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Tech Allows Stable Integration of Wind In the Power Grid
diegocgteleline.es writes "One of the most frequently raised arguments against renewable power sources is that they can only supply a low percentage of the total power because their unpredictability can destabilize the grid. Spain seems to have disproved this assertion. In the last three days, the wind power generation records with respect to the total demand were beaten twice (in special conditions: a very windy weekend, at night): 45% on November 5 and almost 54% last night (Google translation; Spanish original). There was no instability. These milestones were accomplished with the help of a control center that processes meteorologic data from the whole country and predicts, with high certainty, the wind and solar power that will be generated, allowing a stable integration of all the renewable power. You can see a graphic of the record here."
But you also need to transmit _a_ _lot_ of power over hundreds of kilometers. Which is not cheap and easy.
That's why local power storage might be the best way to solve this problem.
One trend I've seen in recent studies is toward distributed, decentralised power generation. We're not talking about one technology taking over, but rather a larger number of smaller generators in a variety of formats coming together to augment the primary generators we have. This is already happening to some degree, and expectations are that it will grow.
So as your city grows - instead of (say) three coal generators, you might add one new coal generator plus a few hundred wind turbines, a few thousand gas fired microCHP generators (similar to the Whispergen Stirling units being deployed in Spain) and quite a few thousand private photovoltaic arrays (in Perth for example, the applications for PV installations are running at better than 3 thousand per month at the moment).
The combination of all these will tend to even out the supply across the grid, but there still needs to be fairly careful power regulation at each end point.
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In the short term ( 1 minute), modern wind turbines have a stabilizing effect on the grid. There's quite a bit of inertial energy stored in the wings when the turbines are running which helps handling unexpected faults (e.g. a power line failure). Also, the electronics can supply as much reactive effect as the peak effect of the wind turbines even when the turbines are completely stopped.
Anyway, in the medium term many countries will have to move towards HVDC lines to help the grid. A completely AC synchronized grid like what is common today is too vulnerable to faults spreading, because each power line can only switch on and off. With HVDC you can say "transport 500MW" and it will transport that amount, and if the consumer end tries to sink 1GW, the line will just keep providing 500MW. With AC the line will be forced to provide 1GW or shut down entirely. To make an AC grid work you need a strong central authority who can tell everyone how much to produce and when, and this is incompatible with both a free market for electricity and a large amount of power producers.
Finally! A year of moderation! Ready for 2019?
As Danish Oil and Natural Gas (DONG) utilities clearly figured out - put a REALLY big (distributed) battery on the grid to soak up the power when it's available and re-feed it into the grid when it's scarce. Not only can they produce more of the baseline power generation from renewable sources, they don't have to PAY the Germans to TAKE their excess power at night when they can't consume it. They can store it instead, use it at peak hour when kilowatt price is insane and drastically flatten the curve. Problem. Solution.
As an OT side-benefit, we get electric cars wrapped around said batteries. For what we already got used to paying for car's fuel, there's enough margin in the operator's plan to subsidize new cars for consumers (think free iPhone on a three-year-plan), we'll get a parallel 1-minute-battery-swap-station infrastructure to petrol stations to enable real (non-golfcart) electric cars to go as far as the stations reach (range limitation is station reach, not battery capacity/petrol tank) without hour-long-charges along the way, remove an entire country's addiction to oil, fix the environment by running every single car in the fleet off renewable, and actually allow everyone in town to plug their car in at 8AM without having the lights in office buildings go down (The 'Everyone owns a Chevy Volt' scenario), while not having to spend tens to hundreds of billions on new power plants to cater to the spike. (But hey, that's just a side benefit ;))
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In addition, conventional hydroelectric dams can save up water and release it when necessary.
I assume Spain simply builds up as much pumped-storage hydro as needed. They seem to have around as much pumped-storage as they have (wind capacity * load factor).
Anyway, I doubt many countries will face the problem of having too much wind power in the near future. Denmark currently has around 20% wind and sells off any excess to Norway, which in turn has huge amounts of hydro. Note that there is currently no other country that has more than the 15% figure quoted by GP. The US has room for building out 10 x the current capacity without worrying about storage.
Coal and oil is not cheap. The problem is that the largest portion of the cost of coal and oil, the damage to the environment, is not paid for my the people profiting for coal and oil but by everyone. We need to charge the coal and oil industry a useage fee for using our environment as a dumping ground for their toxic poison.