Companies engaged in rentals are facing increasing pressure to reduce their carbon footprint by moving away from diesel-powered fleets. But what are the alternatives? And could they be equally or even more harmful to the environment? Here's what a study published by Construction Technology reveals.

"A problem that can drive you mad."

"If you think too much about it, it's a problem that can drive you mad," says Callum Mackintosh, founder of the Highland-based excavator attachment rental company HHH Equipment.

Mackintosh, like many equipment hiring bosses and business owners everywhere, is trying to decide what machines to purchase and how to fuel his small fleet amid a deluge of increasingly complex and contradictory information (and misinformation) on the subject.

A former president of the Scottish Plant Owners Association and a key part of the organization's executive committee, Mackintosh is no stranger to the courtroom controversies. Last year, he clashed with the UK infrastructure international group Balfour Beatty over his decision to avoid the use of hydrotreated vegetable oil (HVO), a fuel primarily made from used cooking oil, on his sites.

The row, which centers on whether, by opting for a fuel with lower carbon emissions, construction equipment users are inadvertently contributing to deforestation in Indonesia and Malaysia.

In a position paper published by the company in 2022, Balfour Beatty said it had stopped using HVO due to its concerns about the "complex and opaque" supply chains associated with it (see below) and "insufficient information provided about its sources, transport, and production methods."

Mackintosh disagrees.

In a strong rejection of Balfour Beatty's position, he contends that HVO offers contractors the chance to immediately reduce their carbon emissions and other pollutants. Waiting for the results of a sustainability lifecycle study of HVO could take years, he says, while Balfour Beatty will continue to burn diesel.

"By using HVO, contractors can dramatically reduce their carbon emissions, nitrous oxide levels, and the amount of soot they produce today," he says. "I suspect that what really drives Balfour Beatty's position on HVO is actually a commercial and financial decision to continue using diesel because it costs 10% to 15% less."

Balfour Beatty responded to Mackintosh, saying that the company's position on HVO "has been carefully considered and does not reflect any commercial or financial decision, but our commitment to acting responsibly and considering all the implications of our actions - ensuring that we are not solving an environmental challenge by creating another one."

And as pressure continues to mount on individuals and companies to take immediate action to reduce their environmental impact, while economic pressures drive many to look for cost-saving measures, the dispute between Mackintosh and Balfour Beatty is typical of an ongoing public debate about how truly "green" alternative fuels are.

Politically charged

One of the most politically charged "alternative" fuels is hydrogen - a fuel with the potential to power heavy construction machinery as a similar replacement for diesel.

In theory, electrolysis powered by renewable sources, splitting water into its hydrogen and oxygen components, should produce hydrogen with minimal emissions throughout its lifecycle. This "green" hydrogen can then be passed through a reverse process in a hydrogen fuel cell or "burned" in an internal combustion engine to produce only electricity and water.

Equipment manufacturers, including JCB, Caterpillar, Volvo, and John Deere, have heavily invested in producing hydrogen-powered machines, which they claim offer a zero-carbon alternative for heavy equipment, primarily due to the high power requirements of these machines.

However, climate change advocates argue that, with limited renewable energy available for hydrogen production, most of the fuel, at least in the near future, is likely to come from so-called "blue hydrogen," which is still derived from fossil fuels but where the emitted carbon is captured and stored underground.

"While truly green hydrogen may have a limited role in hard-to-decarbonize sectors, visions of a rapidly expanding hydrogen economy are a dangerous myth," says Sarah Lutz, a climate campaigner at Friends of the Earth.

Meanwhile, others emphasize that even battery-powered vehicles, often considered the most sustainable option for both transportation and heavy machinery, come with their own environmental costs.

This is mainly due to the large carbon footprint associated with the manufacture of their batteries, as well as the fact that most of the cobalt used in lithium-ion batteries is extracted in the Democratic Republic of Congo, often under conditions similar to slavery.

Back in the Black Isle, Mackintosh says that most rental companies want to transition to more sustainable alternatives to diesel but the ongoing public debate about their real environmental impact, along with some very real practical issues related to cost and availability, is holding them back.

They worry that if they invest too early in a type of fuel that is later discredited for environmental or other reasons, they could be left with an elephant.

"Buyers and end-users are afraid to invest because they don't know which path to take. It's a Betamax/VHS situation," he says, referring to the 1980s competition between two rival video cassette formats that initially left consumers unsure of what type of machine to purchase.

Weighing the Options:

Hydrotreated Vegetable Oil (HVO):

For:

Hailed as a viable alternative to diesel, which generates up to 90% fewer greenhouse gases and emissions, reduces nitrous oxide levels by up to 30%, and cuts particulate matter by up to 86%, the second-generation biofuel, made from existing bio-waste by-products, has been adopted by major construction companies, including Skanska, Lendlease, BAM, and Sisk for at least some of their operations.

The oil is already widely available and can be used as a direct substitute for diesel in internal combustion engines.

Against:

While it does not contain fossils and is not derived from oil, it is still largely derived from vegetable oil and still emits some carbon when burned. Furthermore, most concerns regarding HVO come from attempts to establish its origin.

Critics argue that supply chains for vegetable oil are often opaque. Moreover, they say that if the demand for construction equipment users drives used cooking oil, the primary ingredient of HVO, to become scarce, the price of other alternatives, including palm oil - a major driver of deforestation in some of the world's most diverse forests - is likely to increase.

Batteries:

For:

Battery-powered vehicles produce zero exhaust emissions, meaning they do not produce carbon dioxide or other emissions during operation, reducing air pollution.

Furthermore, even considering the higher manufacturing costs of electric vehicle energy, research by the International Energy Agency (IEA) shows that, over the lifetime of an electric car, the total carbon production is lower than that of a typical internal combustion engine vehicle.

Against:

EV batteries are primarily made from lithium, nickel, and cobalt extracted materials. This means that the manufacturing process of an electric vehicle can lead to more carbon emissions than producing an equivalent ICE.

About 70% of the world's cobalt is mined in the Democratic Republic of Congo, where international aid organizations say child labor, modern slavery, and human rights violations are major concerns.

In many parts of the world, battery charging stations use electricity generated from fossil fuels such as coal and natural gas, further increasing the carbon footprint of electric vehicles. Moreover, the market for recycling EV batteries is in its infancy.

Hydrogen:

For:

When hydrogen reacts with oxygen, it generates only electricity, water, and heat. This means that hydrogen does not produce carbon emissions. It is one of the most abundant elements in the universe.

Furthermore, if obtained through electrolysis of water supplied with renewable energy, the process of extracting hydrogen for production can also be carbon-free.

Against:

The so-called "green" hydrogen produced from renewable sources represents less than 1% of global production, as it is currently so costly to produce.

Most of the hydrogen produced today comes from coal (brown) or gas (gray), a process that not only releases carbon dioxide but also unburned methane into the Earth's atmosphere. In return, energy suppliers say "blue" hydrogen that creates hydrogen mainly using natural gas and then uses carbon capture and storage to bury CO2 underground can be used as a "low-carbon emission" alternative.