SESSA Solar Water Heating on mines in South Africa

Mining companies in South Africa are some of the highest users of electricity. They have been forced to cut consumption since the blackouts of early 2008 came to the South African electricity users.

 There are many parts of mining that cannot be performed easily without electricity, such as refrigeration, milling, hoisting and compressing air. However, there are still areas where solar energy and energy efficiency are still the best options for the long-term running of the mines.

The most high-profile area is solar thermal use to heat change-room water. The change room is the first area to which miners head after a long shift; and a good, hot shower is part of the reward for a hard day’s work.

This water traditionally has been heated by electrical resistive elements but, increasingly, mines are using solar water heating and heat pumps.

The life span of a mine and the life span of a solar water heating system is measured in decades, so the long-term view is an easy fit.

From 9 November 2011, new mines will need to adapt to the SANS 10400-XA building regulation, which requires that “at least 50% by volume of the annual average hot water heating requirement shall be provided by means other than electrical resistance heating including, but not limited to solar heating, heat pumps, heat recovery from other systems or processes and renewable combustible fuel.”

Before this even came into effect, energy efficiency and renewable energy systems had been installed on several mines in South Africa.

Leading this energy drive are individual South Africans who make the decisions to invest in solar and take the step to lead the way for others to follow.

The Sustainable Energy Society Southern Africa (SESSA) solar water heating members have covered roofs of the Brakfontein platinum mine (540 square metres) with flat plate collector, as well as the Middelpunt platinum mine (180m2) and, most recently, Grootegeluk coal mine (230m2).

The key decisions were based around:

• Simple financial benefits – easy to understand, and no difficult calculations;

• Long-term investment;

• Certainty of energy supply (solar thermal);

• Visibility of sustainable practices.

The client requested a 100% solar fraction for the male change house, meaning that all the hot water had to be heated with solar thermal energy. This is extremely challenging because the sun is only available for eight hours to supply hot water needs for 24 hours and beyond. In addition, when there is no hot water demand, the heat gain has to be dissipated back into the air. The eventual design ended up with 98% solar fraction.

Safety mechanisms to protect the system against failure or high maintenance are comprehensive and required special design features such as an enlarged membrane expansion vessel of 1 800 litres.

A eucalyptus tree tried its best to keep the sun’s rays off the solar panels; only now has the client agreed to cut it down, when it was highlighted that not only was the tree alien, but it also came from Australia!

Extensive training was done – not only on the systems, but in general surrounding solar water heating and energy efficiency.

The Energy Efficiency and Renewable Energy Awareness campaign included a forum at Exxaro headquarters, with discussions around energy savings from household (a few watts) to mining equipment in the megawatt range.

Mining, energy efficiency, carbon tax and climate change

The South African government has committed itself to climate change mitigation, energy efficiency and a carbon tax. This is in addition to rapidly rising electricity costs. All these will have an impact on mining. SESSA welcomes this, and commits itself to helping all mines use the most appropriate technology to reduce energy bills, and to incorporate solar water heating wherever possible.

SESSA encourages the use of the best source of non-damaging energy at the most appropriate place for the longest time. The government measures should penalise wastage rather than penalise usage.

Mines that can show they have adopted world and South African best practices to use renewable energy and heat recovery can showcase that sustainable mining practices are cheaper, better for the environment and less risky to the mining companies.

Generating part of their electricity needs by mines for their own use is already possible, given hydropower for electricity generation from water sent underground, and roof space on buildings for photovoltaic systems for buildings occupied during the day. In addition, heat recovery from refrigeration plants and from water pumped from underground will all be part of making South African mines energy-efficient and cost-effective.

SESSA looks forward to the day when South African mines have the lowest footprint in the world, driven by homegrown capacity skills and technology.

Irvan Damon, SESSA Ambassador