Following the recent Clean Energy Week conference, we fielded calls from people interested in understanding the percentage of demand being met from renewable sources currently.
Given the topical nature of the question, we thought it would be of more general interest, and so have included this trend here (percentages have been added to show the market share of each fuel type for 2012 year to date):
It’s fairly clear from this chart that a number of trends have been developing over the 14 years of NEM history, including the following:
1) Most prominently, we see that production from black coal stations across QLD and NSW has fallen significantly from its high point in 2008 (by 15% over the 4 year period) after growing steadily in the 10 years prior. This has been driven by a number of factors, including:
1a) The flattening & decline of demand (a trend we’ve previously noted as beginning around 2006, and which we surmised has been due to a number of factors such as these top 7 factors contributing to decline of demand.
1b) We’ve seen a significant rise in production from gas-fired sources, driven by a combination of the QLD 15% GEC scheme, the availability of cheap ramp-up gas, and the choice of large new OCGT and CCGT plant for all new developments (except Kogan Creek in 2007) since Millmerran in 2002.
1c) We see that the output of hydro plant has increased from the drought-affected low point of 2008.
1d) We also see that the increase in generation from wind will also have had some effect.
2) In contrast, we’ve seen production from brown coal stations in VIC and SA hold relatively steady over the 14-year period. This is in spite of the recent announcements by Alinta of the closure and seasonal closure of the Playford and Northern Power Stations in SA (an illustration of how little they had been running in any case).
3) Because of other questions asked about the intermittency of wind, we have also included the following table to provide further detail about how the growth in wind production is trending:
4) From this table, we can see how the approximate* annual capacity factor for wind farms across the NEM has hovered around the 30% range, which is what is typically quoted for this type of intermittent production:
* Note that the lower numbers shown for 2005-2007 might be shown as lower than the actual values by virtue of the approximations of station capacity over time in the quick calculation performed for this post. Two simplifying assumptions have been made:
(a) That the registered capacity of the plant has not changed over time, and that this is the current registered capacity (this has not been the case with wind farms due to their progressive development and commissioning).
(b) That the capacity has been present from 1st January in the year in which it has been assumed.
These simplifying assumptions will have resulted in the figures above being somewhat lower than actuals, especially in the earlier years.
With reference to these daily production figures we see that average daily output as high as 1540MW has been seen from wind farms in 2011, which would have represented a daily capacity factor of the order of 70% – clearly a windy day.
5) From this table, we can also see how peaking generation from liquid-fuelled plant has dropped almost to nothing as a result of the increased build (and conversion) of gas-fired plant for peaking (and energy) purposes.