Lake Onslow is a man-made lake east of Roxburgh and south of Alexandra in the Otago region of New Zealand. It lies 700 m (2,300 ft) above sea level. It was formed in 1890 by the damming of the Teviot River and Dismal Swamp.
The Government is investigating whether to turn Lake Onslow into a giant hydro-storage reservoir with enough capacity to handle the dry years. This would do away with the need for coal generation.
The NZ Battery Project is investigating solutions to the ‘dry year problem’ when hydro catchments are low and fossil fuels are burnt to generate electricity to cover the shortfall. A number of options are being investigated and will be compared to a pumped hydro storage scheme option at Central Otago’s Lake Onslow.
A consortium of specialist firms has been awarded a major contract to advance the New Zealand Battery Project’s feasibility investigation into a pumped hydro storage scheme at Lake Onslow, the Minister of Energy and Resources Megan Woods announced in OCTOBER 2021.
Facts and figures for Lake Onslow project
The Lake Onslow option referenced by the Interim Climate Change Committee could be anticipated to provide at least 5TWh of annual generation/storage. It is estimated to have a construction timeframe of 4-5 years, with commissioning and filling taking a further 2 years. At its construction peak, it is expected to create 3,500-4,500 skilled and semi-skilled jobs.
What services can a pumped storage project like Lake Onslow provide?
What is the estimated cost of a project like Lake Onslow?
Early estimates indicate a project like Lake Onslow could cost about $4 billion. Our feasibility study will provide greater certainty about the costs.
Funding and financing models along with any potential subsequent levies will be determined through the feasibility study. The use of a levy would need to be justified via a demonstration of significant public good in a feasibility study, including through overall lower prices for consumers in the long term.
Timeline
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Phase |
Scope and decision points |
Estimated costs |
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Investigation and evaluation of long-term, large-scale renewable energy storage options, including pumped hydro and a range of other dry year storage solutions. The project will explore in detail the feasibility of pumped hydro at Lake Onslow, including geotechnical investigations.
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Up to $30 million |
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Phase 1 – feasibility study |
In-principle feasibility decisions In-principle decisions about which option or combination of options to take through for further investigation as part of a detailed business case based on desktop analysis and initial geotechnical investigations for the Lake Onslow option.
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Start May 2022 |
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Final feasibility decisions
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Start December 2022 |
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Phase 2 – Detailed business case (dependent on earlier decisions) |
Final investment decisions Detailed investigation into the construction, funding and/or implementation of the preferred option or options.
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Up to $70 million To start from early 2023 (timing dependent on options) |
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Phase 3 – Implementation (dependent on earlier decisions)
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Implementation of preferred option or options |
Unknown until dry year solution or solutions selected |
The Lake Onslow option is located north-east of the Clutha River in Central Otago.
The diagram shows what a 5TWh proposed lake would look like at the 760 metre contour. This is not the only possible option for Lake Onslow.
In addition to pumped hydro and other hydro-based options, the NZ Battery Project is also looking at other possible technologies or approaches to address the dry year problem. An alternative could be complimentary to, or a substitute for, pumped hydro.
The NZ Battery Project team generated an initial long-list of alternative approaches, which were then screened against criteria and feedback received through targeted external engagement, and in consultation with the Technical Reference Group.
Five broad alternative technologies were identified as having the technical potential to help manage dry year risk:
What hasn’t been mentioned anywhere in the Lake Onslow project is the requirement for a transmission network upgrade that will be needed if this power source is going to provide power to the main areas of use in the North Island.
The current transmission network is at maximum capacity and in need of serious maintenance and upgrades.
There is another option that is not mentioned in this projects publication to date either because it has been rejected or it has not been identified: “Waste to Energy”.
Here in New Zealand we have another option that will allow us to keep the lights on without the need to import and burn dirty coal from Indonesia, as we currently do.
Instead of filling our landfills with waste we can use that waste to produce power by incineration. Given the latest technology available, the relatively simple engineering needed to transform the Huntly Station to use waste, the availability of area for the processing of the waste, the existing transmission network from Huntly to our main centre of use (Auckland) and the existing rail network into the site, there will be less harm done to the environment from using waste as a fuel than there is from importing and using coal.
According to the Waste Hierarchy, the recovery of energy from waste is the next preferred method after recycling. Disposal to landfill is the least preferred method of waste management, yet it is the current best practice in New Zealand.
The Auckland region produces approximately one and a half million tonnes of waste per year that mostly goes into landfills and solid waste levels are increasing alongside the increasing population.
The government has committed to stopping the use of fossil fuels and converting to electricity use instead and given this focus on the use of electricity to replace the use of fossil fuels the demand for electricity is going to increase exponentially.
New Zealand currently does not have the capacity in sustainable generation of electricity to stop the use of thermal generation outright.
If the hydro lake levels drop significantly due to weather effects and the wind doesn’t blow at that time then we will need to rely on thermal generation or see rolling blackouts as happened in August 2021 which is the main reason for the proposed Battery Hydro Storage Project.
There is another option that should be explored as soon as possible and that is to use incineration of waste to fuel power generation rather than using imported coal.
By using waste incineration at Huntly Power station we can achieve the following benefits;
We have the capability on government owned land where the infrastructure could be sited to accommodate the sorting of the waste streams into separate recyclable and incineration resources.
There are many major cities such as Paris, Zurich, Vienna and London, which are converting waste into energy.
Many of these cities have the process of generating energy from waste as a key component in their waste management hierarchy thereby reducing their landfill requirements almost to zero.
The residual waste that would otherwise consigned to landfill uses technology to generate energy from the controlled burning of that waste. The generation plants burn the waste and convert the released heat into steam which is used to generate electricity. The latest filtering technology is used to ensure that the incineration systems comply with all emissions standards from their exhaust chimneys.
We are facing increasing energy demand and the exhaustion of the natural gas supply which provides baseload power (in the near future), solid waste levels increasing alongside the increasing population and most large landfill sites nearing maximum capacity.
Yet with the use of recycling coupled with incineration of the non-recyclable solid waste stream we can move towards global best practice in the treatment of our solid waste and remove the dependence on landfills.
The feasibility study alone is costed at $100 million and the construction of the hydro storage is currently estimated at somewhere in the region of $4 billion and even if we decide to go ahead and this project buys us some more time before we reach the next demand overload, we still have the problem of what to do with our solid waste stream which is growing exponentially with the continuing increase in population.
Converting waste to energy would be solving two problems at once (power generation & waste disposal) and doing so at the Huntly power station would be a much cheaper option than the hydro storage project at Lake Onslow as it would utilise existing infrastructure and is much closer to the source of demand therefore reducing the cost for transmission of the electricity compared to the Lake Onslow option.
Latest estimates put the suggested costs to convert Huntly to use waste to energy technology at approximately $1 billion which is significantly less than the Lake Onslow Project and this is even without taking into account the need for massive upgrades to the transmission network for the South Island.
In my opinion it is an option that requires serious consideration on many fronts, not to be ignored. We need to change our thinking on how we deal with the solid waste stream as we cannot keep putting it into landfills. The technology for incineration has been improved to a state where it is environmentally safe and as time and research goes past this technology will only get better.
As power consumption grows we will eventually need another Lake Onslow but with the waste to energy option as power consumption grows so does the quantity of waste because people create waste and the population is growing all the time. It will be easier to add another incinerator if required, which would have a smaller impact on the environment. Converting the Huntly Power Plant to a waste to energy plant is the best option now, as it has the least impact on people and the environment in the local area and in particular on the people and environment around Lake Onslow.
Waste to Energy makes sense in every way.