Sunday, December 04, 2011

The Problem with Levelised Cost Comparisons of Energy Generation

“Levelized cost” is a way to compare different electrical generation technologies. It is calculated by converting all of the capita costs and ongoing expenses for the project into current dollars, and dividing that by the amount of energy produced over the lifetime of the plant. For the mathematically inclined there’s a discussion of the various inputs and calculations here. Levelized cost is the all-up cost per kilowatt-hour of generated power. The levelized costs in Fig. 1 include transmission costs but not the costs of backup for intermittent sources. _WUWT


The featured article today was written by Willis Eschenbach and published on the excellent climate website Watts Up With That. One should read the article in its entirety (follow the links provided at the end of each excerpt) to understand that Willis' main point is that solar power will not be economical within the foreseeable future.

He provides a large graphic of levelised costs comparing a wide range of different power sources, which appears to suggest that wind power has already become economical based upon its levelised cost. But as Willis explains, levelized costs leave out some critical factors which a wise energy planner would never neglect to include in his calculations.

The costs for backing up wind power, and the extra maintenance costs of big wind, are just the beginning of the problems with wind power compared with gas, nuclear, and coal -- and just two critical factors ignored by "levelised cost comparisons." John Droz clarifies these points more thoroughly in his slideshare presentation -- well worth viewing.
....this doesn’t include the fact that when you add an intermittent source like solar to an electrical grid, you have to add conventional power for backup as well. This is so you will be sure to still have power during the time when the sun doesn’t shine. Even if you never use it, the backup power will increase the cost of the solar installation by at least the capital cost of the gas plant, which is about two cents per kWh. That brings the levelized cost of solar, IF panels dropped to a levelized cost of only one penny per kWh, and IF the backup generation were never used, to 19¢ per kWh … and that’s way more than anything but offshore wind and solar thermal.

However, it gets worse from there. The cost of fuel for the gas advanced cycle power plant is only about 4 cents per kWh. So even if gas prices triple (which is extremely unlikely given the advent of fracking), the gas plant cost will still only be about 14¢ per kWh, which is still well below even the most wildly optimistic solar costs.

...I suspect that the maintenance costs for wind power are underestimated in the report, that in fact they are higher than the EIA folks assume. For example, both wind and water are free, and the EIA claims that wind and hydro have the same operation and maintenance cost of about one cent per kWh.

But with hydro (or almost any other conventional technology) you only need to maintain one really big generator on the ground.

With wind, on the other hand, to get the same amount of power you need to maintain dozens and dozens of still plenty big separate generators, which are stuck way up at the top of really tall separate towers … and also have huge, hundred-foot (30 m) propeller blades whipping around in the sky. You can imagine the trek you’ll have when you forget to bring the size #2 Torx head screwdriver …

Do you really think those two systems, both feeding the same amount of power into the grid, would cost the same to maintain? Check out the windfarms and count how many of the fans are not turning at any given time … _WUWT

There is no way of compensating a utility for the fact that a wind farm rarely produces its nameplate capacity when it is needed -- during peak load times. It happens less than 10% of the time -- which makes a mockery of the claimed "capacity factor" for wind of between 0.2 and 0.3.

Required power backup for intermittent sources is far more expensive than just the capital and operating costs of the plants themselves. You must also factor in the costs to the utility of balancing the intermittent sources plus the dispatchable sources plus the baseload sources with the ever-changing demand. It is a tricky business, and the government mandated requirements to use expensive and unreliable wind and solar makes it that much trickier. Finally, you must include the costs to the economy as a whole, as the quality and reliability of provided power declines.

Maintenance costs for wind are also higher than even Willis suggests. Machines typically do not last to the designed lifespan, and those that do last that long typically require multi-million dollar replacements of expensive bearings, gearboxes, electronics, etc. somewhere along the way. Quite a bit of bother for machines that one can rely on for peak load power less than 10% of the time.

As for Willis' argument against big solar power, it is likely that the genuinely disastrous aspects of investing in big solar will be discovered along the way. We do not have as much experience with the utter futility of big solar power as we do with big wind. But we will. Oh yes, thanks to the carbon hysterics and dieoff.orgy lefty-Luddites, we most certainly will.

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Blogger Whirlwind22 said...

This in a way seems to make the doomers vindicated in their belief that we cannot run our current civilzation without "cheap" energy. Can renewables ever run our civilization? Since I mean one day the fossil fuels will run out.

10:36 PM  

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