Is a Fossil-Free Jobsite Possible?

This story was originally published by MATT WHEELIS on the Bluebeam Blog.

A zero-emission jobsite, with no fossil fuel consumption, means the construction industry has to create a zero-emission construction fleet. It is not as big a stretch as it initially sounds

For Thanksgiving this past year, my mother hosted our family, which meant we would be traveling to my hometown in the middle of Texas. The rental company presented me with an electric vehicle option in Austin, and I decided this would be great. But after driving a bit (OK, more than a bit) over the limit and in cold weather, that 280-mile range was almost exhausted at 142 miles. And there is no EV infrastructure in my hometown. Not one public charger. So I plugged it in, and 36 hours later had enough juice to make the trek back to Austin. Naturally, I started thinking about this in the context of the construction industry, and it led me to wonder what better eco-friendly methods there are to manage all-day usage. I was especially curious about hydrogen.

Imagine a fossil-free jobsite—one where we are not consuming petrochemical-based fossil fuels and with zero on-site emissions. Disregarding vehicular energy requirements, which may still require fossil fuels for generation depending upon the location, for this conversation lets focus on emissions at the site.

Is “zero emission” a realistically attainable goal? In fact, it is not only possible, but available today—for those willing to make the investment and test new processes on their next construction site.

A zero-emission jobsite, with no fossil fuel consumption, means we have to create a zero-emission construction fleet. It is not as big a stretch as it first sounds. There are already options for those willing to make the leap—electric battery or hydrogen-powered equipment.

Battery-powered machinery is a great option, with potential range capabilities per charge or fueling equal to or greater than gasoline or diesel. The downside: these technologies require 2-8 hours to recharge assuming a high-voltage source, which leads to inefficiencies and project downtime. Hydrogen, on the other hand, has the same range as battery-powered machinery without the downtime associated with refueling.

The long-term savings achievable with these technologies can easily offset the upfront costs of switching from gasoline or diesel machinery, while contributing to the fossil fuel- free worksite.

It is also possible to convert existing gasoline or diesel equipment models to hydrogen with minimal machine redesign. This can be achieved by converting to a hydrogen combustion engine, which operates similarly to traditional internal combustion engines (ICE), with cylinders pumping compressed hydrogen gas rather than gas or diesel. Just like an ICE, a spark ignites the hydrogen gas, creating power to drive the machinery. This can often be a more affordable and simpler option to reduce fossil fuel consumption on the jobsite.

However, a challenge with burning hydrogen in internal combustion engines is the possibility of pollutant emissions such as NOx and particulate matter (PM) being produced. These are harmful to human health—in fact, GeoHealth finds that eliminating pollutant emissions from energy-related activities, including construction, could prevent more than 50,000 deaths a year in the US. Because of this there is increasingly stringent legislation against them. One way of reducing the levels of NOx produced involves increasing the amount of air in the combustion chamber, but this reduces efficiencies. Another way is to favor an engine that takes the “flame” out of the combustion reaction altogether. As the harmful pollutants in question are formed around a flame, this approach is extremely effective at eliminating them.

Hydrogen fuel cells use a catalyst to generate electricity through a chemical reaction. With this method, hydrogen is held in a fuel cell on the machinery itself and is powered through a negative electrode terminal—hydrogen is funneled between an electrolyte and another positive electrode terminal. This creates a chemical reaction that results in a continuous flow of electricity to the batteries. Naturally, this seems like the best option because of the continuous creation of energy, but it is more complicated and expensive to implement.

Other solutions use a flameless combustion reaction to generate electricity from fuels. This technology can be fuel-agnostic, using flameless combustion technology, which uses high temperature exhaust heat recovery to unlock pollutant-free power from any fuel at the flick of a switch. With hydrogen being just one option for fossil-free fuel, this approach enables contractors to leverage whichever renewable fuel is most cost-effective and abundant at any one time.

It’s important to protect profit margins from dramatic fluctuations by enabling balance between sustainability and cost throughout the energy transition on a project-by-project, day-by-day basis. This means sites can deploy fuel-agnostic generators at scale today and see immediate carbon and pollution reduction benefits—much to the benefit of site teams, the environment and the local community, offering an alternative and lower-risk entry point for transitioning to fossil fuel-free jobsite.

So what are other downsides of using hydrogen as an energy source? The biggest is safety. Hydrogen has a small molecular size, so if it leaks through solids and mixes with air, it can be explosive, similar to gasoline or diesel. It is also not naturally occurring, so it has to be extracted from fossil fuels, compressed and then used to create a chemical reaction, converting energy into electricity to power electric motors on the construction machinery.