Cement factories can put the brakes on global plastic pollution
Cement factories can put the brakes on global plastic pollution
April 30, 2020
Press Release: SINTEF
Hope in the midst of crisis. Overflowing landfill sites in Asia may prove to be goldmines for local cement producers. So say researchers at the Norwegian research organization, SINTEF, which has extensive experience with the same concept in China
Plastic is made from fossil fuels and contains more energy than coal. Substituting industrial coal consumption with non-recyclable plastic enables us to resolve two problems. The plastic will not end up in landfill or in the sea, and we will reduce levels of coal consumption and thus also CO2 emissions.
China is now investing heavily in the use of plastic waste as a fuel in the cement industry, and it was Norwegian researchers that first suggested the idea. The aim of the project OPTOCE (Ocean Plastic Turned into an Opportunity in Circular Economy) is to assist a number of Asian countries to be rid of their landfill sites and at the same time reduce their coal consumption.
China, India, Thailand, Vietnam and Myanmar are together home to three billion people – about half of the world’s population. The greater part of the plastic and plastic refuse in the world also originates from these countries. China alone accounts for almost a third of the world’s production of plastics.
As well as the plastic they use themselves, these countries also receive large volumes of plastic waste from Europe. Plastic collected in Norway is sent to Germany and that which cannot be recycled – that is, most of it – is often exported onward to Asia. Unfortunately, this is because only a small proportion of our plastic refuse can be recycled. This may be because it has either already been recycled several times, or because it contains additives that mean it requires more energy to recycle than we obtain from its re-use. So, it ends up as refuse.
The standards of living and levels of consumption in the five Asian countries have increased rapidly in recent years, but the effectiveness of their waste management policies has failed to keep up. They simply cannot get rid of their refuse, which accumulates in great landfill sites. Much of it ends up in the sea, where the plastic can do a great deal of harm.
“When the plastic ultimately ends up as microplastic in the oceans it becomes difficult to remove, so by far the best strategy is to prevent it from entering the marine environment in the first place,” suggested SINTEF’s senior research scientist Kåre Helge Karstensen, who is heading the OPTOCE project. The aim of the project is to assist the authorities in these Asian countries to get rid of their landfill sites before the refuse ends up in the oceans.
So where are they going to put all this non-recyclable plastic? Can it be put to any useful purpose? This is where the cement industry enters the stage. The same countries that discharge the greatest volumes of plastic into the oceans also account for two thirds of the world’s cement production. Around 58% of all cement is manufactured in China.
Cement is manufactured by heating limestone until it becomes liquid in a process called calcination. This process currently takes place in large furnaces at temperatures of 1,450°C. This requires enormous amounts of fuel, which for the most part is coal. Cement factories across the world are currently burning half a billion tons of coal every year.
The massive emissions of CO2 this entails, combined with the calcination process itself, make the industry a serious contributor to climate change. If some of this coal is replaced by non-recyclable plastic, we will achieve a two-fold benefit. We will be rid of the landfill sites and at the same time reduce CO2 emissions.
There is nothing new in the idea of using refuse as a fuel in cement production. It was during the oil crisis of 1973 that cement manufacturers in the USA started looking for alternative fuel sources. They discovered that refuse could substitute for much of the fossil fuels they were using.
Norcem’s cement factory in Brevik in Porsgrunn started using refuse as a fuel in the 1980s. SINTEF and Kåre Helge Karstensen participated as a research partner in this process right from the start, and ever since, Karstensen, who is a qualified chemist, has been working to bring the concept developed by his group to the global cement industry.
In Europe today, it is standard practice to use refuse as a fuel in the manufacture of cement. The facility at Brevik substitutes 75% of what would be coal consumption with refuse. In doing so, it is able to utilize 150,000 tons of waste, including plastic, every year. The aim is eventually to stop using coal altogether.
When in 2018, the Norwegian government delegated the Ministry of Foreign Affairs with the task of establishing a foreign aid program to prevent plastic pollution in the oceans, the Ministry contacted Karstensen at SINTEF.
He had been working with waste management processes in China since 2005 and was the person who introduced the public authorities to the idea of using waste as a source of energy.
“At that time, the concept was entirely unknown in China,” revealed Karstensen. “The authorities were skeptical, but at the same time interested in the concept.”
SINTEF took on a facilitation and problem-solving role in an attempt to establish collaboration between local industries and the authorities. Naturally, at first, the industry was unwilling to share commercial secrets with its competitors. However, many years of collaboration have enabled high levels of trust to be established within the industry, and all parties have been persuaded to participate in the development and sharing of concepts that could be profitable for all concerned.
The utilization of refuse as fuel has become a key aspect of waste management policy in China, and the industry has recognized the economic benefit.
“The country has boosted its waste management capacity and reduced its consumption of coal,” added Karstensen. “The use of refuse as an energy source is thus now one of the key strategies in Chinese waste management policy.”
This is the circular economy in practice. When refuse can be exploited as a resource in industrial processes, the world will need fewer incinerators and landfill sites.
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