By Joshua Gliddon and Jordan Manning

New Zealand’s water-powered future?

About 80% of New Zealand’s electricity is from renewable sources, with half of it from hydro power. Getting to 100% renewables could include using pumped hydro storage. That involves pumping water into a reservoir at a time when electricity is cheap, then releasing the water to drive turbines and generate electricity when needed.

The focus for this idea is on Lake Onslow in the Otago region. It would be a NZ$4 billion investment but is it worth it? There is some controversy around the cost and environmental impact of the plan. University of Otago sustainability expert Janet Stephenson has suggested reducing peak power demand by insulating homes and expanding solar and wind projects may be more cost effective.

Offshore wind energy

Picture: Offshore wind turbines at Middelgrunden outside Copenhagen, Denmark.

Wind power is currently the cheapest source of large-scale renewable energy, and new technology means offshore wind turbines can be sited further out to sea where wind speeds are faster and winds more consistent than onshore.

The appetite for offshore wind energy is growing, especially in Europe. By 2030, the UK government plans to have about 5000 offshore wind turbines making 40 gigawatts of power, enough to power every home in the country.

But are Australia and New Zealand falling behind? New Zealand, which is hit with winds straight from Antarctica, has 17 onshore wind farms that produce about 6% of the nation’s power, but no offshore developments as yet.

That could change, however. Capital costs for offshore wind turbines are predicted to fall by 60% by 2030. Oceanex Energy is currently looking at potential locations for offshore wind turbines, including off Taranaki.

Australia has more than 100 onshore wind farms and plenty of potential locations for offshore wind farms, but legislation to allow these offshore developments was only introduced to federal parliament in September.

Australia’s first offshore wind farm may be the 2.2-gigawatt Star of the South project, planned for a 496 square km area off Victoria’s Gippsland coast, which could access existing electricity transmission infrastructure in the Latrobe Valley. It could supply up to 20% of the state’s energy if it powers up as planned in the early 2030s.

Solar is abundant and cheap

Picture: Nyngan Solar Plant in central NSW is one of the largest solar farms in Australia.

Australia receives an average of 58 million petajoules of solar energy per year, which is about 10,000 times as much as the country’s total energy consumption. One in four Australian homes have solar panels – the highest uptake in the world – and large and small-scale solar installations produced about 9% of the nation’s power in the 2020 calendar year (up from 7% in 2019), according to the 2021 Australian Energy Statistics.

In 2020, a record 53.6 terawatt hours (TWh) of electricity was generated from renewables (including rooftop solar) in the National Electricity Market – about 24% of Australia’s energy.

In New Zealand, the share of solar power in the total energy mix will grow from 0.2% (100MW) in 2020 to 1.7% (1.1 gigawatts) by 2030, predicts a 2020 Transpower report. Nearly 10% of New Zealand’s power is expected to be solar generated by 2050.

Last year’s World Energy Outlook 2020 report from the International Energy Agency (IEA) stated that solar-generated power was now consistently cheaper than electricty from new coal- or gas-fired power plants in most countries.

“I see solar becoming the new king of the world’s electricity markets. Based on today’s policy settings, it is on track to set new records for deployment every year after 2022,” said Fatih Birol, the IEA executive director.

“I see solar becoming the new king of the world’s electricity markets. Based on today’s policy settings, it is on track to set new records for deployment every year after 2022.”

The IEA’s analysis sees renewables meeting 80% of global electricity demand growth over the next decade. Hydropower remains the largest renewable source, but solar is the main source of growth, followed by onshore and offshore wind.

Stabilising the grid using batteries

Picture: Hornsdale Power Reserve, South Australia.

Renewable power sources such as solar and wind have a disadvantage: when the sun is behind clouds or the wind isn’t blowing, they don’t generate electricity. Stabilising this variable power supply comes down to batteries. Coupling batteries with renewables means excess power is stored and can be dispatched when needed. Batteries can also be used by households to augment their renewable generation, or at locations where the grid doesn’t go – also called microgrids.

What about hydrogen?

In July 2020, the Australian Energy Market Operator (AEMO) published the 2020 Integrated System Plan (ISP) for the national electricity market. One aspect of the ISP recognises hydrogen, the most abundant element in the universe, as a potential market disruptor. When hydrogen gas burns in air it reacts with oxygen and produces mostly heat and water vapour. Its green appeal seems obvious. The ISP says Australia has the opportunity to become a large-scale hydrogen exporter, but there are caveats. Hydrogen’s affinity for other elements means that although it’s abundant, it doesn’t exist in any meaningful quantities on its own. Splitting hydrogen from hydrogen-bearing compounds (such as water) currently needs a lot of electricity, and with Australia’s reliance on fossil fuels, roadblocks could exist if the country wants to become a ‘hydrogen economy’.

Fast facts

54% – How much of Australia’s power was supplied by coal in the 2020 calendar year. Gas follows at 20%, solar at 9%, wind at about 8.5% and hydro at 5.5%.

Source: 2021 Australian Energy Statistics

70% – How much NZ’s electricity output will need to increase to electrify its transport and industrial heating sectors by 2050.

Source: Empowering Our Energy Future, Transpower, Mar 2020

NZ$15,000 – The cost of a Tesla Powerwall 2 household battery in New Zealand in 2020.

Source: mysolarquotes.co.nz

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