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Renewable heat’s glossary

Hugues Defreville
newheat glossary on renewable heat

Do you speak renewable heat?

Not yet or need to expand your vocabulary?

Here we help you to understand the rather complex vocabulary of renewable energy, in particular renewable heat.

Find all the definitions related to our sector in this glossary. 

Adsorption: this is a phenomenon that allows the attachment of gas molecules to the surface of a solid…and emits heat.  We talk about it in our article on heat storage! [i]

CO2e, CO2eq, CO2 eq: this is the CO2 equivalent. Indeed, CO2 is not the only greenhouse gas causing climate change. There are a number of other gases that contribute significantly to global warming. All these gases are quantified in a single unit called CO2e.

Decarbonation: or decarbonisation, as the case may be! It is the fact of reducing CO2 emissions, i.e. all the actions implemented in order to limit the carbon footprint of an industrial site…or a community for example.

Desorption: unlike adsorption, this phenomenon releases gas molecules from the surface of the solid. It is endothermic, and therefore consumes heat.

DHW: simply for domestic hot water!

District Heating: a kind of large-scale collective heating system for cities or neighbourhoods, which allows different buildings to be heated thanks to centralised production resources (boiler rooms) and a distribution network (via underground pipes). There are about 800 of them in France, the majority of which can be seen here. At Newheat we are developing renewable heat production projects to supply these networks, as is the case with our references in Pons and Narbonne.

Endothermic: a process that consumes heat (see definition of desorption).

Enthalpy: this is a quantity that we use daily in the equations of our thermal system models. It is the thermodynamic potential that synthesises in a single function the internal energy of the system (related to its temperature and quantity of matter) and the boundary work (related to its pressure) required to occupy its volume.

Exergy: this is the usable part of a quantity of energy in a system, for example above a certain temperature. This concept is key to our systems: we deliver to our customers at set temperature levels, any thermal energy created below these levels is “unusable” (at least directly, without without complementary energy supply).

Exothermic: as opposed to endothermic, a process that generates heat.

Fatal Heat: this is thermal energy indirectly produced by an industrial process, which is neither recovered nor used. Our objective? To recover and reuse it, either on the same site in another process, or to supply another site or heating network nearby. This is known as waste heat recovery.

GHGs: for greenhouse gases. Their constant increase causes global warming. This is particularly true of carbon dioxide, methane and nitrogen oxides. Our mission is to reduce their emission in industries and community heating.

Latent heat: this is the amount of heat that is absorbed or given off by a material during a change of state. For a liquid/solid phase change, it is called melting. For example, a 1kg ice cube at a (constant) temperature of 0°C will need 330,000 joules (or about 92 Watt-hours) to melt, which is the same amount of energy taken from your fruit juice (or cocktail) to cool it down!

Heat Pump: it is a thermodynamic electrical system that takes heat from a low-temperature renewable source (ambient air, winter solar heat production, low-temperature waste energy) and delivers it at a higher temperature to a consumer flow (industrial process, district heating, etc.).

RE: for Renewable Energy, as opposed to fossil fuels. Renewable energies are inexhaustible and available in large quantities. At Newheat we develop projects using renewable (non-combustion) heat production sources. And yes, energy is not just electricity!

Phase Change Material: specific materials that are capable of changing their physical state within a targeted temperature range. The use of this latent heat allows them to be used as particularly dense energy storage solutions, although they may be limited in charging and discharging power. The most commonly used materials are paraffins, fatty acids and hydrated salts. They are still not very well developed at industrial level and are relatively expensive at present.

Photovoltaic solar collectors: not to be confused with thermal solar collectors, they can produce electricity. More details in our article on how solar thermal energy works.[ii]

Pit: this is the abbreviation for PTES…which definition can be found right below.

PTES: Pit Thermal Energy Storage. PTES is a so-called inter-seasonal storage technology that allows sufficient thermal energy to be accumulated in summer for use in winter. We explain everything in our dedicated article. [ii]

PV-T: photovoltaic AND thermal solar collectors, designed both to produce electricity through a photovoltaic cell and to collect thermal energy through a system that circulates water or air behind the collector.

Pyranometer: neither a Pokémon nor a tool for measuring the intensity of a flame…it is actually a device for measuring the amount of sunlight energy received on a surface (measurement of global solar radiation in watts per m²).

RE&R: for Renewable and Recoverable Energy (which can be applied to the recovery of waste heat for example!)

Sensitive heat: we’d like to tell you that this is a rather sensitive form of heat…but let’s be serious! It is the amount of heat that is exchanged, without a physical phase transition. More information can be found in our article on heat storage.[ii]

Solar Irradiance: this is a radiometric quantity that measures the amount of energy per unit area of solar radiation incident on a surface.

Solar thermal collectors: a system that transforms solar radiation into heat, which we can use for our projects. There are different types of solar collectors (flat plate collectors, concentrating solar collectors, etc.), which you can find in our dedicated article! [ii]

Stratification: nothing to do with social stratification or your old geology lessons, in our business we talk about the stratification of heat when it is stored, for example in the form of hot water in large tanks. As the density of a hot fluid is lower than that of a cold fluid, the different temperature levels will separate into distinct strata, provided they are not mixed! It is like swimming in a pool that has been heated by the sun!

Thermocline: this is the transition zone between warm surface waters and the cold waters of the deep. We use this term when checking the performance of our thermal storage systems: a thin thermocline means good storage quality! (i.e. hot and cold do not mix).

ThermoDeep: this is the name of our current Research and Development programme, our 2nd programme selected in the i-Nov Innovation Competition of the Programme d’Investissement d’Avenir “! more information here [iii].

Tracker: this is a sun tracking system that we can use for our collector fields. As the name suggests, it tracks the sun throughout the day using a system of motors and transmissions. These systems can track the sun on 1 or 2 axes. The objective? To optimise the capture of the sun’s rays on the collectors, but not only!

Find below the articles mentioned:

[i] Thermal energy storage • Newheat

[ii] How does solar thermal energy work ? • Newheat

[iii] Découvrez le programme THERMODEEP • Newheat

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