Just before the Christmas break one of the Global Cement editorial staff noticed how many solar projects have been popping up in the industry news of late. Looking at stories on the Global Cement website tagged with ‘solar’ five occurred in a six month period of 2017 out of a total of 13 since 2014. It’s not a rigorous study by any means but projects in the US, South Korea, India, Namibia and Jordan all suggest a trend.
All these new projects appear to be providing a supplementary energy source from photovoltaic (PV) solar plants that will be used to supply a portion of a cement plant’s electrical power requirements at a subsidised cost. Typically, these initiatives are preparing to supply 20 - 30% of a plant’s electricity over a couple of decades. These schemes are often supported by government subsidies to encourage decarbonised energy sources and a general trend in societies for so-called ‘greener’ energy sources in the wake of the Paris agreement on climate change.
Global Cement is familiar with this model of solar power in the cement industry from its use at the HeidelbergCement Hanson plant at Ketton in the UK. The project was realised by Armstrong Energy through local supplier Lark Energy and it provides around 13% of the cement plant’s electrical energy needs. Originally the array started off by supplying 10MW but this was later increased to 13MW in 2015. A key feature is that as part of the agreement with Armstrong Energy, Hanson receives 35% of the solar power generated for free and buys the remaining 65% at a fixed rate. Even at this rate the plant expects to save around Euro11m in energy costs over the lifetime of the solar array. In addition it will save 3500t/yr of CO2.
Most of the new solar projects announced in 2017 are of a similar scale and ambition to what Hanson Cement has done at Ketton. However, JSW Group’s plans are a magnitude larger. The Indian cement producer wants to build a 200MW solar plant next to its cement grinding plant at Salboni in West Bengal for US$124m. However, it has hedged its bets somewhat by saying that it might build a 36MW thermal power plant instead if its proposal fails.
LafargeHolcim and Italcementi have also experimented with concentrated solar power (CSP) plants for the cement industry. In 2007 LafargeHolcim and the Solar Technology Laboratory of the Paul Scherrer Institute and the Professorship of Renewable Energy Carriers at ETH Zurich started researching using high-temperature solar heat to upgrade low-grade carbonaceous feedstock to produce synthetic gas. The intention was to use the synthetic gas as a substitute for coal and petcoke in kilns.
Italcementi’s project at the Aït Baha plant in Morocco uses a CSP process that can be used with the plant’s waste heat recovery unit. Its moveable trough-style solar collectors follow the sun throughout the day to warm up a heat-transfer fluid during the day and store the heat in gravel beds overnight. In this way the CSP process allows for continuous operation over 24 hours. Before Italcementi’s acquisition by HeidelbergCement in 2016 the company had long-term ambitions to roll-out its CSP process across plants in the Middle East and North African region.
New battery technology of the kind backing the growing electric car industry may be further pushing the cement industry’s preference to PV over CSP power. The other renewable energy source slowly being built to support cement plants has been wind. Like PV it too suffers from cyclical disruptions to its power. Technological entrepreneur Elon Musk (of Tesla car fame) notably supplied the world's largest lithium-ion battery to Southern Australia to support one of its wind farms in late 2017. Around the same time local cement producer Adelaide Bighton announced in a separate deal that it had struck a deal to use wind power to part-power some of its facilities in the same region. At present it doesn’t look like solar power will be completely powering cement plants in the near future but perhaps a renewable fuels rate along similar lines to an alternative fuels rate might be a growing trend to watch.
The Global Cement CemPower conference on electrical power, including waste heat recovery, captive power, grinding optimisation and electrical energy efficiency, will return in January 2019.