Heat pumps: a gem in renewables

European Heat Pump Association

Climate change must be stopped, but the means to achieving this are less obvious and agreement on the appropriate path to reach the goal is not unequivocal. It is increasingly clear that burning fossil fuels for heating is dated and the search and implementation of viable alternatives is a must for today. This is particularly true for heating and cooling with its large share in today’s total final energy consumption. While the potential for renewable energy sources in this sector is very high, maybe even 100%, the current contribution is still low and often underestimated or overlooked.

Fig 1 Operation principle of a heat pump

A triple dividend

• 1. Heat pumps use renewable energy from air (aerothermal), water (hydrothermal) and ground (geothermal);
• 2. They reduce final and primary energy demand; and,
• 3. They reduce greenhouse gas (GHG) emissions.
  

This dividend has recently been acknowledged by the European Parliament and Commission. In the Directive on the promotion of the use of energy from renewable sources (2009/28/EC | RES Directive, § 2) energy from air, water and ground is seen as renewable and heat pumps recognised as the technology of choice to make it usable.

How do heat pumps work?

Heat pumps transform renewable energy from air, ground and water to useful heat. They can also utilise waste energy from industrial processes and exhaust air from buildings. A heat pump consists of a heat source, the heat pump unit and a distribution system to heat/cool the building. A transfer fluid transports the heat from a low-energy source to a higher energy sink. Auxiliary energy – usually electricity or gas – is needed to run the compressor and the pumps. The direction of this cycle can be switched so the same machine can be used for heating and cooling giving it an additional economic advantage in cases where both services are needed. In heating mode, ambient energy is the heat source and the building is the heat sink. In cooling mode, the cycle is reversed: the building is cooled down using the outside as heat sink (see figure 1).

Today, the majority of heat pumps is electrically driven with more than 600,000 units sold in Europe (2009). Market penetration is expected to increase and heat pumps are foreseen to be used in more application fields (e.g. sorption technology for free solar cooling or heating of electric cars).

Fig 2 Energy and GHG savings as well as RES-Contribution ranges of heat pumps compared to a gas-condensing boiler

Efficiency, emissions and renewable energy use

State-of-the-art electric heat pumps can reach efficiencies (seasonal performance factor) of three to five meaning one unit of electricity is transformed to three to five units of heat. The efficiency of systems depends on the efficiency of the unit, the quality of installation and the building’s energy demand. The higher the system’s efficiency, the lower emissions. This is also largely influenced by the emission value of the electricity mix / fuel used. Consequently, electrically-driven heat pumps will profit from future improvements in efficiency and carbon footprint of the European power mix. Installed and new units benefit from lower final energy demand and lower GHG emissions. On top, these pumps are emission free at the point of operation.

When using green electricity, biogas, or thermal energy from renewable sources, heat pump systems provide a 100% renewable solution for heating and cooling of buildings. In systems where auxiliary energy is provided from conventional (fossil) sources the share of renewable energy used is calculated as the difference between the total final energy demand and the amount of auxiliary energy input.

The comparison of heat pump systems using air or ground as energy sources in residential buildings with a gas condensing boiler reveals a possible savings of between 20% and 50% in primary energy, 35% and 80% in final energy, and 49% to 67% in GHG emissions. Heat pumps use between 65% and 78% of renewable energy to meet their total final energy demand (see figure 2).

A study by the International Energy Agency’s Heat Pump Centre finds an 8% contribution potential from heat pumps towards global CO₂ emissions. The EHPA vision scenario estimates a 5% reduction potential in final energy demand by 2020. There is clearly untapped potential, but heat pumps need to be used more widely. Additional institutional and financial support is necessary.

The dividends are too good to be ignored. With heat pumps, we can reach European and worldwide targets in energy savings, use of renewables and GHG emission reduction – but we must start now.

European Heat Pump Association
M: +49 176 6320 1140
W: www.ehpa.org