An Electric Personality

Max Planck once said that “science advances one funeral at a time”. His point was that for any progress to be made in scientific endeavours, old thinking must be put to rest. Such is the case with electrification. Dr Nesimi Ertugrul, an associate professor at the University of Adelaide’s School of Electrical and Electronic Engineering, shares his thoughts on why the time is ripe for the change to electric at mine sites.

Q: Can you explain what you mean when you speak of a synergy between grid transformation in domestic power networks and mining power networks?

A: That synergy is based on the development of autonomous microgrids with distributed energy resources, primarily using renewable energy. Most mine sites are in remote areas and only few of them are connected to the domestic power network, but even then, usually via long transmission lines.

Therefore, it is logical to develop stand-alone microgrids with renewable energy (solar and wind, and possibly with hydrogen in the near future), which can eliminate the limitations of the centralized network approach. Since microgrid structures are already shaping grid transformation, they can form the power grid in mine sites without significant modification.

Furthermore, electricity infrastructures and operational and maintenance costs of mine sites heavily involve diesel engines and generators, which have an impact on the cost of energy. Mine microgrids can respond to such limitations while supporting a 100 percent renewable powered transformation.

Electricity transformation of the grid by the integration of renewable energy sources, along with maturity in battery storage solutions and electric vehicle technologies, have accelerated mine electrification. While several commercial electric machineries and battery vehicles are already available for mines, some hydrogen-powered vehicle trials are also underway for large-haul trucks on mining sites.

Q: Why do you think that now is the perfect time for electrification, particularly at mine sites?

A: It’s probably about the advances in power electronics, which is the enabling technology in renewable energy and electric transportation systems. In all applications involving power electronics, similar circuit topologies use semiconductors to convert electric power to perform specific tasks. For example, in a microgrid application, a bidirectional converter can charge a battery or feed an electric load, and an identical converter can also charge the battery in an electric vehicle when it is stationary or drive an electric motor (or control it as a generator during braking) when it is mobile. In addition, the advances in semiconductor switches (specifically development in wide bandgap devices) enabled the development of high-power density (volumetric and gravimetric) converters at low cost. Therefore, the mature products of power electronics naturally became available in mining equipment.

Q: What benefits are available to miners concerned about the cost of electrifying their equipment?

A: We can’t underestimate the reduction of carbon emissions as a driver for change from combustion engines in mining equipment. However, I believe that the major benefit for conversion to electric in mining is about the improvements and opportunities in system efficiency and ease of control. Diesel engines have an efficiency not more than 35 percent at rated load (at rated speed and torque) and much lower at light loads. It should be emphasized here that at low efficiency, significant heat and high emissions (diesel particulate matter) are produced as well. However, electric motor and drive efficiency can be more than 80 percent in a wide range of loads. In addition, in the mining industry, uptime needs to be maximized. Electric motor drives have several other benefits to miners, including low noise and vibrations, increased reliability, fewer mechanical components and reduced maintenance and service cost. Furthermore, the electrical systems make the monitoring of mine activities for process control and fault detection seamless and easy, which is critical for future mine sites.

Q: How difficult is the reskilling of staff after mine electrification has commenced?

A: It is both difficult and easy, but most of all necessary. Not all mine workers need to have a similar level of knowledge on electrification. At the highest levels, mine owners must be convinced of the value of electrification, so they need to have the knowledge of how the overall integration works. Ground-level engineers, however, must be trained on a number of fronts, including power electronics, motor drives and microgrid system components and control. At the University of Adelaide, we are already training students to be ready for these new electric realities. Therefore, we have instituted a variety of programmes to help the future workforce in the field. As a part of these, we have developed courses covering all modern distributed energy technologies. We have also created the Australian Energy Storage Knowledge Bank, where we share modern microgrid platforms with utility-scale battery storage. In addition, we are leading the mine electrification programme of the Future Battery Industries Cooperative Research Centre in Australia, which also aims to train the mining community at large.