Streetwise Professor

March 11, 2019

Another Data Point on the Renewables Fairy Tale

Filed under: Climate Change,Economics,Energy,Politics,Regulation — cpirrong @ 7:39 pm

A coda to yesterday’s post. The EIA announced that in 2018 60 percent of new US electricity generating capacity was fueled by natural gas. This outstripped wind by a factor of almost 3, and solar by a factor of almost 5.

But those ratios understate matters, given that capacity factors for natural gas are about double those for renewables. Thus, in terms of actual real generation, natural gas added about four times as much effective capacity in 2018 as renewables. Not to mention that combined cycle plants are available pretty much on demand, rain or shine, day or night. Unlike the wind and the sun.

This despite the continued subsidization of renewables.

So tell me again how renewables will permit the fossil fuel-free electrification of the economy. I like fairy tales.

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  1. I think you might have understated the disadvantage to renewables. Capacity factors for wind are 20% at best, and 15% is more likely. Capacity factors for simple-cycle gas might be south of 50%, but combined-cycle plants are built as base-load, and they will have capacity factors in the high 80% range as a minimum. I don’t know the mix of simple- and combined-cycle (and can’t be arsed to look it up) but I’d be pretty comfortable with the assertion that gas-fired plants have at least 3x the capacity factor of renewables, and more likely 4x. Not to mention the small advantage of dispatchability – you know, so the lights actually go on when you flick the switch.

    Comment by dcardno — March 12, 2019 @ 1:58 pm

  2. @dcardno–Your numbers are in accord with my understanding, but I erred on the side of caution. EIA and DOE report renewable capacity factors ~40 pct for wind. I don’t believe that, but rather than risk being accused of stacking the case against renewables, went with their numbers. Similarly, EIA reports gas generation capacity factors of ~55 pct. I also understand that mixes simple- and combined-cycle, but again I attempted to be conservative.

    The comparison is bad enough using EIA/DOE numbers–it’s appalling use the more realistic figures you mention.

    And yes, the fact that gas generation is controllable, rather than operating at the whims of the weather, is a huge difference–as I point out in the post.

    Thanks for your comment.

    Comment by cpirrong — March 12, 2019 @ 6:11 pm

  3. Capacity factor for UK offshore wind is reported to be about 37% (rising to 41% for more recent (i.e. taller) units). I can’t imagine that hilltop turbines are any worse, and they’re cheaper to install anyway. Dispatchability is easily solved with batteries (for small peaks) and pumped-storage (already widely used for larger peaks).

    I’m actually not in favour of a wholesale changeover to Wind and Solar (except for low-population density countries with good wind/sun, or where micro-grids are a necessity) but with the technology available we can safely add them to the energy mix in meaningful quantity… if only the green-washers would stop saying that we can go full renewable (the physics are impossible with our current patterns of consumption and current tech) but also if sceptics would stop arbitrarily slashing capacity factors in half.

    Now, whether you WANT to add them to the grid is a political question for which nobody has a 100% guaranteed answer, but we need to stop saying that we CAN’T..

    Comment by HibernoFrog — March 15, 2019 @ 5:14 am

  4. Hiberno – Actually, hilltop turbines *are* worse, for both Cap Factor and average wind speed (and thus power production) – otherwise there’s no incentive to build off-shore, which as you note is much (much) more expensive – both for overnight cost and ongoing operations and maintenance. I went and looked at some data for two on-shore wind farms, one of ~150MW and the other of ~100MW nominal capacity. The bigger one averaged 24% Cap Factor and the smaller one 17% over a six and eight year period, respectively. I don’t claim that they are representative, but at least it’s a couple of data points.
    Batteries and pumped storage can’t come close to smoothing out the peaks and valleys, let alone ‘easily’ – batteries don’t have the capacity at any sort of economic cost, and there isn’t enough pumped storage capacity. Expansion of pumped storage is difficult; it’s obviously site-specific, and the round-trip energy loss is 10-15% between pumping and generating efficiency and head losses in the penstocks. That loss has to be charged against the Cap Factor of the intermittent resource (we don’t do that now when we talk about Cap Factors, but it is an economic cost whether we talk about it or not). Euan Mearns has done some interesting work on storage requirements for intermittents and the feasibility of an all-renewable / storage back-up grid arrangement.

    Comment by dcardno — March 15, 2019 @ 10:12 am

  5. The hazards of being (more than) a little OCD…
    I went to bmreports, which reports aggregated UK electricity market data. The average half-hourly MW wind output in the UK for 2018 was 4,498MW, from a total installed capacity of 18,215MW. The generation isn’t broken down between on-shore and off-shore, although the capacity is – it’s about 2/3rds on-shore, 1/3rd off-shore. The average Capacity Factor is a shade under 25% – of course we don’t know the split between on- and off-shore.
    The maximum CF for the year was 12,073MW, or a CF of ~66%.
    Maybe 2018 was an unusual year in the UK – fewer storms, less wind, long calm periods, etc – I have no idea, but I find a reported ~40% CF to be pretty optimistic. The installed capacity will, of course, include some older and possibly less-efficient turbines, but I doubt that turbine efficiency (as opposed to scale) has improved *that* much over the 15 or 20 year history of large-scale wind generation.

    Comment by dcardno — March 15, 2019 @ 11:36 am

  6. I bet the offshore maintenance costs haven’t been fully admitted over the full life cycle either, especially the decommissioning costs. These used to scare oil companies, so I can’t imagine what subsidy-reliant wind farm owners are doing to the numbers to make them seem palatable. And of course, if the oil price picks up again they’ll be back to competing for vessels and rope-access crews with outfits that lose $10m+ down the back of sofas.

    Comment by Tim Newman — March 18, 2019 @ 6:32 am

  7. Tim – from your lips to Gods ear!
    Yoiu hear about these things from time-to-time, but it just seemed appropriate to include this link:

    Comment by dcardno — March 18, 2019 @ 1:06 pm

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