Last week, in the latest episode of our Energy Insiders podcast, the CEO of offshore wind project developer Southerly Ten, Charles Rattray, put the case for the technology, saying that despite its relatively high costs, its advantage lies in blowing at the right time.
Southerly Ten, the developer of the 2.2 gigawatt (GW) Star of the South project, which is regarded as the most advanced in the country, has now shared some more data to underline why they think that offshore wind can match the output of Victoria’s brown coal generators, and displace gas in critical winter peaks.
Rattray told Energy Insiders that the key advantages of offshore wind lay in its ability to blow hard when other technologies – onshore wind and solar – are not.
He says this is particularly the case in the afternoon and evenings in summer heatwaves, and in winter cold spells when expensive gas is typically setting the marginal price. That is important for the offshore wind industry’s contention that, while its technology is pricier than others, its value lies in blowing at the right time.
Southerly Ten has since provided a couple of interesting graphs. The first was to note the modelled output of the proposed Star of the South project versus the average output of the Yallourn brown coal generator that is due to retire in 2028 – one of three remaining coal fired generators that offshore wind is designed to help replace.
Southerly Ten also cited Bureau of Meteorology (BOM) data that it says shows that winds in Bass Strait are highly correlated with Victoria’s peak electricity demand periods.
This includes hot days, above 35°C, where offshore wind builds and becomes stronger in the afternoons and early evening. These weather patters are driven by high-pressure systems over the Tasman Sea that have been prevalent on such hot days over a 30 year period.
The BOM data shows that offshore wind was “materially” more productive than onshore wind and solar between the hours of 3pm and 7pm, when demand is the highest. Southerly Ten’s own data shows that capacity factors at this time are around 70 per cent, compared to 20 to 40 per cent for a typical onshore wind farm.
“This analysis shows that by tapping into a different weather pattern and wind profile, offshore wind increases the overall availability of Victoria’s renewable energy system, mitigating risk, and reducing power prices through a more diverse renewable portfolio,” Southerly Ten says.
“This is because it is in a different location compared with the bulk of Victoria’s wind projects, creating a more balanced system.
“Data taken from our wind and wave monitors off the coast near the project site further confirms the unique weather pattern in eastern Victoria on hot days.
“When looking at four of the hottest evenings during December 2019 and January 2020, the site data showed a capacity factor of around 70%, which is well above the 20-40% capacity factor of a typical wind farm.
Southerly Ten says the benefits are replicated at key times in winter, when there is also a strong correlation between the offshore wind profile in Gippsland, where Star of the South (and the other dozen or so aspiring offshore wind projects) would be located, and gas peaker generation.
“Both time of day and seasonality show high correlation between offshore wind and gas peaking,” Southerly Ten says.
“During these peak hours, gas typically sets the energy prices, and therefore replacement would result in significant savings to end consumers. Over the last 10 years, 2GW of offshore wind in Victoria, would’ve replaced 70.5% of the gas required to firm up the energy profile.”
See also: Energy Insiders Podcast: Offshore wind gets ready for auction
And: Why shape and value are the key buzzwords for Australia’s aspiring offshore wind industry
And: Offshore wind support came out stronger this election. Here’s what Labor can do next
