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A hydraulic collection tower, with a novel energy storage device for wave energy arrays

Periodic Reporting for period 1 - OHT (A hydraulic collection tower, with a novel energy storage device for wave energy arrays)

Reporting period: 2017-06-01 to 2017-09-30

Cost, power capture performance and efficiency are the main user concerns regarding WECs. Ocean Harvesting aim was to to reduce the cost of components in WEC systems and increase the efficiency through their energy storage device. In 2017, reliable electricity supply is a crucial for wide user adoption of any energy system, and it must be provided in a cost-effective manner in order to facilitate the transition from non-renewable, polluting methods to low carbon energy systems. The overall objective of the project was to advance the commercial readiness of the OHT energy storage device by: (1) optimizing the design and performance of the test rig; (2) constructing a prototype of the central gravitational energy storage device; (3) demonstrate and validate the construction towers structural aspects, reliability and efficiency of the conversion of the hydraulic input to a constant electric output.
"Throughout the project both the business and technical viability of the project was assessed. A sound product development plan was prepared consisting of both in-house work and support by third parties. The third parties needed to support the project were contacted and are listed in the Feasibility Report. Despite proving technically viable, commercial success is unlikely due to the increasing difficulty to compete with batteries and have much lower cost. Due to the commercial risk, Ocean Harvesting confirms that it will instead dedicate resources to developing its new ""Infinity Drive Power Take Off"" technology. It is a energy recovery system applied to a WEC to provide full reactive force control capabilities as well as constant electric output. With the novel Infinity Drive, there is no longer any need for a centralized energy storage, since power can be time shifted directly from the WEC units. Ocean Harvesting and its integrator partner has during September – November 2017 completed a high-level system design of a novel full scale WEC system, and will in December 2017 complete also a detailed system design of a test rig setup of for the novel machinery in scale 1:2, with a fully developed supply chain, work plan and project budget."
Ocean Harvesting have designed a hydraulic collection system with energy storage technology for wave energy arrays. Although many advantages of the OHT energy storage system were identified compared to technologies such as mechanical PTO systems, hydraulic PTOs with fixed displacement cylinders and hydraulic accumulators, and hydraulic collectors of power from WECs to a central unit, batteries are becoming increasingly difficult to compete with. Over the last decade, Lithium Ion batteries have shown an unexpected improvement in economy. The cost has reduced 10x and cycles have increased 10x, altogether for a 100x improvement on the economy for high cycle applications. Lithium Ion batteries have now become main stream for utility scale energy storage, and also for the frequency regulation services being targeted by Ocean Harvesting. As such, the potential economic impact of the energy storage system is expected to be far less than was previously forecast, and would not be worthwhile to dedicate resources to advancing the technology which could instead be used to commercialise the Infinity Drive which has proved to be the more promising technology both technically and commercially. Ocean Harvesting continues to operate in the wave energy sector, promoting renewable and cleaner forms of energy for a more sustainable and healthier society.
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