Sustainable Industrial Heat System

TNO develops innovative technologies and processes that reduce the fossil energy use, energy costs and CO₂-emissisions for industry. In this way, we help government, industry and society with a transition to a reliable, sustainable energy system and meeting our climate targets. TNO cooperates with the manufacturing industry and industrial end-users on technological solutions to achieve this more sustainable industry.

Why aim for a sustainable industrial heating system?

Companies are increasingly looking for sustainable solutions for their processes. This is motivated by legislation, consumer demands for more sustainable products and cost reductions. The Netherlands has a large share of energy intensive heavy industry (chemicals, refining, steel, food, paper) with a large demand for heat. By decreasing the dependency on fossil energy carriers, the Netherlands and these industries benefit from increased competitiveness in the global market.

In addition, the Dutch knowledge economy profits from the development of innovative products and processes that have an export potential for technology suppliers. In this way, the transition to a sustainable energy system contributes to reinforcement of Dutch economy and stimulates job creation opportunities.

1. Process efficiency

The first route aims at lowering the intrinsic heat demand of industrial processes (process efficiency). This route replaces existing processes or unit operations by more efficient processes. This may lead to large stepwise reduction in energy use. Implementation of these technology options are often coupled to required replacement or expansion of the existing installations.

2. Reuse and upgrading waste heat

Reuse and upgrading waste heat from industrial processes is the second route. This solution is applied more close to the boundaries of the process, which simplifies implementation on short term to some extent. In addition, this is a generic solution that can be in multiple industrial sectors.

Energy that is used in industry eventually ends up in the ambient atmosphere as waste heat. This waste heat is released by active cooling, by flue gasses or by heat losses from installations. Reuse of this waste heat lowers the energy demand of an industrial process, lowers the energy costs and the emissions.

The problem with the reuse of industrial waste heat is that either the temperature level is too low to be reused in the process or the timing does not correspond with the need for heat. TNO develops several technological solutions to reuse this waste heat in cooperation with  industry and technology partners.

Waste heat to process heat

Waste heat can be upgraded to higher temperature by use of heat pump technology. This can be accomplished in several ways. The generic challenges for industrial heat pump technology are:

• Increase the delivery temperature of industrial heat pumps in order to be interesting for industry to apply. The ultimate goal is to produce steam of 200°C from waste heat.
• Increase the performance of the heat pump to achieve maximal energy and cost savings for the industrial end-user.
• Lower the investments costs to generate a feasible business case for the end-user

A large application market with corresponding energy and emission reduction potential exists for industrial heat pumps, if the three conditions stated above are met. At the same time, this is a very interesting market for equipment manufacturers which would be able to supply innovative heat pump technology.

In cooperation with other similar scientific institutes in Europe, TNO has prepared a whitepaper on the relevance of industrial heat pumps for the industrial energy transition and presented this to the EU.

TNO is active in multiple projects in achieving the targets stated above.

• The LowCapex project aims a developing a full-scale compression heat pump system that generates steam of 120°C out of waste heat of 60°C with a capital costs of 200 €/kW_th
• The FUSE project is targeting higher temperatures. The objective is to develop a 2 MW_th system that is able to produce steam of 150°C from waste heat.
• The next step in the development is set in the ENCORE project. R&D is carried out on somewhat smaller scale (100 kW_th) to increase delivery temperature up to 180°C.
• A thermoacoustic (TA) heat pump is not limited in operating temperatures. The COMTA project aims at heat delivery up to 200°C by means of a in-house developed TA-heat pump.
• Steam compression technology can be applied to compress (very) low pressure steam to useable pressure levels. TNO cooperates with StandardFasel within the SCHP project on a prototype system that upgrades 0.2 bar steam to 5 bar steam.
• Steam compression technology is also being investigated within the SPOT project. A concept developed by DBS is tested, in addition to the StandardFasel technology
• Within the IDEA project, a sorption heat pump is developed specifically for drying processes.

Storage of (waste) heat

Heat that is released from a process at the wrong time, can be stored to be reused at a later time. This can for example be applied in industrial batch processes where waste heat from one batch can be reused to preheat the next batch. Heat storage can also be applied to accommodate fluctuations in either supply or demand. Heat storage can be achieved in different ways, depending on the temperature level and the duration of the storage

Generic challenges with the development of heat storage systems are the efficiency (charge – discharge), stability of materials and investment costs.

Phase change materials (PCM) offer the opportunity to store heat at the melting point of a material. This has the advantage that large amounts of heat can be stored in a small temperature interval. This is an important advantage for the generation of industrial steam. A material with a suitable melting point is selected depending on the application. The FLEXSTEAM project develops a system that stores heat in a very compact way at 150°C.

The application of molten salts is studied for higher temperatures. The molten salt functions both as a heat transfer and heat storage medium. Heat can be transported and stored up till temperatures of 600°C. R&D on this concept is carried out within the SPOT project.

3. Making the heat supply more sustainable

The third route is making the heat supply more sustainable. The use of fossil energy carriers is reduced when a renewable energy carrier is used for the production of heat. In turn, this will reduce the CO₂-emissions.

TNO develop solutions for all these routes and combinations thereof. TNO supplies knowledge of both the technology and the processes and supports industry in their energy transition. The knowledge base is supported by an experimental infrastructure which enables to actually test innovations on a scale level that is relevant for industry:

• Carnot lab, development of technology for reuse of waste heat
• Mollier lab, development of energy efficient drying & dewatering processes
• Membrane separations lab, development of energy efficiency membrane technology
• Combustion lab, development of sustainable combustion technology