Victorian brown coal also seems to be the insurance policy for Tasmanian smelters (Al, Zn, Mn alloy) in dry times. I understand there are various expensive workarounds for the 50 Hz synchronicity problem. Rather than induction generators the wind turbines could use permanent magnets. Power electronics could send out 50 Hz regardless of what is happening to the rest of the grid.

Another issue is that aside from reliability problems the relative emissions savings diminishes (according to Wheatley, NREL and others) as the wind penetration increases. At some point say 50% the irregular operation of combustion backup plant is as emissions intensive as 0% wind so there is no point in having the two systems.

A low carbon least cost combination must have some wind power in the mix but maybe not 40%. From a capital budgeting perspective wind power at $2 per watt is far cheaper and quicker to build than nuclear at $8 per watt. Alternatively the neighbours can help out as we see with Denmark and dispatchable Norway hydro. That won't work with neither SA wind power nor Victorian wind power being dispatchable.

Tom Quirk,

Thank you for this excellent, clear explanation of the impacts of connecting a high proportion of non synchronous, weather-dependent renewable energy generation capacity to the grid.

We should also remember that the CO2 abatement effetiveness of intermittent generators decreases as their share of electricity increases. Wind power at 20% share would be only ~50% effective at reducing emissions - i.e. 1 MWh of wind generation replaces only 50% of the CO2 emissions intensity of the grid.

Thanks, at last a proper contribution to the discussion. I wasn't aware of the pricing arrangements for wind, so that was worth the read all on its own. It explains why there was such an incentive for the wind farms to be kept operating longer than might have been warranted by the weather conditions.

Whether the 6% reduction in CO2 production due to SA wind farms is worth the cost is a value (ie; political) judgement rather than an economic one surely? Similarly, whether it is worth paying the huge amount of money that is spent on subsidising diesel generation costs in remote communities to maintain pricing parity with cities is a value judgement.

It seems to me that the roll-out of renewables generally is going to involve lots of local compromises, just as the rollout of earlier technologies did, but just as it was worth putting up with photochemical smog until it became sufficiently irksome to justify developing catlysers for cars, it will probably be worth putting up with slightly unreliable power until the development of proper and widespread storage and other technologies makes that compromise unnecessary. If we had waited for automotive technology until the development of the Mercedes S class we'd still be riding in bullock carts.

This too shall pass, unless of course the narrow self interest of a few rabble rousers and hucksters is allowed to dominate the discussion.

Thanks for a good article.

Tom Quirk
Mark Lawson here - thanks for the explanation of system inertia and frequency management. I'd tried looking online for explanations but that beats anything else.

As an addenda I might point out that wind farms basically don't produce during storms - something to do with damage to the generators. So the wind farms would have shut off anyway during the SA storm, and that's a lot of capacity that would have had to be replaced quickly, even if the system had been functioning normally.

Excellent explanation of the issues of the need for synchronous generators to run a 50 hertz system. It seems that the fantasy of replacing our coal and gas plants with wind and solar has been put to bed.

We are locked into an AC world for most of our electrical devices particularly motors which drive many of our devices.

This leads us to the issue of CO2 emissions from our current group of fossil fuel generators that keeps the system working.

What we need is a heat source that drives these generators without producing CO2. Solar thermal plants can supply this but again not on the scale that we need.

We have the answer of course but it is considered to be totally unacceptable by many - and that is nuclear power. We have to take this seriously in Australia and stop pretending that renewable energy can replace our GW scale synchronous generators.

Hi Mark,
Wind turbines can be designed to operate in all sorts of wind conditions, including quite high wind speeds. Each turbine has a particular operating range.

Perhaps operators might consider sacrificing ultimate performance on any given site in order to install turbines with a range of operating envelopes so as to minimise fluctuations by broadening the overall site envelope? I realise that would increase capital outlays, but it may be worth it.

Someone may have already done the modelling, I'm merely speculating. It's just another level of redundancy.

Craig, wind turbines are asynchronous generators as expressed by the author. This limits their value as also explained in the article. We need large reliable synchronous generators to keep the electricity network stable. They don't have to be fueled with coal or gas but clean nuclear heat is looking like the best option.

Hi Martin,
Sync is a separate issue, I was simply suggesting that we could minimise the variability of output on any particular site by installing a range of generators optimised for different wind conditions.

There are hard limits, of course: no wind means no blades being turned and very high winds require the blades to be feathered, so there's no getting away from some form of backup.

I'm also not quite sure why we aren't using DC for our turbines. Does anybody know?

Wind generators are not only failing to help in storms but also in the majority of heatwaves when air conditioning demand skyrockets. Similarly solar PV doesn't cook evening meals after or while the sun is setting. In California thermal plant has to ramp up 13,000 MW in the late afternoon. Yet we pay a premium price for wind and commercial solar, now near the LGC subsidy cap of $90 per Mwh, for what is a non-premium service.

If the aim is low carbon electricity then the Renewable Energy Target is the wrong approach. The primary driver should be emissions reduction targets not quotas for political favourites. Wind power should succeed or fail on its merits ie low carbon electricity at an affordable price.

Perhaps these might be a better solution to the problem,
http://machinedesign.com/news/no-more-windmills-wind-catchers-use-venturi-technique-generate-power
although we will still need an equivalent amount of synchronous base load power to maintain a stable system. We will undoubtedly have to bite the bullet and produce nuclear power sooner, rather than later if we wish to close down coal or oil powered generators. There is no other technically feasible means of producing a synchronous base load system.

Martin N has nailed it! But nuclear at $8.00 a watt? What?

Nuclear is only expensive because current practice is to just stop short of thermonuclear fission and try to hold it there?

And at considerable pressure meaning pressure containment vessels and purpose built containment in a highly reinforced building!

That's not for us nor the weapons spin-off or the enrichment decommissioning and so it goes!

All adding to the cost that makes conventional nuclear at least as twice as costly as coal!

And lets not mention a great big extremely vulnerable white elephant of a national grid or the captive market it hoovers/gouges money from!

Or gold plated electricity now too expensive for pensioners and most energy dependent manufacture and irrigation!

This was an event waiting to happen as was the black Wednesday fire storm started by a couple of fallen power poles!

We need to have a good long hard look at ourselves, the national interest and all the self evident advantages of localized power supply with interlocking markets that enable genuine/actual competition; from modest mass produced inside factories, thorium reactors!

To then produce the world's CLEANEST SAFEST CHEAPEST electricity, whether the wind blows or the sun shines!

We need to divorce energy from the market model and redefine it as an essential service! And an essential if we would become an economy that serves the people and one that once again makes things/ enables profitable production/processing/farming in a drought proof country!

That needs to become the smart country! Rather than one mired in exponentially growing debt! NOW WHILE STILL POSSIBLE!
Alan B.

Electric car charging could go major when and if oil prices rebound to unaffordable levels. My guess is that most EVs will be charged at home at night, not so much at daytime parked under a solar panel. Fortunately wind blows at night though not always which is why cherry farms near me have electric fans for frosty nights. If we're talking millions of EVs each wanting say a 10 kwh charge (for ~40 km travel) then that electricity production should be dependable as well as low carbon. Conceivably we could need 15% more electricity or as much as all current renewables produce. Some of that could be from more wind power but there would have to be a reliable alternative source.

Martin N - I'm sure that you could design wind turbines to operate at the higher wind speeds but at the moment the turbines generally used shut out at those higher winds.. what you are proposing is a vast increase in spending on wind farms for not much additional utility. No matter how you cut it, wind is difficult to use.

With development of power generation and distribution being examined so closely, I wonder why the concept of moving away from expensive transmission lines has not been considered.
Why centralise generation then pay huge infrastructure costs to distribute it to consumers.
Why not increase the effort for local rooftop solar/battery storage, as well as make use of whatever local generating sources such as wind, geothermal, tidal, hydro, are available locally, then distribute electricity via existing local street wire networks.
We had a valuable solar selling scheme in place until governments reduced feed-in payments, leaving many homes unable to better their break-even costs and others unwilling to invest in current battery storage systems which tend to have a ten year life before needing recapitalisation.
Increased research and development of localised systems seems one way bout of the problem.

Craig,

FYI, they have already done work on the latest turbines that has considerably widened their operational envelope and in some windy areas these turbines would generate on average nearly 40% of installed capacity. However, as the energy available in wind is proportional to the velocity cubed, low wind velocities are still useless, and the widely fluctuating wind generation has to be balanced with rapidly available other sources.

With respect to DC generation, the problem is that DC generators use carbon brushes that wear down and produce carbon dust in the generator. This requires frequent and expensive maintenance roughly every month. I have looked after DC variable speed drive systems, and would avoid DC generators like the plague.

Thank you SM.

Actually, I just read that again. I only skimmed it previously, looking at the brush comment, which is accurate.

Energy=1/2 mass times velocity squared, not cubed. How do you come up with your claim of a cubic relationship?

Craig,

It's a pleasure.

For a fixed mass e=1/2mv^2, but also the mass passing a particular point is proportional to the velocity giving

Power is proportional to density x v^3

Ah, okay, I see where the confusion arises. I was referring to energy and you were referring to power(energy multiplied by time).

No worries, thanks.

why don't we require wind farms to supply synchronous and steady power? This would require wind farm operators to install any necessary equipment to keep their supply smooth and in phase.

Synchronous generators require a phasing reference to be added to a grid.

Wind farms do provide synchronous power, but they can't readily provide a reliable sync reference due to the nature of their energy source.

It may not be a bad idea to set each one up with some form of independent synchronising source though. It wouldn't help in extreme wind conditions, when they are either underpowered or shut down to prevent overspeed, but it would allow them to provide power independent of a stable grid reference, for example if an interconnector were to be damaged.

I'm coming more strongly to the view that a range of wind generators with different operating parameters should be incorporated within each site. In that way, there would be some power available across a broader range of wind speeds and during some periods there would be extra available as the operating envelopes of different generators overlapped. This extra could then be stored for later use.

To this point there hasn't been much investment in storage, other than pumped hydro. The scope for new investment opportunities is large.

"To this point there hasn't been much investment in storage, other than pumped hydro. The scope for new investment opportunities is large."

That's cart before the horse. The most breath-taking storage breakthrough in history is first needed.

Only, coal, gas, hydro and nuclear truly fuel the world, or very nearly. Oil has nearly had its day in EROEI terms and is reducing to becoming an extension of the main grid, like renewables. Electric cars should soon proliferate.

EROEI of solar is poor and is reduced virtually to break-even when storage is included (Prieto and Hall). Wind has viable EROEI when the wind blows but, like solar, storage eats into this. Both require storage AND F-F backup.

Must we continue dreaming of a storage breakthrough so incredible that it virtually makes renewables dispatchable, or should we go with what has worked in France for 60 years

Yes Luciferase, investment is needed in order to stimulate development, thanks for clarifying that.

In relying on Prieto and Hall, you're not taking any of the development work on renewables into account. I'm not discounting their analysis, I haven't read it, just pointing out that 4 years (since it was written) is a very long time in today's world and many of their references are considerably older than that.

It was a useful snapshot of the situation that obtained at the time and an excellent stimulus to development.

As so often, you're right. South Australia hadn't happened.

P&H looked at future technical improvements in PV's and found EROEI still wallowing.

Nuclear could improve tecnically too, before even going Gen IV, but let's not let ourselves go there. I mean, just look at the horror of France over the last 60 years!

You can carry on about renewables for as long as you like, but for an electricity grid to function reliably, you must have a considerable percentage of power from a large synchronised source otherwise you get the same result as what happened in South Australia. In Victoria, some unrealistic naive people are talking about closing down the power stations in the Latrobe Valley by 2050. The only way you are going to do this is by substituting some form(s) of nuclear energy. There is no other way.
David

There's more than one way to provide a syncing reference David.

It's just a signal with a particular voltage/current phase relationship, there's nothing special about it.

Large generators provide some inertia to the system but there's nothing special about that either.

Gerrard,

Nearly all generators are synchronous. Most have wound rotors and the injected current controls the phase angle of the current and offers some power factor correction. Wind turbines are usually permanent magnet generators that cannot regulate the phase angle.

Given that the entire grid runs in sync, it is up to the generator connecting to the grid to sync its voltage speed and phase angle to the grid before connecting. (it is easier than it sounds). Each wind turbine would require its own sync equipment.

Storage is the Achilles heel of the renewables industry, and it has been worked on for at least 4 decades with very limited results. Until there is something that can be built without the need for mountains, can provide peak power reliably and does not cost an arm and a leg, the renewable industry will need to rely on very expensive gas fired generation to provide reliability.

Sadly, many groups quote Dr James Hansen on the problem of climate change, while ignoring his stated *solution*.
He says:
1. Believing in 100% RENEWABLES is like believing in the Easter Bunny or Tooth Fairy. (Yes, he's aware of all the 'studies' that say we can, but still thinks storage is ridiculously expensive and cannot do the job).
http://goo.gl/8qidgV

2. The world should build 115 reactors a year*
http://goo.gl/Xx61xU
(*Note: on a reactors-to-GDP ratio the French *already* beat this build rate back in the 70's under the Mesmer plan. 115 reactors a year should be easy for the world economy. France did it *faster* with older technology, and today's nukes can be mass produced on an assembly line. Also, GenIV breeders are coming that can eat nuclear waste and covert a 100,000 year storage problem into 1000 years of clean energy for America and 500 years for the UK with today's levels of nuclear waste).

Oz renewablistas point to the German transition experiment as a major success story, not mentioning nordic-hydro and franco-nuclear propping up appearances, or the high cost affecting German big businesses even after subsidy by small business and household users.
(Re nuclear, Germany says "not in our backyard" but hypocritically accepts the French offering)

A massively expensive renewables and gas turbine backup proposal here will not adequately lower emissions enough for a fair and effective share of mitigating AGW. Why bother? Current arrangements leading to the SA blackout must be fixed with adequate storage for load balancing or other approaches that further diminish economic viability.

From every angle renewables are pointless on the main grid in Australia. Let's get nuclear by replacing F-F plants with reactors as they need rep[lacement, or before in cases.

LF,

I think Germany is a good example of the limits to which renewable power can be realistically absorbed by the grid. Already, there are times where renewables generate 100% of the grid capacity and Germany has to pay France to take the power from its coal and gas generators, and many days where wind and solar generate as little as 5% of the demand. It doesn't take a rocket scientist to see what would happen if they increased the % of renewables.

Yep, Germany swings between being a beggar and Santa Claus, France the big winner. It's why Germany is building coal-fired power.

As I see it, because of the Luddites in the Green party, Australia will not go down any nuclear path anytime soon. That leads to the ultimate inevitability that Victoria will have to build another brown coal fired station at Loy Yang. Hazelwood is on its last legs, as of a couple of days ago it appeared that only two of the eight stacks were emitting smoke.
Craig Minns, using GPS based technology, I could build you a 50 Hz reference which is accurate to 1 part in a trillion, but that would not help to feed a windmill into the grid, because the grid actually is not run with that degree of accuracy. The frequency is somewhat dependent on fluctuations in the load, even though it averages out to 50 Hz.
David

Hi David,
What a wonderfully pickled red herring!