What comes after the high efficiency combi boiler?

Hoe gas helpt verduurzamen

In the Dutch "energy test garden" on Ameland the hybrid heat pump project is continuing to take shape. It's interesting for people in the rest of the country to learn about effective investments for keeping their homes warm in the future. The Amelanders are taking the lead and testing it out.

A large gas field was discovered in Groningen at the end of the 1950s. It soon became clear that this natural gas was extremely suitable for heating homes and buildings. Burning coal and oil was considerably more polluting than natural gas. An extensive underground gas network was built during the 1960s; now, many decades later, almost every home and building is connected to it. Thanks to the arrival of the high-performance boiler at the beginning of the 1980s, the efficiency of gas consumption is now almost 100%. For many years this particular boiler has been the standard appliance supplying heat for warmth and hot water comfortably and efficiently in the Netherlands.

The hybrid heat pump is the next step on the energy transition pathway

Natural gas will no longer have a role in our homes if greenhouse gas emissions (CO2), released from burning fossil fuels to heat the built environment, have to be eliminated by the middle of this century. That role will be taken over by a heat supply (such as residual heat from industry), green gases (biogases and sustainably generated hydrogen) and sustainable electricity (combined with heat pumps).

The last option is only viable if there is a significant increase in the production of sustainable electricity and the heat demand in the existing built environment falls considerably due to improved insulation. The electricity infrastructure will also require reinforcement; the existing electricity grid in our country has not been fully developed as the heat demand is almost entirely by natural gas.

A rapid transition from natural gas to an ‘all-electric’ solution (with heat pumps providing all the heat required) would involve converting the entire existing electricity grid. A hybrid heat supply is a promising interim solution. For the built environment, this would be the hybrid heat pump: a small electric heat pump combined with an HE combination boiler. Most of the heat demand can be supplied by the heat pump but if the demand for heat is high (if outside temperatures are lower) then the boiler will step in. If the existing electricity grid struggles to supply the electricity required by the heat pumps, then they can be switched off temporarily and the heat will be supplied by the HE boiler.

Example of a hybrid heat pump (ELGA)  in combination with a HE boiler (Atag).
Example of a hybrid heat pump (ELGA) in combination with a HE boiler (Atag).

Ameland leads the way – 100 hybrid heat pumps installed

The hybrid heat pump is seen as a good option for the existing built environment in order to achieve significant CO2 reductions in the short term. However, this technology is relatively new and the necessary knowledge and experience will have to be gained before attempting a large-scale rollout. More than 100 hybrid heat pumps have now been installed in homes on Ameland, GasTerra has played an important part in this. Measurements are being taken during the 2017/2018 heating season in order to have an overview of the energy performance of the heat pump component. Users of the hybrid heat pumps will be asked about their experiences after the heating season. The information gathered will be shared with installation sectors, suppliers and manufacturers. It's possible that minor modifications may still be necessary to further optimise the hybrid heat pump for the Dutch market. Judging by what we have seen so far, the hybrid heat pump could be a worthy successor to the HE boiler within just a few years.

And how does the future look?

The hybrid heat pump will be able to handle a significant proportion of the heat demand in the built environment in 2050 and beyond, but only if the gas required is renewable. Sustainably generated hydrogen can be converted into sustainable methane with CO2 in a process called methanisation. As methane is the main component of natural gas, it can be easily transported in the existing gas network. Preparations for conducting practical methanisation tests have recently started on Ameland. It may well be that the hybrid heat pumps on the island will produce even more sustainable heat in 2018.