In the first of a series of articles featuring local experts, Ty Christopher, Director of the Energy Futures Network at the University of Wollongong, explains why offshore wind is the best bet to replace coal in the coming decade.

The proposed offshore wind zone in the Illawarra could generate up to 4.2 gigawatts of electricity, enough to power 3.4 million homes.

This would be a “pretty good match” to replace Eraring, Australia’s biggest coal-fired power plant, said Ty Christopher, Director of the Energy Futures Network at the University of Wollongong.

At an interview at UOW’s Innovation Campus in October, Endeavour Energy's former 'chief engineer' said that at the “really important heart of the why of offshore wind … there's not a plan B other than continuing to burn coal and gas”.

“I say that carefully because if taken out of context that can sound like an ultimatum or a threat, something desired to elicit an outcome. I say it as none of those things – I say it as an engineer with almost 40 years’ experience in the power industry and looking at the technology that we've got right here.

“Australia's leading the world in the uptake of renewables, and that's fantastic. But 70% of our electricity still comes from burning coal and gas as we sit here today.”

While he fully supports the push to ‘electrify everything’ by putting solar on homes and businesses, Ty said there is not one silver bullet for decarbonising our energy future. “There is only silver buckshot. There are multiple technologies that need to come into play.”

Something capable of powering steel manufacturing, heavy industry or city centres must replace fossil fuels soon and Ty said it can’t be nuclear (too expensive, too late) or solar (the sun doesn’t shine enough and skinny transmission wires can’t cope with big loads).

“We need three things from our energy at the big grid end of the spectrum," he said.

“We need multi gigawatt scale, we need high capacity factor and we need proximity between where the energy is created and where it's needed to be used, because that's the efficient way to do things.”

Only offshore wind can rival the capacity factor of fossil fuels within the next 10 years, Ty said.

Capacity factor – which UOW’s Blue Energy Futures Lab defines as “a ratio of actual electricity output to maximum theoretical output” – is a key reason why clean energy experts are excited about new offshore wind projects in Australia.  

To clarify the concept, Ty said: “If an electricity generation source was running flat out for a time period, what would be the theoretical energy that it could deliver versus, practically, how much energy does it actually deliver over the same time period.

“So what it's a measure of is how much is the capacity of that electricity generation available when you need it.

“The thing most people don't realise is, even with a lot of the big batteries and home batteries coming online, the reality is our power system has always, and still substantially works, entirely in real time.

“You switch on a light, a generator needs to have an output to match that and commensurately when you turn something off. It's a balancing act in real time between generating the power and using it. And it happens in every second of the day in real time, the way the physics of it works.

“We need electricity to be there when we want it.”

This is the reason that renewable energy sources with low-capacity factors are a challenge.

“Solar is a classic example. The capacity factor of solar is about 20% because of the diurnal window – the sun's only there usably for about five and a half hours a day.

“So 20, 25% at best is the capacity factor of solar. Yes, you can back it up with a battery and extend that, but you still don't get a high capacity factor out of it.

“If we move into onshore wind, so land-based wind turbines, the characteristics of wind onshore is the highs are high, but the lows are low, and the lows are more frequent than they are offshore.”

Onshore wind has a capacity factor of 30 to 35%, he said.

“So you put a megawatt of wind farm out there, you can only really rely on getting a third of a megawatt out of it. There will be material periods of becalment – I think I just invented a word there, but when the wind's not blowing – when you won't get any output from it.

“Now, offshore wind – once you go more than 10km offshore wind is an almost constant resource. The periods of becalment 10km or more out are highly infrequent.

“The wind is there nearly all of the time."

At its peak, coal had a capacity factor of about 80% but, with Australia’s plants ageing, this is declining.

“The capacity factor of offshore wind, depending on your location, is between 45 and 55%. So, on average, the capacity factor of offshore wind is 50%. Contrast that to coal at 65% and declining.”

To put this in context, Ty said, Eraring, the nation's largest coal-fired power plant, generates 2.88 gigawatts of electricity.

“Now, if we look to offshore wind here off the Illawarra, 4.2 gigawatts is proposed, 50% capacity factor. That means reliably, it's a 2.1 gigawatt offshore wind farm. It's a pretty good match for Eraring.

“Coal's ageing out of the system. We need high capacity factor generation to replace it. And soon.”
 

Have your say

The Department of Climate Change, Energy, the Environment and Water is calling for feedback on the Illawarra offshore area proposed for future renewable energy projects. Click here to have your say by November 15.

FAQ at UOW

UOW researchers support the development of offshore wind in the Illawarra, provided the developments are done to the highest environmental, social and cultural standards. They have drawn up an independent list of FAQs, which can be read on the Blue Energy Futures Lab website.

Questions welcome

Find more insights from the Blue Energy Futures Lab in Whale of a tale proves to be fake news.

Do you have a question about offshore wind? Submit article suggestions via our Get In Touch page

Read more interviews with Ty Christopher

• The Why of Offshore Wind
• Why not nuclear, solar or onshore wind?
• Get the numbers on nuclear energy
• Meet electrical engineer Ty Christopher, Energy Futures Network Director at UOW