Prof. Dr. P. K. Jena in Bhubaneswar, August 28, 2021: Mining of minerals being highly energy intensive, at present consumes a lot of fossil fuels with release of large amounts of green house gases and sometimes posing uncertainty in electric supply. This is more so in case of mines situated in remote areas. In recent years, mining companies are more interested to use renewable energy because of availability of better technology to harness unlimited energy stored in sun and wind.

For example, the price for harnessing solar energy has come down to $26,000 per Kw (Photo Voltaic, PV) in 1990 and has further dropped drastically to only $2,500 in 2013. It is reported that, most of renewable energy obtained from sun, wind and biomass can compete with that obtained from fossil fuels in near future. For example, at present, wind energy cost within $ 50 to $160 per mega watt per hour and biomass about $30 to $240 per mega watt per hour.

With lowering of commodity prices in case of most of the minerals along with soaring cost of diesel, it is becoming more expensive to use diesel for mining of minerals particularly those located far from electricity grid. In recent years, mining companies are looking for best available technology to use as far as possible fully renewable energy particularly the solar and wind ones in order to offset their fuel expenditures. In view of this, intense efforts are being made in this regard in most parts of the world particularly in major mining countries like Canada, Australia, South Africa and Chile.

Australian Mines

The Rio Tinto and the Australian Renewable Energy Agency (ARENA) have jointly taken up a project on establishing a solar PV plant of 1.7 MW for mining Conglomerate e.i. bauxite mine, facilities for processing of the minerals and also for township after meeting the requirements of mines and the integrated facilities. It can also provide electricity to nearly 20% of the mining town day time electricity demand. The use of renewable energy is expected to reduce the consumption of diesel at the mine site by about 600,000 litres per year and hence cut down green house gas emission by about 600 tonnes per year.

With success of the project, it is being planned by ARENA to put up a 10.6 MW PV power plant at Sandfire Resources DeGrussa Copper Gold mine in Western Australia for meeting the energy requirements of their mines. By implementing this project, about 5 million litres of diesel fuel can be saved annually. Similarly, in Western Australia, the DeGrussa Copper Gold mine owned by Sandfire resources has included a 6 MW storage facility along with its 10.6 MW solar farm.

Canadian Mines

In Canada, as in many other countries, the fossil fuel cost in case of remote mines has doubled during the year 1999 to 2011. The oil price has also increased about 10 fold during 1999 to 2013 from about $10 US per barrel along with cost per transportation of the fuel. With decrease in cost for producing electricity from sun, wind and biomass through application of improved technology, in recent years, a lot of efforts are being made in Canada to utilize renewable energy in different mines.

The International Renewable Energy Agency has reported that, the average cost of electricity for wind, sun and biomass technology is $0.08, $0.16 and $0.08 per KW respectively in North America. The Glencore at its Raglan mine has set up a 3 MW wind turbine which is expected to meet about 5% of its total energy requirement and has cut down the consumption of about 2.4 million litres of diesel per year. With the success of this test programme, the Glencore is planning to install more wind turbines for generating about 9 to 12 MW of energy and can be able to reduce nearly 40% of their diesel consumption.

The Diavik diamond mine has set up a wind energy farm with a total capacity of 9.2 MW with an annual production of 17 GW per hour. This is about 8.5% of the power needed in their mine. The Diavik diamond mine has made an assessment that, a PV installation is economically feasible if the primary load is in the range of 3000 to 6000 KW hour per day. If this project is implemented they have calculate that, about 9% of the total energy consumed in the mine can be made available saving about 50,000 litre of diesel per year.

They also suggested that, by installing wind turbines the saving may be still larger. It is reported that, a wind energy plant with 5 to 10 wind turbines can generated from 30 to 40% of total power demand, saving from 25 to 35 million litres diesel per year. Installation of an electricity storage facility has improved the application of renewable energy resource and making it possible to provide solar and wind energy throughout the day in most of the remote mines. This is more so in case of off grid mines where it would be possible to cut down the diesel consumption in diesel generator appreciably.

The Glencore Raglan mine has successfully integrated 0.65 MW wind project in Northern Quebec. The Rio-Tinto’s Diavik diamond mine has setup wind turbines in the North Western region in 2013 to reduce the use of diesel fuel. The wind energy reduces diesel demand by 10% with a saving for the mine about 5 million dollars per year and the project is expected to pay back in 6 years.

South African Mines

South Africa is a mineral rich country and the mining industries are highly developed. In this country, quite a sizeable amount of renewable energy is being produced and used in hybrid systems like solar – diesel hybrid and wind -diesel hybrid integration. In Most of the off grid mines, serious efforts are being made to use renewable energy or its combination with diesel generator so that minimum amount of diesel can be consumed. There are three technical options for using renewable energy power in off grid mines. These are as follows:

a) Renewable plus Storage – In this system, the facilities are available to store the energy which is generated from renewable source in order to provide the power supply to the mine throughout the day and night without any interruption in mining.
b) Hybrid Systems – In this case, advanced “Fuel Save Models” is connected to solar or wind energy system with diesel generator in order to utilize the renewable energy completely.
c) Hybrid Systems plus Storage – In this system the renewable energy is produced either from sun or wind hybrid with diesel and the surplus energy is stored in order to maximize the use of renewable energy.

In South Africa, it is claimed that, solar – diesel hybrid system is cost effective particularly for off-grid mines. The Cronimet company is now planning to have storage system so that the use of solar energy can be further maximized. The SNIM Company operates iron ore mines in Zouerate region of Tiris in Mauritania. The SNIM has planned to construct a 5 MW wind farm in Nouadhibou. It is reported that, the wind farm output is 19 GW per hour per year. The fuel saving is 4800 ton per year diesel and the pollution control can be effected significantly by decreasing green house gas emission by 11,500 ton per year. South African chromium mine operated by NUNICH based Chromite mining company is using a 1 MW solar PV system to cut down a good amount of diesel consumption.

Mines of Chile

Chile is a mineral rich country in South America, where mining industries are pioneer in utilizing solar and wind energy in mining sector. The Parabolic Trough technology is the most mature concentrated solar power (CSP) technology. In 2015, approximately 84% (3960 MW) of worldwide CSP plants are parabolic trough ones. Chile has a 10 MW parabolic trough plant in operation and a number of such plants with totaling 360 MW power producing capacity are being planned. The concentrated system modelled, based on CSP technology, has 50 MW of rated capacity plus 1640 MW of storage capacity with a diesel co-firing system ensuring all time mining operation.

The mining sector in the world, the market of renewable energy both from sun and wind is young with the first wind project being commissioned in 2010 and the first solar project in 2012. However, out of this, 91% of electricity sources are solar PV and the rest from wind installations. Half of these projects are in Chile, of which the majorities are grid connected and financed through a Power Purchase Agreement (PPA). The largest off-grid project is 6.7 MW and on grid project is 150 MW. It is reported that, now solar energy has become a cost effective and clean alternative to conventional energy sources. In many countries the electricity cost from coal fired thermal power plant is similar to that of large PV plants.

All over the world, the time has come to maximize the application of renewable energy specially solar and wind energy in mining of minerals in order to make mining more efficient, environment friendly and cost effective. When the mineral rich countries like South Africa, Chile, Australia, Canada, USA etc., are busy in replacing fossil fuels by renewable energy in mining of minerals, India also being a mineral rich country, should not lag behind. The state and central governments should provide incentives to the mining companies to use renewable energy in place of costly and polluting fossil fuel based energy.

• Former Director General, Council of Scientific & Industrial Research, India