The Earth’s surface is mostly covered by salt water, and humanity has had to adapt to this environment to move around the world, explore, trade, exchange, and develop into the society we are today. Maritime transport of people and goods has evolved over centuries, with a key shift toward building larger, more durable ships that can travel quickly and energy-efficiently. Shipbuilding and repair has been—and remains—a vital sector in the economy, with its next evolutionary step being the implementation of technologies that enable digitalization, optimization, and decarbonization.

Currently, shipyards are large energy consumers, with nearly all of their demand in the form of electricity, while fossil fuels are used for material and personnel transport or for generating hot water in buildings. This electricity consumption presents several challenges:

• Shipyards operate intermittently, depending on the stage of ship construction, making it very difficult to characterize daily or monthly consumption curves.
• Energy use varies depending on the type of shipyard, mainly between those focused on construction and those on repairs.
  Most shipyards do not monitor their energy use or know their main energy drivers, making it unfeasible to implement and validate energy-saving or decarbonization strategies.
• The shipbuilding process involves many subcontracted companies working at the shipyard’s facilities. However, their electricity, compressed air, and welding gas consumption is usually unknown and not considered in their contracts.
• Shipyards have extensive lists of machines and energy-consuming equipment, whose usage varies depending on the ship type or repair job. Many machines sit idle for months but may be used intensively at times. A clear example is cranes, which have the highest installed power but are used sporadically.

The TECNAVAL project, part of the PERTE NAVAL program and led by SOERMAR, allowed AIGUASOL to apply its expertise at five shipyards located in Vigo, Huelva, Ceuta, and Gran Canaria, promoting their transformation into more competitive models from both an energy and environmental standpoint. The project’s main goals and tasks were:

• Assessing the feasibility of implementing an advanced energy management and optimization system with AI support.
• Conducting energy audits to define the potential for reducing energy use and emissions.
• Designing a monitoring plan with meters and actuators in the shipyard’s microgrid, identifying strategic energy consumers.
• Evaluating the viability of an energy billing module to monitor subcontractors’ consumption.
• Running energy simulations to assess investment feasibility in energy efficiency and renewable generation technologies.

Methodology and findings

The methodology involved direct communication with the five shipyards, validating progress through interviews, using energy simulation tools like Design Builder and SAM, and applying proprietary hourly consumption analysis tools developed in Python. After a year-long study, the results were grouped into three main areas:

Energy inventory and audits

Hourly consumption and machinery use were analyzed, identifying the compressed air systems powered by compressors and welding operations as the top energy consumers—accounting for 30% to 55% of annual electricity use. Ship construction progresses in stages: shaping steel sheets through bending, heating, and cutting; assembling hull and interior parts; and joining these into larger blocks to form the complete ship. Interior work may be done on land or afloat. Surface blasting and painting are critical for protection from the sea’s harsh conditions. The whole process requires metalwork and welding, and both painting and stripping demand large volumes of compressed air. Secondary uses include domestic hot water (DHW), climate control, lighting, cranes, and various workshop machinery.

Energy reduction and decarbonization strategies

Solutions were proposed in three stages: electrification of diesel-driven demands, efficiency improvements, and renewable energy use. Notable measures include:

• Electrifying transport fleets, forklifts, and lifts: Local emissions minimized, and energy use cut by 70%.
• Electrifying and centralizing climate control and DHW using high-efficiency heat pumps: Annual electricity savings of 4–15% depending on climate and DHW usage.
• Transformer use optimization: Up to 18% reduction in electricity consumption.
• Switchgear sectorization and automation: Electricity savings between 4% and 17%.
• Installing variable frequency drives and reducing air leaks: Savings between 6% and 14%.
  Solar PV and wind turbine installation: Covers 20–60% of electricity use depending on available space.
• Power optimization and reactive compensation: Cost savings of up to 13%. 

Monitoring System

A monitoring system with meters and actuators for energy consumers has been designed based on three key criteria. The first is to understand the operation of the main energy consumers; the second is to monitor processes where key energy-saving measures have been identified, requiring consumption data to assess their feasibility; and the third is to monitor equipment related to the use of renewable resources.

Shipyards are large facilities located by the sea, with most of their area outdoors. Therefore, the use of the LoRaWAN communication system has been proposed, which allows small data packets to be transmitted via low-frequency radio waves. This enables sensors and meters to send their data remotely over long distances, even through walls and other obstacles in the shipyard, while consuming minimal energy.

Participation in Flexibility Markets

Spain’s national grid “Red Eléctrica” offers incentives to entities capable of flexibly adjusting their electricity consumption upon request, helping to relieve congestion in network nodes. These mechanisms have been introduced in recent years in response to the increasing electrification of demand and the integration of renewable energy sources into the grid.

The potential opportunity this represents for shipyards has been studied, analyzing their ability to shift peak hourly demand, the available thermal and electrical storage, and their high potential to incorporate renewable systems. Electricity generation using photovoltaic (PV) technology and batteries has proven to be a highly impactful strategy for reducing emissions, improving the energy sovereignty of shipyards, and lowering costs by enabling participation in electricity trading markets.

The study evaluated the potential for shipyards to participate in flexibility markets using simulations based on real consumption profiles, photovoltaic generation, and hourly market prices. It analyzed 100 different combinations of PV power, battery capacity, and demand response strategies, including scenarios with varying levels of energy inflation and peak-to-off-peak price spreads.

The results show greater benefits for larger shipyards, allowing for a better investment-return ratio, increased energy independence, and a significant reduction in the Levelized Cost of Energy (LCOE). Batteries allow for energy arbitrage, discharging during high-price periods and maximizing revenues when surplus electricity is sold. While battery storage strategies are favorable in environments with high inflation and moderate price spreads, flexible demand response strategies perform better in contexts with both high inflation and large price spreads, where the value of shifting consumption is higher.

Participation in the Active Demand Response Service (SRAD) could generate additional, though more limited, income due to both the limited real capacity to modulate loads hourly and current regulatory constraints that hinder effective participation by industrial consumers. For these strategies to become established and scale up, regulatory evolution is key—something that has already begun with the creation of new figures such as the independent aggregator and services like SRAD.

This study lays the foundation for the development of a future R&D project in which, through the integration of the proposed monitoring system, a detailed analysis of decarbonization measures and participation in demand flexibility markets can be carried out using AI-based analytical tools, supporting both large and small shipbuilders in the ongoing evolution of one of the oldest and most essential trades in our society.

Moreover, the study opens the door to exploring new solutions that can lead to the complete decarbonization of shipyards. Renewable generation potential could be enhanced through the creation of energy communities among port companies, which could jointly consume solar energy by taking advantage of the extensive rooftop areas and the synergies between their different consumption curves.

In light of the growing need for storage strategies beyond conventional batteries, the large, high-power cranes found in shipyards—used only sporadically—present an opportunity to store electricity as potential energy, to be released during demand peaks or network congestion. Likewise, using alternative marine fuels such as methanol or hydrogen offers shipyards the chance to become producers of these fuels or use reversible hydrogen fuel cells to store PV surpluses and sell a portion of the generated hydrogen.

Finally, the increasing droughts in southern Europe, especially critical in islands and coastal areas, pose a challenge in supplying freshwater to shipyards and port zones. This creates an opportunity to integrate desalination systems, which can flexibly adapt their electricity use to solar or wind generation curves and provide the required freshwater while storing renewable energy surpluses.