Bringing clean power to construction sites with hydrogen fuel cell-based generators

Decarbonizing construction operations will play a key role in driving a successful energy transition. While many companies continue to make progress in reducing emissions through electrification, remote sites without grid access remain heavily reliant on diesel generators for onsite power. The use of alternative fuels like renewable diesel and biofuels is seen as a pathway to improving sustainability. However, cleaner options are needed for the industry to meet its long-term climate targets.

Hydrogen fuel cell-based power generators have emerged as a solution to this dilemma and can serve as a clean, reliable alternative to diesel gensets. In this article, we explore the advantages of hydrogen over other types of fuels (including biodiesel) and discuss how fuel cell-based generators can help accelerate the construction industry’s transition to a low-carbon future. 

Why is there a need to move away from diesel generators?

Diesel generators are the primary option for power on construction sites for various practical reasons. They offer a range of benefits that cater to the unique demands of remote environments, including high power density, reliability, durability, etc. However, with the industry’s growing emphasis on sustainability, the environmental footprint of combusting fossil fuels has become an issue, particularly in regions where carbon taxation frameworks exist or will be implemented in the near future.

To put this into perspective, a 1 MVA diesel generator running at full load combusts roughly 225 kg of diesel and emits 720 kg of CO2 per hour. This is in addition to high NOx and SOx emissions, which are coming under increased scrutiny from regulators.

In the Netherlands, for example, new rules now require construction sites seeking permits to submit plans that show how they will mitigate NOx emissions¹. Other countries, cities, and states are exploring even more aggressive measures, with some proposing a ban on the use of diesel generators altogether².

It is logical to expect that as the energy transition progresses and cleaner options for power generation become available this trend will continue, putting construction companies at risk of non-compliance and exposing them to potential monetary penalties. Contractors also have their own internal environmental, social, and governance (ESG) goals to consider.

Noise levels from diesel generators are a growing issue as well, both for workers on the site and residents in surrounding communities. Many urban localities have adopted rules that prohibit the operation of heavy equipment during nighttime hours. Although this is a secondary concern to emissions, it is a factor that companies must consider when evaluating options for onsite power.

Limitations of biofuels

The use of alternative fuels, namely renewable diesel (produced via hydrotreating) and biodiesel (produced via transesterification), is currently seen as the most practical option for addressing emissions associated with fossil-based diesel combustion. However, both come with limitations.

In particular, NOx and SOx emissions are only slightly lower than that of fossil diesel³. Moreover, the CO2 reduction potential of biodiesel is limited due to its blending constraints. In most cases, the use of biodiesel blends over 20% necessitates some type of engine modification or replacement due to compatibility issues. It also has less favorable cold weather performance characteristics than fossil diesel.

Questions also exist about the sustainability of renewable and biodiesel from a total lifecycle (i.e., cradle-to-grave) perspective. Several recent studies have highlighted the importance of considering the GHG emissions associated with direct and indirect land-use change (LUC), along with potential negative impacts on water resources and ecosystems from biofuel production⁴. These concerns will only grow as biofuel adoption increases in the coming years.

Overall, biofuels and renewable diesel can serve as a short-term answer for reducing the impact of fossil diesel, but long-term, they are likely not the best option for deep decarbonization of construction sites.

Battery energy storage is also being explored as a potential solution. However, outside of small portable batteries, electrification with energy storage is simply not viable for meeting the long-term energy needs of remote sites. For context, a 20-foot container can house roughly 1 MWh of batteries. This would only be sufficient to power a 250kW site for four hours before needing to be hauled away for charging.

The case for hydrogen fuel cells

Hydrogen fuel cell-based power generators are emerging as a viable alternative to diesel gensets in many applications and an enabler of electrification where the power grid is inaccessible. 

Hitachi Energy’s HyFlexTM hydrogen power generator is designed for this very purpose. The fully integrated plug-and-play unit is equipped with fuel cell modules, power electronics, cooling, auxiliaries, and an intelligent control system. It is enclosed in an easily transportable container and creates minimal noise output during operation.

During operation, the HyFlex generates electric power with zero emissions through an electrochemical reaction between hydrogen and oxygen. Because there is no combustion, the only byproduct of the process is water and heat, both of which can be used onsite if needed. This contrasts with thermal engines burning pure hydrogen, which are also being considered as an option for power generation. Although there is no CO2 produced when burning hydrogen, engines must be aspirated, resulting in the combustion of air and the production of NOx and SOx emissions.

Efficiency is also higher in fuel cell-based power generators than diesel generators or hydrogen combustion engines. This directly translates into lower fuel expenses, which is often the largest contributor to OPEX. The HyFlex, for example, consumes roughly 65 – 75 kg of H2 per megawatt-hour of electrical energy produced. Fuel consumption in a similarly sized hydrogen engine is ~35 – 45% higher. For context, a traditional diesel generator can consume more than 200 kg of diesel per hour.

The business case for hydrogen fuel cells

When considering options for onsite power, end-users should evaluate each technology on the basis of net present cost (NPC) or total cost of ownership (TCO).

For some applications in regions where a carbon tax is in effect, TCO for a hydrogen fuel cell-based generator is already lower than that of a diesel genset, despite a much higher initial CAPEX investment. If the source of hydrogen is “green” (produced using water electrolysis powered by renewable energy), lifecycle emissions can be reduced by 20-fold versus diesel-based power generation.

Even in the case of “grey” hydrogen (produced via steam methane or autothermal reforming of natural gas), lifecycle emissions are reduced by 30% relative to diesel. Maintenance requirements also tend to be lower with hydrogen fuel cells, as there are no moving parts.

Generally speaking, the return on investment (ROI) for hydrogen fuel cell generators becomes more positive as operating hours increase. The economics will improve further as global hydrogen supplies expand and costs come down. Hitachi Energy has developed specific tools to support customers in determining if there is a viable business case for implementation.

Conclusion: Taking concrete steps to accelerate adoption

Although hydrogen fuel cell power generators are established and proven, they are still considered nascent technology in the construction sector and have been met with skepticism. At Hitachi Energy, we recognize this challenge and are taking steps to foster widespread acceptance.

In March 2024, we conducted the first customer field trial of a HyFlex generator on a construction site in Sweden. Using green hydrogen as fuel, the unit supplied clean power to a charging station, which was used by a battery-powered excavator. The demonstration project represents an important milestone in the electrification and decarbonization of construction sites.

We are currently developing multiple modular variants of the HyFlex generator to suit the needs of various markets. Target applications today are focused mainly in Europe and include construction sites mines, large-scale events, and data centers, among others. Our plan is to expand to markets outside of the EU in the near future.

As part of our efforts to accelerate hydrogen adoption, we are evaluating technical alliances with several rental equipment companies and hydrogen suppliers. We believe establishing strategic partnerships will be important to support growth in both H2 supply and demand, and increase the range of possible use cases across the construction industry.