With new funding mechanisms slashing the cost of combined heat and power systems run on hydrogen fuel cells, now is the right time to look closely at this income-generating, low-carbon technology, according to Viessmann’s Christian Engelke
Hydrogen fuel cell systems that generate both heat and electricity in domestic and commercial buildings while greatly reducing energy costs and carbon emissions are not new.
Despite the numerous advantages these systems offer, it is still not commonly found on the consideration list of UK self-builders.
SUITABILITY
Fuel cell micro-CHPs suit a diverse range of properties and circumstances, from high-end new builds and renovations to more regular boiler replacements where homeowners are looking for an environmentally friendly solution, but where heat pumps aren’t feasible.
They work most efficiently when the return temperatures of the water in the pipe system after heat has been released around the building are very low – ideally with an underfloor heating system. However, radiators that have a maximum return temperature of 50oC can also work well.
Installation requires a gas connection and a three-core power cable electrical connection. The most compact models have a footprint of well under 1 m2, including everything you need for heating, hot water and power – avoiding the need for a bulky water cylinder elsewhere in the building.
HOW FUEL CELLS WORK
Fuel cells work by converting natural gas to hydrogen, which is then used to generate both power and heat through an electrochemical reaction known as cold combustion. In an exceptionally clean and efficient process, hydrogen is used as both a fuel source and energy store, while the carbon-producing combustion that takes place in conventional condensing boilers doesn’t happen, saving around two tonnes of CO2 per year.
As energy and heat are generated on site where they are needed, there are no losses in transmission, and, unlike with conventional power stations, the heat produced is captured and used for heating and hot water, so there is far less waste.
Hybrid models combine a hydrogen fuel cell with a highly efficient combination boiler which is used only to cover peak demand periods, such as when it’s very cold outside or a lot of hot water is required at short notice. This keeps energy consumption and carbon emissions to an absolute minimum while ensuring total comfort.
There are also energy and income advantages. As well as reducing CO2 emissions by up to 30% and energy costs by up to 40% compared to a conventional boiler and electricity, fuel cell micro-CHPs generate green electricity which can be exported to the grid, bringing in income.
A hydrogen fuel cell can generate as much power as 30 m2 of photovoltaic cells, but, unlike solar panels, it will work day and night and in all weather. That’s enough electricity to cover the base load of most households and an electric car, with any surplus stored for later use or exported for profit.
Although the potential revenue that can be earned in this way reduced greatly when the government’s Feed-in Tariff (FiT) was replaced by the Smart Export Guarantee (SEG) in 2019, it is now growing again as energy prices increase. Furthermore, the value of independence from the stresses of spiralling electricity costs is becoming priceless.
Maintenance costs, too, are minimal; a good fuel cell system will only require servicing every five years.
NEW FUNDING
However, with units costing slightly more than air source heat pumps, fuel cell technology can be seen as prohibitively expensive for many homeowners and self-builders. But that could be about to change, thanks to significant alterations to the Ofgem-run Energy Company Obligation (ECO) scheme.
ECO is designed to help low income, fuel-poor and vulnerable households access home improvements that will reduce their energy bills and carbon emissions. Under the latest revisions to the scheme, funding will be allocated according to the difference a new heating system makes to a property’s EPC rating, instead of anticipated fuel savings. As a fuel cell micro-CHP can thrust a building up several EPC bands in one go, that equates to a very substantial grant – potentially enough to cover the entire installation cost.
WORTH THE COST?
But what about higher-income households that are not eligible for ECO funding? How does the financial case for a fuel cell stack up for them? While ECO funding may go a long way to catapulting fuel cell micro-CHPs into the mainstream, it is likely to be some time before that translates into lowering the purchase price for everyone.
The good news is that until 31 March 2027, micro CHPs are zero-VAT rated. Furthermore, if electricity prices continue to rise as predicted, then homeowners could save in the region of £800-900 per year with a fuel cell, based on average annual consumption of 4,500 kWh. In this scenario, the cost to generate a kWh of electricity for self-consumption is half the cost of purchasing from the grid.
A fuel cell micro-CHP offers a big improvement on traditional gas heating products and should be regarded as an alternative low-carbon, low-NOx solution on a par with renewables – a long-term investment that will future-proof your home both financially and ecologically.
Christian Engelke is technical director at Viessmann and also chairman of the Microgeneration Certification Scheme (MCS) Micro CHP (MCHP) Working Group