One of the important considerations when organising power for remote mines is the ability to store power if using renewable power sources. This will be discussed in the January International Mining magazine article on the subject. Based in Sydney, Australia, Ecoult has answers for this. It is a high-tech energy storage and hybrid energy solution company that has spent much of the past decade at the forefront of the push to making renewables stable and dispatchable, rather than dependent on weather. A focus area for Ecoult has been optimising the mix between renewables and diesel at remote sites, combining battery energy storage with diesel generator systems. The company develops applications and software for the sustainable, energy storage solution – UltraBattery®, invented by CSIRO, which combines ultracapacitor and battery chemistry in a single hybrid cell. Ecoult’s operations span small commercial and industrial energy storage in Australia, through to large megawatt systems both there and in North America.
John Wood, CEO, Ecoult notes “many remote sites face a similar set of issues: large swings in load, a diesel power plant, intermittent solar power, and a business requirement for reliability and efficiency.”
Ecoult has shown, in both the kilowatt and megawatt scale, that its energy storage and management systems allow a hybrid diesel/renewable power system to operate with greater reliability, using the power from renewables to reduce dependence on diesel.
“Ecoult’s UltraBattery excels in remote areas,” Wood explains, “because it is dependable, robust in a variety of climates, highly efficient in reducing diesel usage and fully monitored with hardware electronics and software. This means many power functions of the battery – and indeed the whole power control system – can be monitored and controlled without requiring a visit to the site.
“UltraBattery has exceptionally high charge and discharge rates, giving access to faster charging and higher power output than most competing chemistries. The batteries are proven in the toughest multipurpose applications, which means a single installation can do multiple tasks (from smoothing and high peak-power handling through to renewable shifting and UPS), multiplying the overall benefits.
“While diesel continues to play an integral role off the grid, there is an ever increasing synergy and optimisation between diesel, renewables and batteries. The key to efficiency is to have the management systems in place so the diesel generator is in one of its two most efficient modes: switched off, or operating at its most efficient operating point, close to its maximum output.”
On mines, the benefits of renewables and storage are significant. Not only is there the potential to greatly offset diesel directly using solar power during the day and store for part or all of the night, a battery also allows a diesel generator sized for the peak loads (e.g. large surge loads during machinery start-up) to operate at peak efficiency even when it is powering small intermittent loads.
“In the case of the UltraBattery, Wood says, “the high charge power allows it to charge quickly using the peak output of the generator. The generator can then be switched off while the highly-efficient battery reticulates energy at varying rates as small loads are switched on and off across a site.
“In smaller diesel-solar-storage microgrids, operators can reduce 30 to 90% of their diesel consumption – benefitting too from longer maintenance cycles and lower servicing costs, because the generator is used not only less frequently, but also at its optimum loading.”
Ecoult’s systems are designed for continuous, high-rate applications in harsh-climate, remote sites. For example, Ecoult’s UltraBattery provides 500 kW of PV-smoothing capability at the Prosperity solar energy project in New Mexico (pictured). This solar site experiences 136 kW per second ramp rates during cloud events – too steep for grid operators, who prefer a constant and predictable supply. The Ecoult battery installation allows the PV plant to reduce the ramp rate to a suitable level, and also store the midday PV for the evening demand peak.
Unheard of five years ago, examples of megawatt hybrid installations in remote mines are easily found today. A 10.6 MW solar PV plant – with 6 MW storage – is installed at the DeGrussa copper mine in Western Australia integrated with the existing 19 MW diesel generation plant. The use of solar and storage offsets at least 5 million litres of diesel use per annum. See last year’s article (IM, September 2016, pp70-87).
Rio Tinto, at its Weipa bauxite operation in Queensland, uses a ‘hybrid’ model where diesel generation is largely targeted to critical mine operations and solar offsets the township’s energy requirements. Rio Tinto’s 1.7 MW solar PV power station offsets around 600,000 litres of diesel per year and enables it to hedge against diesel price fluctuations.
“In remote Australia, batteries are fast becoming the alternative to prohibitive transmission infrastructure upgrades,” Wood observes.
“Battery storage on remote microgrids is no longer only a ‘green’ option, but one that reduces power overheads, enhances control over the site’s power requirements and quarantines the operator from market-driven changes in grid power and fossil fuel prices.
“The mining sector has begun to embrace multi-source generation, and the challenge of ramp rates, power quality, frequency, intermittency and diesel inefficiency is being mastered with battery energy storage.
