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.