Yes. As with many renewable energy systems, an air source heat pump can be docked with a backup fossil fuel boiler (bi-valent heating) and can form part of an integrated renewable energy system with the likes of MVHR, solar thermal and solar PV.
A bi-valent system can be very cost-effective by designing it so that as fuel costs fluctuate over time the property owner can always ensure he is using the cheapest energy source to keep warm.