Giant sails on cargo ships could slash CO2 emissions by 30%

Fitting sails to cargo ships and sailing more slowly could reduce greenhouse gas emissions from the shipping industry by up to 40% – or possibly more as technologies improve – according to a new report from the Institution of Mechanical Engineers (IME).

The institution recently supported a feasibility study by Smart Green Shipping which showed the potential for reducing emissions on a ship retrofitted with fixed sails could be as much as 30% given the right conditions. And greater use of ‘slow steaming’ – reducing speeds to use less fuel when the engines are running – would cut emissions by a further 10%, according to the IME.

Air pollution from shipping has increased rapidly over the last decade driven by growth in world trade, and as most emissions are from international shipping, they are not included in individual countries’ reduction targets. The UK announced this week that it is to include international shipping in its new emissions targets.

However, the institution’s report said rapid action was needed to clean up shipping because of slow progress on the issue. If unchecked, shipping could account for as much as 20% of global emissions by 2050 compared with 3% today, the IME highlighted.

In its report ‘Accelerating Decarbonisation in Shipping: A No Regrets Approach Using Wind Power’, the Institution calls for the UK government to support the development of a demonstration ship using retro-fitted sails to help ship owners and users understand the business case for how wind could be used as primary propulsion for cargo vessels – as part of the UK’s hosting of the UN Cop26 climate change conference in Glasgow in November.

“We need to use existing and emerging technologies to urgently reduce the impact of our global supply chain on the environment. Continuing with the ‘business as usual’ approach could result in shipping being responsible for up to a fifth of global emissions by 2050,” said Dr Jenifer Baxter, Chief Engineer at the Institution of Mechanical Engineers.

The shipping industry is focused on developing alternative fuels such as hydrogen and ammonia to replace polluting bunker fuel, but these fuels will be at least three times more expensive and will not be ready for the shipping market for at least a decade, the IME noted. It said using alternative fuels combined with wind power makes economic sense.

“Wind is free, clean, abundantly and exclusively available to ships equipped to harness it. It decouples ship owner/operators from volatile land-based commodity fuel supply, critical in an energy-constrained future - and, most importantly, has the capacity to drive emissions out of the shipping sector immediately,” said Diane Gilpin, founder and CEO of Smart Green Shipping.

Recent figures from the International Maritime Organisation (IMO) showed emissions rising by 10% between 2012 and 2018.

The IME said the shipping industry “has limited plans to curb this growth”, noting that in November 2020, the IMO brokered an agreement with the majority of countries, including the UK, that would allow shipping to continue polluting unabated to 2030.

The Times said a number of projects are already underway to develop wind-powered cargo vessels. Last year, designs were released for Oceanbird, a transporter ship to carry 7,000 cars across the North Atlantic using 260ft-high sails.

Cargill, the US agricultural company, also unveiled plans to fix sails to its fleet of bulk ships. However, to date no existing ships have been retrofitted with sails.

The report said: “Twenty-first century wingsails retrofitted on to cargo ships that do not carry goods on the deck will allow for a significant decrease in emissions. This reduction is made by allowing the fixed sails to be used at sea and subsequently use less fossil fuel. A careful analysis of ship types working on suitable routes could allow for even greater reductions in emissions by optimising automated wingsails to harness maximum amount of wind.”