A greener way to make aluminium

Aluminium production consumes vast amounts of power. Helen Tunnicliffe reveals how one producer is investing in hydropower.

Aluminium is one of the most widely used metals in the world, used in everything from drinks cans to space shuttles, and the market is growing by 4-7 per cent a year, mainly due to demand from developing countries.

The metal is valued for its resistance to corrosion and its lightness but its production uses huge amounts of energy. Traditional methods of power generation from fossil fuels produce large quantities of CO₂. In the current climate this is becoming increasingly problematic, both for environmental and financial reasons, due to the introduction of carbon markets around the world.

Because of the energy-intensive nature of the production process, the use of hydroelectric power has long been a feature in aluminium smelting, with most of the world’s biggest producers using at least some hydroelectric power. Indeed, the very first plant to use the Hall-Héroult aluminium production process of electrolysis (see below) made use of power from the Rhine waterfall in Switzerland.
Many large aluminium producing sites have grown up near hydroelectric power plants, although some, for example in the Urals and the Middle East, have been developed because of the close proximity of large quantities of fossil fuels. Globally, coal still accounts for 44 per cent of power for aluminium production.

The world’s biggest producer of aluminium, Russia’s United Company Rusal, is investing heavily in greener technologies and obtains 80 per cent of its power for aluminium production from hydroelectric power plants. UC Rusal produces up to 4.2Mta of the metal and 11.3Mta of alumina (refined ore). It says the use of hydroelectric power is an important part of its business strategy. “Electrical power accounts for 25-40 per cent of aluminium production costs and increasing energy costs have proved a fundamental obstacle to the growth of the global majors,” said UC Rusal’s Director of Corporate Strategy Artem Volynets.

“By creating a buffer of energy self-sufficiency, UC Rusal aims to not only protect itself from the fate of others in the industry, but also develop a key competitive advantage in its own right.”
- Artem Volynets, Director of
Corporate Strategy, UC Rusal

“Electrical power accounts for 25-40 per cent of aluminium production costs and increasing energy costs have proved a fundamental obstacle to the growth of the global majors,” said UC Rusal’s Director of Corporate Strategy, Artem Volynets.

UC Rusal, based in Moscow, was formed in 2007 after the merger of three other companies, Rusal, Sual and a Swiss company, Glencore. The company owns seven mines producing bauxite and nepheline, which are the main aluminium ores, as well as 15 smelters, 12 alumina refineries and three foil mills, not to mention its power generating plants and casthouse businesses for producing alloys. The company has sites in 19 countries across five continents.

High power usage

The main ore of aluminium is bauxite. The ore must first be refined into alumina (aluminium oxide) through the Bayer Process where it is heated in an autoclave with NaOH to between 150-200˚C, then cooled. The waste products, called red mud, are filtered off and disposed of. As the liquid cools fully, aluminium hydroxide precipitates out of the solution as a white solid. This is then ‘calcined’, ie it is heated in a furnace to over 1000˚C. This drives off water vapour, leaving behind alumina. Alumina must then be electrolysed. In the late 19th century, Charles Hall, an American student and Paul Héroult, a French engineer, simultaneously came up with a way to electrolyse aluminium cheaply. The process is now named after them both – the Hall-Héroult process.

Alumina is dissolved in molten cryolite, a whitish mineral, in a large container known as a cell. Cryolite melts at about 900˚C, 240˚C higher than aluminium. The bottom of the cell acts as the cathode, the negative electrode that attracts the positive aluminium ions. The negative oxygen ions are attracted to the anode, made of some form of carbon. These cells tend to operate on a very low voltage of around 3-5V, but draw a huge amount of current, often around 150,000A – this is why so much electricity is needed. Aluminium sinks to the bottom of the cell as it is denser than the molten cryolite and can be drawn off. Heat is kept in the cell by means of a crust of solid cryolite at the top and around the sides. There are two main anode technologies in use, known as the Søderberg method and the pre-bake method.

The Søderberg method involves making an electrode from coke and pitch, surrounded by a steel sheet cover. As this mixture is heated, carbon is formed which reacts with the alumina. The heat used is the lost heat from the smelting operation. This type of anode requires replacing much less often, as more pitch can simply be added to the top of the anode. The main problem with the Søderberg method is that heating pitch produces a lot of harmful emissions. For this reason, more aluminium producers are now using the pre-bake method. Pre-baked anodes produce less emissions than Søderberg anodes and tend to be more energy efficient. Pre-baked anodes are formed from carbon and baked at very high temperatures in gas furnaces. They are fixed into holders and lowered into the electrolytic cell. Unlike the Søderberg anodes they must be regularly replaced, as they cannot be replenished from the top.

Boguchanskaya Energy and Metals Complex

UC Rusal is currently undertaking several construction and upgrading projects, but its flagship development is the Boguchanskaya Energy and Metals Complex. The Boguchanskaya Energy and Metals Complex (BEMO) will be the largest of its kind in the world, sited on the Angara River in South East Siberia in Russia. The complex is a joint venture between UC Rusal and RusHydro (formerly HydroOGK), Russia’s largest energy producing company and has a total budget of US$3.6bn. The project includes a smelter, which will produce up to 600,000tpa of aluminium and 3000MW hydroelectric power plant (HPP), to provide the energy. It is expected to begin production in 2010 and should be at full capacity by 2012. “BEMO is the first project to place a particular focus on the environmental aspects. The investors in the Boguchanskaya aluminium smelter and the Boguchanskaya HPP insisted on having an Environmental and Social Impact Assessment as part of the feasibility study of the construction project,” said Mr Volynets. UC Rusal and RusHydro signed the deal to co-finance and build the complex in May 2006. The Krasnoyarsk and Irkutsk local authorities have been involved with the planning, along with Russian federal ministers, government agencies, the Russian Railways Company and Unified National Electric Grip.

The Boguchanskaya hydropower development will complete a dam
started before the collapse of the Soviet Union.

As well as the Boguchany Dam for the BEMO project, there are two more hydroelectric dams on the Angara river. Using hydropower instead of electricity from traditional thermal coal-fired power stations could save 6.5Mta in CO₂ emissions. “The plant will also provide energy to local power-hungry industries, and open enormous opportunities for local industries’ growth and business development,” said Mr Volynets.

The Boguchanskaya site is ideally suited to the building of the hydropower plant. The area is geologically stable and the river has a solid rock base. The reservoir that will be created when the plant is launched will be relatively small, due to its canyon location, minimising the environmental impact on the surrounding area.

The Boguchanskaya HPP was first suggested in the early 1970s, with construction work beginning in 1974. The dam across the Angara was completed in 1987, but during the break-up of the Soviet Union, funding was cut and progress was slow. “In the early 1990s, Russia’s economic slowdown and shrinking power consumption meant that the project was essentially mothballed from 1994 to 2005,” said Mr Volynets.

As the Russian economy recovered from the Soviet era, its demand for energy increased and the question as to what could be done with Boguchanskaya was raised. UC Rusal and RusHydro are effectively completing an unfinished Soviet project. The new dam has a unique design. Parts of the river are blocked by a cement dam, others with rock-fill dams with a bituminous concrete diaphragm.
The new smelter will be fitted with RA-300 cells, in which aluminium ore is electrolysed. This is UC Rusal’s own technology and is one of the most efficient cells in use in the world, reducing emissions by up to 50 per cent. Each cell can produce 2050kg of aluminium per day.

To date, UC Rusal and RusHydro have invested US$1.8bn in BEMO, and by the end of this year, the figure will have risen to US$2.6bn. Over 6500 people are involved in the construction of the BEMO project. It is the largest construction project currently in progress in Russia. The development of the Lower Angara territories will also include new rail and road networks, a pulp and paper mill, and gas condensate and iron ore processing plants, as well as a new residential town with housing and social facilities. Over 10,000 jobs will be created in the region. BEMO’s infrastructure is being financed by the Russian Government’s Investment Fund.

Business benefits

Going green by relying on hydropower will do more than help the environment. UC Rusal believes it has given them a competitive edge. The cost of energy has doubled and new carbon emissions regulations have meant that the cost of thermal power from coal has risen still further. Therefore, investing in renewable energy will save the company money in the long term.

Rising energy prices may prove to be cyclical but many are likely to reflect a long-term trend. Over the last four years, average growth in power prices hit 150 per cent. This has caused a number of aluminium producing facilities around the world to close because they became uneconomic.

“By creating a buffer of energy self-sufficiency, UC Rusal aims to not only protect itself from the fate of others in the industry, but also develop a key competitive advantage in its own right,” said Mr Volynets.

Hydroelectricity costs 2-4 times less than thermal energy depending on the region, making it ideal for the production of aluminium. Mr Volynets believes that the cost of power has a direct impact on the competitiveness of other aluminium producing companies. “With the volatility in oil and gas prices, we knew that a key strategic tool to help ensure our goal of becoming the world’s number one aluminium producer and our future goal of developing into diversified metals and energy was through our own energy production capabilities. Renewable energy provides a cost-efficient, regionally relevant and environmentally responsible means for us to achieve this in a very energy-hungry industry,” he said.

Environmental commitment

UC Rusal says its commitment to the environment goes much further than BEMO. Between 2000 and 2007, it says it invested US$1bn in activities to protect the environment. It plans to reduce its direct greenhouse gas emissions by half by 2015 and has a long-term goal to be carbon neutral, with the help of carbon offsetting. All of its aluminium smelters and seven alumina refineries are certified in line with the ISO 14001 environmental management standard, and it was the first Russian company to complete the monitoring and analysis of its greenhouse gas emissions. “A US$1.4bn investment is planned between 2007 and 2013 for modernisation programmes aimed at environmental protection,” said Mr Volynets.

The modernisation includes the installation or rebuilding of gas-purifying facilities, enabling the removal of 99 per cent of fluorides, dust and reducing volatile organic carbon compounds, increasing the amperage of cells, and modernising equipment at its alumina refineries.
It has committed to several voluntary initiatives, including:
• UN Global Compact – ethical business framework which includes environmental guidelines, as well as guidelines for human rights, labour and anti-corruption
• International Aluminium Institute’s Aluminium for Future Generations sustainability objectives, which include reducing water consumption, lowering greenhouse gas emissions from road, sea and air transport and rehabilitating land used for bauxite mining
• Compliance with the Kyoto Protocol
• Establishment of the National Carbon Compact Partnership.

In 2002, UC Rusal set up a research and design facility, the Engineering and Technology Centre (ETC), with the intention of increasing output by developing new technologies to modernise its plants and improve efficiency. Over US$8m is invested in research and development every year. In the industry, this capability is essential to stand any chance of competing. All the major players including Alcoa, Alcan and the large Chinese companies have their own research and development facilities, dedicated to producing their own proprietary technologies. To this end UC Rusal’s ETC has introduced the RA-300 cell, mentioned above, and the RA-400 cell to reduce energy consumption and improve efficiency. These cells also help to prolong the life of the smelter and reduce emissions by 50 per cent. At present engineers are also working on an RA-500 cell.

The ETC is also developing technology to improve smelters that still rely on the Søderberg method and hopes new technology involving colloidal anodes will reduce greenhouse gas emissions by up to 70 per cent and improve energy efficiency by 20 per cent. This new technology will be implemented from 2010 onwards. Mr Volynets said that since 1990 the company had reduced emissions by 38 per cent at its major aluminium smelters.

Other projects include technologies to improve the efficiency of the coal-fired power stations still used at some of its sites, for example in the Urals, introducing more efficient methods of bauxite refining, and developing new vertical inert anodes, which will not be consumed during the process and should eliminate emissions. UC Rusal also owns two scrap-processing plants for recycled aluminium. Recycling uses only 10 per cent of the energy required for producing aluminium from its ore. More directly, UC Rusal works with Strana Zapovednaya (The Land of Nature Reserves), a wildlife protection group to help conserve important habitats in areas near its smelters. It partially funds a project called Green Patrol and various other regional environmental charities. Green Patrol projects can include cleaning up a stream or protecting an endangered plant species. In the Altay-Sayans regions, UC Rusal employees help to patrol restricted nature reserves.

The future

Despite the large initial outlay for sustainable technologies, in the future they are likely to be a more economical option. As the prices of coal, oil and gas continue to rocket, the cost of aluminium production is likely to rise further. Some of UC Rusal’s rivals, including Alcan and Alcoa, are investigating the use of geothermal energy in Iceland. For the time being, UC Rusal is sticking with hydropower, and says it is one of the key components of its energy strategy. In February 2008, it formed a partnership with China Power Investment Corporation (CPI) in the hope of creating a vertically integrated aluminium production complex. This will consist of a bauxite-alumina complex in Guinea and an energy and metal complex in China, according to the memorandum of understanding. “The smelter, with a minimum capacity of 500,000tpa will be constructed in Qinghai Province in China, with its energy supply sourced from CPI’s hydropower facilities on the Huang He River,” said Mr Volynets. The bauxite-alumina complex in Guinea will have a capacity of up to 2.8Mta of alumina. Mr Volynets believes that energy self-sufficiency and the continuing use of renewable energy will be vital in the future if UC Rusal’s competitive advantage is to be maintained. “This change in strategy and company development is likely to be emulated across the aluminium sector and possibly more widely,” he said.

Helen Tunnicliffe is a journalist specialising in energy and the environment. For more information visit:
http://www.rusal.ru/en/Default.aspx
http://www.aluminiumleader.com/en/