Heat recovery is directly related to solutions such as Waste Heat Recovery, Decarbonisation, Sustainable Industries, Synergies,  Heat-to Power Solutions, Heat pipes, Absorption Heat Transformers, or Heat Pumps.

Identification of best opportunities for heat recovery within a facility is not straight forward. Depends very much on:

• Exergy balance: Available energy according to its temperature, flow, etc. will condition the potential of a waste heat from the technical point of view.
• Temporal availability: Whether the availability is continuous or intermittent is an important pre-condition.
• Expected paybacks. Financial viability and short paybacks (2-3 years) mark many of these projects.

As enabling conditions, we can group them into two main categories: The first one, any enabler that would help solving technical feasibility. This would include not only the identification of best heat recovery opportunity but also the selection of the best suitable technology for the best business case. Within this group of enablers we can count assessment programs in energy efficiency, energy audits of industrial processes, etc. The second one is the group of financial enablers from subsidies to the recover heat to soft loans to finance the projects. In this second group we can also consider all necessary elements for the business case such as the presence of external operators, investors, etc.

Available waste heat is basically reused back into the same process or into the energy supply of the facility. Recovery for its valorisation outside of the facility presents several barriers (although some are also common to own valorisation in the facility):

Physical barriers related to the site:

There are barriers related to the available space for the recovery units, processes or the distance from the waste heat source and the heat sink.

Low exergy heat:

Not reused waste heat in the facility is, generally speaking, of low exergy and therefore its valorisation may be more difficult from the technical and financial point of view.

Production cycles:

Recovery must take into account the production cycle which also should consider shut downs due to maintenance or capacity. This generates difficulties in guaranteeing a continuous supply of the waste heat.

External operators:

Valorisation out of the facility usually requires an external operator (district heating operator for instance) that will take care of the valorisation. Agreement, considering technical and financial operation of the system between the parties involved will depend on the value proposition perceived by each party.

After implementation there are not substantial adverse impacts as long as the production is not affected at the facility and the waste heat can be recovered as agreed (production changes may produce variations in temperature, flow rates, etc. that also changes available exergy).

It will also require some additional maintenance that should be clear who must provide regularly

• Resource Pack on waste heat valorisation - Improving energy efficiency in process industries (CORDIS)
• Handbook for Increased recovery of urban excess heat (ReUseHeat project)

In terms of KPIs the most usual ones are related to the amount of energy provided through the valorisation of the waste heat. Will definitely vary upon its temperature, flow rate, recovery solution, user, etc. But there will be others related to business model behind the proposed solution to measure the performance of the system.

From the point of view of DNSH principle it must be pointed out that this solution avoids substantial harms. Recovery of waste heat is a circular action that provides energy otherwise wasted and therefore reduces also the footprint. Furthermore, it develops a local solution that will improve local energy capacity. Due to the recovery systems, heat exchangers, piping, etc. metal production is the main source of emissions form a lifecycle point of view.

Most interesting instruments are the ones that can help to finance the CAPEX and OPEX of these projects. From the list of instruments in NetZeroCities we can consider:

• Loan for Energy Efficiency (https://netzerocities.app/resource-1648) to provide soft funding
• Blended finance for Energy Efficiency (https://netzerocities.app/resource-1658)

But it is also interesting to consider instruments related to planning where waste heat recovery from nearby industries or companies may be a renewable source of energy that should also be consider. For instance the following two instruments :

• Integrated land use and urban planning with energy and climate (https://netzerocities.app/resource-1678) for introducing specific measures to foster waste heat recovery
• Integrated climate plans for cities (https://netzerocities.app/resource-1698) for considering waste hear recovery & valorisation as a working line to explore.

Waste heat valorisation: A thematic collection of innovative EU-funded research results:

Waste heat valorisation (EC, 2020) and some Eu-funded projects as HEATLEAP, ReUseHeat, W.E. DISTRICT and LowUP.