Highlights
- Superyacht construction heavily relies on non-renewable resources and materials
- Steel and aluminium production are CO2 and energy-intensive
- Production process of these materials affect soil, water and air quality
- Opportunities for reducing impact include sourcing from suppliers that adopt breakthrough technologies to save resources and emissions, adopting energy systems powered by zero carbon electricity, and shifting to high grade recycled aluminium and steel
Introduction
The leisure boating industry is a cornerstone of the blue economy, generating €28 billion in revenue annually and supporting around 234,000 jobs[1]. With 36 million individuals owning or chartering leisure boats including superyachts in Europe alone [2], the industry’s thriving growth is paralleled by a growing responsibility to reduce its environmental impact.
While much of the focus is on the environmental impact during a yacht’s operational life, it’s essential to consider the entire lifecycle, including construction and end-of-life phases. This is why Water Revolution Foundation adopts a holistic approach that encompasses the entire lifecycle of yachts and its onboard components, to help understand and manage environmental risks or identify opportunities associated with environmental impact reduction within the superyacht industry.
Focusing on the construction phase, superyachts require large volumes of non-renewable materials like steel, aluminium, composites and synthetics, each with a substantial environmental footprint from production to end-of-life. Despite the yachting industry’s efforts to integrate eco-friendlier materials, the sheer size and complexity of superyachts make this transition challenging.
Steel and aluminium, in particular, have considerable environmental impacts due to their hazardous emissions and high energy consumption during production and construction. Given their dominance in the build phase of large yachts, this article explores the environmental implications of using these materials and identifies opportunities for reducing their impacts.
Steel
The iron and steel industry has revolutionized transportation and infrastructure, enabling the development of railways, bridges, roads and automobiles. Steel, a crucial material in yacht construction, is primarily produced from iron ore extracted from earth’s crust. Iron, despite being an abundant resource, is non-renewable and requires extraction, concentration, and processing to create usable steel.
Due to its mechanical strength and corrosion resistance when alloyed with certain elements, shipyards use steel for various parts of a yacht, such as the hull and superstructure. However, the activities involved with steel processing generate considerable environmental risks, including emissions and the deposition of pollutants and toxic waste.
Steel manufacturing consumes large quantities of water for processing and cooling purposes, releasing contaminated wastewater containing an array of contaminants, particularly trace metals such as Mn, Zn, Br, Sr, Cu, Pb, etc[3]. Particles from the blast furnace also release trace element of heavy metals via atmospheric process and particle emissions[4]. Aside that, the extraction and processing stages of steel production releases CO, SOx, NOx and Particulate Matter (PM2).
Although improvements have been made to reduce trace metals from waste products using physicochemical and biological treatment techniques[3], the technology’s efficiency is limited, allowing volatile trace metals to enter the environment. These trace particles can affect the quality of soil used by residents for recreational or agricultural purposes[5] and pose public health risks. In fact, many studies have corroborated heavy metal contamination in soils near steelmaking sites in agricultural lands; see example [6] [7].
According to the World Steel Association, the steel industry consumes 5.9% of global energy and emits 7-9% of global CO2 emissions, doubling the carbon output of the entire African continent (4% global emissions). The EU alone is responsible for 4.7% of the total emissions, amounting to 182 million tons of CO2 [8].
Aluminium
After steel, aluminium is the second most highly produced metal. In yacht manufacturing, aluminium is widely utilised for its lightweight properties, especially in hull construction. This allows for lighter vessels that enhance fuel efficiency, speed, and increased range of navigation in shallow waters. Aluminium also boasts natural corrosion resistance, reducing the need for extensive anti-corrosion measures and maintenance costs over the vessel’s lifespan. These advantages establish aluminium as a critical material in yacht construction.
However, like steel, aluminium production is highly CO2 and energy-intensive, albeit to a slightly lesser extent. The aluminium industry produces 0.42-0.5 Gt of CO2 equivalent emissions per year, translating to 2.5% of global CO2 emissions[10]. The industry also accounts for 1% of anthropogenic greenhouse gas emissions [11].
The production of aluminium involves various processes and materials, including bauxite and alumina extraction, along with the production of chemicals like calcined lime, cathode carbon, aluminium fluoride, pitch, and petrol coke. These activities collectively contribute to several adverse environmental impacts.
One major concern is acidification potential (AP), which measures the acidifying effects of nitrogen oxide (NOx), sulfur dioxide (SO2), and ammonia (NH3) on the environment. These emissions originate from various stages of aluminium production, including electrolysis, refining, casting, and mining. Acidification harms aquatic and terrestrial ecosystems, affecting marine species, plant growth, and human food supplies.
Emissions from aluminium production also contribute to eutrophication, leading to excessive levels of nitrogen and phosphorous in water bodies. These nutrients promote rapid growth of aquatic plants, particularly algae, which depletes oxygen levels, harms aquatic species, and diminishes water quality.
Another significant impact is water scarcity, as large amounts of freshwater are consumed for the mining, refining, smelting, and cooling processes in primary aluminium production. The energy-intensive refining processes further deplete fossil energy resources.
Opportunities for Improvement
The environmental impact of steel and aluminium presents significant sustainability challenges across various industries, superyachting included. Yacht manufacturing’s resource-intensive nature, coupled with the non-renewable origins of these materials, underscores the urgency to improve its practices.
The superyacht industry can significantly reduce impacts by using steel produced with advanced technologies like Electric Arc Furnaces (EAF) and Induction Furnaces (IF). EAF technology melts recycled scrap steel using electrical energy, which can come from renewable sources, thus lowering CO2 emissions from energy use and the need for new steel production from raw materials. Utilising green hydrogen and renewable energy sources in EAF process have proven to emit less than 600kg of CO2eq per ton of crude steel [12] [13]. This process is highly efficient and flexible, making it ideal for sustainable steel production. Similarly, IF technology is also extremely energy-efficient as it does not rely on fossil fuel and produces fewer emissions. It uses electromagnetic induction to heat and melt clean scrap steel, resulting in high-quality steel with minimal impurities. By sourcing steel made with these breakthrough technologies and energy systems powered by zero carbon electricity, shipyards can cut down their environmental footprint. Central to this would be integrating sustainability criteria in the selection process. Shipyards should prioritise suppliers who demonstrate a commitment to environmentally friendlier production methods.
According to the International Chamber of Shipping (ICS), it is claimed that 90% of all steel in the world is transported by ship. Geographical location and transportation logistics are critical factors contributing over 50% of total carbon emissions in construction projects [15]. Shipyards should thus look into sourcing from local steel producers or ensure that producers farther use alternative fuels when transporting their steel to shipyards.
To address the environmental impact of aluminium production, shipyards have several opportunities. They can take advantage of circular economy principles to ensure that aluminium materials are recycled and reused efficiently. However, upgrading recycling methods for aluminium that would allow recycled ingots to be used for high-purity wrought materials would be vital to decreasing emissions and promote a sophisticated resource-recycling industry. This may require shipyards to establish partnerships with recycling facilities and research institutes on such methods. This would also require that yacht designers and builders work together to encourage design and build for recycling, where yachts are designed with easier disassembly and recyclability in mind. Designing products that use fewer alloys or coatings can simplify the recycling process and increase the yield of high-quality recycled aluminium. The industry should also promote the economic and environmental advantage of using recycled aluminium over primary aluminium. Furthermore, when sourcing for primary aluminium, shipyards should procure from suppliers that have transitioned to low-emission power sources such as green hydrogen in their production and adopted breakthrough technology that significantly reduces the environmental footprint. As an example, the use of innovative methods like application of pure argon gas with AI control system in the melt processing of aluminium greatly reduces harmful substances like chorine and fluorine, leading to decreased pollution and perfluoro carbons [16] .
Shipyards can also leverage certifications and standard compliance grounded in the Life Cycle Approach (LCA) as mechanisms to ensure the most sustainably produced materials are used. It is crucial that shipyards integrate in their material selection process environmentally-friendlier production methods, so that suppliers who are committed to these sustainable practices are prioritised.
While steel and aluminium offer durability and performance advantages, their production processes contribute to pollution, resource depletion, and greenhouse gas emissions. Implementing measures to increase the use of recycled materials and adopt energy-efficient technologies are thus essential steps to reducing the industry’s environmental footprint.