The European Union is working hard to cut those CO2 emissions with several schemes designed to make using fossil fuels more expensive.

But the problem for shipping firms is that alternative, or 'greener' fuels are still only produced in tiny quantities compared with traditional marine fuel.

Methanol is part of the alcohol family of chemicals used in paints, plastics, clothing fabrics and pharmaceuticals, and as a vehicle fuel.

Unlike hydrogen, which is also promoted as a green fuel, methanol does not need to be stored under pressure, or extreme cold, and many ports already have the infrastructure to handle it.

"We think this is the good solution to get started with," says Mr Sterling. "It's relatively easy to handle on ships, and the ship technology is well known."

At the moment most methanol is derived from natural gas. Green methanol does not rely on fossil fuels and can be made in a couple of ways.

Bio-methanol is produced from biomass, such as agricultural waste. Heat, steam, and oxygen are used to convert the biomass into useful fuels, including methanol.

There's also e-methanol. Here renewable electricity splits water into oxygen and hydrogen, which is combined with carbon dioxide.