Author: refest

REFEST has reached Milestone 6 with the validation of a 20% reduction of energy losses through electrification after retrofit. This achievement was led by ELKON, contributing to the project’s work on battery packs, photovoltaic panels and electrical power management.

The milestone focuses on the development and validation of Power Management System and Energy Management System solutions, which play a key role in improving the energy performance of retrofitted fishing vessels.

Through electrification, REFEST aims to optimise the way energy is generated, stored, distributed and consumed on board. The PMS and EMS support the integration of different energy-saving technologies, including batteries, flexible PV panels and hybrid propulsion systems, helping vessels operate more efficiently and with lower energy losses.

This achievement is particularly relevant for traditional fishing fleets, where reducing energy losses can directly contribute to lower fuel consumption, reduced greenhouse gas emissions and improved operational efficiency.

The work led by ELKON provides an important basis for the next phases of REFEST, supporting the integration of electrical and energy management solutions into the demonstration vessels and contributing to the overall validation of the project’s retrofit approach.

REFEST was presented during the technical event “Lightweight Materials for Electromagnetic Signature Reduction”, organised by AIMPLAS in collaboration with Fundación Círculo. The event took place on 24 September 2025, from 9:30 to 16:30, at AIMPLAS facilities in Valencia, Spain.

During the event, AIMPLAS representatives showcased REFEST as a relevant example of an EU-funded project working on innovative solutions to support the transition towards more sustainable and energy-efficient mobility and transport systems. The project was presented in relation to its contribution to reducing fuel consumption and greenhouse gas emissions in the fisheries sector, while highlighting the role of advanced technologies and materials in enabling low-carbon transformation.

REFEST’s participation in the AIMPLAS technical event represented a valuable opportunity to increase the project’s visibility among industrial and research stakeholders, promote knowledge exchange on innovative materials and sustainable technologies, and strengthen connections with sectors working towards cleaner and more efficient mobility solutions.

REFEST has reached an important technical milestone with the experimental and computational study of the selected hull appendage configurations. This achievement was led by Klaipeda University, contributing to the project’s work on improving the hydrodynamic performance of traditional fishing vessels.

The milestone confirms that the selected configurations have been analysed through both experimental testing and computational studies, with the objective of reducing vessel resistance in water and limiting underwater noise.

The results show that the studied hull appendage solutions can contribute to at least an 11% reduction in hydrodynamic resistance and a reduction of underwater noise of at least 5 dB. These improvements are highly relevant for REFEST, as reducing resistance means that vessels can operate more efficiently, with lower energy demand and reduced fuel consumption.

This achievement supports the wider REFEST objective of developing easy-to-deploy retrofit solutions for existing fishing vessels. By improving hull efficiency, the project contributes to reducing greenhouse gas emissions while also addressing environmental pressures linked to underwater noise.

The work carried out by Klaipeda University provides an important technical basis for the next phases of the project, supporting the integration and validation of the proposed retrofit solutions on demonstration vessels operating in the Baltic and North Sea regions.

By achieving this milestone, REFEST moves one step closer to demonstrating practical and scalable solutions for cleaner, quieter and more efficient fishing fleets.

The European Union has committed €116 million to support 13 projects focused on restoring oceans and waterways across Europe. These initiatives aim to preserve offshore marine protected areas, protect migratory fish habitats in the Danube, reduce the environmental impact of fishing on marine species, and strengthen citizen science in the marine sector.

These investments highlight Europe’s growing commitment to sustainable oceans and waterways, showcasing innovative approaches to marine conservation and ecosystem restoration. REFEST shares these ambitions, aiming to promote sustainable solutions and innovative technologies to protect and restore aquatic ecosystems.

Cover image by Aleksandar Popovski on Unsplash

Sound is a mechanical vibration that propagates as an acoustic wave through a transmission medium such as gas, liquid, or solid. The way sound travels depends on the medium. Water, due to its high elasticity and tightly bonded molecules, is an excellent medium for sound transmission. In fact, sound travels nearly five times faster in seawater (~1500 m/s) than in air (~300 m/s). At low frequencies, underwater sound can travel hundreds of kilometers with little loss in energy—enabling long-distance animal communication, but also potentially resulting in far-field impacts.

Factors influencing underwater sound transmission include the sound frequency, water depth, density stratification (driven by temperature and pressure), seabed morphology, and substrate type. Therefore, underwater sound behavior is complex. The marine underwater “soundscape” consists of biological, geophysical, and anthropogenic sounds occurring at a given place and time.

Among anthropogenic sources, fishing activities contribute significantly to underwater sound: sounds from small, medium, and large vessels; various types of echo sounders and sonars used to locate target species; and pingers used by fishers to mark gear.

• Large commercial vessels (over 100 m) produce loud, predominantly low-frequency sounds (180–195 dB; 10–50 Hz), mainly from propeller cavitation, on-board machinery, and hydrodynamic flow. They dominate the low-frequency soundscape in many marine environments globally.
• Medium-sized vessels (50–100 m), including many fishing boats, generate broadband sound in the 165–180 dB range, mostly below 1 kHz. These vessels often operate in coastal and continental shelf waters, overlapping with marine fauna both spatially and temporally.
• Small vessels (up to 50 m) with inboard or outboard engines emit mid-frequency sounds (1–5 kHz) at source levels of 150–180 dB. Though their acoustic impact is geographically limited, they can dominate soundscapes in bays, harbors, and estuaries. Recreational boats—linked to recreational fisheries—are key contributors to mid-frequency ambient sound in coastal habitats.

Sonars, especially fish-finding sonars (24–200 kHz), are widely used on commercial and recreational vessels and operate year-round in shallow shelf seas. Though lower in source level than military sonars, their widespread use makes them a notable contributor to underwater noise.

Acoustic Harassment Devices (AHDs) such as pingers are used to deter pinniped predation at fish farms and fisheries. With high-intensity signals (≥185 dB) ranging from 2 to 40 kHz, AHDs can significantly elevate local underwater noise levels, especially in areas of intensive aquaculture.

Noise is defined as sound that is loud, unpleasant, or disruptive. All underwater sound comprises sound pressure and particle motion. Marine mammals are primarily sensitive to pressure, but may also respond to particle motion. Fish and invertebrates detect particle motion, and some fish species are sensitive to both components, particularly those with swim bladders functioning as pressure-to-motion converters. Additionally, particle motion can propagate through the seabed, affecting benthic habitats.

Anthropogenic underwater noise is known to cause a variety of direct, indirect, and cumulative impacts on marine species—from no observable effect to behavioral disruption, hearing loss, or even mortality. Effects depend on multiple factors: noise duration, frequency, intensity, overlap with marine organisms, and the context of exposure. Despite scientific and methodological challenges, there is growing evidence that anthropogenic underwater noise can have adverse consequences for marine wildlife, ecosystems, and fisheries-dependent communities.

Cover image by Hiroko Yoshii on Unsplash

Behind REFEST mission: Since the 18th century, when the technological era of steam-driven ships began to replace traditional sailing vessels, the maritime sector has contributed significantly to environmental pollution through engine emissions and oil-based lubricants. This impact intensified in the 20th century with the transition from steam to diesel engines, leading to the continuous accumulation of pollutants in marine ecosystems.

Although emission control technologies began to emerge in the 19th century, their widespread implementation only started towards the end of the 20th century, following the adoption of the International Convention for the Prevention of Pollution from Ships (MARPOL) by the International Maritime Organization (IMO). Since then, various clean shipping technologies have been introduced to reduce emissions, limit the use of harmful oil-based products, and prevent the release of other pollutants into the environment.

From an engineering perspective, older engines typically exhibit lower thermal efficiency and are more prone to wear and tear. This degradation not only reduces performance but also increases fuel consumption, resulting in higher CO₂ emissions per unit of energy produced.

Over the years, significant advancements have been made in engine technology. Innovations such as electronic – and later digital – control of fuel injection and valve timing, along with improvements in turbocharging, have significantly enhanced efficiency. For example, modern common rail systems with multi-phase injection enable more efficient combustion and reduce the formation of harmful by-products such as carbon monoxide (CO), volatile organic compounds (VOCs), and particulate matter.

These technological improvements have been supported by extensive academic research and continuous innovation by engine manufacturers, who must also comply with increasingly strict environmental regulations, such as those defined by the MARPOL Convention. This rapid development has played a vital role in making marine operations cleaner and more sustainable.

Looking ahead, the transition to low- or zero-carbon fuels represents the next major milestone in the evolution of marine engines, moving away from traditional fuels like diesel and heavy fuel oil.

In line with global trends toward pollution reduction in the maritime sector, the REFEST project aims to develop a modernization strategy and technological solutions for small-scale fishing vessels. These efforts will support the transition to cleaner technologies and help reduce the environmental impact of such vessels.

Cover image by Jean Carlo Emer on Unsplash

REFEST was promoted at Net Zero Tech Barcelona 2025, which took place on 4-5 June 2025 at La Farga Exhibition Centre in L’Hospitalet de Llobregat, Barcelona, Spain.

Organised by Five Continents Exhibitions, the event brought together professionals and companies from the energy sector, public administrations committed to the energy transition, startups and SMEs working on sustainability, researchers and academics in the field of decarbonisation, and investors interested in clean and sustainable technologies.

Net Zero Tech Barcelona 2025 provided a valuable platform to discuss industrial decarbonisation and the energy transition, with a strong focus on energy efficiency, electrification through renewable energy, green hydrogen, biomethane, CO₂ capture and reuse technologies, digitalisation, and other innovative solutions for low-carbon industries.

Representatives from AIMPLAS attended the event on behalf of REFEST, sharing project dissemination materials and engaging with participants interested in learning more about the project. Through brochures and direct exchanges with AIMPLAS colleagues, visitors had the opportunity to discover how REFEST is contributing to the reduction of fuel consumption and greenhouse gas emissions in the fisheries sector.