Comments on: Wind Integration: Incremental Emissions from Back-Up Generation Cycling (Part I: A Framework and Calculator)

By: Kent Hawkins

Kent Hawkins — Sat, 11 Feb 2012 20:38:28 +0000

Calculator Updates

Anyone coming across this as their first reference to my calculator you should be aware that updates have been provided, first at http://www.masterresource.org/2010/02/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-v-calculator-update/, and subsequently at http://www.masterresource.org/2010/11/the-calculator-14-results-part-i/ .

By: T. Boone’s Windy Misadventure And the Global Backlash Against Wind Energy | Toronto Wind Action

Mon, 30 Jan 2012 17:36:30 +0000

[...] In November 2009, Kent Hawkins, a Canadian electrical engineer, published a detailed analysis on the frequency with which gas-fired generators must be cycled on and off in order to back up wind power. Hawkins findings: the frequent switching on and off results in more gas consumption than if there were no wind turbines at all. His analysis suggests that it would be more efficient in terms of carbon dioxide emissions to simply run combined-cycle gas turbines on a continuous basis rather than use wind turbines backed up by gas-fired generators that are constantly being turned on and off. Hawkins concludes that wind power is not an “effective CO2 mitigation” strategy “because of inefficiencies introduced by fast-ramping (inefficient) operation of gas turbines…. [...]

By: Kent Hawkins

Kent Hawkins — Fri, 02 Dec 2011 22:07:23 +0000

Andrew,

Interesting comment on magnitude, as no one knows the magnitude of the inefficiency of gas turbines in the wind mirroring role. Well that’s not true, because I have indications that some people do know, but they are not saying, publically.

That is why in the technical appendix I show a range of inefficiencies (heat rate penalties), so your comment is bordering on the non applicable.

You do raise the matter of newer gas turbine technologies and cite a 30 minute ramping capability. It’s not clear what this means. I suspect that you mean from start-up to full power. I think you will find that only a few cycles a day are assumed, versus hundreds.

Another point in this regard is that the ramping requirements to mirror wind are in much smaller time intervals – from seconds to a few minutes, and importantly, continuously 24 hours a day – except of course when the wind plants are not producing or are curtailed. You should revisit your point on the full implications of this impact on efficiency, as well as the maintenance burden of this constant load change. Compare mirroring wind to driving a car on the highway and alternately pumping the gas and brake on a continuous basis. Imagine the gas efficiency.

Regardless of the capabilities of newer gas turbine technologies, as already stated, wind requires these to mirror its volatile output on a continuous basis. This represents a duplication of capital costs to produce electricity that the gas turbines could supply on their own.

One also has to consider the transmission requirements of duplicating wind with gas turbines – no matter how efficient. We require substantial (and otherwise unnecessary) electric grid upgrades to gather the widely dispersed wind energy source and transmit it over large distances to demand centers. As well, the wind balancing will have to be done rather locally due to grid topology considerations. This likely means a dispersed network of gas plants for this purpose, which will require additional gas transmission/storage facilities. Think of these unnecessary additional costs and difficult permitting process for these.

Incidentally, the calculator has been updated so the results change somewhat but not materially. The latest is at http://www.masterresource.org/2010/11/the-calculator-14-results-part-i/

In short you have a lot of work to do to support your thoughts here.

By: Andrew Ponec

Andrew Ponec — Fri, 02 Dec 2011 17:11:30 +0000

I have to disagree with the magnitude of the inefficiency of gas turbines relating to ramping rate. While this effect is significant, and does require study, newer technologies have reduced the need for inefficient OCGT to rapidly respond to changing demand/wind production
For example, GE’s new Flexefficiency combined cycle gas turbine is one of the most efficient on the market (>60%) and can be ramped in 30 minutes.
These advances in turbine technology will allow significantly more variable renewables to be integrated into the grid without excessive file burn/emissions to compensate for wind variability.

By: T. Boone’s Windy Misadventure And the Global Backlash Against Wind Energy « Ontario's Wind Performance

Fri, 29 Jul 2011 15:35:20 +0000

By: On the Global Backlash Against Wind Energy, Vinalhaven Included « Fox Islands Wind Neighbors

Fri, 29 Jul 2011 02:50:45 +0000

By: KHawkins

KHawkins — Sun, 19 Sep 2010 19:39:15 +0000

My response to the comments by Anatomy of a Wind Myth have been delayed due to the press of other activities. There is little merit in the analysis and knowledge of the matters raised by the author of “Anatomy”, and this will be dealt with quickly here. Here are some highlights:

• The author depends extensively upon ad hominem arguments, which is a very questionable tactic in this type of discussion.
• I did not help write the le Pair and de Groot paper. Their method of analysis is quite different from that used in my calculator. I did point out some mathematical issues in one of the tables, which the authors acknowledged, and they do cite one of my papers. Neither of these, or both together, is hardly evidence that I “helped to write” their paper.
• The author points out the presence of a reasonable, standard warranty disclaimer in the Bentek report, which is presumably done in an attempt to cast doubt on its results.
• In the analysis of the Bentek Colorado case, he makes the all-too-frequent, and ill-informed, mistake of assuming the fossil-fuel electricity production is directly related to emissions. The two are not well correlated, say year over year, for many reasons including changes in: (1) the mix of fuels, (2) actual despatch of available generation resources, (3) net interstate trade in electricity, (4) introduction of new plants and retirement of old, and (5) installed technology that improve the efficiency of a plant or that incorporate technologies for removing emissions. A good example of this can be seen at http://www.masterresource.org/2010/09/windpower-overblown-part-ii/#more-11930 in Figure 3.
• In his criticism of the Bentek Colorado analysis (some of which is reasonable), he does not mention their analysis of the Texas case, which confirms the admittedly more limited Colorado results.
• The author does not understand the Katzenstein and Apt study. His points are addressed in Part II to this post at (http://www.masterresource.org/2009/11/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-ii/ and with a more careful look at the cited report. Katzenstein and Apt properly point out the limitations of their analysis. The casual reader might miss this.
• With respect to the Milligan report, see my critique of this at http://www.masterresource.org/2009/12/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-iii-response-to-comments/
• As I have pointed out elsewhere (http://www.masterresource.org/2009/12/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-iii-response-to-comments/ , the correlation of production between wind plants up to distances of 1,000 km, and more, is still positive. Zero correlation would produce a random result with increased range of variation. Any smoothing effect would require significant negative correlation. As in the case of help from improved forecasting of wind well in advance and for short time intervals (significantly sub-hour) is a faint hope.

In summary, there is not much in the way of bones in this “anatomy”.

By: Anatomy of a Wind Myth « Decline of the Logos

Anatomy of a Wind Myth « Decline of the Logos — Mon, 23 Aug 2010 15:57:16 +0000

[...] This implies that adding wind to an electricity grid that contains lots of old coal plant would not result in many emissions savings. Unfortunately for Bentek’s analysis, the emissions from Colorado’s electricity generating plant have been decreasing since wind came onto the system, by nearly the same amount as the added wind capacity. Wind events of the magnitude used by Bentek’s report are rare – far more common sources of cycling are daily changes in demand levels, which you can see in Figure II-7 in Bentek’s report. Indeed, Bentek did not present us with the changes in generation for the days they analysed beyond the times of the wind event, making it very difficult to claim that only that event caused the rise in emissions. It’s therefore not clear at all that cycling caused by wind leads to a net rise in emissions even from old coal plants. However, this doesn’t stop Kent Hawkins from claiming that using gas to balance wind leads to a net increase emissions. [...]

By: Cape Wind: costs rising fast @ Coalblog

Cape Wind: costs rising fast @ Coalblog — Thu, 13 May 2010 07:44:07 +0000

[...] Natural gas used as wind back-up in place of baseload or intermediate gas (in the absence of wind) results in approximately the same gas burn and an increase in related emissions, including CO2. Extrapolating from this example to the whole, the working hypothesis is that intermittent wind (and solar) are not effective CO2 mitigation strategies because of inefficiencies introduced by fast-ramping (inefficient) operation of gas turbines for firming otherwise intermittent and thus non-usable power. [...]

By: Emissions Savings References - Wind Farm Realities

Emissions Savings References - Wind Farm Realities — Tue, 06 Apr 2010 22:10:12 +0000

[...] Part 1 [...]