Fluid Power: Paving the way for renewables

Published:  13 November, 2024

OEE explores the key issue of how fluid power systems can evolve to support the renewable energy transition while addressing the technical challenges involved

As the global push for sustainable energy intensifies, industries are grappling with how to adapt traditional technologies to meet environmental goals. One such challenge lies in the integration of fluid power systems – encompassing both hydraulic and pneumatic technologies – with renewable energy sources. Fluid power systems are indispensable in industries like construction, manufacturing, aerospace, and agriculture, providing precise control and high-power density in essential machinery. However, their historical reliance on conventional energy sources, including fossil fuels, raises concerns about their long-term sustainability.

Fluid power systems, especially hydraulics, are fundamental in many industrial operations due to their ability to transmit large amounts of power through relatively small components. Hydraulic systems are commonly found in heavy-duty machinery, such as industrial presses, cranes, and mobile construction equipment. Yet, these systems are often powered by diesel engines or electricity from non-renewable sources. While many stationary hydraulic systems already operate on electricity, and in some regions this electricity is sourced from renewables, the integration of renewable energy into mobile and off-grid hydraulic applications remains a key challenge.

The challenge of powering fluid systems with renewables

The main obstacle in transitioning fluid power systems to renewable energy is the inconsistency of renewable energy generation. Wind turbines only produce electricity when the wind is blowing, and solar panels generate power only during daylight hours. On the other hand, fluid power systems—particularly in industrial and mobile applications—often require a continuous and reliable energy supply. This mismatch between the variable nature of renewable energy and the constant power demand of fluid power systems presents a significant hurdle.

Energy storage solutions are critical to bridging this gap. Technologies such as batteries, flywheels, and hydraulic accumulators are being developed and refined to store excess renewable energy when it is available and release it during periods of low generation. Batteries, in particular, are becoming increasingly important in renewable energy systems, but their cost, limited lifespan, and the challenges of scaling them to industrial applications remain obstacles. Hydraulic accumulators, while useful for short-term energy storage, are not yet capable of storing sufficient energy for large-scale operations over extended periods. As a result, hybrid systems that combine renewable energy with traditional energy sources, such as diesel generators, are often necessary to ensure fluid power systems have a stable power supply.

Improving the efficiency of fluid power systems

A critical issue in the transition to sustainable energy is the inherent inefficiency of traditional hydraulic systems. In some cases, up to 60% of the energy used by hydraulic systems is lost due to friction, heat dissipation, and fluid leakage. While this figure may vary depending on the system’s design, maintenance, and application, it underscores the need for more efficient technologies. In an era where energy efficiency is paramount, the inefficiency of fluid power systems is a significant barrier to their widespread use with renewable energy.

Advances in fluid power technology are helping to address these inefficiencies. Variable speed drive (VSD) pumps, for example, have been developed to adjust their output based on demand, as opposed to traditional pumps that operate at a constant speed regardless of the workload. This allows for more efficient use of energy by only providing the necessary power for a given task. VSD pumps not only reduce energy consumption but also extend the lifespan of hydraulic components, as they experience less wear and tear when operating at lower speeds.

In addition to VSD pumps, modern hydraulic fluids are being developed to reduce friction and improve heat dissipation, which helps minimise energy losses within the system. However, the broader adoption of energy-efficient components across industries will be crucial for fluid power systems to become more compatible with renewable energy sources.

The role of biodegradable hydraulic fluids

Environmental concerns also extend to the hydraulic fluids used in fluid power systems. Traditional hydraulic fluids are often petroleum-based, which poses a risk to the environment if leaks or spills occur. Hydraulic leaks are a common issue, particularly in mobile systems, and can result in soil and water contamination. To mitigate these risks, biodegradable hydraulic fluids have been developed from renewable sources that break down more easily and are less harmful to the environment.

While biodegradable fluids offer clear environmental benefits, they also come with certain trade-offs. These fluids can be less effective in extreme operating conditions, such as high temperatures or high-pressure applications, which are common in industrial environments. As a result, the choice of fluid must be carefully considered depending on the specific requirements of the system. Although biodegradable fluids are becoming more popular, their performance limitations in certain contexts mean they are not yet a universal replacement for conventional hydraulic fluids.

Digitalisation and the role of IoT

In addition to advances in hardware, digitalisation is transforming the efficiency and sustainability of fluid power systems. Smart sensors, data analytics, and the Internet of Things (IoT) are enabling more precise monitoring and control of hydraulic and pneumatic systems. These technologies allow for real-time tracking of system performance, enabling predictive maintenance and optimisation of energy usage. By monitoring the condition of components such as pumps, valves, and hoses, sensors can detect inefficiencies or potential failures before they cause significant problems, reducing energy waste and minimising downtime.

The integration of digital technologies is helping to drive the adoption of more efficient fluid power systems that are better suited to the demands of renewable energy. These smart systems can automatically adjust their operation based on real-time data, ensuring that energy is used as efficiently as possible. Digitalisation is also facilitating the development of more flexible, modular systems that can be more easily adapted to different energy sources, including renewables.

The role of fluid power in renewable energy sectors

While the integration of renewable energy into fluid power systems faces challenges, there are already some promising applications. One of the most notable is in the offshore wind sector, where hydraulic systems are used to control the pitch of turbine blades and to adjust yaw mechanisms, ensuring optimal energy capture. Hydraulics are also crucial in the construction and maintenance of offshore wind farms, particularly for subsea operations and lifting heavy components.

However, it is worth noting that newer wind turbine models, particularly onshore turbines, are increasingly adopting electromechanical systems instead of hydraulic ones for pitch control. This shift is driven by the need for improved efficiency and reliability in turbine operations. While hydraulics remain important, particularly in harsh offshore environments, their role may evolve as the industry continues to develop more efficient alternatives.

Looking ahead

The integration of fluid power systems with renewable energy is a complex, ongoing process that involves overcoming significant technical and economic barriers. While the use of renewable energy to power hydraulic and pneumatic systems is theoretically possible, practical challenges, such as the intermittent nature of renewable power and the need for reliable energy storage, must be addressed.

Nevertheless, the future of fluid power in renewable energy looks promising. Ongoing technological advancements – such as the development of more efficient hydraulic components, biodegradable fluids, and digital technologies – are making fluid power systems more compatible with the needs of a sustainable energy future. As industries continue to embrace renewable energy, fluid power systems will need to become more efficient, flexible, and environmentally friendly to remain a key player in industrial applications

While significant challenges remain, the evolution of fluid power systems is crucial in the broader transition to renewable energy. With continued innovation, these systems can play a vital role in supporting industries that rely on high power density and precision control, all while reducing their environmental impact. By improving efficiency, embracing digitalisation, and adopting greener practices, fluid power technology can bridge the gap between conventional industrial power and a more sustainable, renewable energy future.