Following another summer of intense storms and windy days, new records have continued to be set for the unprecedented amount of renewable energy being generated by offshore wind farms. In a timely and extensive blue paper commissioned by the High Level Panel for a Sustainable Ocean Economy, Peter Haugan and Lisa Levin consider to the role of ocean-based renewable energy in the sustainable transformation of the global energy system. Moreover, they build on previous analysis by further exploring the links between ocean-based renewable energy options and to what extent, if any, minerals, and metals found in the deep sea are needed to facilitate this energy transition.
Progress Made, Challenges Ahead
While highlighting the great progress made in offshore wind, which can now offer parity or even beat comparable fossil fuel projects on price, this paper also considers the potential offered by other ocean-based renewable energy sources (or marine renewable energy) including floating solar and ocean energy, which encompasses tidal range, tidal stream, wave, ocean thermal energy conversion (OTEC), current and salinity gradient.
Clearly a rapid transformation of our energy systems is required if we are to achieve the Paris Agreement goals and limit the global average temperature rise to 1.5°C, or even 2°C, above pre-industrial levels. In addition to expanding land-based renewable energy, the ocean offers significant potential for supporting this transition. There are broader benefits, too. In terms of employment opportunities, offshore wind provides more jobs than fossil fuel electricity, while gender balance is generally better in renewable energy jobs than in fossil fuel. Training and re-skilling of the oil and gas workforce is also an attractive opportunity given the relevance of many skills. Jobs will mostly be in coastal areas often away from big cities, some of which may currently suffer from a lack of employment opportunities.
However, new technologies must be implemented in a sustainable way to avoid unintended consequences that could undermine other aspects of ocean health. This paper analyses the underlying tension between the need for rapid decarbonisation, including that required for scaling up ocean-based renewable energy, and the resource and environmental implications related to that metal demand, with particular attention on current proposals to mine the deep seabed.
Indeed, construction of offshore wind turbines requires significant amounts of conventional materials, in particular steel. However, rare earth elements (REEs) are also needed, especially in the construction of the direct-drive permanent magnet generators that are currently preferred. For offshore wind, the authors note that it is the use of REEs in the generators that appears to be the biggest potential challenge when it comes to supply of minerals. Each megawatt (MW) of installed capacity can require 42 kilograms (kg) of neodymium and 3,000 kg of copper.
The trend for newer multi-megawatt wind turbine generators is to use direct-drive systems with permanent magnet generators. Since most other ocean-based renewable energy technologies are still in early phases of development with little deployment, few studies have been completed on what materials will be needed to scale up the use of these technologies. If these technologies have similar metal requirements to modern wind turbines, which is likely, implementation will rapidly increase the demand for many metals, such as lithium, cobalt, copper, silver, zinc, nickel and manganese, and rare earth elements (REEs).
Potential Below the Waves
The authors note that building a sustainable global energy system is intimately linked to both scaling up renewable energy and finding a way to source and use rare minerals in a more sustainable way. The demand for specific metals to serve the global energy transition is highly dependent on their cost. Often, alternatives to specific metals can be found. The industry is continually developing solutions that can use cheaper and more abundant resources avoiding specific costly metals.
However, selected metals and minerals are increasingly difficult to find in large quantities or high grades on land but are present in higher concentrations in some parts of the deep seabed. As such, the deep seabed resource potential has attracted interest in mining for copper, cobalt, nickel, zinc, silver, gold, lithium, REEs and phosphorites. Regulations for the exploitation of seabed minerals and for associated environmental management are currently under development by the ISA.
While a regulatory framework is being developed, questions remain as to whether deep-seabed mining should be heralded as the key to a transition to a sustainable energy sector, based on whether it can be accomplished in a way that appropriately ensures a healthy and resilient ocean.
In addition to the more obvious material benefits, the authors highlight that further benefits – especially in the case of small island developing states with limited land resources and economic options – may include new creating jobs and training opportunities, strengthening the domestic private sector, encouraging foreign investment, funding public service or infrastructure improvements, introducing a new supply of metals, and supporting other economic sectors.
Other benefits may involve technological innovation and the advancement of deep-sea science, with exploration and impact monitoring expanding scientific knowledge that is currently lacking.
However, the complexity of the stakeholder input to decisions about deep-seabed mining cannot be underestimated. The authors note that greater knowledge of the potential environmental impacts and measures to mitigate them to levels acceptable to the global community will be crucial. They conclude that full analysis of the perceived positive and negative impacts is required before there can be confidence that engaging in industrial-scale deep-seabed mining would achieve a global net benefit.
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