Ternium took an important step in 2019 to reduce its carbon dioxide emissions in steel manufacturing in Brazil by starting to use biomethane from a landfill as part of the transition to greener and circular production methods.

In 2023, the Company signed a new agreement to buy biofuel supplies from Gás Verde, a biomethane producer from the Seropédica Sanitary Landfill in Rio de Janeiro. This new agreement aims to increase the share of biomethane in the steel manufacturing process, according to availability, a strategy that has vast potential.

Ternium has been using biomethane – a renewable energy source – since 2019 in making steel at its mill on the outskirts of Rio de Janeiro. It’s the first steel manufacturer to use biomethane in Latin America, allowing it to scale back the use of fossil natural gas.

Biomethane is made from biogas, a mixture of carbon dioxide, methane, and other gasses produced naturally through organic matter degradation from solid waste. Gás Verde captures the biogas at the landfill and purifies it in a plant. The resulting biomethane is delivered by truck to Ternium’s mill for injection into its low-pressure piping to generate the heat to make steel slabs.

The main benefit for Ternium – and the environment – is that non-renewable fossil fuel is swapped for clean and renewable energy made from Rio de Janeiro’s garbage to produce the exact same steel quality. At the same time, the flaring of emissions is avoided at the landfill, which is outside Ternium’s operational boundaries.

“We were pioneers,” said Ingrid Person Rocha e Pinho, the Green House Gas Senior Manager at Ternium Brazil. “We have set a good example of sustainability for not only the steel industry but any industry so that they can potentially substitute natural gas with biomethane into a sustainable process.”

This fuel switch is the Company’s latest step to reduce greenhouse gas emissions at the mill. It has already made the plant more energy efficient, with much of its electricity coming from renewable sources. The result is that fossil natural gas accounts for only 1.4% of the plant’s total energy matrix.

In this context, Ternium wants to reduce the use of fossil natural gas as much as possible by increasing the share of biomethane, helping to demonstrate to the rest of the steel sector – and other industries – that this can be done to fight climate change.

Biomethane has long been used to generate power, and it is starting to gain the attention of manufacturing industries now that Ternium has shown that it is economically viable for steel production in Brazil.

“Everybody in Brazil is looking at it,” Person said of the biomethane project. “Everybody is saying, ‘Oh, you did it. Yeah, we can also do it. Let’s do it.’”

There are hurdles, however. One is the logistics. While the biomethane source is only around 30 kilometers from Ternium’s steel plant, regulations have not yet allowed the company to build a pipeline for delivering supplies directly to the plant. It must use a steady stream of trucks, which burn diesel and emit carbon.

Even with the use of trucks, however, the process is cutting overall emissions from Ternium’s steel production, she stated.

Another challenge in this circular process of using everyday waste to produce energy for making new products is to secure more biomethane supplies.

There is plenty of waste to make biomethane. The Seropédica landfill receives some 11,000 metric tons per day of waste from Rio de Janeiro and surrounding areas. If the biogas is not converted into biomethane, it must be flared. Capturing the biogas to make biomethane reduces greenhouse gas emissions in Rio de Janeiro.

The problem is that not all biomethane is available for manufacturers because of production restrictions and the competition for supplies.

In Brazil, compressed natural gas is widely used by cars, and this fuel can be made from biomethane. The makers of this biofuel pay a premium price for biomethane to reduce their overall greenhouse gas emissions. This makes it hard to compete for supplies because biomethane producers prefer to sell at a higher price to supply gas stations – and that price is still prohibitive for the costs of producing steel, given that there are no carbon markets, taxes, or cap-and-trade schemes in Brazil to offset the higher cost of biomethane.

However, the benefit for the biomethane producer is that Ternium is a huge off-taker, Person said. “We are a secure sale,” she assured. “We can substitute all our fossil natural gas if the biomethane is available.” This is her hope as a self-declared “carbon killer” at the company.

“We are working fiercely towards the deep decarbonization of Ternium,” she remarked. “We have renewable energy in our matrix, and now we are studying biomass, green hydrogen, and other things. But biomethane is already available. It’s a low-hanging fruit.”