Are fuel cell appliances fed by natural gas fit for the future?

Fuel cell heating appliances have now been on the market for several years. The choice, however, is limited and the prices are high, which explains the slow growth in the number of installations. Yet, perhaps there are other reasons why this section of the market has yet to pick up. For although there is currently a great deal of funding available for initiatives that encourage a switch to energy-efficient heating appliances, particularly when upgrading from an outdated oil-fired system, fuel cell heating units – just like condensing boilers – have the drawback of burning natural gas, thus making them a source of carbon dioxide emissions.

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Modern fuel cell heating appliances share the same shortcoming as gas-fired boilers: their reliance on fossil fuels. For this reason, the installation of a fuel cell will in no way support efforts to meet the climate goals of the Paris Agreement. In 2015, the world entered a pact to limit global warming to well below 2 °C – or ideally 1.5 °C – compared to preindustrial levels. In order to meet the 2 °C target, global greenhouse gas emissions must be scaled back to zero by 2050 at the very latest. Any fuel cell systems fitted today with an operational life of more than twenty years will doubtless be an improvement on oil-fired boilers, but their capacity for saving carbon will be limited due to the continued combustion of hydrocarbons and the significant quantities of carbon dioxide that they release into the atmosphere.

Previously, the only commercially available alternative to a condensing boiler for domestic heating had been a heat pump; that is apart from wood pellet or biomass heating systems which, as part of a continuous cycle, emit only the carbon dioxide that was formerly stored as a biological raw material. Heat pumps draw heat from their surroundings – in other words, the air, water or ground – and “pump” it indoors. If the necessary electrical energy is provided from solar or wind resources, either through an eco-tariff or a PV panel on the property itself, the amount of carbon dioxide emitted is negligible – not taking into account the materials and energy required to make the components.

Even so, fuel cell heating appliances have long been considered innovative, efficient pieces of equipment which could pave the way for a cleaner energy ecosystem in the future. Yet awareness is now growing that the environmental benefits are, in fact, modest. While fuel cell heating systems are proven to be highly efficient, condensing boilers have, for many years, yielded efficiencies of over 100 percent through the recovery of heat stored in the flue gases. In addition, they cost only a third of the price of fuel cell heating units and – assuming a preexisting connection to the gas grid – can be installed within one working day.

One advantage cited in relation to fuel cells is their ability to generate both heat and electricity. However, it is this cogeneration that can lead to a homeowner’s environmental footprint increasing overall if they choose to install a fuel cell system. If an existing condensing boiler is replaced with a fuel cell heating unit, the consumption of natural gas will rise because the module supplies electrical energy in addition to thermal energy. Supposing that the homeowner had previously been supplied with carbon-neutral electricity from a green energy provider, total carbon dioxide emissions from the building would immediately increase since under the new fuel cell arrangement the electricity would be generated from natural gas.

Fuel cell heating appliances consequently offer no real prospect of aiding the transition to a carbon-free world – at least while they are fueled by a fossil gas. It would appear that this is now the view taken by the German economy ministry which has recently stated that hydrogen will not be an option for the heating market before 2030.

It is therefore understandable that the gas sector is presently seeking its salvation in blue hydrogen. For example, the industry initiative Zukunft Gas, formerly Zukunft Erdgas, has hosted an online event examining the subject of “Climate-neutral hydrogen from natural gas.” At the meeting, which was also attended by representatives from Norway, the case was made for carbon capture and storage, otherwise known as CCS. Discussions focused predominantly on “climate-neutral” hydrogen, since CCS and blue hydrogen both have an image problem in Germany – a fact that was conceded by the speakers themselves.

Singing the praises of this fossil fuel-based technology during this round of talks were also members of the German parliament such as Andreas Rimkus (“We need it in the transitional period.”), Timo Gremmels (“We are open to blue, turquoise and green hydrogen. […] The Social Democratic Party is closed.”) and Karl Holmeier (“You have us on your side.”).

An inquiry from H2-international as to how the IBZ fuel cell initiative assesses the carbon footprint of fuel cell heating appliances remained sadly unanswered. However, the IBZ did disclose that annual growth in the number of installed units in previous years was around the 50 percent mark. In absolute terms, that corresponds to a figure of around 6,000 appliances in 2020. It was also stated that the consortium is aiming to have half a million units in the field by 2030.

Meanwhile, 2020 proved a record-breaking year for the gas sector when it came to the heating market: Over 600,000 gas-fired heating systems were installed, quite a number of which will still be in operation beyond 2040 and will continue to emit carbon dioxide up until this point.

“The German gas network is capable of conveying 100 percent hydrogen. This is due to polypropylene pipelines. […] We need more than green hydrogen, otherwise we will not be able to ensure decarbonization. […] We should also open up toward pyrolysis. Then we will have hydrogen that is carbon neutral.”

Timm Kehler, Zukunft Gas and IBZ spokesman

Ready for hydrogen

For some time now, heating system manufacturers have been busy making sure that their fuel cell appliances are hydrogen ready. It has also become apparent that 100 percent hydrogen gas networks will be established in Europe sooner or later. It is expected that, at first, a small percentage of hydrogen by volume will be blended with natural gas. Mixing 10 to 20 percent is considered harmless for pipework and most consumers. The injection of amounts up to 30 percent is currently being tested.

… Read more in the latest H2-International e-Journal, May 2021