a high-altitude reservoir. [Photo credit: Martin Holladay]

As scientists and ordinary citizens see increasing signs of climate change, forward-thinking leaders on every continent are taking steps to make our electricity grids less dependent on fossil fuels. For climate activists, the goal is a grid that obtains 100% of its electricity from renewable energy sources like wind turbines and photovoltaic arrays. Most analysts have concluded that transitioning to a 100% renewable grid would be feasible but expensive. Pessimists, on the other hand, doubt whether a 100% renewable grid is even possible.

Here’s the good news: the cost of wind turbines and photovoltaic modules has dropped faster than most experts predicted. In many parts of the world, it is now cheaper to build a new wind or solar facility than a new coal-fired plant of the same capacity. Global wind and solar capacity continues to increase at a rapid rate, driven in most cases by simple economics.

The bad news, as most GBA readers know, is that renewable energy sources are intermittent. If we want a grid that is 100% renewable, we need to include some method of energy storage. Several technologies for energy storage already exist; the main hurdle to their deployment is not technical — it’s the high cost of the systems. At current rates of renewable energy deployment, a 100% renewable energy grid in the United States is still a long way off. For anyone aware of the looming deadlines that we face to avoid climate catastrophe, our slow adoption of energy storage solutions is bad news.

Some island grids are out in front

Many forward-thinking renewable energy engineers are now working on islands. Of course, some islands have no electricity at all. Others have undersea cables that connect to a mainland grid. The interesting ones are those that have independent electricity grids that depend on local electricity generation —…

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  1. dankolbert | | #1

    Fascinating stuff, Martin. I hope you got hazard pay for the terrible environs!

  2. vivian_girard | | #2

    I don’t think that small islands are the best case study since they import just about everything (with a lot of embodied energy) from elsewhere. A large diversified country is a better example.

    Renewable leader Germany now gets 35% of its electricity from renewables, but the country’s carbon emissions have hardly gone down because much of that generated “green” electricity is untimely and unusable. It's a little more complicated, but the gist of it is that most of that power gets wasted or dumped onto neighboring countries, destabilizing their grids. All the relevant information is only a Google search away and the issues are partially summed up in the article linked below.

    The main environmental benefit I see with intermittent renewables is that they make electricity much more expensive overall, but that’s not an efficient policy. Rates are around $0.35/kWh in Germany for residential use compared to $0.13/kWh in the US. It’s no coincidence that German household uses only around 3,000 kWh/year, as opposed to 12,000 kWh in the US. Norway where electricity prices are comparable to the US uses 15,000 kWh/household/year. Higher prices leading to wiser consumption is the main factor that makes Germany quite “greener” than the US.

    We are spending $ tens of billions to subsidize solar and wind, but as I walked down the street this morning (Boston), I passed my neighborhood’s gas station were folks were filling their gas guzzlers with regular at $2.47 a gallon (20 lbs of CO2 emission/gallon). That’s complete non-sense.

    I wish that we could learn something from Germany’s less than convincing experiment. Carbon emissions should be taxed (and dividend) across the board, and people should be free to decide how they want to tackle the issue, in whatever way makes the most sense for them. It’s not a new or original idea; thousands of economists, 27 Nobel laureates and all the former Chairs of the Federal Reserve have signed in support of a carbon dividend policy.

    1. GBA Editor
      Martin Holladay | | #4

      I reported on a powerplant visit on El Hierro. I never claimed it was "the best case study." You are free to draw any lessons you choose from my reporting.

      Nor did I advocate that everybody move to El Hierro -- and frankly, it's irrelevant that "they import just about everything (with a lot of embodied energy) from elsewhere." Does that make reporting about how they tackle their energy challenges irrelevant? I made no claims concerning the embodied energy of items purchased on El Hierro.

      You note that "We are spending $ tens of billions to subsidize solar and wind," without also noting that U.S. subsidies for the fossil fuel industry are far higher than those for solar and wind.

      You're quite right that "carbon emissions should be taxed ... across the board." You'll get no argument from me on that point. I have been advocating in favor of carbon taxes for many years.

    2. PMatt | | #7

      Renewable leader Germany got 43 percent of its gross electricity production from renewables in 2019 so far. The 35 percent number is outdated by about 2 or 3 years.

      And CO2 emissions have fallen substantially in Germany in 2018 and 2019.

  3. Expert Member
    Dana Dorsett | | #3

    >"The bad news, as most GBA readers know, is that renewable energy sources are intermittent"

    No, that is a common disinformation description used by incumbent centralized generation vendors.

    Wind and solar are not "intermittent"- a better descriptor is "variable-output", but predictable enough to bid into day-ahead markets, and VERY predictable in 5 minutes-ahead time frame.

    Wind and solar are also fast-rampable, much faster than fast ramping peakers, and can be controlled to provide precise voltage & frequency stabilization services at very low cost, within some range of their output. The large midwestern & Rocky mountain utility Xcel has been using wind assets to advantage for years now to be able to turn off spinning reserves & fast ramping peakers wheneever there is adequate wind on the system, delivering those services by varying the output of wind farms. While that results in a few percent of potential output curtailment when using them that way, the minor curtailment is far cheaper than keeping the peakers running.

    Comparisons of the US electricity gris with Germany is in-apt, and comparisons with island grids is ridiculous. The US has much better transmission line capacity that is being underutilized, but could also be improved. The broader the geography, the easier it is to balance the variable output assets.

    Norway is a special case, with HUGE hydro capacity, and is able to take effectively "free" wind when Danish or Swedish wind is over-producing, and exporting hydro regionally when it's under-producing. (Those transmission assets could also be improved.)

    >"Germany’s now gets 35% of its electricity from renewable, but the country’s carbon emissions have hardly gone down because much of that generated “green” electricity is untimely and unusable."

    The argument that Germany's renewables are being excessively curtailed is simply not so. Even though within the country regionally curtailment due to grid constraints does happen regularly, it's still in low single digits percentage of the total. That isn't really very"... much of that generated “green” electricity...", and transmission line projects to deal with it are already planned or under way. The only part of the US that is anywhere near as constrained as Germany is the ERCOT grid in Texas, but even there they are ahead of Germany on transmission line planning and construction.

    1. GBA Editor
      Martin Holladay | | #5

      You appear to be trying to start an argument with me on whether we should call solar and wind "intermittent" energy sources or "variable-output" energy sources. I have no problem with the term "variable-output" -- frankly, if I were writing a thesaurus, I would list "variable-output" as a near-synonym of "intermittent" (especially when variable-output energy sources vary down to zero output -- as do solar arrays and wind turbines). This is a fight without any underlying disagreement.

      Let's call these energy sources "variable-output," if that's your preferred term. The fact that wind is a variable-output energy source is a technical challenge, but as you and I agree, not an insurmountable -- or even a particularly difficult -- one. It will be solved by engineering.

      1. Expert Member
        Dana Dorsett | | #6

        I'm not really trying to start a fight, but the "intermittent" characterization has been intentionally politicized by the incumbent industry, and I prefer to use more nuanced & careful language than the terms used in fossil fuel industry talking points, terms intentionally chosen to evoke a sense that renewables are somehow not secure or can't be relied upon.

        The terms "intermittent", and "unreliable" don't correctly describe wind & solar, but that's how they are often described by those with a pro-fossil (and sometimes nuclear) generation agenda. Short of widespread transmission line failures you can't lose a gigawatt of wind or solar in a few milliseconds, the way it can if a tornado rips through a large coal or nuclear plant's interconnect. When Rick Perry's DOE tried to conflate "reliability" with "baseload" and having 90 days of fuel on hand the FERC rightly shot it down, but it's all part of the same inside-energy game being played by the fossil fuel interests.

        The terms "intermittent" and "variable output" are NOT synonymous- not even close. Most gas fired powerplants have highly variable output, and even coal & nukes are somewhat variable output. Shall we call them "intermittent" too?

        The real distinction is fully dispatchable vs. sometimes not fully available. Typical combined cycle powerplants run at an annual capacity factor comparable to midwestern wind, and less than what is anticipated for offshore wind, but the cc gas can be cranked up & down to follow the average grid load, whereas renewables can only be cranked down (curtailed), and only when available. From a grid management point of view predicability of the variable output resources and the variable load are far more important than mere dispatchability.

        That said, solar + batteries to make the solar more dispatchable is are already cheaper than simple cycle gas peakers in most of the US, cheaper than keeping existing coal plants running in some parts of the US, even without subsidy.

        Dispatchable load is becoming an important grid management tool tool (since FERC Order 745 was blessed by the Supremes a few years ago), which at scale can and will ease the transition to variable output less-dispatchable resources too. As more electric cars are sold, smart car chargers have the potential to soak up a huge amount of mid-day solar excess or overnight wind excess for grid-balancing purposes. This is already being done in Norway & Denmark, though it's still in it's infancy. In Denmark EV owners are paid to stay plugged in, and in some cases paid extra if 2-way power flows are allowed, using the EV battery to provide a modest amount grid power for frequency & voltage support. The power draws on those EV batteries are pretty modest compared to accelerating onto a freeway ramp, and don't have much affect on battery life, but the EV owners are compensated enough to cover any battery degradation that can theoretically occur from that use.

    2. AndyKosick | | #9

      I recently pointed out somewhere else that we've had a pumped-hydro plant operating up here in Michigan since the 70's, before there were any significant renewables on the grid. The variable nature of the wind and solar get bad mouthed seemingly without a realization that demand has always been variable. Which is to say that storage has always made sense it just looked expensive because we have been able to abuse cheap fossil fuels by subsidizing and externalizing some of the most significant costs.

      1. Expert Member
        Dana Dorsett | | #10

        >"I recently pointed out somewhere else that we've had a pumped-hydro plant operating up here in Michigan since the 70's, before there were any significant renewables on the grid."

        In California during the 1960s when the Diablo Canyon nuclear plant was being proposed it became clear that it needed a large dispatchable load to flexibly suck up the overproduction during off-peak hours. Nukes can be turned down fairly rapidly, but can't be ramped back up in just a few hours- it takes several days. To make the Diablo Canyon project viable the Helms Pumped Storage hydro facility was built at the same time to create that grid-balancing dispatchable load.

        Long story short, large slow-ramping baseload plants need grid storage (or dispatchable load) every bit as much as wind & solar do.

        But pumped storage doesn't work everywhere. It needs both reasonable topography and available water resources, and reasonably proximate access to the grid, all things that Norway have in abundance.

    3. bje11 | | #12

      Another region to watch is the South Australian region of the Australian National Electricity Market which has fairly limited interconnection to the main east coast grid. Yesterday, rooftop PV supplied around 50% of the midday load and wind supplied around 60%. The surplus 10% was exported across the interconnector. This happens with increasing regularity. You can see plots here:

  4. kevin_in_denver | | #8

    Anyone interested in the grid use of EV batteries can google V2G or "Vehicle to Grid"

  5. fwsolar | | #11

    Interesting article and an excellent view into some of the better ways of making electricity. But...

    Even though I run a (small) solar installation business, I'm left to wonder whether deployment of renewables are distracting us from the real challenge: drastically reducing consumption in the west, and perhaps also getting comfortable with some domestic power intermittency.

    I'm very comfortable with the idea that renewables are the best way to run the massive industrial program that might be termed "domestic electricity." And, I'm comfortable with the notion that some domestic electricity is a net positive for humanity, full stop.

    But I'm increasingly uncomfortable with the scale of the industrial program itself, and the truly massive use of resources implied by an effort to transition the insatiable electricity demand of western cultures to renewables. In most articles I read, this is presented under the banner of preventing a climate disaster, as though rapid deployment of renewables has the potential to allow us to continue on our merry way. In my estimation, nothing short of a sea-change in the way we run our society has a reasonable chance at averting a large-scale climate catastrophe (a medium-scale climate catastrophe being already baked in the cake and essentially unavoidable).

    To borrow an analogy from aviation: renewables have the potential to lengthen the glide path and reduce the force of impact. They do not have the potential to keep the plane in the air.

    Nevertheless, we must do what we can, and the efforts you highlight here are laudable and worthy. As you make clear at various points in the article, the climate is changing now, the challenges are daunting and the task of avoiding "runaway" climate change is really the task at hand. It may not be possible, in fact. If it is, articles like this add another weight on the positive side of the scale, and thanks for that.

  6. lutro | | #13

    It's hard to write an article on this topic without attracting a lot of opposition. I'm grateful, Martin, for the information you provided on the specific cases that you examined. I'd like to offer a couple of comments and a link on renewables more generally. Like Dana, I am concerned that misinformation is common, and tends to exaggerate the costs and problems with renewable electricity generation.

    While every action has a cost, so does most inaction, in the field of energy. Many people are not aware that new records are being set every few months for large-scale contracts to deliver solar and wind electricity plus storage at amazingly low prices. For example, in September 2019, I read that the Los Angeles Department of Water and Power (LADWP) and Glendale Water and Power had signed a contract with Eland Solar and Storage Center for 400 MW of new generation with 300 MW / 1,200 MWh of battery storage, at a price less than 2 cents per kWh.

    This is the best price I have seen, but prices under 3 cents per kWh have been announced in various US locations for several years. These new contracts for renewable electricity plus storage show that it is incorrect to state, as mainstream press articles tend to do, that renewable costs are too high, and that storage is impractical or too expensive. I agree with Brian Bailey that society can't continue its profligate ways, but big increases in renewable energy generation combined with storage are a piece of the sensible and economically advantageous path forward.

  7. JustHousing | | #14

    The Fall 2019 issue of Catalyst, the quarterly publication by the Union of Concerned Scientists (UCS), has an excellent article on this topic. Titled "Clean Energy + Battery Storage = Game Changer" and written by Elliott Negin, it makes the case for two integrated major national changes and investment: updating our aged electricity grid and pouring money into R & D for grid-scale energy storage technologies. Grid improvements, he argues, need to be designed to allow for distributed generation, variable (renewable) energy sources, and advanced storage technology. UCS is engaging in efforts with industry and government to advance such a plan. The article isn't online yet, but you can get your subscription to Catalyst by donating here:

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