Can anyone already switch today to sustainable heating with heatpumps so we can ditch without natural gas? That is the question that keeps us busy these days. But what do we mean by ‘sustainable heating’? Perhaps our european neighbours express this better: people over there speak more about ‘Renewable Energy’. That makes it clearer right? Because the word ‘sustainable’ is used almost everywhere nowadays. Electricity generated with solar panels or wind energy is ‘renewable energy’. “So when I go heating with electricity, am I sustainable?” No, unfortunately not yet today. unless you are in Scotland where the share of electricity that is generated in a sustainable manner is fortunately 67%. However, we will probably never be able to cover everything with the renewable energy mentioned. Also our electricity grid is not suitable for such a large demand in power. That is why we are looking for ways o the future. What will it be? Everything electric? Or even use hydrogen, for example? The future will learn.
Sustainable heating without natural gas by using a heat pump
Currently a ‘heat pump’ is the solution that is frequently used as the first answer to ‘heating without natural gas’. A heat pump works on electricity. The heat pump extracts ‘free’ energy from the environment (energy that is renewable). With every kWh of energy from the ‘socket’ the heat pump gets 3 to 4 kWh ‘free’ from the environment. A heat pump is therefore up to 5 times more economical than an electric central heating boiler. This means that we therefore need fewer wind turbines and solar panels if we opt for the heat pump. The heat pump is at its most economical at low temperatures and low temperature is best used in a well insulated building. And a well insulated building needs little energy again. In short, we come in a circle that offers many possibilities!
But it will of course be a great challenge to make the government’s goal of making 100,000 homes a year ‘gas-free’ in order to ultimately have all homes gas-free in 2050. In the installation world it is very clear that heat pumps are currently on the rise. There are currently many innovations, innovative systems and pioneering heat pump projects in Scotland and the North of England. Whether it is done with an air source heat pump, water source heat pump or a ground source heat pump: companies do their utmost to drive technology to the limit in all these technologies, to the benefit of efficiency, durability and ease of use. That is not to say that everything in the field of heat pumps is a smell of roses and moonlight: for example, energy can not be extracted from the soil everywhere, and not every house is suitable for a heat pump like the ones that are available today and where do install an outdoor unit of an air/water source heat pump in a terraced house for instance? With a heat pump you save directly on energy costs, only the difference in energy costs (euro per kWh) with natural gas is not too big. It is therefore difficult to recoup an installation. Not that it always needs to be recouped, of course, but it does make a difference to attract people. Also, not all people just have money available to switch to this modern way of heating. According to many, the energy price of electricity will need tp go down and that of natural gas has to be slightly higher. That way we can slowly but surely move to electrically driven heating. We say deliberately SLOWLY because our electrical infrastructure is, as stated earlier, far from being ready to provide enough power for this. In addition, politics often go for short-term solutions, a long-term focus thought to be much better. It is clear that we have to start making a beginning for a future without natural gas.
(Ground source heat pump with underfloor heating in Aberdeen)
What is a heat pump?
Heat pumps are appliances that provide heating and hot water in an environmentally friendly way and can be used for cooling as well. A heat pump uses for the most part ‘free’ renewable energy from the environment, they are a sustainable energy-saving alternative to the gas-fired central heating boiler. A heat pump in Scotland, compared to natural gas, is profitable at low temperature delivery systems such as underfloor heating, LT (low temperature) convectors and LT radiators. The amount of energy that the heat pump uses is low compared to the yield. 65% to 80% of the energy supplied by the heat pump is ‘freely’ extracted from the environment. This means that a heat pump installation consumes less energy than a conventional heating system. CO2 emissions from heating by means of a heat pump are also significantly lower than, for example, in the boiler.
Heat pump type and source household heat pumps can roughly be divided into four categories. Air-air, air-water, ground-water and water-water. Which type of heat pump you choose best depends not only on your budget but also on the type of home and the environment where you live. In the case of a groundwater system, for example, it is necessary that you have a certain surface area in order to be able to use the heat that is in the earth. Furthermore, geothermal energy (water catchment areas) may not be used anywhere in Scotland.
Heat pumps absorb heat at a low temperatures (source side) and release it at an elevated temperature (emission side). Of course that does not happen by itself, so that some form of work needs to be done by a compressor that runs on electricity). The most common types of heat pumps work by allowing a liquid to evaporate at low temperatures and allowing the vapor to condense at high temperatures. In the first case, the boiling point must therefore be lowered and / or increased in the second case. The boiling point can be increased by increasing the pressure with a compressor (pump type), on the other hand, the boiling point can be reduced again by lowering the pressure by increasing the space for the refrigerant (via expansion valve) The whole of evaporating, compressing, condensing and expanding forms a closed cycle. Energy is needed to bring the low temperature energy from the soil, water or outside air to a higher level. Because the required energy is lower than the energy supplied, heat pumps contribute to a large reduction in CO2 emissions. The efficiency of a heat pump is expressed in COP (= delivered energy / used energy) and reaches values, depending on the application, of 2.5 to 5.