Orbital Marine Power – powering the tidal revolution
2018 was a big year for Orbital Marine Power. Their technology demonstration project at the European Marine Energy Centre in Orkney passed the 3GW hours of electricity production mark, at times meeting over 25% of the islands’ electricity requirements.
Following a successful fund raise at the end of the year, the team is now gearing up to embark on their most advanced project yet.
Orbital Marine Power manufacturers the world’s most powerful floating tidal turbines. Incorporated in 2002 and with offices in Orkney and Edinburgh, the company recently rebranded to Orbital, and was previously known as Scotrenewables Tidal Power to illustrate the new direction as a commercial business and capture the essence of tidal power.
Testing at EMEC’s Fall of Warness test site. ©Scotrenewables
At its core, Orbital is about delivering innovative technology. 18 of its 24 staff are engineers and technicians focused on the technical projects and workstreams associated with the tidal technology. Engineering competencies include structural and mechanical, electrical, control and instrumentation, hydrodynamics and mooring, and offshore engineering.
Since 2003, Orbital has tested its technology at increasing scales, culminating in the delivery of the 2MW SR1-2000 tidal turbine in 2016. The SR1-2000 started delivering power to the grid at the European Marine Energy Centre in Orkney from the start of 2017 and was in continuous operation without any major maintenance during the last 12 months of its operations until August 2018. At times, the turbine met over 25% of the electricity requires of the Orkney Islands alone.
This has provided a crucial pathway for the development of the second generation Orbital O2 2MW tidal turbine, the next big milestone on Orbital’s mission to commercialise tidal power.
Tidal energy – how it works
The force of gravity between the sun, earth and moon pulls our oceans in different directions and creates tides. As tides rise and fall, the difference between ebb and flood causes water to move, creating currents with significant kinetic energy. This movement of the tides, amplified by geographical features along the coastline, focusses these tidal currents into a single predictable and concentrated form of renewable energy which can be harvested by tidal energy technologies.
Orbital makes use of tidal stream energy by extracting energy from naturally occurring tidal currents without the need for any barrages or dams.
Tidal stream energy – 800 times more energy dense
Tidal stream energy harnesses the energy from moving water generated by the tides using turbines to generate renewable electricity. It is one of the newest entrants into the renewable energy market and as costs continue to fall it could make a significant contribution to energy generation portfolios in areas around the world featuring large amounts of the resource.
Tidal stream turbines are broadly similar to wind turbines in that they use tidal flows to drive impellers and convert a portion of the kinetic energy in a tidal current into electrical energy and send it back to shore through a submarine cable. Since seawater is around 800 times denser than air, blades can be smaller and turn more slowly for the same output as their land-based counterparts. A tidal stream is usually stronger nearer to the coast where shallower waters speed up the flow.
Tidal stream energy has many advantages making it an attractive source for electricity generation:
- as tides are driven by the relative movement of the earth, moon and sun rather than intermittent weather conditions, tidal power may confidently be predicted years in advance.
- its predictable nature makes it attractive for grid management and reduces the need for fossil fuel powered back up plants.
- tidal resources are predictable which means turbines can be optimised for a site’s specific characteristics to provide lowest cost configurations with highest energy output.
- tidal stream energy is a largely untapped resource and technology risk is falling.
Global tidal stream resource and potential market size
The International Energy Agency’s 2012 Energy Technology Perspectives forecasts up to 100 GW of tidal stream capacity could be achieved globally by 2050. In the same timeframe, RenewableUK predicts that global marine energy, which includes tidal stream and wave energy, could develop into a £76 billion market.
The UK is a global leader in tidal stream energy owing to its active and innovative engineering sector, especially in the marine space, and the abundance of natural resource. According to RenewableUK, the UK holds 50% of Europe’s tidal stream energy potential and the number of sites in development accounts for more than 1,000 MW (Offshore Renewable Energy Catapult). In 2017 tidal stream energy saw a net capacity increase of at least 4 MW to a total of 17 MW (according to REN21’s Renewables 2018 Global Status Report).
At 2 MW, the SR1-2000 which was installed in 2016 represented a significant proportion of total capacity installed around the world.
Key drivers for success
Orbital believes that installation and especially maintenance costs will be the main drivers in establishing tidal stream energy as a competitive source of renewable energy. The Orbital turbine is a novel floating technology that can be installed and maintained using low cost workboats (day rates currently range from £700- £4,000) and is designed so that the majority of maintenance work can be carried out on site which helps minimise costs and turbine downtime.
Floating systems can also be deployed over a wide range of tidal sites and positioned within the most energetic part of a tidal stream (near the surface – away from the turbulent seabed). These factors all contribute to driving down the cost of the energy produced while offering greater versatility.
The importance of cost of energy
Levelised Cost of Energy (LCOE) is a standard metric used to compare the economic feasibility of energy generation technologies. It determines how much money must be made per unit of electricity to recover the lifetime costs of the generating device.
As has been the case with other renewables such as PV and wind, tidal stream costs will fall as the number of tidal turbines deployed increases and operational experience brings further refinements. That in turn strengthens investor confidence and in doing so lowers the perceived risk and associated cost of capital.
The Offshore Renewable Energy Catapult forecasts the industry average LCOE could reduce to £150 / MWh by 100 MW installed down to £90/ MWh by 1 GW. This would mirror the pattern seen in the offshore wind industry, which has seen a tenfold capacity increase in the last 10 years.
The FLOTEC project – Producing the next generation tidal turbine
Building on 16 years of research and development amounting to over 100 engineering years within the Orbital team, the Orbital O2 2MW is the commercial demonstrator model that will be deployed at EMEC in 2020, with support from the EU’s Horizon 2020 funded project, FLOTEC.
The new Orbital O2 2MW will replace the SR1-2000 at EMEC and operate for over 15 years. There will be a significant focus on reducing LCOE at every stage of the design, build and demonstration of the Orbital O2 2MW.
Areas of innovation range from low cost manufacturing approaches and more efficient design to specialist composite turbine blades, the most significant of which are highlighted in the diagram. Orbital anticipate a ~20% cost reduction between the SR1-2000 and Orbital O2 2MW turbines in addition to a similar improvement in energy yield.
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