42 Design services in connection with the planning, retrofitting and refurbishing of plants for the conversion of gases containing carbon dioxide to methane; design of apparatus for chemical plants for the conversion of gases containing carbon dioxide to methane; design services in connection with the planning, retrofitting and refurbishing of plants for the catalytic conversion of gases containing carbon dioxide with hydrogen to methane; design of apparatus for chemical plants for the catalytic conversion of gases containing carbon dioxide with hydrogen to methane; design services in connection with the planning, retrofitting and refurbishing of plants for the catalytic conversion of gases containing carbon dioxide with hydrogen produced by electrolysis to methane; design of apparatus for chemical plants for the catalytic conversion of gases containing carbon dioxide with hydrogen produced by electrolysis to methane; consultancy in relation to the aforesaid services.