2. Science and technology enabling economic growth and ecosystems preservation

2.1.1. Ocean-sustainability challenges that science needs to address

Science is crucial to achieving global sustainability and adequate stewardship of our ocean, since it provides the wherewithal to deepen our understanding and monitor the ocean’s resources, its health, as well as predict changes in its status.

Recent years have seen the publication of numerous reports by national and international organisations setting out, from their standpoint, the main challenges and priorities that ocean science need to address. There are a good number of shared themes, for example: climate change and its impacts on the ocean (sea-level change, acidification, etc.), the deterioration of ocean and coastal ecosystems as a consequence of human activity, marine biodiversity loss, plastic pollution, declining fish stocks, ocean-related disasters, geohazards, and ocean governance, to name but a few.

However, there are also some divergences among the organisations in terms of national and regional priorities. For example, the impact on coastal communities and the issue of the Arctic are of key importance to the Canadian ocean scientific community’s report (Council of Canadian Academies, 2013[1]); the future of marine food webs figures prominently in the US National Research Council Decadal Survey of Ocean Sciences (National Research Council, 2015[2]); the European Marine Board identifies the need for a functional and dynamic definition of marine ecosystem health (European Marine Board, 2013[3]); and the uneven global distribution of benefits from the use of the ocean and its resources represent an important source of concern for the United Nations First Global Integrated Marine Assessment (United Nations, 2017[4]). A significant achievement of the UN Sustainable Development Goals for the ocean (SDG 14) was to capture for the first time and compress the essence of many diverse challenges facing the ocean science community (Box 2.1).

One crucial element that all reports agree on is that the ocean is a very complex ecological and biogeochemical system that is under serious threat (e.g. pollution from human activity, overfishing in most parts of the world, destruction of marine ecosystems affecting the subsistence of local coastal populations) but which is still not well understood. How much pressure can the ocean take? How will an increasingly unhealthy ocean impact the planet’s biodiversity, the weather, the climate and our societies?

Two important interdisciplinary capabilities are still needed to get a better understanding of the ocean:

• The capacity to study and integrate many diverse ecosystem dynamics and various biogeochemical cycles across different scales -- including temporal scales (in the order of days or centuries) and spatial scales (from a few kilometres to very large basins);

• The capability to observe throughout the water column, all the way to the sea floor, the pressures and ecological-biogeochemical responses in the ocean interior (e.g. nutrients, oxygen, components of the plankton and indicators of their physiological status) to describe how very small processes could contribute to critically important and much wider variability.

This much needed multifaceted understanding of the ocean requires many scientific disciplines, from biology to physical sciences, to build up and analyse years of data from across broad expanses of the ocean, to collect new data, and deploy new technologies. International cooperation will be key, bearing in mind that organisational setups and ocean science capacities also vary greatly from country to country (IOC, 2017[6]). In addition to the different ocean science communities, other scientific disciplines are also joining in fundamental research that may ultimately benefit the ocean. For example, dedicated research and development into new sustainable petrochemical production routes (from production to use and disposal of products) may contribute to efforts to curb and stop the leakage of plastic pollution and other harmful chemical products into the ocean (IEA, 2018[7]). This primarily land-based pollution finds its way to the ocean via domestic and commercial wastewater (e.g. cleaning and sanitary products), agricultural run-off, and seepage from disposal sites. Much progress needs to be made to tackle the root of this chemical pollution, both in terms of the R&D required to find potential alternatives that would be less damaging to the environment, and in terms of changing current production and consumption practices (e.g. building on the circular economy concept) (OECD, 2018[8]).

Two milestones for the global ocean science community are forthcoming. For the first time, the Intergovernmental Panel on Climate Change (IPCC) will be producing a Special Report on the Ocean and Cryosphere in a Changing Climate in the second half of 2019 (IPCC, 2018[9]). Over 100 scientists from more than 30 countries are currently assessing the latest scientific knowledge about the physical science basis and impacts of climate change on ocean, coastal, polar and mountain ecosystems, and the human communities that depend on them. And 2021 will see the launch of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), with the objective that very diverse scientific communities and users of the ocean work together to develop further the knowledge base on the ocean (IOC, 2018[10]).

2.1.2. Selected trends in ocean science and technology

The OECD report on the ocean economy in 2030, written in 2015, already described many of the key advances under way in science and technology to help address the bulk of the challenges outlined above (OECD, 2016[11]).

In the course of the next couple of decades, a string of enabling technologies promises to stimulate improvements in efficiency, productivity and cost structures in many ocean activities, from scientific research and ecosystem analysis to shipping, energy, fisheries and tourism. These technologies include imaging and physical sensors, satellite technologies, advanced materials, information and communication technology (ICT), big data analytics, autonomous systems, biotechnology, nanotechnology and subsea engineering (Table 2.1). In addition to incremental innovations, there is the prospect of different technologies emerging and converging to bring about quite fundamental shifts in knowledge acquisition and marine industry practices.

A cursory glance at the more recent literature suggests that, in the short period that has elapsed since the writing of the Ocean Economy in 2030 report, there has been an acceleration of research interest in the potential for applications of some of those technologies in gaining a better understanding of marine ecosystems, their workings, and the requirements for their better management (Box 2.2).

Enabling technologies appear set to contribute in important ways to the sustainable development of the ocean economy, not least by vastly improving data quality, data volumes, connectivity and communication from the depths of the sea, through the water column, and up to the surface for further transmission. While the examples are far from exhaustive, they do serve to illustrate the richness of current innovations in the ocean economy that are addressing either the one or the other objective. Two are particularly highlighted below:

• Blockchain and big data analytics applications, for example, are starting to be deployed in port facilities and maritime supply chains. Shipping companies, logistics businesses, port operators and other maritime transport stakeholders are looking to more integrated services across the entire supply chain as a means of generating cost savings and greater efficiencies, as well as improvements in quality of service. The prospects for achieving those benefits by getting the various relevant operations (administration, logistics, shipping, terminal and port) to work together more smoothly have been boosted by the advent of digital platform technologies. For example, within the administrative segment of shipping operations, transport operators are currently exploring the potential for using distributed ledger technology (DLT), most notably blockchain. This technology does away with the need for an intermediary in transactions between stakeholders, while potentially offering a rapid and secure authentication method for freight transport. New players are emerging in the form of shipping tech start-ups with the capacity to leverage higher data volumes. They include digital freight forwarders, rate analytics services, collaboration or exchange platforms, tracking platforms and service fulfilment networks (International Transport Forum, 2018[41]).

• The emergence of autonomous ships is also an important disruptive element for some industries, as are autonomous underwater vehicles (AUVs). AUVs and gliders with improved sensor platforms have progressed from niche status to an established part of operations in various marine sectors. In the oil and gas sector, however, the technology still has to mature to a stage at which oil and gas operators consider it a vital component of operations (Wilby, 2016[42]). This technology is deployed in monitoring and inspection for leakages in underwater carbon capture facilities, as well as in the inspection of deep-sea pipelines (Forshaw, 2018[38]). There are future opportunities for deployment in offshore decommissioning (Westwood Global Energy Group, 2018[43]) and possibilities for use in offshore wind (Westwood Global Energy Group, 2018[44]).

Other selected innovations primarily supporting the development of the sustainable commercial use of the seas and ocean are presented in Box 2.3.

2.1.3. Introducing the four case studies

Beyond recent advances in science and technologies, the focus of this chapter is on innovations and combinations of innovations which embody the very the notion of green growth in the ocean by successfully fostering economic development and ocean sustainability simultaneously. To do this, it presents four in-depth innovation case studies: floating offshore wind; ballast water management; marine aquaculture; and rig- and renewables-to-reefs.

The four case studies are very different. They differ in scale and in the degree of maturity of the respective activity. Floating wind power is still in its infancy, with only one commercial-scale facility in operation in the world. Ballast water treatment technologies have so far been installed in only a small number of ships, but expansion could be rapid. Oil and gas rig conversion into artificial reefs is current in some parts of the world, but not in others, and no renewables-to-rigs programmes exist anywhere. Marine aquaculture, by contrast, is well established in many parts of the world, is undergoing rapid expansion, and is being transformed at great speed by a whole host of innovations. For this reason, the marine aquaculture case study is addressed in more detail and at greater length, in order to illustrate the sector-wide dimension of the innovation process.

Moreover, innovation in the four activities is driven by different forces and different challenges. Innovation in floating wind power is largely science and technology driven; rigs-to-reefs conversions are driven both by industry’s need to reduce decommissioning costs and conservationists’ desire to create or restore ocean ecosystems; innovation in ballast water treatment is propelled essentially by regulation; and innovation in the marine aquaculture sector is motivated by multiple factors: the challenge of feeding a growing world population, the incentive to develop business opportunities, and the need to reduce pressures on coastal environments. As different as the drivers may be, progress in all the cases is science-led or at least science-based.

Each case study endeavours to address a number of key issues: the background and global context; the economic and environmental issues at stake; the research and technological innovations in prospect; and the contribution that the innovations could make to enabling economic development within the sector (e.g. through cost-savings, new business generation, emergence of new industries) and environmental sustainability to go hand in hand.

2.2.1. The economic and environmental issues at stake

Until recently, floating offshore wind technology was largely confined to research and development, but the coming decades could see it emerge on a commercial scale. For that to happen, however, a wide range of technological, economic, regulatory and environmental challenges will need to be addressed.

The offshore wind industry has grown at an extraordinary rate over the last 20 years or so, from almost nothing to a total capacity of 18 GW in 2017. The way has been led mainly by Europe and China. Growth prospects are strong. Between 2017 and 2023, total global capacity is expected to almost triple to 52.1 GW (IEA, 2018[59]).

The potential economic benefits of such a rapid expansion are considerable. The OECD’s 2016 report on the Ocean Economy in 2030 suggests that, on a business-as-usual basis, the global gross value added generated by offshore wind power could increase eight-fold and employment more than twelve-fold between 2010 and 2030. As a consequence, its share of the global ocean economy could grow from less than 1% in 2010 to 8% in 2030 (OECD, 2016[11]).

Wind power also offers considerable benefits to the environment through its contribution to reducing global CO2 emissions. By way of illustration, estimates of carbon emissions from offshore wind generation conducted in 2015 place life-cycle emissions in the range of 7 to 23 g of CO2 equivalent per kilowatt (gCO2e/kWh). This compares with around 500 g for gas-fired conventional generation and about 1 000 g for coal-fired conventional generation (Thomson and Harrison, 2015[60]). A similar result was arrived at in a more recent study by Kadiyala et al. (2017[61]) which estimated the mean life-cycle emissions of the offshore wind installations surveyed at 12.9 gCO2e/kWh (with an environmental payback period of just 0.39 years).

Figure 2.1. Forecast of regional offshore cumulative capacity (GW) and wind generation (TWh) 2017-2023

Source: Adapted from IEA (2018[59]), Renewables 2018: Analysis and Forecasts to 2023, https://dx.doi.org/10.1787/re_mar-2018-en.

Moreover, the potential contribution to reducing CO2 output stands to benefit indirectly the world’s ocean ecosystems by helping to slow the increase in acidification, de-oxygenation and the rise of sea temperature and sea levels. Hence, further rapid expansion of offshore wind power suggests further gains for the environment in terms of CO2 reductions.

To date almost all offshore wind turbines are of the fixed-bottom type, installed in shallow water (up to around 50-60 meters) in proximity of the coast. Fixed-base wind turbines are arguably today successfully delivering low energy costs, improved energy security and low environmental impact, and much of the future growth in total offshore wind generation will continue to stem from this type of platform. However, over time, fewer near-coast shallow-water sites will become available due to growing competition for space from other ocean users, as well as to the lack of physically suitable locations. The latter applies in particular to countries like Japan and parts of North America and Latin America whose coastal zones are situated in deep water. Floating offshore wind platforms offer a way out of this dilemma. They could be installed in positions benefitting from more space, less potential interference with other ocean activities, and stronger more regular winds. In principle, the potential is very large indeed (Table 2.1).

Despite being able to draw quite heavily on the experience that the offshore oil and gas industry has with floating structures, seabed fixtures and related technologies, floating wind farms have taken some time to emerge as a commercial-scale installation. Indeed, to date, there is only one single large-scale offshore wind platform operating in the world: The 30 MW Hywind is situated off the Scottish coast and has been operating successfully – even surpassing expectations – since 2017 (Hill, 2018[63]). Nevertheless, at the time of writing, not one floating offshore technology has proved itself to the extent that it could be purchased off the shelf (Dvorak, 2018[64]).

However, many more projects are approaching fruition or are currently under development. The Scottish government has approved the 50 MW Kincardine Floating Offshore Wind Farm. The Council of Ministers in Portugal has given the go-ahead to the development of the 25 MW WindFloat Atlantic (WFA) project in Viana do Castelo, 20 km off the coast of Northern Portugal. France has approved a total of four pilot floating wind projects: a 24 MW pilot floating wind farm in the Gruissan area; a 24 MW floating wind farm planned by Eolfi and CGN for the Groix area; a 24 MW floating wind farm in the Faraman area; and another 24 MW project off Leucate. Work is also underway on the 2 MW Floatgen floating wind project in the Port of Saint-Nazaire. Japan installed the Fukushima Hamakaze floating wind turbine in 2016, and has initiated several further floating wind projects, such as the demonstration one off Kitakyushu. In the United States, the 12 MW New England Aqua Ventus I floating offshore wind demonstration project is under way in the Gulf of Maine. More developments are in the pipeline for projects off the coasts of Scotland, Wales and Ireland (offshoreWIND.biz, 2017[65]).

Consequently, expectations are running high that the market will develop rapidly in the coming decade, growing from almost nothing in 2017 to around 1 300 MW in 2030 and providing a total installed capacity of over 5 GW by 2030 (GWEC Global Wind Energy Council, 2017[66]). The basis for such optimism would appear to be, inter alia, recent progress in research, development and innovation.

2.2.2. Developments in research and technology

At the moment there are three designs of substructures under development: spar-buoy, spar-submersible, and tension leg platform (TLP); see IRENA (2016[67]), for more detail. A fourth foundation design – barge – is also well advanced, though less so than the others.

The high expectations of vigorous market expansion in the coming years are built on estimates of the potential for floating solutions and on the progress that has been made in bringing floating wind turbines up to an advanced level of technological readiness. According to Wind Europe (2017[68]), the spar design is already at technology readiness level (TLR) 9, and the others are expected to reach that score within the next five years: Expectations are further fuelled by advances that are being made in such areas as the siting of turbines, construction materials and methods, new designs, and monitoring and inspection, as the following examples illustrate.

2.2.3. Challenges facing floating wind technology

The high expectations with respect to the near and medium term development of floating wind technology need to be put in perspective, since there are many economic, technological, institutional and environmental challenges ahead.

While much can be learned from fixed-base offshore wind farms, floating wind technology is far from being a simple extension of that technology innovation system. The supply chain is different from that used for fixed-base turbines in shallow, near-shore waters; the technologies are different, as are the cost structures; the impact on the marine environment is different; and other ocean users may be affected in other ways (Bento and Fontes, 2017[77]). The difference in cost structure is particularly striking with respect to capital expenditure. While the foundations make up only 20% of total capex for conventional fixed-base offshore turbines (the main cost components are related to the turbines themselves), they account for around two-thirds of total capex in the case of tension-leg (TLP) floating wind platforms (Kausche et al., 2018[73]).

Costs figure among the most important potential barriers to rapid development of floating offshore wind farms. Higher average distance to shore correlates with higher wind speeds and higher capacity factors, but entails lengthier export connection cables to grid. Water depth usually increases with distance to shore, but is associated with higher installation and foundation costs, in particular mooring costs (Myhr et al., 2014[78]). Compensating cost savings may be expected from more integrated supply chains, economies of scale, upscaling of turbines, and major repairs conducted onshore, but most such savings will take time to come through. The longer term also holds further challenges. For example, grid integration costs are likely to increase as levels of penetration by variable power generation sources rise. The Levelised Cost of Energy (LCOE) for existing offshore wind farms in Europe in 2015 ranged from 7.3 €ct/kWh to 14.2 €ct/kWh, higher than the LCOE of onshore wind energy or conventional generation technologies (Höfling, 2016[79]). The LCOE of floating wind turbines, in turn, will very probably be higher than for both onshore and fixed-bottom offshore installations: according to the IEA, about 6% higher than the 2014 baseline in the IEA medium-term scenario (Wiser et al., 2016[80]). The results of the IEA’s survey of over 150 world experts in offshore wind power suggest that trend reductions in the LCOE of floating wind energy solutions could converge with those of fixed wind power platforms, but not until around 2030.

According to the findings of the IEA survey of experts, the most significant enabler for driving down the levelised cost of energy is – in addition to learning from experience – research and development. Significant technical innovations will be required to improve the competitivity of floating wind farms, but so will innovations in site identification, serial production, supply chain integration and management, and logistics during construction and operation.

2.2.4. Impacts on the environment and marine ecosystems

As noted earlier, the net contribution of floating wind energy to the reduction of CO2 emissions is significant compared to fossil-fuel based energy sources. There are nonetheless non-negligible drawbacks for the marine environment. These include the impact on (migrating) birdlife, the effects on fish and marine mammals, as well as those on the seabed and benthic habitats.

Most of the available research on ecosystem impacts draws on Northern European experience with fixed-base offshore turbines. Offshore structures can under certain circumstances enhance the marine environment due to increased biological productivity (of fish, molluscs and other forms of marine life). However, the construction phase would appear to be particularly invasive, with construction noise and disturbance of the seabed having effects on benthic habitats and many species of marine life, and once complete may in addition disrupt habitat connectivity both in and beyond the immediate area. Once in operation, the turbines can be a source of acoustic disturbance for a range of marine animals. There are also risks to bird life: potential flight displacement, risk of collision, and fragmentation of habitat by creating a barrier between birds’ nesting grounds and their feeding grounds. Some progress is being made in developing the technological and scientific tools to address some of these problems. In the case of risks to avian species, for example, techniques ranging from radar monitoring, Thermal Animal Detection Systems (TADS) and acoustic detection, to video surveillance and computational collision models are currently being deployed in the study of bird flight and behaviour in the proximity of offshore wind farms.

The view is emerging that, at least as concerns the construction/installation phase, floating wind turbines would be less intrusive during dredging and seabed preparation operations than fixed-bottom turbines (Carbon Trust and Offshore Renewable Energy Catapult, 2017[76]). Nonetheless, numerous issues remain. For example, for floating platforms, cable routes still need to be prepared and cables laid, activities that are associated with considerable disturbance of sediments. Also, the mooring systems for floating turbines need a large mooring spread. For a typical (catenary) mooring system, the spread diameter increases by 14 m with every 1 m increase in water depth. For a wind farm installed at a water depth of 150 m, for example, this would translate into a mooring system that required a 2 km diameter area of seabed for every turbine in the farm. Not only does that significantly raise the cost of mooring system materials, it also increases the lease area and expands the seabed environmental impact (Hurley, 2018[81]).

Also, the ornithological impact would depend greatly inter alia on how close to shore the floating facility is deployed. In relation to interaction of the floating foundation with fish and marine mammals, little research appears to be available, not least due to the fact that as of today few floating platforms exist.

The construction and operation of floating facilities should benefit from the experience of installing and running fixed-base wind turbines with ecosystem impact assessment. But even here, there are still large knowledge gaps. Lack of baseline data is a considerable impediment to the evaluation of impacts. Indeed, baseline research is needed on a whole range of natural phenomena including on marine species’ population structures and status, and their distribution and abundance over many annual cycles. And much remains to be done to improve the knowledge base on long-term ecosystem impacts as well as on the cumulative effect of multiple impacts. Similarly, information about the effects on the whole ecosystem (as opposed to those on single species or specific ecosystem components) is generally quite limited, although there are signs of progress; see for example Pezy, Raoux and Dauvin (2018[82]).

2.2.5. Concluding observations

With innovation evolving apace and levelised costs of energy projected to follow a downward trajectory similar to those of fixed-base wind platforms, a promising future is discernible for the floating wind energy sector. The growth potential is considerable, and from a broader ocean industry point of view, one would expect economic spill over benefits to flow to other maritime sectors such as ports, shipyards (construction and repair), marine equipment, and shipping. But given the many challenges this new sector faces, it seems unlikely that floating wind energy will be making a perceptible impact at commercial level in the near or medium term. Hence, also the indirect and direct benefits to the marine environment through displacement of fossil fuels will take time to have any effect. Science and technology are at the leading edge of developments to address the engineering and cost-reduction challenges, just as they will be required to play a key role in closing knowledge gaps and resolving many of the uncertainties still surrounding the environmental impacts of floating wind platforms.

2.3.1. The economic and environmental issues at stake

The marine invasive alien species’ problem is extraordinarily diverse and truly global in geographical scale, as the International Maritime Organisation’s (IMO) list of the world’s most troublesome invasive species indicates. In many instances, the impact on the environment has been devastating, depleting zooplankton stocks, competing with, displacing and sometimes wiping out local native marine life, disrupting food webs, obstructing coastal structures, and even posing a threat to public health. The environmental impacts are often associated with substantial economic costs, ranging from losses to fisheries and aquaculture, foregone revenues from tourism, deterioration of port facilities, and so on. The overall costs are thought to run into the USD tens of billions annually (King, 2016[83]).

Some examples of aquatic bio-invasions causing major impact are listed in the table below, but there are hundreds of other serious invasions, which have been recorded around the world (Table 2.3).

The two main vectors by which marine invasive species are redistributed globally are biofouling (largely on ships’ hulls) and ballast water (Figure 2.2).

Figure 2.2. Biofouling and ballast water

Source: Fernandes et al. (2016[85]) Costs and benefits to European shipping of ballast-water and hull-fouling treatment: Impacts of native and non-indigenous species, https://doi.org/10.1016/J.MARPOL.2015.11.015.

This case study focuses on the latter, namely the water that is used to maintain ships’ stability and integrity under different operational situations. As the size of merchant vessels increased and maritime traffic expanded over the last seventy years or so, the volume of untreated ballast water being transferred unintentionally from one location to another has grown enormously. It is thought that today tens of billions of tons of ballast water are carried between the world’s seas every year (Davidson et al., 2016[86]), spreading thousands of marine organisms – larvae, plankton, bacteria, microbes, small invertebrates, etc.- into the local marine ecosystem when discharged. This ballast-related redistribution of invasive species is widely recognised as a major environmental and economic problem, challenging, complex and currently still unresolved (Batista et al., 2017[87]). As a result, the need to treat ballast-water has become a priority initiative at global level, encompassing national efforts to strengthen regulation as well as multilateral efforts to design and implement an international convention.

2.3.2. Current state of regulation

International ballast water management regulation has been long in the making. Indeed, the International Maritime Organization (IMO) has been tackling it since the 1980s, when Member States of the organisation began alerting its Marine Environment Protection Committee (MEPC) to their concerns. The year 1991 saw the adoption of Guidelines to address the issue, followed by work to build the IMO Ballast Water Management Convention, adopted in 2004. The Convention was eventually ratified by the IMO in September 2016. Although scheduled to come into force on September 8, 2017, implementation has been delayed until 2019 (see Box 2.4). All ships to which the Convention applies should be equipped with a Ballast Water Management System (BWMS) no later than 8 September 2024.

Full success of the Convention depends on a number of issues, the most important being the following:

• It will only apply to ships from flag states having ratified the Convention, and to ships entering their jurisdictions. At present the treaty has been ratified by more than 60 countries representing more than 70% of world merchant shipping tonnage. Given that this includes the dominant shipping nations as well as a host of other countries, it would be practically impossible to sail internationally without complying with the Convention. This effectively puts a brake on the exchange of invasive species, as vessels from nations not complying with the Convention are restricted to their own territorial waters.

• In view of the widespread lack of awareness about the environmental and economic consequences of ballast water, major efforts will be required to integrate and train ship crews and port staffs.

Further international negotiation and collaboration in the years ahead will be critical factors in consolidating, implementing and expanding the Convention.

2.3.3. Current state and future development of ballast water treatment technologies

The Ballast Water Management (BWM) Convention standard applies to water upon discharge. However, ship owners are fully aware of the biological growth in ballast tanks, and so many already have or will in future have procedures for ballast water treatment in place for both water uptake and discharge.

The design and operation of BWM systems face multiple challenges. They have to be usable for many different types of vessel, prove effective in destroying a wide range of organisms, and be able to operate efficiently and safely under all kinds of ballast water conditions such as varying ranges of salinity and temperatures. Consequently, research has given rise to hundreds of different BWM applications that use a variety of underlying technological principles. These currently range inter alia from ultra violet, oxidation and de-oxygenation, to electrolysis, ultrasound and heat, as well as chemical biocides. (Latarche, 2017[89]). However, among the many vessels already equipped with BWM systems that are approved for use by the IMO and United States Coast Guard (USCG) , the vast majority utilise two main technologies for disinfection purposes – electro-chlorination or ultraviolet irradiation – often in combination with filtration (Batista et al., 2017[87]).

Both technologies have been subject to criticism. For example, common and abundant seawater phytoplankton have frequently been found to be resistant to UV treatment; especially smaller organisms and microbes often survive; and so the question of population re-growth in the ballast tank persists (Davidson et al., 2017[90]; Batista et al., 2017[87]; Wollenhaupt, 2017[91]). Electro-chlorination, in turn, has been found to demonstrate lower disinfection efficiency in upper reaches of estuaries and freshwater surroundings because of their lower salinity (Batista et al., 2017[87]). Moreover, environmental concerns have been raised about problems related to pollution from some chemical treatments being applied to ballast water (Davidson et al., 2017[90]).

In the absence of more effective treatments today, what is in the innovation pipeline for tomorrow?

One solution may lie in the development of green, environmentally friendly treatments that can handle the double challenge of making significant inroads into the spread of invasive species at reasonable cost while at the same time reducing impacts on the marine environment. An example is pasteurisation technology that does without UV, filters and chemicals. The Danish Bawat BMS (2018[92]), for example, is aiming for USCG-type approval in the course of 2019.

Meanwhile, currently available technologies are undergoing continual improvement through evolutionary (rather than revolutionary) advances, and through innovations that aim to mitigate the shortcomings of existing techniques. To date, over 65 ballast treatment systems have been given type approval by the IMO. And in terms of mitigation (e.g. sampling), research is apparently generating numerous applications that allow testing for some organisms whose continuing presence post-treatment would involve severe penalties from the regulators. While such applications do not detect all organisms or bacteria identified by IMO or USCG regulations, they can provide indications of whether the treatment system is working effectively and allow the vessel operators to undertake further action. Increasingly, these are small, relatively inexpensive hand-held devices that detect the presence of viable algal organisms, microbial activity etc. in the ballast water. (Latarche, 2017[89]). In addition, advanced lab-on-chip detectors have been tested recently which can measure various characteristics of certain microorganisms in ballast water, for example number, size, shape and volume (Maw et al., 2018[93]), and detection of bacteria in ballast water by new-generation DNA techniques has also been successfully tested (Brinkmeyer, 2016[94]).

2.3.4. Estimating economic costs and benefits

In complying with the requirements of the Convention, there are clearly large potential gains for the environment. For the shipping industry however there are costs involved, in the form either of installing BWMS in the newly built vessels or in retrofitting existing vessels. The flipside of the coin is that the shipbuilding and maritime equipment sectors stand to benefit from the extra revenue this involves. But how large is the additional revenue likely to be?

Several attempts have been undertaken in recent years to estimate the size of the potential additional BWMS market. All of them necessarily entail building multiple scenarios because the many different types of ship of different size require different ballast water volumes and different equipment. In their work on the costs and benefits of biofouling and ballast water in the European market, Fernandes et al. (2016[95]) rely upon three categories of ballast water volume (< 1 500 m³, 1 500 to 5 000 m³, > 5 000 m³), five categories of vessels and four categories of tonnage. Splitting each of the three categories of ballast water volume into two categories of vessels accounts for 93% of the world fleet that uses ballast water. Creating categories in this way reduces the complexity of assessing the potential costs of measures across a range of vessels. For example, all ships with ballast waters volume of less than 1 500 m³ are passenger and fishing vessels of less than 10 000 tonnes.

Estimates of the number of ships in the global merchant fleet likely to install/retrofit ballast water treatment systems vary considerably depending on the model used, assumptions made, and possibly the juncture in the shipping/shipbuilding cycle at which the estimates were made. (King D.M. et al., 2012[96]) ventured a rough estimate of 68 000 vessels installing on-board BWTS between the time of writing and 2020, assuming full compliance of the Convention. Linder (2017[97]) suggests between 30 000 and 40 000 vessels could be candidates for retrofitting. Clarksons Research (2017[98]) projects potential retrofit demand at around 25 400 ships, plus 1 000 to 2 000 ships per year in newbuild demand. And the OECD (2017[99]) indicated around 27 000 to 37 000 existing vessels might be expected to retrofit BWMS between September 2017 and September 2024.

Estimates also vary when it comes to the average cost of retrofitting BWMS. Linder (2017[97]) estimates capital expenditure at USD 80 000-1 500 000, installation cost at USD 100 000-1 000 000, running cost at USD 0.01-0.02 per ton of ballast water, and sampling at USD 75 000-125 000 per vessel. Recent work of the OECD Secretariat (Figure 2.3) assess the impact of the Convention on additional demolition volume and retrofitting activity on the basis of three scenarios (OECD, 2017[99]). These are a high level scenario with installation costs reaching USD 3 million per ship; a medium level scenario with costs of USD 1.5 million per ship; and a low level scenario of costs of USD 0.5 million per ship.

Figure 2.3. Potential demand for retrofitting ballast water management systems under low, medium and high installation cost scenarios (number of vessels)

Source: OECD (2017[100]) Analysis of Selected Measures Promoting the Construction and Operation of Greener Ships, http://www.oecd.org/sti/shipbuilding.

A highly simplified calculation, taking 25 400 existing vessels at an average retrofit cost of USD 2 million, would suggest a potential global BWMS market in the order of USD 50 billion. [The figure is in line with estimates of USD 45 billion by Linder (2017[97]), and at the low end of estimates of USD 50-74 billion by King et al. (2012[96]), albeit for the period 2011-2016). What is clear, however, is that the Convention could have a significant impact on the ship repairing industries, generating business opportunities which – under the proviso of further analysis – “may occupy around 20% to 50% of retrofitting capacity in the coming 7 years” (OECD, 2017[99]).

How likely is it that the huge additional potential of the global BWMS market will materialise in the coming years?

Economic theory at least suggests that uptake could well be slower than expected. As noted earlier, concerns have been raised by the shipping industry about the effectiveness of many ballast water treatment systems and their ability to meet consistently IMO and USGC discharge standards. Furthermore, King (2016[83]) indicates that IMO guidelines for certifying and testing are considered by many observers as vague and open to interpretation, and that USGC is thought to be tending towards lowering BWMS testing standards in order to facilitate market access for USCG-certified BWMS. King (2016[83]) goes on to apply two well-established theoretical approaches to analyse the situation in the budding BWMS market. The first, based on work by the economists Akerlof, Spence and Stiglitz, indicates that “quality uncertainty” may prevent markets from developing or at least may result in poorer quality goods or processes, especially in regulation-driven markets. In the BWMS market, lack of strict quality criteria from the outset is likely to see bad quality replace good quality, thereby undermining a potentially successful regulatory regime. The second theoretical approach, namely “game theory”, draws on work by the economists Harsanyi, Nash and Selten, to explore inter alia how regulated industries react to such quality uncertainty by deploying strategies aimed at avoiding or delaying compliance, or reducing the costs of compliance. This would suggest that further action by governments and regulators will be required if an effective and viable regulatory regime is to emerge.

However, a counter-argument can be made to the effect that lowering the USCG standard may in fact prove beneficial, to the extent that it could result in one single common international ballast water standard. After all, the fact that the USCG standard is stricter than the UN IMO standard is thought to have caused uncertainties in the maritime industry – both among developers of ballast water treatment technologies and among ship owners – in respect of which standard to apply and which technology to purchase.

Finally, it should be noted that it may prove difficult to meet the requirements of the Ballast Water Management Convention within the proposed time range given both the limited conversion capacity and the corresponding costs for ship owners.

2.3.5. Concluding observations

Successful implementation of the BWMC, underpinned both by further improvement of conventional treatment technologies and by innovation in greener technologies (such as pasteurisation), holds out the prospect of substantial benefits to marine life and to biodiversity more generally in ocean ecosystems. Economic benefits should arise on multiple fronts: cost savings in the maintenance of coastal and port facilities, enhancement of native fishery stocks, reduction of harmful impacts on marine aquaculture, increased tourist revenues, to name but a few. Even the shipping sector, that undoubtedly shoulders the lion’s share of the costs associated with installation and retrofitting of ballast water treatment systems, ultimately also stands to gain as the knock-on effects expected from compulsory BWT feed through to lower levels of bio-fouling and consequently to fuel savings and lower emissions; see for example Fernandes, (2016[85]). However, it may prove difficult to meet the requirements of the BWMC within the proposed time range given the limited conversion capacity and the corresponding costs for ship owners. There is room for public policy both to encourage innovation in ballast water treatment and to ensure that a viable, effective regulatory system be implemented and sustained.

2.4.1. The economic and environmental issues at stake

The importance of aquaculture has been growing rapidly in recent decades as an expanding world population, rising incomes and changing food consumption patterns have all combined to push up global demand for fish food. Moreover, with growth in capture fisheries having plateaued, future growth in seafood production is expected to come largely from aquaculture, further underlining its key role in global food security.

Marine aquaculture production – finfish, crustaceans, molluscs and aquatic plants – currently stands at about 59 million tonnes, equivalent to just over one-half of global aquaculture production (FAO, 2018[101]). It produces some 6.6 million tonnes of finfish, almost 5 million tonnes of crustaceans, and almost 17 million tonnes of molluscs (FAO, 2018[101]). The vast bulk of farmed aquatic plants consist of macro-algae or seaweed. At 30 million tonnes, they make up more than half of total marine aquaculture by weight, but in terms of value – USD 11.7 billion – their share is quite small (FAO, 2018[101]). Global production of seaweed has been growing quickly, more than doubling over the period 2005-16, but remains dominated by China and Indonesia, which account for over 85% of the total (FAO, 2018[101]).

Future growth of aquaculture production volumes appears to be set on a slowing trajectory compared to the last few decades. The latest OECD-FAO Agricultural Outlook (OECD/FAO, 2018[102]) for example sees growth slowing to 2.1% p.a. in the period 2018-27 compared to the 5.1% of the previous decade. Important contributing factors are the increasingly scarce raw materials for fish feed, limited availability of appropriate sites at current levels of technology, concern about the environmental footprint of aquaculture, and increasingly crowded coastal waters raising the risk of disputes among other ocean users (shipping, fishing, oil and gas etc.). In addition to these, the licensing environment (Innes, Martini and Leroy, 2017[103]) and national policy have a significant role to play. The development of “investment ready” aquaculture zones for example in places such as Australia show how national policy can encourage production. Conversely, China’s 13^th five-year plan (2016-20) is expected to slow growth in domestic production. Objectives there have shifted away from the past emphasis on increasing production and moved towards a more sustainable and market-oriented sector, where the focus is on improving quality and optimising industry structure. This will affect global aquaculture production due to the importance of China’s output at world level (OECD/FAO, 2018[102]).

Higher rates of growth in the coming decades are conceivable, but this would necessitate marked progress at several levels. Improvements in policy, licensing approaches and marine spatial planning could make important contributions. In addition, however, steps would need to include a reduction of the environmental impact of fish farms in coastal regions (e.g. destruction and/or pollution of coastal and aquatic ecosystems, introduction of exotic species into ecosystems, transmission of disease and parasites to wild populations), improved disease management, significantly higher proportions of non-fish feed for carnivorous species, and more rapid advances in the engineering and technologies required to establish offshore aquaculture operations (OECD, 2016[11]). In other words, future fish farming methods will need to be technically more sophisticated and more intelligent, requiring a “shift from experience-driven to knowledge-driven approaches” (Føre et al., 2018[104]). That in turn highlights the need also for scientific and technological innovation on multiple fronts.

2.4.2. Innovations in the pipeline

Innovation in aquaculture has in the past been largely technology driven. With some notable, albeit relatively recent exceptions, it has operated much through technology transfer, i.e. through mono-disciplinary research producing new technologies that emerge from the research system, get diffused by intermediaries such as advisory services, and adopted by users at farm level. Technology transfer is still regarded as the predominant approach to innovation in aquaculture, and is indeed considered the dominant culture in developing countries in South and Southeast Asia and Africa (Joffre et al., 2017[105]). While it has undoubtedly given rise to continuous innovation and remarkable increases in productivity, its practices have been subject to increasing criticism for what is considered to be inadequate consideration of ecological and social sustainability, and for creating growing challenges for ensuing generations of innovation processes. Systemic approaches on the other hand (e.g. systems innovation, socio-ecological approaches) which take a contextual, more holistic perspective on innovation, have become somewhat more widespread in recent years in developed countries. These tend to be multi-dimensional approaches, integrating technical, biophysical, environmental, economic and institutional dimensions into account (Joffre et al., 2017[105]).

In light of the above-described challenges and changes facing aquaculture development in the years ahead, especially for larger-scale intensive fish farming in developed countries, systemic approaches to innovation are moving increasingly into focus. Growing complexity of operation will call for novel solutions. In salmon farming, for example, direct observation as a means to garner key information on the state of populations and optimise their growth and welfare may become unviable for facilities housing millions of individual fish. And if, as expected, farms begin to move offshore2 into more exposed locations, access for personnel will become more problematic and remote automated operation more necessary (Føre et al., 2018[104]).

What kind of innovations are in the pipeline, which would contribute to addressing many of the challenges outlined above? What follows is an overview of advances unfolding in the various phases of aquaculture planning, implementation and operation, namely: aquaculture site selection, breeding, feeding, waste control, health monitoring and treatment, and engineering solutions.

Feed

Feed is an extremely important input in marine aquaculture. It accounts for between 50 and 80% of total aquaculture production costs (FAO, 2017[114]). Moreover, feed can have a high impact on the environment in the form of waste (excess food, nutrient excretions, etc).

Significant progress has been made in recent years towards reducing or replacing fishmeal in the diets of many aquaculture species without compromising health or performance. Fish processing by-products, for example, currently make up around 25-30% of marine ingredients (Shepherd, Monroig and Tocher, 2017[115]). Efficiency increases are helping recover increasing quantities of oil and fishmeal from fish waste, along with increased demand for fillets which produces more waste. This means that production of fishmeal and fish oil from fish residue is expected to continue to rise (at rates of 2.8% and 1.6% per year, respectively) over 2018-27, taking the share of total fish oil obtained from waste fish from 39% to over 41% and that of fish-waste based fishmeal from 29% to more than 33% over the same period (OECD/FAO, 2018[102]). The consequences on the composition and quality of fishmeal and oil of increasingly relying on fish waste to produce them is also a source of uncertainty, as it will generally result in more minerals and less protein.

New ingredients for fishmeal include micro-algae, insect-based feeds, and plant-based feeds. Micro-algae are considered an environmentally sustainable alternative as they can be cultivated on a large scale and are not typically products destined for human consumption ( (Perez-Velazquez et al., 2018[116]; Henry et al., 2015[117]). Plant-based feeds include yeast-fermented rapeseed meal, soya, cereal grains, and so on. Results have been encouraging with respect to the proportions of fish meal replaced by plant-based inputs (Dossou et al., 2018[118]; Torrecillas et al., 2017[119]; Davidson et al., 2016[86]).

Similarly, much research has gone into the replacement of fish oil, not least because global fish oil supplies will not be able to satisfy the growing future demand for fish oil in aquafeeds, especially for carnivorous fish, and new alternative lipid sources are required to secure the future expansion of the aquaculture sector (Davidson et al., 2016[86]). Some of the studies indicate the possibility of high to very high replacement rates through vegetable oils (e.g. soybean, linseed, rapeseed, olive oil, palm oil, and so on) and algal-based oils across a wide range of fish and crustaceans, e.g. European seabass, red seabream, Atlantic salmon, red drum, rainbow trout and shrimp. For reviews of recent studies, see for example (Yıldız et al., 2018[120]; Torrecillas et al., 2017[119]; Shepherd, Monroig and Tocher, 2017[115]).

The effects on the composition of fish nutrition that the increasing replacement of marine products can bring about is illustrated very clearly in the farming of Norwegian salmon where between 1990 and 2013 the proportion of total marine sourced inputs fell from almost 90% to less than 30% (Figure 2.4).

Figure 2.4. Nutrient sources in Norwegian salmon farming feed resources from 1990 to 2013

Each ingredient type is shown as its percentage of the total diet.

Source: Ytrestøyl, Aas and Åsgård (2015[121]), Utilisation of feed resources in production of Atlantic salmon (Salmo salar) in Norway, https://doi.org/10.1016/J.AQUACULTURE.2015.06.023.

In environmental terms, a downside has been that the fishmeal-free diet has been found to generate greater quantities of fish waste, notably total phosphorous and total suspended solids, as well as affecting oxygen demand in the water, although the poorer water quality did not negatively impact fish performance (Shepherd, Monroig and Tocher, 2017[115]). However, this is a matter that can be addressed inter alia by waste treatment technology (see following subsection).

On the economic front, the growing demand for fishmeal and fish oil replacements is translating into growing demand for alternative aquafeeds and supplements. The industry estimates the value of the global aquafeed market in 2017 at well over USD 100 billion and projects that figure to reach over USD 172 billion by 2022. That is equivalent to a compound average growth rate of around 10% (Research and Markets, 2017[122]).

2.4.3. Concluding observations

If a large part of the many innovations described in this case study were to come on stream in the years ahead – especially those achieving a reduction in the environmental footprint of seafood farming – then marine aquaculture production could expand at more rapid rates than those generally projected. Since growth in the value of aquaculture production has been outstripping volume growth for some years now, the economic returns on innovations that help loosen the aforementioned constraints on output expansion could be substantial. Indeed, it could mean that gross value added of the global marine aquaculture sector could grow at well over 5% per year, trebling the sector’s value between 2011 and 2030 to around USD 11 billion (OECD, 2016[11]). Moreover, recent research indicates that there could in addition be positive knock-on effects further down the value chain. Input-output analysis for Ireland by Grealis et al. (2017[136]) suggests that expansion of aquaculture output could generate revenue and employment gains for both the aquaculture and seafood processing sectors on a significant scale.

2.5.1. The economic and environmental issues at stake

Decommissioning of offshore oil and gas structures is a rapidly expanding industry with strong growth prospects. There are currently over 8 000 offshore oil and gas platforms in use around the world (OFS Research/Westwood Global Energy Group, 2018[137]), the vast bulk of them in the Gulf of Mexico and Western Europe .Close to 1 400 platforms operate in South East Asia and some 1 800 in the Asia Pacific region (Jagerroos and R Krause, 2016[138]).

Although several thousand platforms have already been decommissioned over the last few decades, principally in the Gulf of Mexico, the decommissioning industry is considered to be still very much in its infancy. The oil and gas industry currently decommissions around 120 structures annually (International Energy Agency, 2018[139]), the bulk of them in North America. This is set to continue apace over the coming years. It is estimated that more than 600 structures will be decommissioned over the 2016-20 period, and a further 2 000 more between 2021 and 2040 (Cimino, 2017[140]; IHS Markit, 2016[141]). These estimates are broadly in line with those recently published by the IEA (2018[139]), namely between 2 500 and 3 000 offshore projects by 2040. While to date the bulk of decommissioning has occurred in North America, the next 25 years will see a much wider geographical spread of such activities, including Central and South America, Europe, Africa, Middle East, Eurasia and the Asian Pacific.

Moreover, it is mainly steel platforms in shallow water that have been decommissioned so far. In the coming years, however, many more deep-water installations and subsea tie backs (connecting subsea equipment on the seabed to the floating vessel or platform via risers) will be coming to the end of their service life. Such installations are more complex to decommission, signifying a steep increase in the engineering, financial and environmental challenges involved. As time goes on, decommissioning of wind turbines will add to the list of structures requiring removal as they reach the end of their life expectancy of 20-30 years (Smyth et al., 2015[142]).

Technically speaking, a range of options is available for decommissioning offshore rigs which range from complete removal from the site to partial removal to conversion into an artificial reef (Table 2.4).

The status quo approach to decommissioning prescribed in many countries is complete removal of the platform. That generally entails a series of steps by the oil and gas company to safely remove the structures: shutting down production, securely plugging and abandoning the subsea wells below the mudline, cleaning and removing all production and pipeline risers, removing the platform from its foundation, disposing of the platform on land in a scrapyard or fabrication yard, and ensuring that no debris remain that could potentially obstruct other users of the site location. This makes decommissioning an expensive business. The lion’s share of the expenses is often consumed by the plug and abandonment of the well, usually requiring a cement plug fitted by dedicated rig. Also very costly are the topside and substructure removal, transport and onshore deconstruction. Some cost savings may of course be achieved through the sale of the scrapped steel, whereby subsea materials in particular can prove to have high scrap value. There is also a growing interest in the circular economy, potentially making other cases of re-use more attractive, which should be taken into account when considering decommissioning. Estimates put the total decommissioning expenditure in Western Europe to 2040 at around USD 102 billion (Westwood Global Energy Group, 2018[144]), USD 100 billion in the Asia-Pacific region (Slav, 2018[145]), and around USD 40 billion for Australia (Khan, 2018, whereby a substantial proportion of the cost is likely to be borne by the public through tax concessions (Osmundsen and Tveterås, 2003[146]).

The environmental dimension of decommissioning is highly controversial, with decommissioning practice varying considerably across the globe. In regions where decommissioning is performed within a regulatory framework, the regulations often dictate that platforms should not be left standing and have to be removed. In some of these regions there is also a general public opinion, that the industry has a duty to restore, to the greatest extent, the environment to its original state. In other regions, however, there is a policy to encourage platforms to be left in place where appropriate (e.g. United States); in others (e.g. OSPAR) derogations are possible but are the exception. In yet others (e.g. Indonesia) no regulatory framework exists.

To a large extent, such differences are due to diverging views on the environmental impacts of partial or complete removal of structures. Indeed, the decision on how to decommission often entails difficult trade-offs. Partial removal of platforms which leaves substructures in place can for example lead to chemical contamination of the natural ecosystem or, in the case of intertidal offshore structures, favour conditions for the spread of invasive species. Complete removal, on the other hand, may result in contamination spreading beyond the site, threats to endangered species, destruction of benthic habitats and disruption of food webs.

At global level, little change to regulatory regimes appears to be on the horizon, with some notable exceptions (see further below). However, at expert level opinion may be shifting. The authors of a recent worldwide survey of experts by the Ecological Society of America (Fowler et al., 2018[147]) suggest that their findings support a growing global concern about the risks of infrastructure removal to the environment and marine ecosystems. While participating experts identified negative impacts for both partial and complete removal options, many considered the mass removal of infrastructure to be a potential source of new large-scale disturbance, and called for decommissioning options to be evaluated against a wider range of environmental issues, including biodiversity enhancement and provision of reef habitat, and protection from trawling.

In the final analysis, however, every case of decommissioning is governed by its own geophysical, financial, regulatory, technical and environmental specificities.

2.5.2. Converting oil and gas platforms into artificial reefs

Much as a result of the growing awareness of environmental impacts, but also of the possibilities opening up for ecosystem restoration, interest has been growing in recent years in converting redundant oil and gas platforms into artificial reefs.

Artificial reefs as such have been employed for centuries. A more recent phenomenon however is the design and implementation of plans and programmes to permit and indeed encourage the conversion of offshore structures into artificial reefs, known as rig-to-reef projects. A few such projects have been initiated in for example Thailand, Malaysia and Brunei. But it is in the United States that they are most firmly established, especially in the Gulf of Mexico (Figure 2.5). Indeed, the United States hosts the largest rigs-to-reefs project in the world, namely the Louisiana Artificial Reef Program. Responsibility for decommissioning offshore platforms lies with the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEM), in consultation with state authorities and several federal agencies including the Environmental Protection Agency, NOAA, the Army Corps of Engineers, Fisheries, and the Coast Guard.

Figure 2.5. How the Rigs-to-Reefs Programme works in the United States

Source: Grasso (2017[148]) Rigs-to-Reefs Program, presentation at the OECD Workshop on Innovation for a Sustainable Ocean Economy, October 10-11, 2017, Naples, Italy.

Not all platforms are suitable for conversion. Eligibility for transformation is subject to engineering standards, and numerous criteria play into the decision making process, including the size, structural integrity and location of the platform. In general, the preferred candidates for reefing are complex, stable and clean structures (BSEE, 2015[149]). By 2016, a total of 516 platforms had been converted into reefs, equivalent to around 11% of all platforms decommissioned in the Gulf of Mexico since 1987 (Grasso, 2017[148]).

United States practice offers insights into how savings and economic benefits come into play in the conversion process. For the oil and gas company, the economic incentive consists in the difference between complete removal of the platform and only partial removal for the purposes of reef conversion. The monetary benefit for the environment is that around half of that saving by the oil and gas company goes to the government’s artificial reef programme to support the creation of the reef.

2.5.3. From offshore wind platforms to reefs

There is also potential for transforming fixed-bottom offshore wind platforms into artificial reefs. As pointed out previously, the offshore wind industry has witnessed spectacular growth over the last couple of decades, from almost nothing to a total capacity of 14 GW in 2016. Growth in the medium-term future is also well on track, with total global capacity expected to triple to well over 40 GW by 2022. The longer-term prospects suggest a further tripling of capacity to around 120 GW by 2030, the vast majority of which will be fixed-bottom installations (GWEC Global Wind Energy Council, 2017[66]).

Offshore wind installations have an expected service life of around 25 years. Those that started operating in the early years of the 21st century are expected to be decommissioned in the course of the 2020s. However, it will be a number of years still before decommissioning will be required on a major scale. When, and how many, will depend on a variety of factors, including the advent of new technologies, the identification of more suitable sites, and the cost of equipment upgrades, all of which may render many existing installations uneconomical sooner rather than later (International Energy Agency, 2018[139]).

In light of those prospects, and reflecting the largely positive experience of North American conversion of oil and gas installations into artificial reefs, attention is now turning to the potential for converting also offshore wind platforms into artificial reefs. For legal, financial and environmental reasons, decommissioning requirements are usually an integral part of licensing and consent for all marine developments, and offshore wind is no exception – the options for offshore wind structures being either full removal, or partial removal leaving some elements in place. While the overall structure of offshore wind platforms is different from that of offshore oil and gas rigs, it is thought that the general principles of conversion into artificial reefs apply, including the potential benefits to ecosystem conservation and development, fisheries and recreational activities. A major difference does pertain, however, insofar as oil and gas rigs may be installed in deep water, thereby presenting fewer navigational risks than wind farms located in shallow waters. But it can be argued that such risks may be outweighed not only by the ecosystem benefits attached to partial removal, but also by the lower energy and labour costs as well as reduced safety risks compared to full removal (Smyth et al., 2015[142]).

Similar to rigs-to-reefs, there are issues around the net benefits of offshore wind platform conversion that would accrue to the ecosystem in terms of new marine life production. To date, very few wind farms have been decommissioned, and so evidence is limited. However, numerous studies indicate increased species abundance around offshore wind foundations, and they are typically associated with positive effects for the local ecosystem; see for example (Bergström et al., 2014[162]). Using improved data and advanced modelling techniques, some scientists have recently begun to link the projected expansion of offshore wind farms with future impacts on certain marine species. Slavik et al (2018[163]), for example, anticipate that on completion of all planned offshore wind installations in the southern North Sea, the overall abundance of the blue mussel will have increased by more than 40%, providing an additional food source (also for some crustaceans), and benefitting ecosystem functioning thanks to their filtering of phytoplankton. Examining offshore wind projects for the Bay of Seine (English Channel) ecosystem, Raoux et al. (2017[164])) projected the potential impacts of benthos and fish aggregation resulting from the installation of the concrete piles and the turbine scour protections. Their results suggest an increase in total ecosystem activity as well as in some fish species, marine mammals and seabirds as a reaction to the biomass aggregation around the infrastructures.

What is clear already at this early stage is that the long-term effects of offshore wind farms on local marine ecosystems as well as on ecosystems further afield are still unknown. If the environmental and economic potential of decommissioned offshore wind farms as artificial reefs is to be fully captured, much more scientific evidence will need to be gathered and evaluated.

2.5.4. Concluding observations

Experience to date, gathered primarily in the Gulf of Mexico and the Pacific since 1987, suggests that only a fraction (around 10%) of oil and gas rigs is suitable for conversion to artificial reefs. Nonetheless, in light of the thousands of rigs to be decommissioned in the coming decades around the world, the number of potential future conversions is significant. Yet, while the United States has accumulated some 30 years of experience with rig-to-reef conversions, most other areas of the globe have been slow to follow, not least because rig-to-reef conversion is not easily transferable from one region to another. Indeed, suitability of rig-to-reef conversion is highly site-specific. Moreover, in many cases, the concern has prevailed that leaving part of the rig infrastructure in place risks serious pollution of the marine environment and that complete removal of the infrastructure should be required; in many other cases, no regulatory framework even exists and needs to be developed. However, the decommissioning issue is increasingly controversial. Support among marine scientists and conservationists is growing in favour of the view that in some instances, complete removal of the platform may cause more harm to the marine ecosystem than leaving the lower structure in place, and that, unless serious pollution risks exist or maritime traffic safety is threatened, some consideration should be given to partial removal.

The economic effects of only partial removal tend to be significant and immediate. The oil and gas companies (and, in the longer term future, offshore wind operators) stand to make significant savings from the reduced decommissioning operation. Governments do however have the option – as they do in the United States, for example – of requiring the companies to pay a specified share of those savings into a fund for reef conversion. (It should be noted however that governments may still be open to criticism from conservationist quarters for allowing oil and gas companies to gain financially from such a reduction in clean-up effort.) There are also likely to be positive effects for the marine environment resulting from less disturbance of the seabed and the water column, which can translate into improved stocks of fish, molluscs and so on.

A potentially positive long-term economic contribution may also be associated with the decision to convert to artificial reefs. Healthy artificial-reef ecosystems can make for more productive commercial fisheries, attract tourism, diving, and recreational fishing, while the decommissioned structure itself may come to serve multiple alternative purposes in support, for example, of aquaculture facilities or marine renewable energy (OECD, 2016[11]). It should be noted though that benefits to the fisheries may depend upon the type of fisheries undertaken (Multiconsult, 2011[165]). Moreover, there are potential positive spill-overs for other sectors. For example, specialised engineering companies stand to profit from the business generated by the creation of the artificial reefs; see for example Smyth et al (2015[142]), on subsea eco-engineering, and Offshore Digital Magazine (2017[166]), on emerging rigs-to-reefs business partnerships. And even insurance and re-insurance companies look set to engage in the business of ecosystem resilience and restoration (Leber, 2018[167]).

In addition, the growing volume of scientific assessment, inspection and monitoring involved in the decision-making and implementation of rig and (eventually) wind turbine conversions promises to offer considerable opportunities for the owners and operators of AUVs, ROVs and other subsea vehicles. The sector, while still small, is currently expanding rapidly. The latest world AUV forecast (Westwood Global Energy Group, 2018[44]) for example, sees total global demand increasing by almost 40% between 2018 and 2022. Demand growth in the research sector is still modest, but is nonetheless expected to see its share of total demand reach 25% by 2022. Commercial demand should see the fastest growth rates, expanding by 74% over the next five years.

Rigs-to-reef programmes and renewables-to-reef projects are at very different stages of development. Yet both offer long-term potential for synergies between economic gain and ecosystem benefit. Neither will be able to unfold that potential to its full extent unless long-term strategies, appropriate incentives and effective regulatory frameworks are put in place by public authorities working closely with the private sector and the many other stakeholders concerned. Such strategic policy decisions and collective actions, however, need to be founded on the best possible scientific evidence with respect both to the environmental issues surrounding the debate of partial versus complete removal of infrastructures, and to the question of the successful creation and long-term viability of artificial reefs. As this case study has endeavoured to show, much work is still required from the scientific community to deliver that evidence.