In the recent past, setting up any mineral-based industry has been very challenging. Cement production is entirely based on minerals. Till date, no research has been able to offer disruptive alternative for cement manufacture or cement as a product. It continues to be the same old story. Let us see what the technology may offer?
The Indian cement industry occupies a pride of place in the cement universe. The annual cement manufacturing capacity is now close to 500 million tonne per annum (MTPA) and thus has the distinction of being the second biggest producer in the world. Broadly speaking, cement is termed as a binder, a substance used for construction that sets, hardens and adheres to other materials. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement is the most widely used material in existence and is only behind water as the planet's most-consumed resource.
A Cement as a product is very widely used only next to water. It is primarily high volume low cost material. On the economic barometer; cement consumption denotes the prosperity index of a country. Though India is the second largest country in cement production, yet we stand low in numbers of per capita consumption. In the present situation, we find consolidation happening in the cement sector and yet new plants are being added. It has become more difficult and challenging to set up a Greenfield project compared to the past. Let us look at some of the hurdles faced by the industry players. However as the subject goes, we take a stock of few of the challenges faced while setting up of a cement plant.
Today land acquisition is topmost on the list. In spite of putting best efforts and giving good price, it may end up into difficult situation. The land acquisitions for mining are increasingly becoming more and more complicated. At least 10 years'of limestone deposit needs to be acquired and getting the surface rights for such contiguous land becomes exorbitant resulting in huge capex cost for the project.
Another major hurdle that a new cement plant has to cross is water requirement. Water neutrality or water positivity is when you preserve/recycle more water than you consume. Cement factories, which are spread across various geographical locations, face water issues, not only for their operations, but also for the communities living around the plants.
Technology has enabled the cement companies to migrate to platforms that require less water intake. Today's cement manufacturing is limited its water consumption for captive power plant operations ranging from 16 MW to 45 MW. Second major water requirement is from the residential colonies in and around cement factories for domestic use. Third requirement is for dust suppression, dust quenching and horticulture. Therefore, the new plants have to initiate water positive programmes right from inception. Water neutrality programmes include water storage, rainwater harvesting, groundwater level recharging, recycling of waste water, availability of potable water to the communities, setting up of check dams and water storage facilities.
Day-by-day the environment regulations are becoming tighter not only for cement but for industries in general. Cement, being one of the highly polluting industries, the revised norms adds to the cost. Norms with respect to dust and noise have been well accepted. But modified permissible limits for environment particularly NOX and SOX is putting additional burden and increasing the cost to put up the plant.
Limestone: Basic raw material
From the point of economy of scale, currently, clinkering units of 6,000 tonnes per day (tpd) to 10,000 tpd capacity are preferred entailing a capital cost in the range of Rs 1,500 to Rs 3,500 crore and it takes three years to complete the project. Such large upfront capital investment calls for assured life of more than 30 years of plant to get viable returns. When the capital is barrowed from the market it puts more stress on the borrower to repay the loan. The recent sale of assets what we have witnessed has been primarily due to mismatched financial decisions.
Talking about the raw material, compared to other parts of world, the Indian limestone deposits are considered to be of inferior grade meaning marginal or sub-marginal in quality and therefore need additional processing step/s to enrich lime content alternately it may call for adding high grade limestone to enhance overall lime content before it is fired in the kiln. The problem of low grade in limestone gets further compounded by the fact that the Indian coal that is used as a source of heat is also poorer grade meaning low in heat value and high in ash.
Bill Gates and cement
Now let us cover what we have unheard of so far and that is "solar-powered" cement production. Recently in the month of November 2019, Microsoft co-founder Bill Gates entered the world of cement with a public relations blitz for Heliogen. He's one of the backers of a new Californian technology startup looking to use concentrated solar power (CSP) to power heavy industrial applications like clinker or steel production. The company says it has concentrated solar energy commercially to reach a temperature above 1,000 degree Celsius.
Its process, called HelioMax, uses a closed-loop control system to improve the accuracy of a heliostat system. It says it achieves this by using computer vision software to better align an array of mirrors to reflect sunlight towards a single target. Temperatures of up to 1,500 degree Celsius is one of its targets so that it can apply itself to a variety of processes in the cement, steel, mining, petrochemical and waste treatment industries. It says it can do this for $4.5/MCF. Another target once it reaches 1,500 degree Celsius is to start manufacturing hydrogen or synthetic gas fuels.
Heliogen's press release was picked up by the international press, including Global Cement, but it didn't mention the similar work that SOLPART (Solar-Heated Reactors for Industrials Production of Reactive Particulates) project is doing in France. This project, backed by European Union Horizon 2020 funding, is developing a pilot scale high temperature (950 degree Celsius) 24 hour/day solar process for energy intensive non-metallic minerals' industries like cement and lime. It's using a 50 kW solar reactor to test a fluidised bed system at the PROMES (PROcédés, Materials and Solar Energy) testing site in Odeillo, France.
Heliogen's claim that it can reach 1,000 degree Celsius is significant but it doesn't go far enough. Clinker production requires temperatures of up to around 1,450 degree Celsius in the sintering phase to form the clumps of clinker. SOLPART has been only testing the calcination stage of clinker production that suits the temperature range it can achieve. Unless Heliogen can use its method to beat 1,450 degree Celsius then it looks likely that it will, similarly, only be able to cut fossil fuel usage in the calcination stage. If either Heliogen or SOLPART manage to do even this at the industrial scale and it is cost effective then the gains would be considerable. As well as cutting CO2 emissions from fossil fuel usage in cement production this would reduce NOx and SOx emissions. It would also cut the fuel bill.
As usual this comes with some caveats. Firstly, it doesn't touch process emissions from cement production. Decomposing limestone to make calcium oxide releases CO2 all by itself with no fuel. About one third of cement production CO2 emissions arise from fossil fuel usage but the remaining two thirds comes from the process emissions. However, one gain from cutting the amount of fossil fuels used is a more concentrated stream of CO2 in the flue gas. This can potentially reduce the cost of CO2 capture and utilisation. Secondly, concentrated solar power systems are at the mercy of the weather, particularly cloud cover. To cope with this SOLPART has been testing a storage system for hot materials to allow the process to work in a 24-hour industrial production setting.
Looking more broadly, plenty of cement producers have been building and using solar power to supply electricity. Mostly, these are photovoltaic (PV) plants but HeidelbergCement built a CSP plant in Morocco. Notably, PPC Zimbabwe said this week that it was building a solar plant to supply energy to two of its cement plants. It is doing this in order to provide a more reliable source of electricity than the local grid. India's Birla Corporation has also said that it is buying a solar energy company today. The next step here is to try and run a cement plant kiln using electricity. This is exac
tly what Cementa, HeidelbergCement's subsidiary in Sweden, and Vattenfall have been exploring as part of their CemZero project. The pilot study demonstrated that it was technically possible but only competitive compared with "other alternatives in order to achieve radical reductions in emissions."
None of the above presents short or medium-term reasons for the cement industry to switch to solar power in bulk but it clearly deserves more research and, critically, funding. One particular strand to pull out here about using non-fossil fuel powered clinker production systems is that it produces purer process CO2 emissions. Mounting carbon taxes could gradually force cement plants to capture their CO2 but once the various technologies above become sufficiently mature they could bring this about sooner and potentially at a lower cost. In the meantime the more billionaires who take an interest in cement production the better.
- VIKAS DAMLE