Meeting electricity demand in 2050: Climate change & energy supply


Meeting electricity demand in 2050: Climate change & energy supply


Spotlight on Deep South Challenge energy researcher, Jen Purdie

Jen Purdie, lead researcher in our Climate change impacts on NZ electricity project, is helping to future proof our energy supply, as we move away from fossil fuels and towards 100% renewables.

Having worked across industry and research, Jen is now bringing her experience to bear on the problem of climate change. How will future rain and snow supply impact hydroelectricity? Can we hydro our way out of our energy issues, or do we need to think more holistically about this critically important challenge?

Jen has spent most of her career in the electricity sector, working for 14 years at Meridian Energy as a water, wind and energy modeller, and then a climate change modeller. She’s currently a Senior Research Fellow at the University of Otago. Jen describes her industry and research experiences as complimentary. In industry, she explains, you have to respond to issues immediately as they arise, while research gives you “the luxury of sitting back and looking at things with an umbrella view… taking time to go into things in more detail”. 

Jen is now modelling the impact of climate change on our electricity sector up to 2050. The electricity model she’s using is on loan from Meridian Energy, while Richard Turner from NIWA is providing wind projections. Jen’s team also includes previous Deep South Challenge researchers, including NIWA hydrologist Christian Zammit, and University of Otago community development and energy guru Janet Stephenson

In rare good news, unlike the impact of climate change on other sectors, hydro-electricity may be in better shape by 2050. Our largest hydro dams are based in the west of the lower South Island, an area expected to get wetter under climate change. More winter rainfall is likely in the Southern Alps, which along with warmer temperatures will mean 10 percent more water flowing into hydro lakes in winter (when we need it) instead of being stored as snow. 

Pumped-storage hydroelectricity works like this: When there’s a period with excess water – say, when there’s a lot of snow melt in the summer but little demand for power – that water is pumped back uphill to an upper reservoir (using the excess power). In winter, when electricity demand increases and there may be a shortage of water, the dammed water is released downhill to the generator. 

Jen Purdie at a southern hydro-scheme, December 2021

These hydro schemes are key to our electricity system. They’re the “big battery banks,” as Jen puts it, which supply 55 per cent of the nation’s power. However, building more hydro dams as a means for meeting future demand is not necessarily the best or only option. Hydro schemes face difficulties obtaining resource consents, in part because “there is little appetite for flooding valleys”. 

And this option for meeting future electricity demand is also costly. The government has turned its attention to the feasibility of building a pump hydro-scheme at Lake Onslow in Central Otago. If funded (a decision is expected in 2023), the scheme could cost $4 billion. 

It’s one solution, and “a good one…,” Jen says, “but there might be other solutions that don’t have such an environmental impact and don’t cost as much”.  

Another “dry winter” solution the team is exploring in the project is demand response, where consumers opt to reduce or cut off their power during peak hours, using smart appliances. So, for example, while you might plug in your electric car as soon as you get home from work, it may not begin charging until 2am. 

This can be taken further, Jen says. For instance, the grid assesses how much power is already in the vehicle when it’s plugged in, figures out how much may be needed overnight, and, if the vehicle has excess energy stored, can take back some of the power back into the network. 

Consumers would get paid for the service they’re providing to the grid… There’s talk already in industry that we need to get systems set up so this can happen smoothly, efficiently and fairly invisibly to people.

Jen Purdie

Project modelling by Jen, student Aleida Powell and colleague Michael Jack has found demand-response could take 20 percent off electricity demand during the winter peak by 2050. One obvious benefit is a reduced need for expensive infrastructure. 

And in 2022, one of Jen’s students will potentially looking at the practicalities of demand response: whether smart meters and appliances are up to the task; whether government regulations require updating; and whether the Electricity Authority would need to build demand-response solutions into its code. 

Modelling our future electricity sector is full of “massive uncertainty”, Purdie says, which is a major challenge for her and her team. As an example, uncertainty around how many electric cars we’ll have in 2050 (anywhere between 200,000 to 4 million), means Purdie must model a wide range of scenarios. 

Her approach is to take the extremes of these kinds of scenarios, and find a middle ground. This gives industry some confidence and the tools to consider their investment options, from hydro to hydrogen plants, from solar to wind, and including devices that control demand response. 

There’s no single solution, Jen says. For Aotearoa to reach its carbon zero goals by 2050, it will take all of these, big industry participation and a change in the way consumers expect to use electricity.

Jen’s project is set to conclude in late 2023, so there’s a lot of water left to run through the river. If you want to get in touch with us about Jen’s research, please email our Partnerships Director Waverley Jones.


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