How heat pumps achieve energy savings and CO2 emissions reduction: an introduction
This section gives a brief introduction to heat pumps. Based on six basic facts about heat supply the value of heat pumps is discussed. It is argued that heat pumps are very energy efficient, and therefore environmentally benign.
An efficient technology
Heat pumps offer the most energy-efficient way to provide heating and cooling in many applications, as they can use renewable heat sources in our surroundings. Even at temperatures we consider to be cold, air, ground and water contain useful heat that's continuously replenished by the sun. By applying a little more energy, a heat pump can raise the temperature of this heat energy to the level needed. Similarly, heat pumps can also use waste heat sources, such as from industrial processes, cooling equipment or ventilation air extracted from buildings. A typical electrical heat pump will just need 100 kWh of power to turn 200 kWh of freely available environmental or waste heat into 300 kWh of useful heat. For more information about the technical aspects of these energy savings are achieved, see the section Heat pump technology.
Six basic facts about heating
Through this unique ability, heat pumps can radically improve the energy efficiency and environmental value of any heating system that is driven by primary energy resources such as fuel or power. The following six facts should be considered when any heat supply system is designed:
•direct combustion to generate heat is never the most efficient use of fuel;
•heat pumps are more efficient because they use renewable energy in the form of low-temperature heat;
•if the fuel used by conventional boilers were redirected to supply power for electric heat pumps, about 35-50% less fuel would be needed, resulting in 35-50% less emissions;
•around 50% savings are made when electric heat pumps are driven by CHP (combined heat and power or cogeneration) systems;
•whether fossil fuels, nuclear energy, or renewable power is used to generate electricity, electric heat pumps make far better use of these resources than do resistance heaters;
•the fuel consumption, and consequently the emissions rate, of an absorption or gas-engine heat pump is about 35-50% less than that of a conventional boiler.
A large and worldwide potential
If it is further considered that heat pumps can meet space heating, hot water heating, and cooling needs in all types of buildings, as well as many industrial heating requirements, it is clear that heat pumps have a large and worldwide potential.
Of the global CO2 emissions that amounted to 22 billion tonnes in 1997, heating in building causes 30% and industrial activities cause 35%. The potential CO2 emissions reduction with heat pumps is calculated as follows:
◾6.6 billion tonnes CO2 come from heating buildings (30% of total emissions).
◾1.0 billion tonnes can be saved by residential and commercial heat pumps, assuming that they can provide 30% of the heating for buildings, with an emission reduction of 50%.
◾A minimum of 0.2 billion tonnes can be saved by industrial heat pumps (estimation based on a study by Annex 21).
The total CO2 reduction potential of 1.2 billion tonnes is about 6% of the global emissions! This is one of the largest that a single technology can offer, and this technology is already available in the marketplace. And with higher efficiencies in power plants as well as for the heat pump itself, the future global emissions saving potential is even 16%.
In some regions of the world, heat pumps already play an important role in energy systems. But if this technology is to achieve more widespread use, a decisive effort is needed to stimulate heat pump markets and to further optimise the technology. It is encouraging that a number of governments and utilities are strongly supporting heat pumps. In all cases it is important to ensure that both heat pump applications and policies are based on a careful assessment of the facts, drawn from as wide an experience base as possible. The IEA Heat Pump Centre sees it as one of its key roles to ensure that these facts are available to a wide audience, including policy makers, utilities, market parties and heat pump users.