An unsustainable future

One of the centre pieces of the Federal Government’s approach to reducing carbon dioxide emissions is a move to renewable energy sources. A specific target is to supply 20 per cent of the demand for electricity from renewables by 2020. But as the Government’s existing energy policy would in practice allow only the use of wind power, this approach is totally unrealistic. Wind is so intermittent that it would require an impossible building programme of 20,000 MW of wind farms by 2020 at an overall cost of some $40 billion! 

A target of 20 per cent from renewables by 2020 requires about 6,000 MW of deliverable renewable power in order to meet the projected future energy demand. 

Realistically, only nuclear and wind power could conceivably provide this. Since the government will not consider nuclear power, wind power is, by definition, the technology of choice. 

But this is not a feasible solution. 

The east coast Australian energy market is supplied with electricity by 45,000 MW of established coal, oil, gas and hydro power generators. In a “Statement of Opportunity for 2007” NEMMCO (now absorbed into AEMO – the Australian Energy Market Operator) projected new generator requirements out to the year 2017-18. Taking this and adding the extra years to 2020 indicates a need for 11,000 MW of new generation by 2020. 

The NEMMCO view was that the technology of choice would be gas turbine generators. Gas turbines, which have about one-third of the carbon dioxide emissions of coal fired generators, are most effective in supplying fast changing demand. 

However the Government’s objective for renewables should reduce the need for gas turbines. But the question is by how much? 

Wind power is intermittent. It is known to be intermittent across South Australia, Victoria, New South Wales and Tasmania where the performance has been measured with wind farms dispersed over 1,000 kilometres north-south and east-west. An example is shown for the month of June 2009. 

Wind occurs in bursts. It does not blow continuously. More importantly it does not blow at the same time all over south-east Australia. Building more wind farms in south-east Australia will not help if the wind does not blow. Again the example shows that even with as many wind turbines in each of the four states, if there is no wind then there is no power. As a visual check, just look at the weather reports at the end of an ABC news programme. The weather systems extend for 1,000 kilometres covering most of south-east Australia! 

Wind power cannot be relied on to supply peak demand power so it is most sensible to use it for replacing base load power with some contribution for peak demand times. Unlike thermal power stations or gas turbine generators which have the capacity to provide 100 per cent of their installed power for well over 90 per cent of the time, wind farms produce on average 30 per cent of their installed power. This is a consequence of the intermittency of wind. This means that to supply an average of 6,000 MW of power requires installing 20,000 MW of wind power, taking the average output to be 30 percent of installed power. This would be a building programme of 10,000 2 MW wind turbine towers. This is building three each day for ten years. 

But again because of intermittency, at times of peak demand wind can only be relied on to deliver 10 percent of its installed power. So, for the target set by NEMMCO of 11,000 MW and wind only being good for 2,000 MW at peak demand times, a total of 9,000 MW of gas turbine generators will be needed. 

This program doubles the cost of supplying the extra energy from gas turbines alone. It is an increased expenditure of $36,000 million over 10 years! The present wind farm development has added a few hundred MW each year so the target does not look achievable either physically or financially. 

How well would the electricity network cope with this change in energy source. First the electricity grid systems would need substantial enhancement to cope with highly variable and dispersed sources of energy. At $2 million per kilometre it could be further $4 billions of new connections, transmission lines, transformers and controls. Then can the system cope with variations of energy from 0 MW to 20,000 MW as the wind varies? The answer is almost certainly no without heavy costs in keeping thermal generators in reserve or standby mode. There is then the issue of whether the thermal generators are able to ramp their output to compensate for falling wind energy. It can possibly be done with extraordinary co-ordinated management of coal, gas and hydro generators. 

The best match for wind power is hydroelectricity with about 9,000 MW of installed power but only some 3,500 MW in the Snowy with the rest dispersed throughout the states. However hydro is used in meeting peak energy demands so the management of limited water resources would present a challenge. 

In summary, the renewable proposal is unachievable. It is unachievable in terms of installation, present transmission network capacity and present market operation. 

In addition it is an economic folly where the use of natural gas would substantially reduce carbon dioxide emissions, provide energy when needed and save some $40 billion in expenditure. 

So why not convert some thermal power stations from coal to natural gas like the British "dash for gas"? This would be no more than a short term fix. Long term this is a misuse of a vital petrochemical feedstock. 

So again following the lead of the British Government with the example of the Tate Modern in the old Battersea Power Station, will we see governments create a string of art galleries and museums in the Latrobe and Hunter Valleys or will some sanity return to the essential provision of electricity? 

Wind farm performance in June 2009. The sum of the power output normalised to rated capacity for eleven wind farms in New South Wales, South Australia, Tasmania and Victoria and assuming all states have equal rated capacity in wind farms.