In a context where reducing energy consumption is becoming a universal necessity, the exploitation of waste heat represents an opportunity that is still little used, particularly in the industrial sector. Its implementation, both simple and economical, brings a multitude of advantages. Focus on the recovery of the waste heat of his company.
Fatal heat: what is it?
The heat emitted naturally and inevitably by a process is known by various names, such as "waste heat", "recovery heat", or "waste heat". This last expression underlines its inescapable nature. If no recovery method is implemented, this heat dissipates, thus causing significant waste, hence the term "lost". However, it offers very promising reuse potential.
Examples of recoverable waste heat
Many circumstances lead to the production of unused heat:
- In the industrial and tertiary sectors, cooling processes often result in the emission of heat, which is generally underestimated;
- Heating equipment, whether domestic boilers or industrial ovens, emits not only usable heat but also reusable energy through fumes or heated walls;
- The combustion of household waste;
- The discharge of lukewarm wastewater;
- The drying process releases hot water vapor, representing a significant source of energy.
Depending on the situation, these heat releases can be in liquid form (waste water, purges, etc.), gaseous (hot air, steam, smoke, etc.) or diffuse (losses due to insufficient insulation, natural cooling, thermal radiation). ...). The temperature of these releases varies greatly, ranging from less than 30°C to around 500°C.
Why should a company recover its waste heat?
Optimize energy consumption and reduce costs
The exploitation of waste heat is an economically advantageous approach, responding to the growing interest of economic players in energy saving.
By reusing this heat for other thermal, cooling or electrical production needs, companies reduce their energy consumption and, consequently, their energy expenses.
These initiatives also contribute to improving their carbon footprint and support their approach towards decarbonization. They also offer better comfort to users, in particular by controlling areas of high heat. These advantages make companies more efficient, competitive and well-regarded by their partners.
Prepare for regulatory developments
These advantages encourage anticipation of future regulations. In France, certain industrial sectors are already obliged to carry out a cost-benefit analysis for the recovery of waste heat in heating networks for installations of more than 20 MW subject to regulationsICPE (ICPE designates installations classified for environmental protection, and their regulations aim to supervise the dangers associated with industrial and agricultural activities, with the aim of safeguarding both health and the ecosystem.). The European Union, with its Green New Deal and the "Fit for 55" plan, is aiming for carbon neutrality by 2050, with an intermediate objective of reducing emissions by 55% by 2030. Specific measures concerning heat fatal, with a return on investment of less than five years, are under discussion.
Take advantage of various financial supports and financing solutions
In France, heat recovery benefits from significant financial support. The ADEME Heat Fund finances 20% of investments for large companies and up to 90% of studies for renewable heat networks. The Energy savings certificates (CEE) cover on average 50% of the necessary investments.
How to recover fatal heat?
Audit and feasibility study
Before considering the recovery and valorization of energy, it is essential to focus on optimizing its use. This involves reducing losses by improving the energy performance of devices, reconsidering operational processes, or even reinforcing insulation, for example.
Subsequently, it is essential to carry out an audit. Each site, activity and building has its own sources and possibilities for heat recovery. In addition, the recovery options can be diverse, involving technical, economic, organizational or regulatory aspects.
It is therefore inadequate to establish a universal strategy. The audit will identify various opportunities in terms of energy performance, waste heat recovery and the exploitation of renewable energies.
For further investigation from a recovery perspective, a feasibility study is required. Its objective is in particular to determine temperature needs, by carrying out measurements on the sources of waste heat (flow, temperatures, etc.) and the corresponding needs. This study will help to choose the most suitable form of recovery, whether direct or indirect, with or without modification of the energy vector
It is also crucial to consider the temporal and seasonal correspondence between heat sources and needs. For example, the heat recovered from a cooling system in a hospital will not necessarily be useful for heating the establishment.
From a technological point of view, heat recovery generally relies on an exchanger and a heat distribution system. Their capacity must be adapted to specific needs. If necessary, a high temperature heat pump can be used to achieve the required temperature levels.
Valorization of its fatal heat with change of energy vector
The recovered heat can be used in various ways. To begin with, it can be used to heat a thermal fluid, thus meeting the needs for domestic hot water, air heating for spaces or for industrial processes.
Furthermore, it can be transformed to offer a different service. Several forms of energy vector exist:
- Electricity: in particular through the ORC (Organic Rankine Cycle) technology, used by companies like Enogia and Enertime;
- Pressurized air ;
- Cold: for example with an adsorption machine.
