Steel production is an incredibly dirty affair. Each ton produced produces about 2 tons of carbon dioxide. With the industry producing around 2 billion tonnes of steel a year, it is a lot of CO2 that is released into the atmosphere – in fact, about 7% of all global emissions. This makes finding ways to make green steel vital to controlling global heating.
The problem is that the traditional way of making steel – heating iron in a blast furnace – has existed for centuries. It consumes a lot of energy both to heat the contents inside the furnace and to convert the coal to coke, which then reacts with the iron ore and converts it into pig iron ingots. Some of this energy comes from electricity, but much comes from the combustion of methane, which is often incorrectly referred to as “natural gas”.
ArcelorMittal is one of the largest steel producers in the world. It attempts to reduce carbon emissions from steel production by replacing coke with green hydrogen. This eliminates significant emissions from coke production, but still requires a huge amount of electricity for the rest of the process.
RWE, one of the largest electricity producers in Germany, and ArcelorMittal signed a memorandum of understanding this week. Under the agreement, they will work together on the development, construction and operation of offshore wind farms and hydrogen facilities that will supply the renewable energy and green hydrogen needed to produce low-emission steel in Germany. The plan is to replace coal with wind energy and green hydrogen as the main energy source in steel production at ArcelorMittal’s steel mills in Germany.
Reiner Blaschek, CEO of ArcelorMittal Germany, says: “ArcelorMittal Germany is embarking on a radical transition to ensure that our CO2 reduction targets are met, which means that the energy used to produce steel will have to be clean energy. The partnership we announced with RWE today is significant for several reasons. will provide us with the renewable, affordable electricity and green hydrogen we need to produce low-emission steel, while remaining competitive in the global market. It also offers essential security in the supply chain by integrating energy and hydrogen supplies into our business. New offshore wind farms will be located in the North Sea.
Boston Metal jumps the step of green hydrogen
Boston Metal is an MIT spinoff based in Woburn, Massachusetts. Unlike most steelmakers, it wants to skip the green hydrogen step and move straight to zero carbon steel using a molten oxide electrolysis process that uses electricity to separate oxygen from iron ore, a critical step in the steelmaking process. “The advantage we have is that it’s a one-step process that directly electrifies steel production,” said Adam Rauwerdink, vice president of business development for Boston Metal. Canary Media.
“When you look around your landscape, you don’t realize how ingrained and ingrained it is [steel] is in the company, “said Chathurika Gamage, climate intelligence manager at the non-profit research organization RMI. “Everything we do, the buildings we are in – provides structural stability to literally all of these spaces.”
“Decarbonising the iron and steel industry basically means decarbonizing the blast furnace,” said Zhiyuan Fan, a researcher at Columbia University’s Center for Global Energy Policy. “If you solve the blast furnace [issue]”Half of your problem is gone.”
Last year, Fan’s team in Columbia published a study comparing several strategies for decarbonizing steel and found that electrification was the key to eliminating emissions. The more the process can take advantage of clean electricity instead of burning coal and other fossil fuels, the easier it will be to reduce emissions. “We know how to decarbonize the network better than we know how to decarbonize the blast furnace,” adds Fan.
“Ten or 20 years ago, the grid was not clean, so it didn’t make sense and there was no demand for a greener version of steel, but now both are available,” says Rauwerdink.
Reducing steel production costs
Doing something in the lab is all very nice, but the ability to scale technology to produce millions of tons of green steel is something else entirely. Boston Metal thinks it has the answer.
Electrolysis has been a key component of aluminum production for more than 100 years. Boston Metal’s molten oxide electrolysis process applies this technique to iron, which requires higher temperatures. Aluminum electrolysis takes place at temperatures just below 1000 degrees Celsius, while iron electrolysis requires about 1600 ° C, which is much higher than molten lava.
First, the iron ore is melted with heat made from electricity. It is then placed in a cell structured almost like a giant battery. The anode provides an electric charge at the top. At the bottom, the cathode receives an electric charge. The charge in between flows through the electrolyte, which in this case is the combustion of molten materials. The electrolyte contains various oxygen-bound elements, including aluminum, silicon and calcium.
According to Boston Metal, this process also works with low-quality iron ore, which is cheaper and more abundant than higher-quality ore, which has fewer impurities. “Some other technologies are evolving [to manufacture] green steel needs super premium types of ore, ”says Rauwerdink. “We can use all the much more abundant types of ore, which is the key to the long-term growth of this technology.”
Another advantage of molten oxide electrolysis over direct iron reduction is its efficiency. By omitting the hydrogen step, the MOE inserts energy directly into the steel production, thus eliminating transient phases where energy loss may occur. MOE requires higher temperatures than hydrogen-based production, which is beneficial, but even when we take it into account, MOE is still more efficient.
Fan, a green steel expert from Columbia, estimates that producing green steel with green hydrogen requires at least 30% more energy than MOE – and perhaps as much as 50% to 60% more. “By skipping these different processes, you can actually achieve a lot of efficiency improvements,” he says.
The road to scale
The commercial plant can produce several million tons of steel per year. The first Boston Metal demonstration cell, which operates continuously, produces less than 100 tons of steel a year, so the company has a long way to go. “It’s just about the aggregation of these cells, so the proof is the pudding of how much it can scale,” said Gamage of RMI.
Scale is important in the steel business, but it is equally important to use capital-intensive systems that have already been built. Green hydrogen plays an important role in this area because it is compatible with the direct reduction of iron, which is already used on a commercial scale with natural gas. It is relatively easy to exchange natural gas for hydrogen. Therefore, major steel producers such as SSAB and ArcelorMittal have focused on green hydrogen in their short-term plans.
“We’re here for class,” Fan said. “If we want to fully decarbonize by 2050, we have to think about replacing the production unit in the next 10 or 20 years. If the MOE is not commercially available at that time, it just missed the window.”
Boston Metal is working on a larger demonstration cell at its headquarters in Woburn, Massachusetts, which will be able to produce several hundred tons of steel a year. Once the design is perfected, multiple cells can be built in the same plant and then potentially lined up in hundreds, a design common to aluminum smelters.
“Because it’s a modular technology, the path to scaling will be relatively fast,” says Rauwerdink. “It’s like having a wind turbine and showcasing five turbines, and once you do, build 100 or 200 for a commercial plant. It is the same approach with us. Then we don’t have to go back and remodel a cell that is 100 times bigger. “
Need for zero emission electricity
Boston Metal technology will need electricity produced from low-carbon sources to reduce carbon emissions from steel production. “The future of steel production really depends on clean electrification,” Gamage said.
Steelmaking equipment tends to be in continuous operation for months, and changing the chemical composition of a metal by its very nature requires a lot of energy, so if the process is electrified, it will need an enormous amount of electricity. Boston Metal says its technology uses 4 megawatt hours of electricity to produce 1 ton of steel. That’s enough to power the average U.S. household for more than four months.
According to Columbia’s steel decarbonisation research, replacing all of the world’s blast furnaces with MOE production processes would require almost 20% of global electricity consumption in 2018. This would make the steel industry one of the largest users of electricity. on the planet.
But replacing all steel production by direct reduction of hydrogen to hydrogen could require even more electricity. This means that there is no way to deal with the climate impact of steel without installing an enormous amount of clean energy production, except that it is ensured that the grid is ready to reliably transmit all that extra electricity.
“You will need to strengthen your network at a rate that energy companies and network operators have not planned,” said Thomas Koch Blank, CEO of the RMI Breakthrough Technology Program. And it would have to be done on a “10 to 15 year timeline.”
Sometimes the development of new decarbonisation technology runs counter to the deployment of established solutions, such as renewable energy, but in many circumstances these challenges are the same. Green steel is a shining example of this.
“For us or for green hydrogen, you will need clean energy,” said Rauwerdink, “so all the work that goes into cleaning the grid allows for solutions like ours.”
As the demand for green steel grows, more solutions will be needed to meet the world’s appetite for steel without overburdening the atmosphere or the electricity grid. Koch Blank emphasizes that both molten oxide electrolysis and direct reduction of hydrogen-powered iron promise to decarbonise the steel industry and are worth continuing. “In the end, I would be surprised if there wasn’t enough room in the market for both technologies,” he said.
Green hydrogen has recently received a great deal of attention in the press, as it promises ways to significantly reduce carbon emissions from industrial processes such as steel and cement production. However, it is entirely dependent on access to clean, reliable and affordable electricity. The way forward to zero emissions of building materials is clear, but getting there will require a fundamental reassessment of renewable energy and how it is distributed through the electricity grid in each country.
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