Solar heat is an essential asset for our cities' and territories' energy transition

While heat production is the main sector generating greenhouse gas emissions, solutions exist. Solar heat can help decarbonise our use of fossil fuels, foster energy independence, and preserve purchasing power, explains Hugues Defréville, Co-founder & President of Newheat.
Solar heat is an essential asset for our cities' and territories' energy transition
This article (also available in  French) is part of a series in which OECD experts and thought leaders — from around the world and all parts of society — address current global challenges, discussing and developing solutions now and for the future. Aiming to foster the fruitful exchange of expertise and perspectives across fields to help us rise to this critical challenge, opinions expressed do not necessarily represent the views of the OECD.

As climate change becomes more and more visible around the globe, it is essential that we drastically reduce our greenhouse gas (GHG) emissions and abandon the use of fossil fuels (oil, gas and coal) as soon as possible.

A look at the energy use in Europe shows that 50% of our energy needs come from the consumption of heat, whether for industrial processes or to supply buildings and homes (heating, domestic hot water, cooking). However, more than 80% of this heat is currently produced by fossil fuels—mainly gas. Heat production is thus the main sector generating greenhouse gas emissions, more than the transport sector or electricity production. Developing renewable thermal energy is key in the fight against climate change. Given the context of the Russian-Ukrainian war of 2022, it is also an asset for regaining energy autonomy and protecting the purchasing power of consumer citizens, who are directly subjected to the sudden rise in the cost of fossil fuels.


Renewable heat must be considered as a priority in public policy development, to decarbonise our use of fossil fuels, regain our energy independence and preserve the purchasing power of citizens

Decarbonising the heating needs of buildings and housing is a huge challenge for our cities and territories. The most effective tool to address this issue, is the development of district heating networks, mutualising the production and distribution of heat within the most densely populated areas. These networks allow the integration of centralised renewable thermal energy production means, which are particularly competitive for producing heat at these temperature levels below 100°C. The development of district heating networks is very heterogeneous in Europe. While some countries such as Denmark, Finland, Sweden and more generally the eastern part of the European continent have historically made this a priority, this is not the case in other countries, which mainly use individual heating installations, directly exposing their citizens to fluctuations in the price of fossil fuels and soaring electricity costs.

To supply these heating networks, reliable and competitive renewable thermal energy production solutions exist. One of these is the combustion of wood or its by-product, "biomass" in all its forms, which is currently the most developed. When properly managed, it can be part of a positive cycle in which the wood growth compensates a large part of the emissions induced by its combustion. However, this sector has limited development potential: the extensive use of forest resources implies the use of huge land areas, increasing the pressure on biodiversity and not allowing any carbon sink effect. Furthermore, the social acceptability of this energy clashes with the problems of road traffic and air quality that it creates.

However, there are also other solutions for producing renewable heat, without the need for any input or combustion and using free and unlimited resources. This is the case of large-scale solar thermal plants.

This sector, which is still underdeveloped in Europe, is yet the most virtuous and relevant solution for supplying our heating needs below 100°C.

Based on a particularly simple and robust technology—a flat-plate solar thermal collector is a simple metal plate that heats up in the sun, behind which water circulates and heats up by contact—this sector first appeared about a decade ago, with the emergence of large installations (plants with unit areas of several thousand or even tens of thousands of square metres), particularly in Denmark, a country counting 1.5 GW of solar thermal plants currently in operation.

This sector, which is still underdeveloped in Europe, is yet the most virtuous and relevant solution for supplying our heating needs below 100°C. Its development potential is huge: a "low tech" solution using readily available materials and the sun, it uses an energy source that is a local, free and plentiful resource (even in Northern Europe). With the best carbon footprint of all renewable energies, it does not generate any local nuisance, whether in terms of air quality, noise emissions, visual impact or road traffic. Moreover, in terms of landgrab, solar thermal power plants are a "lesser evil": for a given land area, they produce five times more energy than a photovoltaic solar power plant, and 40 times more than a forest area cleared every 30 years to supply a biomass heating plant.


Based on these observations, Newheat has chosen to develop the necessary skills to offer to our customers (industrial sites and public authorities in charge of developing district heating networks) complete decarbonation solutions, combining large solar thermal installations, with innovative thermal storage systems and, where possible, waste heat recovery systems. Thanks to our investments in R&D and the success of our first projects, we are now offering "at the meter" heat supply services throughout Europe, where we bear 100% of the investment and operating costs of the plants, enabling our customers to focus on their core business and accelerate their transition to a low-carbon production model.

It is clear that solar heat is an optimal solution for supplying district heating networks. Its large-scale development will make it possible to limit the use of our planet's rare and precious resources (biomass, green gases or electricity) to the decarbonisation of the most complex uses (mobility, very high temperature thermal needs, etc.). Let us define the decarbonation solutions to prioritise for each use—and let us provide ourselves with the means to deploy them at the rate necessary to preserve our environment for future generations.

This article was published in the context of the 4th OECD Roundtable on the Circular Economy in Cities and Regions, which has now ended. For more information, check out also OECD work on the Circular Economy in Cities and Regions.

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