Sorting out some claims about Danish wind power

Michael Giberson

A shortened version of Michael Trebilcock’s commentary on wind power, mentioned here the other day, was published in the Financial Post under the not so subtle title of, “Wind power is a complete disaster.”

The Financial Post subsequently published a reply by Sigurd Lauge Pedersen, a Senior Adviser to the Danish Energy Agency: “Wind power works.”

Trebilcock is back in the Financial Post with “The myth of the Danish green energy ‘miracle’.”

Pedersen begins, “It is perfectly legitimate to hate wind power. But it is more convincing if you do your homework first.” Trebilcock, in his reply, begins by casting aspersions on the Danish government’s sensitivity to criticism of their wind power experience. Both authors have some helpful points to make, but I object to the unnecessarily strident and snide tone of the exchange. (Hey, that’s what blogs are for! -ed.)

If Pedersen had done his homework, say by reviewing the Arthur Campbell paper cited in Trebilcock’s submission to the Ontario Legislative Committee on the Green Energy Act (mentioned in the original op-ed), Pedersen would have realized that claiming wind power raises CO2 emissions is not absurd. Instead it is merely unlikely.

If Trebilcock were more careful, or maybe if he understood wind power better, he’d have avoided the modest non sequitur of, “Most wind turbines run at about 25% of rated capacity, requiring back-up generation for the balance of the time.” No one, so far as I am aware, expects to get a constant 100 percent of nameplate capacity delivered from their wind power (or any other) generation, so what “balance of the time” is he referring to?

It is well known that “facts” circulating in public discourse sometimes stray from their original meaning, so it is sometimes useful to track down sources.  In the continuation I try to sort out two disputed claims made by Trebilcock in his first Financial Post op-ed.

One factual matter of dispute is whether or not Denmark has closed any fossil fuel plants as it has added wind power capacity. (Treb.: “Denmark … has yet to close a single fossil-fuel plant.” Ped.: “There is no citation for this claim, which is wise, in a sense, for the claim is wrong. Denmark has closed several coal and oil fired plants in the last 10 years.” Pedersen offers no citation to support his claim.

Trebilcock and Pedersen also debate whether or not C02 emissions have gone up due to wind power. (Treb.: “[Denmark] requires 50% more coal-generated electricity to cover wind power’s unpredictability, and pollution and carbon dioxide emissions have risen (by 36% in 2006 alone).” Ped.: “Trebilcock claims that CO2 emissions went up by 36% in 2006 as a result of wind power. This does not make sense.  …the claim that wind power increases CO2 is absurd.”)

On both points, Trebilcock in reply said, “These claims are literally quotations from a recent detailed study by Tony Lodge, a widely cited writer on European energy policy.”  Excellent. The reference to Tony Lodge is the closest thing to a citation in this exchange, so I went looking for this “recent detailed study.” It turns out that Lodge is a “political and energy analyst” at the Centre for Policy Studies in the U.K. The “recent detailed study” is presumably Lodge’s report, “Wind Chill: Why wind energy will not fill the UK’s energy gap,” published last year by the CPS.

In “Wind Chill,” Lodge said, “not a single conventional power plant has been closed in the period that Danish wind farms have been developed.” (p. 6) Unfortunately, the claim is not backed up with any sort of reference. Examining the Danish Energy Agency’s report, Energy Statistics 2007, it is clear that Denmark had very little wind power in 1980, but significant wind power in 2007 (output of 38 terajoules in 1980 and 25,823 terajoules in 2007).  On the other hand, consumption of oil for electric power production has fallen (from over 47,000 TJ in 1980 to just over 11,000 TJ in 2007); as has consumption of coal (from near 214,000 TJ in 1980 to almost 167,000 TJ in 2007). If you’d rather think in gigawatt-hours rather than terajoules, you can divide the TJ numbers by 3.6 to get GWh.

I don’t find reports on numbers of powerplants, or plants retired, but it is hard to believe that “not a single conventional power plant has been closed” since 1980, given the reduction in output. Or else all of those oil-fired plants are operating with a poorer capacity factor than wind power in Denmark.  I’ll score Lodge’s claim about powerplant closures as undocumented, and agree with Pedersen that there is no citation for this claim (And Trebilcock’s claims are not “literally quotations,” and I’m not sure I’d characterize “Wind Chill” as a “detailed study”, either).  Of course, as noted, Pedersen doesn’t cite a source for his counterclaim, either.

On the second point Lodge said, “For example, the Danish grid used 50% more coal-generated electricity in 2006 than in 2005 to cover wind’s failings. The increase in the demand for coal, needed to plug the gap left by under performing wind farms, meant that Danish carbon emissions rose by 36% in 2006.”  (p. 7) This remark does come with a citation, “Energinet (Danish grid operator journal), February 2007”, I haven’t been able to trace that exact reference. However, the Energinet “Environmental Report 2007“, dated July 2007, does indicate that coal use and CO2 emissions increased in 2006 over 2005, but the report attributes the increases to the dry year (low hydro power condition) in the Nordic countries rather than to “under performing wind farms.”

In any case, writing in 2008, Lodge should have been aware that in 2007, Danish wind power capacity increased a little (comparing to 2006), Danish wind power output increased notably (from 15.8 percent of domestic electricity supply to 18.8 percent), and Danish power output from coal was off significantly (from 53.9 percent to 50.8 percent).  Sometimes there is a lot of hydropower in Norway and Sweden, and imports in Denmark (some re-exported further south) go up, mostly displacing fossil fuel generation. Sometimes there is not so much hydropower, and fossil fuel generation mostly takes up the slack.  It happened that 2006 was sort of an atypical year, which gave Lodge a dramatic number on emissions which he missatributes to wind variability, and Trebilcock repeats. I’m scoring Lodge’s claims on increased coal use in 2006 “to cover wind’s failings” as entirely misleading. Trebilcock was unwise to rely on this misleading claim. Pedersen’s counterclaims, “makes no sense,” “absurb,” suggests that he hasn’t looked too closely at the related literature. (As I noted in the earlier post, the best answer seems to be “It depends.”)

Sloppy, unscholarly, unscientific, and in sum, unreliable.

In all I find the exchange a little frustrating, but I suppose I shouldn’t look to partisan exchanges in newspaper columns for carefully supported facts and opinions.


5 thoughts on “Sorting out some claims about Danish wind power

  1. “However, the Energinet “Environmental Report 2007“, dated July 2007, does indicate that coal use and CO2 emissions increased in 2006 over 2005, but the report attributes the increases to the dry year (low hydro power condition) in the Nordic countries rather than to “under performing wind farms.””

    There is a point here which is too important to ignore: “source of opportunity” power sources require conventional backup for the periods when they are unavailable.

    Hydro, as I have argued here previously, is in part “reliable power” and in part “source of opportunity” power. The difficult issue, as BPA discovered several years ago, is accurately allocating installed hydro capacity between “reliable” and “source of opportunity”. The Danes were fortunate that they had conventional capacity available when hydro availability declined as the result of low precipitation. Hopefully, both they and BPA have reevaluated the fractions of “reliable” and “source of opportunity” power available from their hydro capacity.

    Wind, on the other hand, is exclusively “source of opportunity” power, used when it is available and substituted for when it is not. Wind also tends to be most available during periods of low demand, as Mike’s posts regarding ERCOT West have illustrated.

    While it is true that no power generator is available 100% of the time, the difference between a 90+% capacity factor and a 20+% capacity factor has a significant impact on system planning.

  2. Not sure how they handle things in Denmark but in the U.S. natural gas plants have to be used to level out fluctuations in weather-dependent power sources. It’s very likely that Denmark has had to do the same thing. A lot of the gas imported from Russia now goes to electricity generation. This could well mean that Danish CO2 production has used more windpower.

    Weather-dependent power require at least a 70% non-weather-dependent back up just to keep the lights on. Depending on conditions, it might be prudent to plan on 100% backup. This makes it highly unlikely that windpower will produce the CO2 saving advertised.

  3. I do long-term power scenario modeling for a living. One of my findings is that above a certain level of wind penetration, it causes a shift from coal to gas generation, for a couple of reasons: build enough wind, and some baseload coal plants will be pushed up the stack into intermediate-operation territory. It is very difficult and expensive to run big coal plants in intermittent operation, so some of them will retire. This means that the remaining baseload part of the retired coal units is replaced by gas. Also, you have to run peakers more frequently to deal with wind volatility. So you’re likely to see new gas-fired combined cycle units being built to meet baseload requirements and new gas-fired peakers being built (and existing ones run more often.)

    Since gas releases 40% the CO2 of coal for the same amount of energy released, and since gas CCs have a better heat rate than the coal they’re replacing, you will see a modest reduction in carbon ceteris paribus, but given any sort of “normal” load growth (0.5 – 1.5% PA), all that fuel shift does is slow down the growth of emissions, it certainly does not abate them.

    To get significant carbon reduction you need several things: a drastic reduction in load growth (between zero and 0.2% growth) coupled with an onerous carbon tax – maybe $50/ton, which will cause widespread coal retirement, coupled with huge builds of wind and gas-fired generation to replace the coal. This will not be cheap – you can expect the marginal cost of wholesale electricity to go up to maybe $100/MWh (from the current $30-$40), and we also have to figure out a way to socialize the “hundreds of billions” cost required to build this new generation slate.

    We like to think of the current slate of energy bills as the “Energy Analyst Lifetime Employment” bills.

  4. Although there is very little factual information in these articles it appears that Sweden and Norway do at least some of the frequency regulating for the Danish system. Hydro, providing an adequate amount is available, can respond very rapidly to changes in the flows on the interconnection. If a suitable interconnection agreement is in place inadvertent interchange brought about by the rise and wane of wind power can be a win-win situation for both parties.

Comments are closed.