By Professor Lasse Rosendahl, Head of Department at AAU Energy
Photo: Colourbox

There are many places to look if, as Commissioner for Energy, you are charged with managing the EU’s major plans for improving energy efficiency as part of the green transition. I would like to congratulate Dan Jørgensen on his appointment and approval as a new European Commissioner. I am sure that he and his staff are already looking at some of the areas that are repeatedly in the spotlight, such as the transport sector, agriculture and construction. But I am also afraid that he – like far too many politicians before him – will overlook an area of huge energy waste which urgently needs to be addressed!

Cranes, excavators and other hydraulic machines have so far managed to avoid attention in the green transition, which is quite amazing as machines based on hydraulic systems emit almost twice as much CO2 worldwide as all international aviation.  It has been overlooked or ignored by most people until now, and while it may not look like low-hanging fruit for technological reasons, it will be incomprehensible if new demands are not soon placed on hydraulic climate culprits.

Hydraulics should be under the spotlight

Some of the worst culprits are construction machinery such as excavators, cranes and bulldozers. These emit almost as much CO2 as the entire international aviation sector (2022). But inefficient hydraulic systems are also found on ships and in agriculture, the transport sector, the plastics and cement industries, various types of manufacturing companies and many other places.

The problem is that hydraulic systems have extremely inefficient energy transmission, averaging only 35 percent. For excavators, the efficiency can be as low as 12 percent, so that almost nine-tenths of the fuel fed to these machines is simply wasted.

Perhaps we just have to accept that there is an extra energy cost associated with operating these important hydraulic machines, as they would surely have been improved long ago otherwise? Unfortunately, that is not the case.

For various reasons, there has always been a relatively large hydraulics industry and a relatively small academic research environment compared to other production and energy technologies. Manufacturers and suppliers have created the successes in this sector so far, but one gets the feeling that the sector has not been particularly interested in reinventing an energy-efficient version of itself, as long as there is no outside requirement to do so. This is why we need Dan Jørgensen and his colleagues – in the commission and the Danish parliament – to realise how far behind one of our biggest climate culprits actually is.

Manufacturers may not want to take the lead and admit their machines are lacking in energy efficiency, but others among us dare to point this out. If we do not address this in Europe, there is a risk that Asia will suddenly launch alternatives that can help to dramatically reduce energy consumption.

Batteries are the future – but not yet

We have come a long way in many sectors in replacing fossil fuels with electrification based on renewable energy. Just think of electric vehicles, or the green electricity which can now satisfy the hunger for light, heat, ventilation etc. among companies and households.

In hydraulic systems, electrification will involve replacing the traditional combustion engines with battery-powered electric motors. But this is not realistic right now, because the waste element in the enormous energy consumption is so great that no battery can keep these large machines running for a whole working day. Even the best batteries can only provide enough power for three to four hours. However, if we can just halve the energy waste, it is definitely within reach to have enough battery power for a full working day.

Solution near at hand

Fortunately, research is showing promising possibilities for optimising the energy efficiency of these systems. For example, there is great potential in transforming the energy flow between different consumers in systems, or in controlling the energy flow using variable speed pumps, significantly reducing energy loss compared to traditional hydraulic systems. These technologies have been tested in laboratories and in small machines with well-defined applications, and provide a direction for future research.

However, more research is needed on their application across industry segments, demonstrations and tests, and how they can be scaled up to realise the significant potential they hold.

While we cannot transform all our machines tomorrow, making hydraulics more efficient is not a distant, utopian scenario. The success of the Danish wind sector is also a great example of what can be achieved with targeted initiatives.

Unfortunately, the major focus today is on other key areas such as agriculture, transport and construction, and while Denmark has a strong hydraulics industry, optimisation in this area rarely attracts attention or financing.

We must seize export opportunities

In the time ahead, some of our energy researchers – together with colleagues from other European universities and companies, will travel to Brussels to talk to relevant people in the EU system. We hope the new Energy Commissioner and his colleagues will also listen to the experts from his home country and focus on the hydraulic climate culprits. Asia has cheap production and USA is developing new products, so we must keep advancing in Europe also. If we do it intelligently, it will not only benefit the green transition and the climate.

Denmark and Europe can lead the way in the green transition and forge a path that inspires the rest of the world and that our business community can greatly benefit from.

It will require research, focus and funding if we are to achieve a future where hydraulic systems are sustainable and the climate footprint significantly reduced.