Denmark breaks even, for a short time, using just wind power

When wind power is spoken of in the US, it is as a source of unreliable auxiliary power that supplies a small fraction of the total energy needs. Hence I had always viewed it as a fringe source of power that did not have the long term potential of solar power as an alternative to fossil fuels.

So this report that says that Denmark uses wind power to get more than 100% of its total needs took me by surprise. It is true that it was for just one day, a Sunday evening when the power consumption is relatively low, but still that is impressive. But Denmark is rapidly approaching a time when wind power will be able to meet even peak power consumption needs on weekdays.

We clearly see why Denmark has a more ambitious target for its energy transition – 100 percent renewable energy by 2050, compared to “at least” 60 percent renewable energy in Germany by the same year. The Danes have loads of relatively inexpensive wind power, and they plan to store the excess partly as heat simply by running electric heating systems when power is cheap. Eventually, it could also be stored chemically, such as via electrolysis to produce green hydrogen.

One thing that I have wondered about is what effect the large-scale use of wind energy would have on climate. If you are sucking a lot of energy out of the wind, it must have some side effect on other things like wind currents and flow patterns. It may be that the net extraction is small compared to the total amount of energy present in the wind and so has negligible effects.


  1. daved says

    I think wind farms may have some small local effects on wind speed, but the overall global effect is negligible. The biggest environmental effects are on flying creatures that are hit by the turbines: birds and bats. (Of course, the emissions from conventional power plants aren’t exactly good for birds and bats either.)

  2. says

    I don’t think the effect on wind speeds or patterns will be all that great — at least not above the height of the windmills. As for bird-strikes, is there any chance that painting the blades some loud color might scare birds and bats away?

  3. says

    I would expect the loss of wind energy to be fairly small, even if we had them up all over the place. We’re not finding that there’s less wind in the world because so much more of the wind’s energy is pushing against tall buildings than there was 200 years ago, no? It’s just not a big enough factor.

    Denmark is, of course, ideally situated for wind power, being a big flat spot lying across the relatively narrow entrance to an effectively inland shallow sea. Bornholm, especially, has been a wind-generator for a long time; a Danish friend once told me that in school they would joke that Bornholm’s chief import AND export was wind…

  4. elipson says

    When I look the Window from my office in Esbjerg, Denmark, I often see wind mill bodies driving past on their way down to the docks.
    On the plus side wind power is a great boon, but on the negatie side it’s really annoying having to bike i strong winds 😉

  5. Wylann says

    Also, wind turbines don’t affect wind any more (and probably less) than any large building. They are really not much different than a tall tree or similar structure.

  6. says

    It may be that the net extraction is small compared to the total amount of energy present in the wind and so has negligible effects.

    That is correct. Simple illustration:

    Effective scale height of the atmosphere: 8000 km or so.
    Typical wind turbine height: 80 m (a few get close to 200 m)

    So even if the turbines extracted 100% of the kinetic energy from the wind they intercept (they don’t) and even if there were so many that they formed a solid line across the landscape, they would pull out only 1% of the energy in the windfield.

    In practice, we are many orders of magnitude below that.

  7. Rob Grigjanis says

    Not quite so rosy a picture here, but not the final word either;

    In a paper published online Feb. 22 in Atmospheric Chemistry and Physics, Wang and Prinn suggest that using wind turbines to meet 10 percent of global energy demand in 2100 could cause temperatures to rise by one degree Celsius in the regions on land where the wind farms are installed, including a smaller increase in areas beyond those regions. Their analysis indicates the opposite result for wind turbines installed in water: a drop in temperatures by one degree Celsius over those regions. The researchers also suggest that the intermittency of wind power could require significant and costly backup options, such as natural gas-fired power plants.

    Prinn cautioned against interpreting the study as an argument against wind power, urging that it be used to guide future research that explores the downsides of large-scale wind power before significant resources are invested to build vast wind farms. “We’re not pessimistic about wind,” he said. “We haven’t absolutely proven this effect, and we’d rather see that people do further research.”

  8. angharad says

    Here, being South Australia (which is a state not a general area), we get 25% of our base load power from wind. One notably windy day we got up to as much as 80%. When we make that much we sell it on to other parts of the country, so they burn less fossil fuels too. And we’re still building wind turbines.

    We’re also ideally placed for wind farms -- our southern coast basically aligns with the Roaring Forties.

  9. abear says

    There is a lot of energy in ocean currents and if you could site in extremely deep water, there are abundant locations where the currents are constant. “Run of the river” hydroelectric projects that don’t require the dams that traditional hydro does are being built now that make the claim of not interfering with fisheries.
    It would seem the same technology could be used in the ocean on a much larger scale.
    If cost of installation and maintenance issues could be handled, it would seem that a practically limitless amount of energy is available there.

  10. Mano Singham says

    Thanks for the link. So it looks like if we do it on a large enough scale, the effects are non-negligible. There is truly no free lunch.

  11. Corwyn says

    they would pull out only 1% of the energy in the windfield.

    Energy in wind goes up drastically as height increases, so the bottom 80m of 8000m is a lot less than 1% of the total.

    The real question though is, where is the energy coming from and where is it going? Much wind is driven by temperature differences. If we stopped the wind dead, the temperature difference would still exist (only more so since it wouldn’t be mitigated by the wind mixing cooler air). Thus pressure would increase, and we would get *increased* wind.

  12. Lofty says

    Further to angharad:
    South Australia’s excess wind energy export to neighbouring states drives the installation of better interconnectors. West-to-east population spread along Australia’s southern coast means that our wind energy can be used more efficiently over a larger area. Apart from significant west facing coasts, South Australia also has many bare hill ranges trending north-south, ideally placed to capture large anounts of consistent wind energy. Daily summaries of south eastern Australia’s wind farm outputs can be found here.

  13. colnago80 says

    The main argument against both windmills and solar power is, what does one do then the winds are calm or during the night. If the generated power during the up times is greater then the demand, the excess power can be used to hydrolyze water to produce hydrogen and burn the stored hydrogen during down times to generate electricity. In principal, this seems to be feasible, except possible for the issue of cost. Burning hydrogen produces no carbon byproducts, although the heat of the burners might generate oxides of nitrogen.

  14. wtfwhateverd00d says

    Interesting article that is enlightening, though I take it with a huge grain of salt and will look in the future for confirmation. Thank you.

  15. mildlymagnificent says

    The main argument against both windmills and solar power is, what does one do then the winds are calm or during the night.

    There are plenty of avenues to dump surplus wind power when demand is low -- especially overnight. All you need is a responsive switching arrangement for various systems. Street lighting, shop and office lighting as well as advertising displays are obvious channels for a quick response to increases or dropoffs in grid supply. Air conditioning and lighting in warehouses, unused hotel rooms, schools, conference facilities, stadium spaces could all be switched to respond quickly when required. Overnight heating of large hot water systems and swimming pools, changing the temperature of commercial refrigeration and freezing facilities by a couple of degrees -- most of them are adjusted to the most cost efficient safe operating temperature rather than the absolutely ideal operational temperature. There is no exact opposite of any of these for a drop in grid supply, but they’re good start-to-think points.

    The great advantage of solar power is that it’s most in supply when power is most in demand. Afternoon air conditioning in both public and private spaces and household cooking peaks in the afternoon. When you have daylight saving combined with a hot day, this takes a big, big bite out of maximum demand. And if we had any sense, we’d be ensuring that facilities with large roof spaces and very little power use at such times were covered with solar arrays -- schools, stadiums, warehouses, even churches -- to get the biggest advantages from sunny afternoons.

    And both wind and solar will become more and more stable in supply as grid scale, business scale and domestic scale battery storage technologies develop. Along with lots of electric cars as a balancing mechanism -- household or shopping centre or central carparks with power connections for cars can readily be set up to either begin or to cease drawing power from the grid when there are extremely dull periods on otherwise sunny days or when the wind is raging or becalmed at various times and places.

  16. Lofty says

    I suspect that when battery technology becomes cheap enough, most houses will have batteries installed so that they are buffered against sharp changes in demand. Blackouts due to peak demand at 4-6pm in high summer will be a thing of the past. Distributed storage will complement local generation, just as off grid houses already work in remote regions. My friend the country doctor runs a stand alone system on her farm even though power lines run past her property on the town bondary. She just prefers the reliability of having all her own needs met on site, with diesel backup.
    It’s hard to envision grid sized batteries being mainstream but the same questions are posed to all emergent technologies. Decent storage will complement wind and sun energy perfectly.

  17. says

    Important quibble: BURNING hydrogen could create nitrus oxides, if nitrogen from the atmosphere gets into the burning process. Using surplus power to charge hydrogen fuel-cells, then taking power from said fuel-cells when necessary, might not yield nitrus oxides.

  18. Corwyn says

    Everyone loves bringing up this argument. Trouble is, that we have exactly the opposite problem. Currently we have excess power at night, and moving generation to the daytime would make things better. This only works for a while of course, and when we have that much solar, we will have to revisit it. Until then, get over it.

    We would probably be better off using excess renewable energy to produce methane (or methanol) from captured carbon dioxide, than hydrogen.

  19. Corwyn says

    Generally our houses in the US are amazingly inefficient with respect to heating and cooling. Bringing them up to a reasonable standard would not only save money, and energy, but it would also lengthen the response time of the house to changes in outside temperature. This means that the house could be kept at a comfortable temperature by only using energy at off-peak times, and coasting the rest of the day. That alone would probably save 5% or so.

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