The Environmental Impacts of the Heat Industry

Along with electricity, heat is one of the most used forms of energy in the world. The main sources of energy used for heat production are coal and gas, both fossil, electricity, whose fossil content depends on the used electricity mix and biomass, which is renewable. New types of energy have emerged in the past decades with decreased environmental impacts, geothermal and heat pump being one the most performing ones. Heat is mostly produced onsite by consumers themselves, on industrial sites and in the heated buildings. It can also be provided via urban heat networks where heat production is centralized at industrial scale and then distributed locally by a district network.

The two main environmental impacts of heating solutions are:

+ Climate change: the heat production sector still relies heavily on fossil fuels as a source of energy. The fuel combustion reaction releases quantities of CO2 that are proportional to the carbon content of each type of fuel. Coal has the highest carbon content, while natural gas (methane, CH4) has the lowest carbon content of all fossil fuels.
+ Air quality deterioration: alongside CO2, the fuel combustion releases airborne pollutants such as SOx, NOx, CO, volatile organic compounds – VOC – and particulate matters. These compounds cause significant-to-high damage to living species including humankind.

This high impact intensity framework includes equipment manufacturers and service providers at all stages of the value chain, from heat generation to heat distribution. As electricity or fuel are used as heating energy sources, the heat framework is interfaced with the fuel and electricity frameworks.

How the NEC measures impacts of heating solutions

For each type of heat, industrial and space heating, the impacts are measured per thermal energy unit, usually expressed in Mega Joules (1 MJ = 277.8 thermic Wh). The Heat NEC is thus calculated by averaging two equally weighted environmental performance components, as follows:
+ Climate component: based on the greenhouse gas emission factors of each technology, expressed in kg CO2eq/MJ
+ Air quality component: based on the endpoint indicator of the ReCipe LCA method for particulate matter, used as a proxy air quality deterioration intensity and expressed in ReCiPe points per Joule or pointsx106 per MJ.

The NEC is thus calculated by summing the above Heat NEC with two optional components:
+ Final use NEC: when specific final use is identified and different from 0%, in order to incorporate the worsening effect of a negative NEC final use or the bettering effect of a positive NEC final use;
+ Specific incremental NEC: when the heating performances significantly differ from average framework values (default values), such as specific energy yields or specific air treatment devices, the difference is converted into kg CO2eq/MJ or ReCiPe points/J, which provides a NEC delta.

What about heat pump NEC?

In the case of electric radiative heating or heat pumps, a prevailing share of the environmental impacts is embodied into the electricity used. The resulting NEC is then highly related to the NEC of the electricity itself. As a result the NEC of heat pumps varies from -100%, if electrified by a coal-fired power plant or by the Polish power network, to +100% if connected to a wind park or to the Brazilian, Swiss or Swedish power network.

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