If the aim is to reduce the global emissions of carbon dioxide by 45% to 55% by 2030 as outlined in the Paris Agreement, there is one simple way to do it. Stop burning coal. The arithmetic is really quite simple, using – obviously – pretty basic numbers. Very roughly, one tonne of coal on combustion produces around 2.420 tonnes of CO2. The global output of CO2 in 2020 was around 34.81 billion tonnes. Reduce that by 45% and it would reach 15.66 billion tonnes. Current global coal consumption is around 8 billion tonnes according to the IEA. Cut that out completely and we reduce CO2 output by 19.36 billion tonnes and we conveniently overshoot our target reduction by 3.7 billion tonnes of CO2.It is that simple really. It is tempting to go through all the major fuels in this way. Global oil consumption produces around 15 billion tonnes of CO2 but other calculations will have to wait. Meanwhile, it should be pointed out that coal provides around 37% of global power output, around 70% of steel output, 60% of aluminium production, 20% of hydrogen production and an awful lot of cement.

So, our new zero coal world would clearly prevent the production of any new airplanes for a time and a pause in the creation of any new skyscrapers. Mind you, after suitable fire tests, the US Forestry Service is pleased to have opened the 25-story Ascent MKE building in Milwaukee made of wood in July 2022, while a 20-story wooden building in Sweden’s Shelleftea claims to have avoided producing 9,000 tonnes of CO2 in its construction.

Large wooden buildings are very much in fashion in architectural circles and there are plenty more on the way. That said, wooden structures will have to be four times as high to approach anywhere near the Empire State Building, and the tallest building in the world – Dubai’s Burj Khalifa at 160 stories – is 60% higher still. Regarding doing without cement and steel in buildings, we are still at a very much lower stage of construction, beautiful as these wooden buildings are.

With that in mind, the Great Pyramid of Giza required no steel at all, but seems to have had remarkably little living space inside. Mind you, it has lasted a very long time and seems to require very little maintenance. Furthermore, we have recently discovered that the Romans made better cement then we do, so there is room for improvement anyway.

However, the central point about cement is that it requires significant quantities of heat to gets component parts – calcium, silicon, iron etc – to fuse, commonly put at around 1,500°C. There is really nothing to stop this being done by electricity alone. Indeed, the large multinational cement maker CEMEX is currently experimenting with the Finnish-Dutch company Coolbrook, with the avowed intention of reducing its emissions by 47% by 2050, this way. It is no mean task however, with some 63 plants in 29 countries but, as they repeatedly point out, to reduce the carbon output, the electricity has to be green. As things currently stand, around a tonne of cement requires an output of 900 kg of CO2.

Much the same goes for steel production, although with two awkward problems. First steel actually contains carbon, which is necessary for its strength and as a consequence steel-makers use metallurgical coal, which contains more carbon that standard thermal coal. Globally, the world uses around 1.8 billion tonnes of steel a year, of which around 0.45 billion tonnes is from recycling. To make new steel requires a temperature of around 1,600°C. It will melt at 1,300°C, so recycling does reduce its carbon footprint, but not by much. It takes roughly 0.77 tonnes of coal to produce a tonne of steel and the whole exercise produces around 3 billion tonnes of CO2 every year.

On a positive note, the amount of steel required to have the same engineering result has been falling through the years. It is now estimated that the Eiffel Tower could now be built with 25% less steel, while modern cars use roughly 30% less. That said however – combined with greater recycling capacity – this has not remotely kept up with demand. Back in 1960, the amount globally produced was only 380 million tonnes, but it has accelerated rapidly, reaching a billion by 2000 and almost doubling since. Hardly surprising then that reducing the carbon footprint of steel has been seen as the holy grail of climate change.

One amusing statistic, produced by the excellent Max-Planck Institut website recently, was that for every 40,000 scientific papers produced on climate change generally, there were only 600 on what to do about steel production’s carbon. This could be a statistic for the whole debate, given the general ratio of “this is happening” articles to “what can we feasibly do about it” pieces, but no matter. This is merely a sign of irritation at having to wade through mountains of the same repetitive cries of impending disaster, without any suggestions more sophisticated than banning all oil, gas and coal production and watching people freeze to death.

That said, there are technologies being created to produce steel without any carbon output. The best so far looks like using hydrogen as a reductant in electric arc furnaces. Leaders of the pack here are a team from Sweden comprising Vattenfall, the power company, LKAB, the iron ore producer and the Swedish Energy Agency. These now have a Hydrogen Breakthrough Ironmaking Technology (HYBRIT) pilot plant in northern Sweden, which started producing iron in 2021 and a demonstration plant is scheduled for 2026. Using hydrogen from electrolysis of water from renewable sources, the waste is water, which has a nice circularity. Given that there are over 900 steel furnaces globally in 82 countries, there is clearly a long way to go yet.

Aluminium is unusual in that none of the pure metal is actually present on earth, while aluminium-containing minerals make it the third commonest element on the planet. The result is that its production effectively goes through two phases, first to produce alumina – or aluminium oxide – from bauxite, then to produce aluminium. Both require considerable amounts of heat. In theory, as with iron, hydrogen could be used as a reductant at even greater heat, but ironically it is much easier to produce hydrogen from aluminium rather than the other way around.

Nonetheless, efforts to reduce the industries carbon footprint have been going on since 1990 with the Voluntary Aluminium Industrial Partnership (VAIP) and significant reductions are claimed. Elsewhere, Alcoa and Rio Tinto have created a joint venture in Canada, called ELYSIS to utilise “inert anodes” in the electrolysis of alumina, whose waste process produces oxygen rather CO2. Those involved emphasise, as always, the need for renewable electricity.

Here to, increases in efficiency and new technology are being outweighed by a growth in demand. Production in 2020 was around 86 million tonnes and this is predicted to rise to 119 million by 2030. Admittedly these numbers come from the International Aluminium Institute, as cheerleaders, but ironically the main driver in anticipated demand is for solar power structures and electric vehicles.

And one matter has to be mentioned. The staggering increase in global steel production comes primarily from one place: China. In 2021, China produced 53% of the world’s steel. In that year, China produced 12 times more steel than the USA and 8.8 times more than India, according to the World Steel Association. Furthermore, this production has grown with an astonishing rapidity. It overtook the USA in 1993 and started to produce more than the rest of the world combined in 2017. It also produced 52% of the world’s cement, or around ten times more than the whole of the European Union, according to the Global Cement and Concrete Association. It also smelted around a third of all the aluminium. As for glass…but enough already

It is tempting to question the statistics, but there are reasons to believe them. Back in 1990, according to the Geographical Society of China, only 26 % of the population lived in cities. By 2017, it had reached 58.5% and still continues eastward away from the poor interior. In 1990, Shanghai’s population was a mere 8.6 million, or a little less than London now. It is now over 27 million and still growing. Housing these people can be seen as a triumph, but even only in concrete and steel, it reinforces China’s centrality to the whole climate change debate. And will the West allow the technology transfer on the lines noted above, as a necessary part of the battle against climate change? We shall see

The real function of coal’s use for steel and cement is heat. As will be noticed from the above, the shift in the direction of greener manufacturing processes seem to demand greater use of electricity, although a caveat has to be noticed here. Some metals are produced using heat, which can be created by electricity. Others, like aluminium and copper in part of their processes are produced by electrolysis, which does not involve the process of turning electricity into heat, prior to use. Electrolysis systems thus use considerably less electricity than those using it simply for heat production and this, particularly associated with hydrogen, may provide a number of mechanisms for future manufacturing, most notably with glass, which currently requires heating to 1,700°C. 

Yet the problem remains that the commonest myth around climate change mitigation remains that electricity is necessarily clean. In fact, heat generated by electricity suffers from being roughly 60-70% less than heat used directly to produce it. The average efficiency of coal-fired power stations around the world is +/- 33%. Clearly an increase in their efficiency would save a lot of CO2 production, even if only by 10%. Needless to say, the world’s coal industry is only too aware of this and with the usual love of ridiculous abbreviations have announced that they have to go to HELE or high water.

HELE, in this case, stands for “Higher Efficiency Lower Emissions” and there are two basic ways to do it. Contrary to the probable popular view, coal-fired stations are not fed by dumping lumps of coal into a large hot stove. It is more sophisticated than that, since the coal is powdered first and effectively blown into the combustion chamber. This has led to the idea, known as fluidised bed combustion, where air is pumped into the chamber sometimes under pressure to get higher combustion at lower temperatures, less NOx and SOx and the coal can be mixed with biomass. This does not need to be pulverised first. One of the problems appears to be that it is difficult and rather expensive to scale up the technology to the standard 1,000 MW power station.

The second available technology for improvement lies in “Integrated Gasification Combined Cycle (IGCC). This takes a tip from gas-fired Combined Cycle Gas Turbine (CCGT) power plant, where the heat created by a gas turbine is used to create steam to run a steam turbine, greatly increasing efficiency in electricity production. The IGCC, in effect tries to do the same thing by adding a gas turbine to utilise the hot gases produced from the burning coal.

Way back when in the 1980s, the UK Coal Board, as was, got very excited about this technology, but then rather rapidly became disillusioned. The problem lay in the numerous particulate matter and other pollutants in the hot gas, which stripped the gas turbines bare. They thus discovered the problem with the idea, which was that the waste gases involved had to be cleaned, which turned out to be hideously expensive. While a number of IGCTs have been built in the US and Holland, the idea never really caught on. In theory, the technical knowledge gained could be used in future for CO2 capture, but there are other ways to do this.

Overall, most of the EU plus also the G7 are proposing facing out coal in electricity production by 2038 at the latest, although this has been interrupted by Putin’s war in Ukraine and the resulting shortage of natural gas. In practice, this has merely resulted in the Europeans readying some of their additional coal-fired capacity for use, but has not meant a substantial increase in CO2 output yet and seems unlikely to do so.

So, who would be the losers in all this, if coal consumption declines? The biggest coal selling companies are Australia’s BHP and Rio Tinto with roughly $40 billion in profit apiece in 2021. But it really is not a surprise that by far the biggest producer and consumer of coal is…you have guessed it; China. Back in 2021, China was producing 3.9 billion tonnes of the stuff and importing a further 330 million tonnes. The nearest rival is India which produced 767 million. Hardly surprising then that a shiver went through the coal community when China announced that it planned to go carbon neutral by 2060. Both Australia and Indonesia have plans for new mines to expand production.

Perhaps they do not have to worry that much yet. According to the IEA, China’s coal demand reached a record 4,230 million tonnes in 2021, while Europe’s declined to 160 million. While not intending to disparage the efforts of climate change activist in their protests against both the UK’s new Whitehaven mine and the German Garzweiler mine expansion, the respective production numbers at 2.8 million tonnes and 40 million a year respectively, do put matters into perspective. Mind you, the Whitehaven mine is for high grade coking coal for steel-making, while Garzweiler is for rubbish low grade, low-calorie lignite. RWE, in their insistence on the mine’s expansion, plan to demolish the small town of Lutzerath and a wind-farm as well. Sorry RWE, you are heading too hard against the zeitgeist. Wake up.