Lithium-ion batteries work by a process of charging and discharging, generating an electrical current. They consist of an anode, a cathode, positive and negative current collectors, an electrolyte and a separator.
The electrolyte is conductive gel or liquid which carries positively charged lithium ions from the anode to the cathode, and vice versa. This movement takes place through the separator, a porous plastic film that separates both electrodes. Free electrons generate a charge at the positive current collector, which then flows through the machinery or appliance to the negative current collector. When all ions have been received by the cathode, the battery needs to be recharged, whereby the opposite process happens: ions are released by the negative electrode and received by the positive.
Electrical heavy machinery without a doubt offers a range of benefits, for contractors, the environment and for local people.
Minimised Noise
Equipment noise is a big factor to consider when planning your project, particularly when working in busier commercial or residential areas. Consider the fact that Volvo’s ECR25 electric excavator reduces noise levels from 93 dB to 84dB, a massive decrease in noise disruption when a 10 dB increase represents a tenfold increase in sound intensity. Diesel engines are much louder and affect not only those operating them, but also the environment and local people.
The advantage of quieter electrical construction equipment is that, while also safer and reducing the likelihood of tinnitus among users, operating hours can potentially be extended, or moved to more convenient times, such as earlier starts on hot summer days. Less noise pollution also has a positive effect on local wildlife and minimises disruption to populated habitats in both urban and rural areas.
Another benefit of electrical construction machinery over diesel counterparts is the reduction in vibration. Extreme vibration over extended periods of time can result in headaches, fatigue and back pain, leading to discomfort. By using battery powered heavy machinery, working conditions can be optimised to offer greater comfort and increased productivity.
Battery powered construction machinery delivers a 100% reduction in exhaust emissions when compared to traditional diesel powered engines. As the only requirement is electricity, these greener alternatives contribute to international decarbonisation efforts and address the push for more sustainable industry practices from both the public and private sectors. The World Green Building Council’s 2019 report suggests that the building and construction industry can reduce carbon emissions by 40% by 2030, and can reach zero emissions by 2050. Of course, this is not a simple task, however it does highlight the potential of lithium-ion batteries as at least one solution to consider.
While battery powered heavy machinery technology is looking promising, globally it seems we are not quite ready for a full scale electric-revolution. Companies such as Volvo and Komatsu are making leaps and bounds within the industry, reflecting the fact that battery powered equipment certainly has great potential. Volvo’s well-received ‘Add Silence’ campaign, for example, highlights the comparable performance of electric equipment to the original diesel powered options, with the added benefits we have already mentioned. Coming from a slightly different angle, Komatsu are focusing their technological efforts on hybrid systems for excavators. However, the question as to whether these industry advancements are ready for a larger scale roll-out is not a simple one.
Industry wide considerations have to be made for the practicality of such machinery; where it seems that smaller machinery is headed in the right direction, larger equipment isn’t quite there yet.
While these innovations are looking encouraging, it’s only when battery powered options are as consistently accessible and reliable as traditional diesel engines that they can be confidently considered the future of heavy machinery.
Another hope are hydrogen fuel cells and their own ‘zero emissions’ properties. No harmful emissions are released by the generation of energy through hydrogen fuel cell technology; the only by products are heat and water. Cited as the ‘clean fuel of the future’, hydrogen fuel cells offer a potentially cleaner way forward within the heavy duty machinery industry, and the costs associated with handling and storing diesel fuel or toxic battery acid would not apply.
Hydrogen fuel cell technology, where used, is very reliable. It can operate at temperatures as low as -40°c with ease, not to mention its applications across all different climates. Hydrogen fuel cells can also be reliably used at scale too, whereas the likes of lithium powered batteries are limited with regards to increasing battery capacity due to structural issues.
Hydrogen fuel cells are 40-60% energy efficient, according to US Department of Energy. Compare that to the typical internal combustion engine of a vehicle, running at typically around 25% efficiency. Hydrogen also has an energy density of 120MJ/kg, three times greater than diesel. This means that more energy is generated per kilogram of hydrogen fuel than that of diesel, ultimately leading to cost savings down the line.
So, why aren’t we seeing more hydrogen-fuel-cell-powered heavy duty machinery?
Despite the proposed advantages of hydrogen fuel cells for heavy duty machinery, the technology does have its drawbacks.
Firstly, there is the fallacy that hydrogen fuel is completely clean. While a heavy duty machine running on hydrogen fuel cell power will not release any polluting gases into the atmosphere, the cost to the environment is not free. Hydrogen is, by and large, not harvested using renewables and the process emits significant amounts of carbon dioxide.
‘Grey hydrogen’ is a term used to describe non-clean hydrogen sources, and currently fossil fuels account for 96% of hydrogen production, while ‘green hydrogen’, made using electrolysis and renewable energy only, makes up a mere 5% of hydrogen production.
Storage issues are another one of the large drawbacks concerning hydrogen-fuel-cell-powered heavy duty equipment. Hydrogen is very reactive, and ‘hydrogen embrittlement’ corrodes metals over time. This makes storage both heavy and expensive, reducing its practicality for some within the industry.
What this tells us is that hydrogen technology is far from being a perfect solution to energy within the heavy-duty machinery sector, and industry experts question whether hydrogen fuel cells are really worth it, when other options like reliable low emission diesel or battery powered options exist.
