THOUGHT LEADERSHIP

Powering a greener mining future with hybrid renewables

This article reflects on a panel discussion chaired by Ray Massie at the Energy and Mines Australia Summit 2023, which you can read more about here.

The discussion about powering mines with renewable energy has moved a long way in a short time. As the imperative to go green has escalated, the mining sector has grown hungrier for viable, rapid and cost-effective strategies to decarbonise, build greater social licence and tap into the competitive market for products with a lower carbon footprint. Integrating cheap, abundant renewable energy into mining operations is the natural solution.

These are exciting times as the sector moves far beyond the ‘why’, ‘whether’ and ‘when’ of renewables – and digs much, much deeper into the nuances of ‘how’.

Early forays into small hybrid off-grid renewable energy systems have demonstrated and built confidence in the technology – so there is no longer any question in the mining industry of whether off-grid hybrid renewable systems will work. Off-grid hybrid projects aren’t small test beds anymore. They’re ground-breaking, large-scale, cutting-edge renewable power systems of the future, able to be deployed on a fully commercial basis with clearly understood risks and operational adjustments. In many ways, the mining sector is out ahead of the pack, and the deployment of renewables on off-grid mine sites is offering lessons for the wider power sector and the future of the grid.

With many of the early technical risks resolved, the driving focus now is how to take full advantage of what a hybrid system can offer. How can the system be optimised to maximise its benefits? What’s the required level of reliability? How much storage is enough – and in what form?

Of course, every mine site is different, so there are no one-size-fits-all answers. And today’s answer may not be the right fit for tomorrow, given the rapid and continuous transformation of the energy landscape – in terms of technology advances, policy shifts, price volatility and global trends. It’s a dynamic space.

Integrated control and storage change the game

Traditionally, the relationship between mining operations and power supply has been a relatively simple transaction requiring a given amount of power with a set level of reliability and availability. The modelling of the power system was based on simple load metrics and power quality dictated by the capabilities of thermal generation plant. This equated to a very simple, flat cost of energy with any variance at the macro scale driven by changes in the price of fuel.

As we all know, when we switch over to multiple intermittent and variable generators, things become more complex. One of the keys to unlocking the benefits of a hybrid renewable system is the integrated control approach. With the correct control philosophy in place, you have many more ‘levers’ that can bring each element into play for a given operational mode or system event. This enables achievement of the levels of power quality and reliability that are needed, rather than being limited to the levels that traditional thermal plant could supply.

With this sophistication of control, we can start to think differently about reliability across the whole mining operation. Does the mining plant process or works need the same reliability or availability across everything all the time? Perhaps, for example, power supply for pumping may not require as high a level of reliability as other more critical areas of the plant. A clear understanding of the true reliability needs will help derive the optimal design at minimal cost.

When storage comes into the mix, we can also start to think differently about how to best match energy supply, timing of energy-intensive activity, and storage of excess energy to get maximum value from the renewable resource and minimise both the cost of energy across the operation overall and the cost per tonne of the mine’s output. The economics of long-duration storage are improving all the time.

New horizons for energy storage

Although the technology and the sector have travelled a long way already, there are still issues to finesse. One area of uncertainty is the optimal and most cost-effective storage technology and duration.

Going back a decade, the economic storage duration was 10 to 20 minutes, using the battery primarily for its discharge capability. Now we are seeing economic storage durations approaching 4 hours, which lend themselves to energy-shifting roles in which the charging capability comes into play as well as the discharge mode. The economics of longer duration storage will continue to improve but the optimum arrangement will vary site by site.

Funding for advancing novel long-duration energy storage (LDES) technologies has increased by 36 times over the past 5 years[1]. While lithium-based batteries still dominate and are likely to continue to do so for the foreseeable future, many more types of storage are now possible, including metal-air, pumped hydro, compressed air, flow batteries, gravity, thermal and various novel chemistries. Some storage technologies require specific topography and geology, for example pumped hydro and large compressed air storage, and others are at varying stages of technical readiness. Flow batteries of various chemistries are experiencing a significant amount of support aimed at breaking through the long-term storage cost barrier, though this is yet to be achieved at scale, and more likely to be competitive at longer durations (>10 hr) and in larger sized systems (>100 MW).

It is clear, however, that finding the best LDES for a mine project is not just for the mining sector to solve alone. The entire global power industry is looking at storage – and the mining sector can take full advantage of this as LDES evolves. What the mining sector can do right now is to identify the energy use and demand side opportunities that various storage durations could unlock for their projects.

Another key learning we have found over years of hybrid system development is that not every bit of energy produced by renewables needs to be stored. Some can be spilt or, better still, adjustments can be made on the load side to better match the variability in generation. Once the system stability, reliability and demand-side opportunities have been addressed, the storage of ‘spill’ really comes down to economics, which will change over time as storage costs decrease.

Collaboration and risk management

With all these new approaches and possibilities – and the many factors that always come into play such as mine life, capital limits and risk – it’s possible to over-analyse. Not every new project needs to break barriers and set new records. There is definitely still a place for choosing the low-hanging fruit, as the primary case for renewable hybrids being cheaper than thermal-only is well established. You will never really be able to answer every question in a single project – or even predict every question that might arise.

This is where you simply don’t have to go it alone. The key to overcoming hesitation is collaboration. Getting the correct advice is always worth the investment, as is sharing learning at an industry-wide level. There are many players that specialise in one or more aspects of the future mix of technology, mining process, hybrid power operation, renewables knowhow, integration skills, commercial thinking and so on – and bringing these skills together is a must.. Collaboration is the key to solving problems, reducing risk and its appropriate allocation, and a successful project that will benefit all industry players more than competition and working in isolation.

We also believe in learning by doing, through delivery of a specific project. Forming a group of key parties to drive forward a tangible project makes it far more manageable. In innovative projects, ‘pushing risk through’ often just comes back as significantly increased cost. A better approach in these cases is a shared risk profile. The learning is a significant part of the return in early adoption.

Are the right people and the right materials available?

The industry is already experiencing a shortage of experienced hybrid system operators. This needs to be managed through increased training and backup. We believe that operational personnel should be engaged very early in the design of a hybrid power system so that they can have input into development of the system, gain familiarity with it, and consequently feel a level of ownership of the assets.

It is also important to have a close relationship between those involved in the mining process and those operating the power system. For the power system operators, this is a chance to better understand the criticality of various mine plant processes; for the mine operators, it’s a chance to get a better understanding of the mix of operation modes that can be used to meet the mine’s changing power needs.

In many ways, the people skills and resources needed across all the project delivery stages (design, deployment, operation, maintenance and support) are more important than the technology – and this needs to be considered carefully for hybrid projects to be successful.

Finally, neither the mining industry nor the energy sector at large will be able to transition to renewables if we don’t have the right minerals and materials on hand to manufacture clean energy technologies such as wind turbines, solar panels and batteries. Having the mining industry supply these resources in a sustainable way is a powerful contribution to the clean energy transition.

ABOUT THE AUTHOR

Ray Massie has more than 30 years of expertise in renewable energy technology. He managed the development phase of the Hydro Tasmania iconic King Island Renewable Energy Integration Project (KIREIP) and Flinders Island Hybrid Energy Hub as well as undertaking key roles for hybrid system projects at Coober Pedy, Rottnest Island and more recently EDL’s Agnew Hybrid Renewable Microgrid powering Gold Fields’ Agnew Gold Mine and Scott Base in Antarctica.

Entura is an expert in hybrid off-grid renewable energy systems, from our world-leading King Island Renewable Energy Integration Project through to large-scale off-grid mining solutions such as EDL’s Agnew Hybrid Renewable Microgrid, powering Gold Fields’ Agnew Gold Mine. If you would like to talk to us about integrating more renewables and storage into your energy equation, contact Patrick Pease, Donald Vaughan or Greg Koppens.

[1] “The long and the short of energy storage tech”, Climate Tech VC (CTVC), March 2023