Abstract: A heat store (10) for an energy storage system includes: an inner vessel (40) housing a thermal energy store (14); and an outer vessel (50) surrounding the inner vessel (40), the inner and outer vessels (40, 50) being spaced by a vacuum region (11) extending therebetween.

Abstract: A heat store (10) for an energy storage system includes a solid body (20) comprising a solid thermally conductive matrix (22) with a solid thermal filler material (21) embedded therein. The solid thermally conductive matrix (22) forms a thermally conductive pathway to the solid thermal filler material (21) distributed within the solid thermally conductive matrix (22). The heat store (10) for the energy storage system also includes a thermal transfer element (30).

Abstract: A vessel (10) for traveling on water comprises a hull (20) and a keel (30) comprising a member (34) depending from the hull, the member (34) comprising two limbs (44) each depending from a respective lateral side of the hull (20), the two limbs (44) defining at least in part an enclosed flow path extending in a bow to stern direction, the enclosed flow path being configured to allow water incident on the vessel to flow over inner and outer surfaces of the limbs (44a, 44b). The limbs (44) each have a zero-lift surface which is angled to generate in use a component of hydrodynamic force directed away from the enclosed flow path when there is a net flow of water along the enclosed flow path.

Abstract: A vessel (10) for travelling on water comprises a hull means (20) and a keel (30) comprising a member (34) depending from the hull means, the member (34) comprising two limbs (44) each depending from a respective lateral side of the hull means (20), the two limbs (44) defining at least in part an enclosed flow path extending in a bow to stem direction, the enclosed flow path being configured to allow water incident on the vessel to flow over inner and outer surfaces of the limbs (44a, 44b). The limbs (44) each have a zero-lift surface which is angled to generate in use a component of hydrodynamic force directed away from the enclosed flow path when there is a net flow of water along the enclosed flow path.