Climate change is one of the greatest threats of this century and is already affecting many regions around the globe. Such impacts are driven by rising GHG emissions, especially from the energy sector, which is responsible for two-thirds of the global total. As a result, energy systems around the world must transition to renewable and clean energy sources and experience significant changes, owing to a combination of technology advancements, the need for affordable energy sources, and the compelling need to combat climate change. In this regard, the world’s oceans are a source of abundant renewable energy, which can be tapped through offshore wind (with fixed and floating foundations, or airborne), floating solar photovoltaics and other emerging ocean energy technologies.
Offshore wind is a viable solution for cost-effectively supplying electricity to highly populated coastal areas. Progress in turbine technology, as well as foundations, installation, access, operation, and system integration, has made it possible to reach areas with greater energy potential in deeper waters and farther from shore. Offshore wind has progressed over the last 5-10 years, making it the most advanced technology among offshore renewables.
Fixed-foundation offshore wind farms are the most common type of installation, with nearly 34 GW of installed capacity by the end of 2019. They are also the most advanced of the offshore renewable energy solutions. As a result of R&D, such turbines are now being installed in sea depths of up to 40 metres, and in some cases up to 60 metres, and at distances of up to 80 kilometres from shore.
Floating wind farms are a relatively new invention in offshore renewable energy technologies that present a number of opportunities. Unlike fixed offshore wind farms, which can only operate in shallow water, floating foundations may operate in waters up to 60 metres deep. Furthermore, they make it easier to install turbines even on mid-depth sites (30-50 metres), which could be a more affordable option to wind farms with fixed foundations.
Patenting activity can be used to assess and investigate development in offshore wind technology, as patents play an important role throughout the technology cycle, from early R&D through successful commercialization. When looking at towers, the overall patent family activity climbed steadily from 2010 to 2015, peaked briefly in 2016, and then stabilised in 2017.
Market Status for Offshore wind
The first commercial-scale offshore wind farm, with a capacity of 160 MW, was installed in Denmark in 2002. Over the last two decades, global installed offshore wind capacity has increased dramatically. By the end of 2020, offshore wind had a total installed capacity of roughly 34 GW, a more than 10-fold increase from 2010.
Collaboration in research and development has become a key vehicle for sharing knowledge, cooperatively advancing innovation, understanding constraints in many contexts, and assisting in crossing the valley of death and bringing research to market. Between 2010 and 2019, over 90 national and international RD&D collaborations focused solely on offshore wind technologies were developed.
Efforts are being made around the world to enhance the market presence of floating offshore wind in particular, as it is becoming more integrated into national goals and strategies. Despite Europe’s ambitious intentions to preserve its leadership in offshore wind, Asia is predicted to overtake Europe in the following decades, with a share of global installations of more than 60% by 2050, followed by Europe with 22% and North America with 16%.
Overall, offshore wind’s global weighted average levelized cost of energy (LCOE) has fallen, from USD 0.162/kWh in 2010 to USD 0.084/kWh by 2020. However, between 2010 and 2014, the LCOE rose as projects moved further into the sea, peaking at USD 0.171/kWh in 2011 and USD 0.165/kWh in 2014. Between 2010 and 2020, the global weighted-average LCOE of offshore wind fell sharply by 48%.
Emerging trends: Offshore wind
- Manufacturing of larger offshore wind turbines: Larger turbines are being pursued globally in order to get higher energy yield and lower costs.
- Floating foundations: Floating foundations allow for installations in deeper waters and further away from the shoreline.
- Use of versatile foundations and structures: The search for adaptable and adjustable foundations and structures is being sought due to the rising deployment of offshore wind, increasing turbine sizes, and the pursuit of greater wind resources in deeper seas and farther from shore.
- Creation of offshore energy hubs for renewable power production: Artificial islands for capturing wind energy are being studied due to limited land availability and increased wind resource availability offshore.
- Powering sectors of the blue economy: Offshore wind is being utilised to electrify a variety of blue economy operations, both directly and indirectly.
- Generation of green hydrogen through coupling with different offshore renewable technologies
Offshore Wind and Green Hydrogen
Several reasons have contributed to the growing interest in combining offshore wind with hydrogen production:
- Among all renewables, offshore wind has one of the greatest capacity factors. This translates to a greater electrolyser utilisation rate (run time), resulting in more hydrogen production and, as a result, lower total costs and higher revenues.
- Advantage of being close to demand centres as industrial clusters are concentrated around coastlines, making them the primary beneficiaries of hydrogen produced for their activities.
- Land availability restrictions are no longer an issue, and the power system is more flexible. Onshore development of gigawatt-scale green hydrogen plants, in contrast to offshore development, necessitates significant land resources.
Floating Solar Photovoltaics
Floating solar PV (FPV) is a new technology that has a lot of promise for expansion. By definition, FPV panels are suspended from a body of water on buoyant platforms or membranes, rather than being attached to piles or bridges. Due to the growing demand for FPV, whether on freshwater or seawater, it may be regarded as the third pillar of the global PV industry, alongside ground-mounted and rooftop solar PV.
The majority of FPV capacity has been placed on artificial freshwater areas. According to a research conducted by NREL, a total of 7.6 TW of electricity might be generated globally using hydro-linked floating PV. In this scenario, FPV on freshwater has a potential yearly power output of about 10,600 TWh, which is equal to half of world energy consumption in 2018.
R&D along saltwater coastlines is being done to meet the particular demands of islands and regions with restricted water surfaces. Another aspect boosting interest in this technology is that, in principle, FPV at sea performs 13 percent better (in terms of kWh/m2 installed) than solar PV on land, owing to lower temperatures and less cloud cover.
Market Status for Floating Solar PV
The first commercial FPV power plant, with a capacity of 175 kW, went online in California in 2008, and the FPV industry has seen a fast rise in installed capacities since then. The FPV market has expanded internationally, with more than 60 nations planning to deploy FPV plants in the future; 35 of these countries now have 338 FPV power plants. The installed capacity of floating solar PV power plants has increased rapidly in the commercial market.
FPV research has resulted in a decrease in the technology’s LCOE, which is now projected to be approximately USD 0.354/kWh (Bellini, 2020c). However, with ground mounted and rooftop solar PV, FPV has attained record levels of competitive LCOE in several nations.
Emerging trends: Floating Solar PV
- Deployment over water reservoirs and dams: Many nations have launched projects for such deployment because of the huge potential of exploiting the surface area of water reservoirs and dams to create energy from floating solar PV, as well as the possibility of coupling with hydropower facilities.
- Increasing deployment in seawater: In contrast to the traditional deployment in man-made water reservoirs and lakes, the technology is currently being explored in open saltwater due to the pressing problem of land availability as well as the enormous potential of FPV for islands and SIDS.
- Creation of combined-technology power generating plants: Floating solar PV began sharing foundations with ocean energy technologies and/or offshore wind devices to save money on foundations, capital, and operating expenses.
- Powering sectors of the blue economy: FPV is being examined for direct and indirect electrification of many blue economy operations, same to how offshore wind and ocean energy are being evaluated.
Ocean energy technologies are emerging and have the ability to both power coastal towns and fuel the blue economy. Around 2.4 billion people, or 40% of the world’s population, live within 100 kilometres of the shore. Most ocean energy technologies have not yet achieved commercialization and are still in the development phases, with the bulk of innovations in the prototype stage, with the exception of a few that have already reached early commercialization.
Not just among the two primary tidal methods, but among all ocean energy technologies, tidal barrage is the most mature. Since the 1960s, certain tidal barrage power stations have been operating. However, tidal energy’s theoretical power output capacity is the lowest of all ocean energy sources, at about 1,200 TWh per year. Tidal turbines are also getting bigger: instead of 100 kW turbines, 1.5 MW units have been successfully installed in recent years, and developers are trying to scale up turbines even further (2 MW).
Wave height, wave speed, wavelength (or frequency), and wave density all impact wave energy, and these properties are most potent at latitudes between 30 and 60 degrees and in deep water (more than 40 metres). The distribution of wave energy resources is better than that of tidal energy resources. This is seen in their enormous resource potential of about 29 000 TWh per year, which would be sufficient to fulfil current world power consumption. Wave energy devices are becoming larger and more powerful, with about 100 MW of installations planned in the next several years.
Ocean thermal energy conversion (OTEC)
As energy is created utilising cycles with heat exchangers and turbines, the OTEC operating concept is based on the temperature differential of ocean waters between the surface and deeper layers (800 to 1 000 metres depth). The temperature differential must be approximately 20 degrees Celsius (°C) for the OTEC to work, implying that the surface temperature must be around 25°C, since the water temperature tends to stabilise at roughly 4°C at 1000 metres depth. To collect ocean thermal energy, three thermal energy conversion techniques are being explored globally: open cycle, closed cycle, and hybrid devices.
Salinity gradient technologies create energy via reverse electrodialysis (RED), in which energy is generated as a consequence of a difference in salt concentration between two fluids. This may be seen in riverbeds where freshwater runs into the sea because the salt concentration difference is large, implying more potential for energy generation. Salinity gradient is the least established ocean energy technology, with only one project with a capacity of 50 kW operating in the Netherlands by 2020.
Over the last two decades, tidal and wave energy technologies have progressed through several technological readiness levels (TRLs), followed by an increase in innovation activity. As a result, tidal and wave energy now possess the bulk of internationally filed patents for ocean energy technology.
While tidal barrage has the most capacity, tidal stream has the second-largest installed capacity among all deployed ocean energy sources, with significantly more projects than tidal barrage. Around 9 operational wave energy plants with a combined capacity of 2.3 MW were installed internationally across 8 countries and three continents. The projects are minor in scale, with just one exceeding 1 MW of installed capacity set to be deployed in late 2020.
Emerging trends: Ocean Energy
- Gaining momentum for wave and tidal energy technologies: The worldwide market is shifting away from tidal barrages and toward wave and tidal stream technology.
- Technology convergence in tidal stream: Tidal stream technology is gaining traction, with more than 79 projects in the pipeline, the bulk of which will use a horizontal-axis turbine design.
- Pursuit of multiple wave energy prototypes in parallel: Multiple configurations/technologies are being explored in parallel in the field of wave energy, rather than a convergence towards one kind of technology.
- Creation of combined-technology power generating plants: Offshore wind and/or floating solar PV technologies are being combined with ocean energy technologies.
- Business models based on powering sectors of the blue economy: Diverse blue economy activities are powered by ocean energy technology.
Conclusion and Current Market
Offshore-Wind: Because of falling costs and in accordance with climate goals, policymakers are setting aggressive expectations for offshore wind. The European Commission’s new offshore renewable energy policy, part of the EU Green Deal, aims for 60 GW of offshore wind by 2030 and 300 GW by 2050. Ireland wants to build 5 GW of offshore wind by 2030, whereas the Netherlands wants to build 11 GW. The emerging markets for floating wind foundations include France, Japan, Spain, the Republic of Korea, and the United States.
Floating Solar PV: India, Indonesia, Singapore, Thailand, and Vietnam are all working hard to develop and install floating solar PV in Asia. Ghana constructed the first 5 MW floating solar facility in Africa in 2020. France, Italy, and the Netherlands all have major factories in Europe.
Ocean energy: Ocean energy projects are being pursued by 31 nations across the world. European nations such as Finland, France, Ireland, Italy, Portugal, Spain, Sweden, and the United Kingdom, as well as Australia, Canada, and the United States, are in the forefront. However, these technologies are still at varying stages of development.