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Sunday, April 23, 2017

Renewables and storage

The new administration in the US is taking a leaf out of the rabid right so-called Liberal Party's playsheet in Oz, suggesting that renewables can't be integrated into the grid, because (a) they're variable, and (b) our paymasters in coal want to stop the renewables revolution.

These two videos are instructive about just how you integrate large percentages of renewables into the grid without having to also install storage.   (At least when renewables grid penetration is under 50%--my guess is that some storage will make the grid operator's task much easier when renewables start to exceed 50% and will be essential at 100%.)

The key points are:

  • Because the grid is already designed to handle the potential failure of one or more large "baseload" generators, it can handle the variability caused by renewables
  • Diversifying the sources of renewable electricity helps: solar PV, solar thermal (CSP), wind and biomass can together produce electricity as stable as old-fashioned baseload power stations
  • For the last 10% or 20% of renewables penetration (i.e, going from 80 or 90% renewables to 100%), demand management is critical
  • Below 10% penetration, renewables require no special provisions.  The real change is not technical but in the mind--how to handle renewables as part of the grid.  It used to be firmly believed that renewables could not exceed 5% of the grid, but that was wrong.  In many regions, renewables exceed 25% of electricity generated without problems.
  • To increase renewables from 10 to 30 or 40%, good forecasts are essential.  If we know ahead of time the likely output from wind farms and solar we can plan for gaps.  
  • From 40% on, the cheapest way to diversify supply is to increase grid connections.  
  • Wind turbines are "perfect" for maintaining the frequency of the grid when a power line goes down (or a big fossil fuel generator trips)  Some engineers maintain that this service (FCAS -- frequency control and ancillary services) can't be provided by renewables.  The engineer in the video makes it abundantly clear that they can.

The first video is a little out of date.  Since it was made solar has dropped 50% in prices and wind 30%.

The second is from an interview with the head of 50Herz, the German grid operator for what used to be East Germany.


 Listen for his confident assertion that integrating renewables into the grid is easy. This video is a couple of years old, now, and since then the percentage of renewables in the East German and pan-German grid has increased further.

[Read more here]

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