The island of Vatersay’s wild Atlantic location makes it an excellent place to grow sustainable seaweed. However, when it comes to economic activities, renewable energy and the intersection between them, the island’s remote and peripheral position is both a strength and a weakness. Natural Power’s work with a community development organisation highlighted some of the weird and wonderful solutions that are required to overcome the challenges of being at “the end of the line” geographically, but at the forefront of sustainable business innovation.
Vatersay is the most southerly populated island in the long chain that makes up the Outer Hebrides or Western Isles. It is linked by a causeway to its larger neighbour, Barra, which is a 5-hour ferry journey from mainland Scotland or a 40-minute crossing from the next island in the chain (Barra also has a small passenger airport).
Coimhearsnachd Bharraidh agus Bhatarsaidh (CBaB) is a community owned company which supports sustainable community development on Barra and Vatersay. CBaB is developing a pilot commercial seaweed farm off the coast of Vatersay. However, what sets this proposal apart from controversial projects in other areas is the community buy-in. If the pilot proves successful, seaweed aquaculture could add to the list of local economic activities which includes land-based agriculture, fish farming and tourism.
Seaweed growers can achieve the highest revenues by drying the seaweed immediately after harvest. Once out of the water, seaweed rapidly starts to decay and many of the valuable natural chemical compounds in the plants are best preserved by removing the water in the product through accelerated evaporation.
Natural Power’s renewable heat team members are not seaweed experts. However, drying of agricultural and food products is a common industrial process that uses large amounts of heat – and as such, it’s right up our street. Whether it’s grain, woodchips, hot drinks powders or seaweed, drying involves the application of heat, dehumidified air and/or a vacuum to remove water from the product. In delivering a feasibility study for CBaB, Natural Power determined the types of dryers which are viable to operate at the scale of production that is realistic for Vatersay.
However, a more unusual dimension to this work was the consideration that we gave to the dryers’ operability within the local energy system. Vatersay’s electricity network distributes an unusual type of power: two-phase power, rather than the three-phase power that is near-universal elsewhere in the UK. This severely limits the ability to use anything with a large electrical motor (two-phase machines are very rare and the convertors that are available are not designed for near-continuous operation). Unfortunately, we found that many of the solutions that are optimal in other locations – such as heat pump dryers – could only be used on Vatersay if they were powered by a dedicated off-grid power source such as a diesel generator or renewably-fuelled alternative.
Ultimately, the answers to the challenges posed are not straightforward and a lot depends on the direction of travel of the local energy system as a whole. Will local hydrogen production, storage and use become a reality? Could Vatersay’s electricity grid be upgraded to the modern standard three-phase power? What proportion of the islands’ buildings and local transport are electrified? Although biofuels and zero-carbon synthetic fuels are not the solution to the world’s energy needs, are they needed in locations like Vatersay when diesel, kerosene and LPG sometimes seem like the default choices? What technical opportunities can be unlocked when developers are motivated by community benefit and sustainability in addition to profit?
These and related questions affect our team’s work in many other locations across the UK, but especially in remote and rural places – and we are eternally curious about the answers. Whatever pathway is followed in the future, the pioneering work being undertaken by communities in places like Vatersay will continue to deliver lessons for the rest of us.