FUTURE ENERGY
IT’S DARK, IT’S STILL – IT’S DUNKELFLAUTE by Chris Gilbert, Energy Networks Australia, Senior Economic Advisor Dunkelflaute (dunk-el-flout-eh) is a German word meaning ‘dark lull’ and is a phenomenon energy professionals need to know about and energy systems need to manage. It describes extended events with minimal wind or sunshine in highly-renewable electricity systems – and as Australia’s energy system transforms, it’s something we need to be aware of, plan for and overcome.
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hether you’ve heard of it or not, the challenge dunkelflaute presents is obvious – how to guarantee electricity supply when the dark lull descends? In Australia, this has been referred to as a renewable drought. A recent lull in wind generation in South Australia is a smallscale snapshot of what could become a much larger problem in the future. AEMO data (via Open NEM) shows that from 11-12 June, wind power (represented by green in Figure 1) generated fewer than 4,800MWh of a total demanded 55,000MWh, only 8.7 per cent of total generation. This is compared with 9-10 June when wind power generated 46,000MWh out of a total demanded 73,000MWh, contributing 63 per cent to generation. Germany is in a similar position as South Australia in terms of renewable penetration. Renewable electricity in Germany contributed 45.4 per cent of electricity consumption in 2020, more than coal, oil and gas combined. Germany also has a significant transmission connection with the
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Figure 1. SA generation by resource type, 9th to 12th June 2021. Source: Open NEM.
EU, possessing more interconnectors than any other country in Europe. In Germany there is a growing fear of dunkelflaute, as the share of renewable generation increases and displaces dispatchable generation. The type of event to cause dunkelflaute doesn’t have to be severe weather like we saw in Texas in February, it can be as benign as several still winter days in a row.
How do we manage dunkelflaute? A recent Grattan Institute report, Go for net zero, referenced dunkelflaute as ‘the winter problem’. In the document, Grattan
notes that an energy system with 90 per cent renewable electricity would reduce emissions by 105 million tonnes at a cost of less than $20 per tonne. The final 10 per cent, however, is much trickier to achieve because the electricity system must increasingly rely on firming options. The immediately available electricity storage option that might come to mind is batteries – but batteries tend to be best suited to managing hourly fluctuations across the day, charging from the midday sun and then discharging to help with the evening peak.
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