This large hydro base brings advantages with the ability to store water in lakes and turn generation on and off when needed to meet the demand. Further geothermal, wind and other renewable sources such as solar will be an essential part of meeting the country's growing power demand, but don’t have this same dispatchable nature, given that they are more intermittent (wind, solar) or operate best as a steady load (geothermal).
However, renewable energy requires an abundant source and in dry hydrological years we use non-renewables such as gas or coal to generate electricity. These plants now demand a higher market price due to their irregular use and don’t meet our zero carbon goals.
The reality is that without these non-renewable sources we’d struggle to provide a secure supply of electricity for current needs using our current electricity generation and distribution system. Electricity demand is expected to double in the next 30 years due to EV uptake and a growing population. Hotter, drier summers will push up electricity consumption to meet the need for cooling – during a period that typically is lower demand.
Although we can certainly increase our renewables to meet the increase in demand and to work towards the 2035 target of 100% renewables, getting rid of the last of the thermal generation isn’t so straightforward. We still need a cost-effective solution to provide generation when required without having to overinvest in renewables.
Climate change adds to this challenge, especially as the exact nature of the change and its impact on the power generation market isn’t fully understood. We know it’s likely to mean an increased frequency and severity of droughts, which will reduce river flows and lake storage levels. This will increase our susceptibility to dry years and our current dependence on non-renewables will become more pronounced.
High or more extreme wind conditions may impact wind generation if the turbines are unable to operate in the conditions. In the high wind areas around Wellington and the Wairarapa, conditions are already more challenging than other countries. Other potential impacts on our renewables may be from heavy rainfalls resulting in flooding and risks to dam safety, or damage to infrastructure, as well as a rise of sea levels resulting affecting river flows.
In effect, more extreme weather will impact most forms of renewable power and could make it harder to consistently meet demand from renewable sources.
Sustaining a 100% renewable generation portfolio in a world of climate change, coupled with the drive to zero carbon emissions is a topic of much thought and debate.
Options for providing renewable energy storage are being implemented or explored here and globally. It is consideration of these technologies and innovations that will ultimately allow us to meet the 100% renewable goal.
These include utility scale batteries, which are coupled with wind farms or solar PV, and pumped hydro schemes, where water is pumped during times of low electricity cost / demand. Other trends include the use of distributed energy resources (smaller scale wind / solar / batteries) that can help optimise the balance between supply and demand, with it being managed at a local level with reduced reliance on the traditional large-scale generation and transmission.
Use of digital data and improvements in this area support these changes, such as enabling more advanced weather forecasting or providing a better understanding of demand loads and patterns.
In the short term, until storage technologies catch up, getting the most efficient use of our thermal infrastructure is likely to still play a role. Consideration may be given to fast starts of gas plants and / or minimising the start-up costs of thermal generation by running at minimum loads and using excess energy in other ways, such as generating hydrogen. Hydrogen has the potential to use excess energy from renewables and, for example, we could use wind to create hydrogen to be used as an alternative form of energy for buses.
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