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With an estimated potential of 29,500 TWh/year, wave technology could easily supply the entire globe's energy demand. Slow technological advancement has resulted in only a percentage of this capacity being realized. Closer working between wave energy developers and industry will provide tailored solutions, allowing a clear route for wave technology implementation.
Converting Wave Energy
Waves form across the ocean as the wind blows, gaining both kinetic energy (velocity of the water) and potential energy (water displaced from mean sea level). Most powerful between 30 and 60 degrees of latitude, waves are a predictable and reliable form of energy. A wave energy converter (WEC) is required to harness this energy.
Current WEC designs include:
- Oscillating water columns
- Oscillating bodies
- Overtopping devices
Oscillating Water Columns
The ingress of waves at the base of a hollow, semi-submerged column causes the air to compress. The compressed air then drives a turbine to generate electricity.
Several oscillating body sub-types are based on wave position, mooring, and conversion technology.
The most developed is the attenuator type, whereby connected segments sit on the water surface and move parallel to the wave's motion. The movement of the sections generates energy.
Passing waves flow into a reservoir where the water releases through a shaft. A turbine is located in the shaft, and energy is generated as the water passes.
These are the three most common devices out of several technologies currently being developed. Unlike other renewables that have completed significant research and development, a market leader in WEC technology has not yet converged. The result is investments spread over a wide array of technologies.
Small-Scale Wave Energy
The massive potential of wave energy has led to sustained interest in wave energy worldwide. However, there are currently only a small number of operational wave power sites producing a combined total of 2.3MW.
The lack of wave energy progress may be related to the inherent challenges of operating in a marine environment, such as changing sea state, wind, salt, marine life, not to mention the existing users (oil and gas, navy, fishing, etc.). The resultant difficulty in design is one of the reasons why WEC device technology lags behind other renewables.
The second factor impeding progress is a lack of investment. Wave energy companies rely on small-scale grants and investments for funding. With limited resources, technological advancement has been slow. However, there is hope. Unlike other renewable technologies, a market for small, purpose-built devices exists to meet specific industry applications.
Targeted Development by Mocean Energy
Both oil and gas and utility companies operating at sea have shown interest in using WEC devices to power offshore equipment. Mocean Energy, a renewable energy start-up based in Edinburgh, Scotland, recently announced a £1.6million investment in its Blue Star Wave Energy Converter. Blue Star is a hinged raft design, which operates via the oscillating body principle. The kinetic energy generated as the raft’s two parts move is converted into electricity via the raft's hinge.
The Blue Star WEC has been developed specifically for the oil and gas sector. It is designed to power subsea tiebacks and autonomous underwater vehicles (AUVs).
Subsea tiebacks are currently powered via cable to a surface-located power supply. The same is true of AUVs. Using a WEC would remove geographic restrictions and, as they are unmanned, reduce personnel's requirement to be located in often hazardous locations. Therefore, the potential for local, renewable power could make some oil and gas developments more environmentally and economically viable.
Wave Energy in Oil and Gas
With a goal of powering subsea tiebacks and AUVs, Mocean Energy will work with industry experts to develop fit-for-purpose solutions.
Oil and gas energy company Chrysoar and energy storage experts EC-OG and AUV specialist Modus plan to complete a major workshop in 2021 to review the Blue Star technology and its application for oil and gas. The goal is to demonstrate that wave power can cost-effectively lower subsea activities' carbon footprint via a working model.
A successful workshop will allow Mocean Energy to progress to sea trials. These are currently scheduled for late 2021 at the European Marine Energy Centre in Orkney.
The UK’s established oil and gas industry means Mocean Energy is well placed to generate a repeat and long-term revenue stream with the Blue Star WEC. Current decarbonization efforts of oil and gas companies will ensure vested interest in the development of this technology. Future diversification of the technology is also a real possibility, making remote and hard-to-reach locations more economically viable.
The continued interest and support of big business in wave energy development are vital to realizing this massive resource's full potential. In a world where the global drive is toward clean, carbon-neutral energy, convergence on a market-leading technology in small- and large-scale wave power generation is critical.
References and Further Reading
Mocean Energy Press Release (2020) Mocean Teams up with Subsea Sector [Online] Mocean Energy. Available at https://www.mocean.energy/mocean-teams-up-with-subsea-sector/. (Accessed 25 March 2021)
IRENA (2020) Innovation outlook: Ocean energy technologies, International Renewable Energy Agency, Abu Dhabi.
Robertson, L. (2021) Coalition of energy companies invest £1.6 million into demonstrating wave power. [Online] Deadline News. Available at: https://www.deadlinenews.co.uk/2021/03/04/coalition-of-energy-companies-invest-1-6-million-into-demonstrating-wave-power-for-subsea-projects-technology-news-scotland/. (Accessed on 25 March 2021).