Point and Sandwick Trust, in collaboration with a number of industry partners (Wood, Siemens-Gamesa, Engie, ITM, CMAL, Johnston Carmichael and Ferguson Marine) have published a feasibility study to assess the suitability of using hydrogen produced from local wind farms to power future ferry services operating in the Western Isles and West Coast of Scotland.

Of the nine routes analysed, the highest-scoring route using a small ferry on a short crossing was from Barra to Eriskay and the highest scoring route using a large ferry on a long crossing was from  Stornoway to Ullapool.

The hydrogen requirement for the former would be 219 tonnes and for the latter would be 3,676 tonnes. A single 4.3 MW wind turbine generator would be capable of supplying the required hydrogen for the Barra to Eriskay route, whilst fifteen turbines would be required on the Isle of Lewis. 

The study was part-funded by the Scottish Government’s Low Carbon Infrastructure Transition Programme.

The project looked at the practical and economic feasibility of using new island wind farms to produce zero-carbon “green” hydrogen fuel for future types of clean emission ferries operating on the established Caledonian MacBrayne routes. 

Green hydrogen is produced by using electricity to split water molecules (H2O) into oxygen (O2) and hydrogen (H2) via an electrolyser. When the electricity is produced from wind power, the hydrogen generated is 100% renewable.  When the hydrogen is then used in an on-board fuel cell, the only emission from the ships is water vapour. 

Although trials elsewhere have used surplus or ‘free’ electricity to drive small ferries, this does not reflect the full economic cost of switching from marine oil to hydrogen. 

The Western Isles study is the first to look at the feasibility of using electricity derived from a local wind farm built specifically to power shipping on existing and established ferry routes.

The feasibility study examined the manufacture of the hydrogen using local wind power, the challenges of how to handle, transport and store the hydrogen on local piers, and how the frequency and bunkering requirements of each of the nine routes studied affected the amount of hydrogen fuel required.

In particular the study assessed:

  • The most practical locations and likely output and cost of island wind farms
  • The cost and operation of electrolysers
  • The transport, storage and cost of hydrogen produced from local wind turbines
  • The best location and likely cost of local storage facilities
  • The frequency and bunkering requirements of nine West Coast ferry routes
  • The conversion of the marine oil currently used on these routes into their hydrogen equivalents

The potential emissions savings from the replacement of the Barra to Eriskay and Stornoway to Ullapool routes with hydrogen vessels is estimated to be around 676 and 21,815 tonnes of carbon dioxide equivalent per annum respectively, roughly equivalent to taking 147 and 4,742 cars off the road each year. 

The price of hydrogen that could be sold to ferry operators was calculated to range between £3.70 and £5.60 per kilogram. This would equate to between £0.11 and £0.17 per kilowatt-hour as compared to the current marine diesel fuel of £0.05 per kilowatt-hour. 

However, if hydrogen produced from renewable resources for marine transport was to be included in the UK government’s Renewable Transport Fuel Obligation mechanism, it was calculated that the price would fall to between £2.90 and £4.00 per kilogram (£0.09 and £0.12 per kWh). 

Greening the marine transport sector would contribute to meeting the Scottish Government’s emissions reduction commitments and assist the Government’s ambition to increase low emission vessels in the publicly owned ferry fleet by 30% and contribute to the 37% (4.7 MtCO2e) fall in transport sector emissions targeted for 2032 Climate Change Plan 2018-2032.

Scotland has a number of complementary hydrogen projects, both ongoing and planned, in what can be considered a nascent hydrogen economy with a promising future given the right economic and political support.

Speaking of behalf of the Point and Sandwick Trust, Project Manager Calum MacDonald said:  “This is an exciting first step towards a future where zero-emission ferries are serving the Western Isles using hydrogen sourced from local and renewable wind power.  

We need to make our ferries zero-carbon to protect the planet but at the same time we need to use our local, renewable resources to fuel those ferries to protect and strengthen our communities. 

When we have the best renewable resources in Europe on these islands, it would be crazy to replace the import of marine oil with the import of hydrogen.  By sourcing the power locally we can create a virtuous and sustainable cycle that benefits both the nation and local communities.

The most exciting finding of the study is that the price gap between using imported oil and local renewables is smaller than many would have expected.  To close that gap even more we need further progress in the economics of wind farm and hydrogen production, we need to see the climate consequences of marine oil reflected in its pricing and, of course, we need progress in the design and manufacture of ships to make them more energy-efficient.

I have no doubt that we will continue to see rapid progress being made in these areas and, as they happen,  it is essential that local communities are supported and motivated to take advantage of the new hydrogen economy.”

Euan Scott, Project Manager at Coimhearsnachd Bharraidh agus Bhatarsaidh (Barra & Vatersay Community) Ltd, welcomed the report as a “significant first step in challenging the status quo” and said the potential  economic benefits could not be overstated.

“The publishing of this study is timely with the declaration of a climate emergency and dates for reaching net zero emissions being set.

“The Western Isles has an established community renewable sector that has to date not been able to capitalise fully from the wealth of renewable resources on its doorstep. Grid export is severely constrained and new renewable assets must be associated with new demand. Juxtapose this to the Western Isles having far higher rates of fuel poverty than most urban or suburban areas in Scotland, with up to 58 per cent of households struggling to keep their homes warm.

“It is to be hoped the relevant stakeholders will agree to proceed to a detailed feasibility phase. Power-to-gas-energy storage is the logical next step in further developing the renewable sector in the Western Isles given the intermittent nature of wind energy. This study constitutes a significant first step in challenging the status quo and ensuring a place for hydrogen in the future energy economy of the islands.

“Yes there will be challenges ahead in terms of making the unit cost of production competitive but where better to do it than at point of consumption and against a target of net zero emission. Islands make natural laboratories because they’ve got relatively simple networks and infrastructure and if you trial new technology in the islands then it’s scaleable.”

He added: “The potential direct and indirect economic benefit to wider local community cannot be overstated. Once established in the local energy economy, other applications and uses for hydrogen will emerge.

Councillor Uisdean Robertson, Chairman of Comhairle Nan Eilean Siar’s Transportation and Infrastructure Committee, said: “The richness of the Outer Hebrides renewable energy resource will allow the islands to make a significant contribution to the UK and Scotland’s green energy targets.

“In addition to energy generation, however, it is essential that we look to new and innovative methodologies to decarbonise our transport infrastructure. The potential of fuelling Calmac ferries using hydrogen offers real potential and as such I welcome these studies and look forward to seeing the next stage of activity on the two West Coast routes progressing.”