The future of green bunkers could include fuel produced from sewage and sawdust.

Dutch supplier GoodFuels is looking to scale up production of sustainable biofuels — and is casting its net wide to look for new feedstocks.

It currently uses recycled cooking oil and forestry waste for its MR100 product.

But chief executive Dirk Kronemeijer told TradeWinds: "Cooking oil is not very scalable, so we are expanding towards feedstocks that have more scalability potential while keeping our sustainability."