The Band That Makes Steel and Steals the Show

How Boston Metal is Decarbonizing Steelmaking

The built environment is not low impact. According to McKinsey, the built environment drives 39% of global emissions with 11% coming from materials (mostly concrete and steel). We’ve spent a lot of time talking about concrete; see our pieces on CarbonCure, CarbiCrete, CarbiCrete The Sequel, and more. So, today we’re going to be digging in on green steel.

In 2021, the US consumed approximately 98 million metric tons of steel. Traditional steel production, which relies on fossil fuels to reduce iron ore, emits about two tons of carbon dioxide for every ton of steel. And with the housing and construction sector accounting for 52% of steel production, it’s easy to see why the environmental impact from our buildings is so high. Nonetheless, steel is one of the most commonly used and versatile materials in construction and will remain because it’s hard to find an alternative. Steel is renowned for its strength and durability, both crucial qualities in commercial construction, and finding a one size fits all green alternative is nearly impossible (and that’s before accounting the switching cost due to out of date building codes/regulations and green premiums).

Instead of finding a replacement, the metal industry has been investing in advanced technologies like electric arc furnaces and direct reduction methods that improve emissions and energy consumption. 

Boston Metal; Change the Process not the Product

Boston Metal is an industry leader in metal production technology, developing new technology to produce steel without generating carbon dioxide emissions. Recently they raised a $262 million Series C to scale their molten oxide electrolysis technology, open a pilot plant to produce steel, and commercialize their high-value metals business. 

Boston Metal isn’t trying to change the product, but instead the process. Their technology is based on molten oxide electrolysis (MOE), which has enabled them to produce metals with a lower environmental impact compared to traditional methods. The process uses (renewable) electricity to remove oxygen from metal oxides, leaving behind liquid metal; because their process doesn’t require  carbon-based reduction they are able to eliminate carbon emissions, reduce energy consumption, and use lower grade feedstocks to get the most out of the ore mined.

In any hard tech industry one of the key challenges emerging technologies must overcome is scaling up their processes, which can be prohibitively expensive. Boston Metal is no exception. MOE is a capital intensive technology that requires large upfront investments and high operating costs. Through their series C, which was led by ArcelorMittal the world’s second largest steelmaker, Boston Metal is building a plant in Massachusetts to reach scale and bring green steel to the market in 2026. 

The second challenge facing Boston Metal is plant location. While their process reduces scope 1 emissions by replacing the traditional blast furnace with molten oxide electrolysis, to reduce scope 2 emissions they are dependent on the availability and affordability of renewable electricity. The Massachusetts’ electric grid is only 15% renewable energy, which isn’t great. If their plant shifted a bit further north to Vermont, whose electric grid is 76% renewable energy (primarily from hydro), the steel production would create less carbon emissions. 

How does this technology compare? 

Molten oxide electrolysis is one approach the industry is taking to produce green steel. Other green steel technologies include hydrogen-based direct reduction, natural gas based direct reduction, and carbon capture and storage. Out of these technologies we’re betting on Boston Metal’s approach. Hydrogen availability is far from a solved problem, other reduction processes still produce some carbon emissions and steel slag byproducts, and carbon capture and storage is just transferring blame and making it someone else’s problem. MOE is a one-step process that converts ore directly into liquid steel, is cost-competitive with coal-based steel processes, and doesn’t incur as much of a green premium. 

Instead of trying to create a better product, Boston Metal is giving you the same great product just with a better process. We’re excited to follow along their journey to bring green steel to market over the next few years.