Lego A/S has dropped plans to use recycled plastic bottles to make new building blocks and will instead pursue other materials to cut carbon emissions.

Two years ago, the world’s largest toymaker unveiled a successful prototype block from discarded bottles, saying it appeared to be the best among more than 250 variations of sustainable plastic materials. But now Lego has found that using recycled PET won’t reduce overall CO2 emissions because it requires too much new production equipment.

Lego will instead look for other solutions, it said by email on Monday, adding that PET was just “one of hundreds of different sustainable materials” it’s evaluating.

“We’re currently testing and developing Lego bricks made from a range of alternative sustainable materials, including other recycled plastics and plastics made from alternative sources such as e-methanol,” Lego said.

Lego said it expects to spend more than $1.2 billion on sustainability over the four years to 2025. The story was first reported by the Financial Times.

Lego has a goal to reach net zero emissions in 2050 and an interim 2032 target of a 37% reduction from a 2019 base. The company has so far made limited progress cutting its absolute emissions amid high sales growth, but has invested in new CO2 neutral factories in Vietnam and the US.