Microwave methane reforming for low carbon hydrogen

Their process uses catalytic microwave reforming of methane to generate hydrogen. Methane consumption is reduced by about 30% compared to conventional reforming techniques. The result is low cost, low-carbon hydrogen.

Carbon capture is integral to the process and compression of the carbon dioxide to yield supercritical CO₂ that can be transported to a nearby CCS scheme is all part of the concept. That results in blue hydrogen. When biomethane is used as a feedstock the process can yield carbon-negative green hydrogen.

The colours of hydrogen must change

More than 95% of the hydrogen produced worldwide today is derived from thermolysis of fossil fuels. Reforming of natural gas is by far the largest source of hydrogen, accounting for around 80% of hydrogen production. In this category, Steam Methane Reformers (SMRs) lead the way and Auto Thermal Reformers (ATRs) play a supporting role. Gasification of coal and petcoke is the second largest hydrogen production pathway. POX, or partial oxidation of natural gas, a process that is like gasification, is also a significant thermal process to produce hydrogen.

Electrolysers are being built at an increasing pace at ever-larger scale. When fed with renewable electricity from sources such as wind, hydropower or PV solar panels, ‘green’ hydrogen is the result. Hydrogen production on electrolysers is growing at around 50% per year. From a low base, this kind of growth is not surprising.

To meet the need for additional hydrogen that will be required to support decarbonisation of industry, transportation, and the energy sectors hydrogen production from fossil fuels, such as natural gas is also likely to see growth in future decades. But grey hydrogen production will not be sustainable. The process must include carbon capture and utilisation, or storage (CCUS), to yield low-carbon hydrogen, or ‘blue’ hydrogen.

Electrification of steam methane reforming

An SMR is fed with methane from natural gas or biomethane and steam. The reaction proceeds inside an array of vertical tubes filled with a Nickel-based catalyst to produce syngas, which is around 70% hydrogen and 30% carbon monoxide. To drive the reaction kinetics, heat energy must be applied at a high temperature. This is achieved by burning natural gas in air to heat the outside of the reactor tubes. Approximately 75% of the natural gas flows through the reactor and the balance of 25% is fired in the burners.

In regions where natural gas is abundant and CCUS is possible, this natural-gas intensive process for hydrogen production can be viable. The South Eastern United States or the West coast of Norway are two locations that fit these conditions. If, on the other hand low cost renewable electrical power is abundant then the use of the gas to fire the process might not be the most economically and environmentally sustainable option. Electrical heating would be preferable and allows the opportunity to significantly improve the emissions profile of hydrogen production, while reducing equipment cost.

Renewable electrical power to replace reformer burners

Microwave energy is produced from electricity, it is used in our homes to heat food. Radio communications masts transmit information using microwave frequencies. Industrial microwaves are used for drying pharmaceutical powders, cereal grains, and timber. Microwaves are now also being used to provide the energy to drive steam methane reformers.

Jan Boshoff is the CEO of Nu:ionic Technologies. He says that “using microwaves from renewable power instead of burning natural gas or biomethane to create the energy required for the reforming reaction can reduce gas consumption by 25 to 30%. It also reduces the fossil fuel footprint by a similar amount. By eliminating the fired heater, which is the most polluting part of steam methane reforming, through electrification, we are reinventing gas conversion for a cleaner future.”

Nu:ionic Technologies has developed and validated steam methane reforming based on microwave energy input, a form of electrical reforming. Microwave energy is applied directly into the reforming reactor and penetrates deep into all the catalyst pores. This overcomes one of the issues with traditional reforming, where heat and temperature distribution through the catalyst bed is uneven and results in reaction slow-spots meaning that lots of catalyst and a very large reactor are required.

Beyond the reduction in methane consumption, the process benefits from a significantly more compact reforming reactor size, simpler materials of construction and an almost instantaneous ramp rate. This means the process is ideal to be combined with variable renewable power such as wind or solar. A traditional SMR takes hours to ramp up due to the thermal inertia, and once it is on, the flexibility to turn up and down is very limited.

“The innovations that we have packed into our process go beyond the microwave”, says Boshoff; “The catalyst must allow the microwave energy to freely flow through it. We use a Nickel based catalyst as most other reforming processes do, but the trick lies in our choice of catalyst support and the way we have mounted the catalyst on that support.”

After the reformer, Nu:ionic has introduced a further innovation: an amine-wash carbon capture system, which uses waste heat from the process to remove carbon dioxide gas prior to hydrogen purification in a traditional PSA system. Removal of the CO2 prior to the PSA reduces the size and cost of that equipment. As a further energy conservation measure, the PSA tail gas is used to generate the steam that is required to feed the reformer.

Localised hydrogen supply

It is hard to imagine what could derail the development of the emerging hydrogen economy. Positive sentiment and momentum related to the use of hydrogen as a renewable energy vector are at an all-time high. Many industrial applications will inevitably pull for more hydrogen to displace fossil fuels.

The conviction to use hydrogen will stimulate major infrastructure investments such as hydrogen distribution pipelines. Liquid hydrogen storage and distribution networks may also emerge. However, the infrastructure is not yet in place. Boshoff adds that “the great thing about the Nu:ionic hydrogen generator is that it is a small to mid-scale plug and play solution for on-site hydrogen supply.

“All you need is water, methane, and power. These utilities are ubiquitous today and mean that we can put hydrogen in the places where it is needed, even before the hydrogen transmission and distribution infrastructure is ready. We are enabling localised hydrogen supply.”

Scaling up

Boshoff is keen to see his company’s technology develop further. “We will be building a 1 tonne per day hydrogen reformer this year, which will be based on our proven pilot plant in New Brunswick. Beyond that, we intend to scale up to plants capable of 100+ tonnes per day of hydrogen. We have had interest from several investors to support our growth trajectory and we are always open to enter into partnership and financing discussions.”

Dry reforming, where most of the steam that is fed to the reformer is replaced with carbon dioxide (CO₂) is also on the radar. “We had some encouraging results with CO₂ injection”, confirms Boshoff; “Microwave catalytic chemistry allows unique solutions to the conventional challenges associated with dry reforming.”

The track record of the team at Nu:ionic is remarkable. Boshoff himself was a senior executive at Sasol with responsibility for gas conversion to synthetic fuels processes. His co-founder and CTO, Jim Tranquilla, is a renowned world leader in applied microwave technology with more than 40 years of expertise under his belt. He was the CTO at Atlantic Hydrogen, where microwave pyrolysis was proven to be a potential means for turquoise hydrogen production.

“In addition to our openness for financial sponsors, we are developing strategic partnerships in biogas utilisation, hydrogen mobility and renewable energy storage markets”, adds Boshoff; “We see high levels of synergy in north American, North Asian, Australian and European markets. We believe that the decarbonisation focus, biomethane availability, CCUS readiness, and the gas / power cost mix in some of these regions will be highly compatible with our process.”