One of the key parts of the Rudd Government’s efforts to reduce emissions is a bill now in draft form, the Renewable Energy (Electricity) Amendment Bill requiring generators to source 20 per cent of their electricity from renewable sources by 2020. But as matters are set now the emerging renewable electricity sector is set to consume a lot of money for comparatively little reduction in emissions.
As has been confirmed in a series of reports by different bodies, renewables, particularly wind farms, are a lot more trouble and far less effective than those who support these targets realise. Renewables in general, and wind energy in particular, can still make a contribution, if the approach is rethought. The problem is that no one seems to have thought about the sector’s problems.
Exhibit A in the case against relying on renewable energy is an attachment to a submission to the draft bill by a group called the Carbon Sense Coalition (PDF 171KB), which is definitely not sympathetic to the push for renewables or the rationale behind it. The attachment is an analysis of the usefulness of wind energy by a retired power engineer of considerable experience, Peter Lang, which says that the main problem with wind farms is that the energy they supply is so variable and unpredictable.
The power company may be happily taking in, say, 100 megawatts from wind farms and then suddenly the wind dies away and the power grid is short 100 megawatts. Storing power on power station scale is not feasible (we will return to that point), so unless the power company wants unpredictable brown outs in part of its grid, the only answer is to have the equivalent generating capacity on standby, as in operating at nearly the wind farm’s capacity, to take over at a moment’s notice. Power stations are not like car engines - they take time to get up to full speed. Coal stations take hours, certain types of gas turbines can power up and down within minutes, provided they are already operating. Hydro power is the easiest to change but is limited in Australia.
In other words, the wind farms are not replacing 100 megawatts of emissions, but an amount much less than that. Further, Mr Lang notes that the use of renewables will require more of a certain type of fast-response gas turbines, so that the mix of plants - coal, gas, hydro - required to power the network, will be overall far less efficient than if the wind farms were not in the grid at all.
Those who wish to brush aside such inconvenient technical issues may well try various political arguments, such as pointing to Mr Lang’s experience in the nuclear industry. Unfortunately for those arguments, very similar points have been made in at least three other major reports. In 2004, a report by the German power company E.On Netz GmbH, which has considerable wind farm capacity on its network, said that it had to maintain “shadow power stations” at 80 per cent of the installed wind farm capacity.
The 2005 report is a little softer but notes that the output of wind farms on the network was at its maximum at 6,024 megawatts on Christmas Eve and then fell to less than 2,000 megawatts within only 10 hours, a difference of more than 4,000 megawatts. The report notes that this corresponds to a capacity of eight coal fired power plants.
“Handling such significant difference to feed-in levels poses a major challenge to grid operators,” the report notes.
A July 2005 report entitled Security assessment of future UK electricity scenarios (PDF 851KB) produced by the Tyndall Centre for Climate Change Research (the centre is associated with that green bastion, the University of East Anglia), came to very similar conclusions. It notes that wind energy’s contribution to future power generation will be of largely symbolic importance. As in the German report, the UK study notes that a common winter weather pattern is for periods of intense cold to coincide with little or no wind. Forecasting changes in the wind is also very difficult.
Another study by PB Power for the UK’s Royal Academy of Engineering entitled The Cost of Generating Electricity produced last year notes that the cost of renewable energy is increased because “additional, fast response, standby generating plant may have to be provided to maintain system security as the energy source fluctuates”. The report estimates that the requirement for standby generating capacity adds 46 per cent to the cost of onshore wind farms (offshore are more expensive again).
There is plenty of other, similar material for those who hunt for it, but you get the picture. The use of wind as a replacement for any electricity capacity is much less effective than is generally known. But all is not lost - yet.
In its defence the Green Energy Council (which merged with the Australian Wind Energy Association in 2007) says that if wind farms are spread all over Australia then some wind farms must be operating somewhere. Also, European power companies have developed sophisticated wind forecasting software which removes some of the problems of variations in wind power. Perhaps. This software is mentioned approvingly in more recent publications by E.On but very little information is available on how effective it is in Europe, let alone in Australia. The National Electricity Market Management Company or NEMMCO says it is monitoring the performance of software connected with wind energy.