The Ergosphere
Sunday, October 04, 2015

How unreliable is wind?

Someone on The Energy Collective suggested that 24/7/365 facilities like data centers could run on "renewable energy" (meaning unreliable wind and solar) by taking the first pick of power from a wind farm or other facility and letting others take the surplus.  Specifically, he said this:
The wind farm that HP is drawing from is 300 MW. If they get first dibs on generation,it's not out of the question that 95 percent of the time it will generate more than 112 MW which would be a 37 percent CF.
Is that true?  I decided to find out.

Here's a plot of Texas wind generation over March of 2014, courtesy EIA:

I cut this down to a 143-by-489 area (69927 px²) of just the plot itself trimmed down to the production maximum, and used Gimp's histogram function to measure the red area.  It came to 32026 red pixels.  If we assume that the production peak was 100% of nameplate (unlikely, but it's favorable to the case) that's a capacity factor of 45.8% for the month.

45.8% of the 143 pixel height is 65.5 pixels.  Cutting the graph down to 65 pixels from the baseline yields this:

The curve never quite goes to zero, but it gets close to it several times; it stays very low for an entire day.  Even the wind across the entire state of Texas, cut down to its capacity factor for the windy month of March, is not reliable enough to keep data centers running; the net capacity factor for the entire state of Texas is just 73.9%, far less than the 95% assertion of "wind smith".  The infrastructure of an information economy needs reliability more like 99.99%.

But what's left over?  Here's what that curve looks like:

In the windy state of Texas, in March 2014, the "leftovers" from preferred loads taking everything up to 45.8% of the peak has a capacity factor of just 22.1%.  It's a very spiky curve that has gaps lasting days when there is little or no power available.  What sort of business or process could anyone operate using power that was so unreliable?  I can't think of one.  Maybe you could dump this power to heaters or some other extremely cheap load, but what you'd do with the heat I'm not sure.  At one point I had the idea of using surplus electricity to heat crushed concrete, with the goal of dehydrating the cement and converting it back to separate streams of cement, sand and aggregate for recycling into new concrete.  I don't know if this is chemically possible (does hot cement react with sand or otherwise become inseparable and unusable?), but at 22.1% capacity factor the kilns and sifters and whatnot would have to be very cheap to make this a workable proposition and you'd have to get the power for close to nothing.

"Renewables" fanatics (maybe I should start calling them "windbags")  like to say that the wind is always blowing somewhere.  At least for Texas in the month of March 2014, that much was true.  However, there were many periods even in that blustery month where it was certainly not blowing hard enough to keep essential 24/7 things running.  When it comes down to e.g. pumping stations filling up and backing raw sewage into homes and buildings because the unreliables are not there that day, even the most fanatic Green is likely to burn fossil fuel instead.

The unreliable sources of energy are simply not going to replace fossil fuels.  They can't; their characteristics make it an engineering impossibility.  This is why Greens need to drop their contrived objections to those sources of energy which actually can.

I think it is overly simplistic to label all advocates of renewable energy as "Greens" and then dismiss them.

It is similarly over-simplistic of these "Greens" to say that all "non-renewable" sources (e.g., petro, nuclear, etc.) are to be avoided, period, as you rightly inferred in your post.

In reality, however, a combination of renewables and non-renewables is an essential interim solution.

- Petroleum will not be available forever
- Renewables like wind, solar, hydro and even (arguably) nuclear) must be utilized in increasing amounts as petroleum becomes more and more difficult to mine, and ultimately runs out.
- The carbon footprint of all-petroleum electric grid is unsustainable, because it will eventually run out and the carbon emitted by such a grid will continue to damage the environment and exacerbate climate change.

If you disagree with any of the above bullet points, then we are at loggerheads and I don't know how we will ever go forward.

The rational solution MUST involve building renewables into our grid as much as is economically feasible (with gov't. subsidies as an unavoidable collateral necessity), but with a concentrated and on-going research initiative studying energy storage.

Currently, we have pumped-hydro, battery-based, flywheel-based, compressed air-based storage techniques. Fuel cell technology can be considered as partially renewable, because current designs still involve methane or other simple hydrocarbon fuels, which do not have a zero carbon footprint.

There is no single solution. Some are geographically limited, some are simply too expensive, and some have well-known environmental impacts of their own to overcome.

Only when we have solved the energy storage problem will it be possible to rely on just renewables. HOwever, we cannot forget that without renewables, our society is eventually doomed to having no practical source of energy by some point this century and/or no livable environment left in which to continue human history.

This is NOT a suitable matter for "Greens" (progressives) and petro-friendly conservatives to endlessly argue partisan political talking points. It involves an existential threat to human society and even, eventually the survival of all life on earth as we know it. This issue is too important to allow it to devolve into just a shouting match between progressives and conservatives.

For those of you interested in investigating energy storage more fully, you can start here:

Franklin J. Rudolph, PhD, PE
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