Hydrogen: An Opportunity to Reduce Industrial CO₂ Emissions

To date, the mainstream application of hydrogen has been held back by a variety of factors, including a lack of infrastructure, limited production capabilities, high costs and unique properties that make the element tricky to handle. However, the balance is now tipping toward a hydrogen-propelled future.

One fundamental challenge has been how to safely transport and store hydrogen, which has a wide flammability range compared to natural gas. Natural gas is flammable between 4 and 16 vol% gas in a gas and air mixture, while hydrogen is flammable between 4 to 77 vol% hydrogen in an equivalent mixture.

Whereas suitable infrastructure was limited in the past, new transmission networks and storage facilities are now being built to accommodate hydrogen. Moreover, energy companies are realizing that their natural gas grids can be adapted to accommodate hydrogen at reasonable cost. Europe, for instance, has a vast gas grid that could be converted relatively quickly, and there are separate initiatives underway in Scotland and Australia, for example, to build 100% green hydrogen-powered energy grids.

Then there’s the high cost of hydrogen which has traditionally deterred energy companies from taking it seriously. But today its cost is falling, and it’s expected to continue to do so over the next decade. This year, the Hydrogen Council said it expects hydrogen to be competitive across 22 industry applications with other low-carbon alternatives and even some conventional energy sources by 2030 .A further challenge to hydrogen has been the lack of machinery and components from which to harness it for the manufacturing of goods –specifically, via thermal appliances in which heat is required. However, companies such as Honeywell Thermal Solutions are rapidly expanding their solution portfolios to encompass hydrogen-ready burners, valves, combustion controls and other specialty equipment.

A final challenge is that nitrogen oxide (NOX) emissions produced with hydrogen combustion, in general, are greater than with natural gas due to faster flame speeds and higher flame temperatures associated with hydrogen. Typically, NOX increases steadily as the amount of hydrogen increases in the blend with natural gas up to about 60% hydrogen. The impact on NOX can become quite dramatic for blends with more than 60% hydrogen, depending on burner design. Regulations on NOX emissions are growing stricter and more widespread as well. The convergence of CO2 and NOX emission regulations will likely necessitate the development of new combustion technologies once higher concentrations of hydrogen achieve broader adoption.

Exploiting the potential of hydrogen—with care

In addition to the technical and cost barriers of hydrogen production, hydrogen requires specialist know-how to harness its potential. It must be handled differently to other fuels, with a wide range of precautions taken to process it safely.

Because of hydrogen’s wide flammability range, combustion systems must be designed differently than those of natural gas. They must undergo extensive risk assessments at both proposal and execution phases to help them meet hydrogen application safety requirements and comply with local safety codes and standards. In addition, hydrogen’s high flame speed and low ignition temperature require proper electrical design and wiring principles to be followed, with special attention paid to purging, ratio-control, temperature protection and burner management functions. Knowing a burner can fire safely and reliably on hydrogen is one thing; knowing its effect on an application is another. When firing a burner on hydrogen, the combustion characteristics are different compared to the same burner firing on natural gas. The differences in flammability, speed of the combustion reaction, flame luminosity, flame length and changes in flue gas composition all impact how products are heated and how combustion chambers or ovens should be constructed to accommodate them. Burners should be test-fired on hydrogen and the integrity of components such as mixing plates, mixing cones, gas nozzle materials and ports checked to foster that hydrogen combustion remains stable and safe without overheating or even destroying parts of the equipment.

Conclusion

Hydrogen is rapidly emerging from the shadows to present a viable solution to reducing global CO2emissions. Governments are seeing the potential for hydrogen to decarbonize sectors that were once considered too complex for transformation, such as transportation, freight and logistics, industrial heating and industry feedstock. At the same time, companies within oil and gas, chemicals, heating and automotive and other sectors now regard hydrogen as a credible way to achieve long-term sustainability objectives.

Today, climate change impact, diminishing barriers to adoption and better industry understanding of how to handle hydrogen safely and harness its potential, are pointing to a potentially hydrogen-driven, carbon-neutral future for us all.