of the supply and demand. The key features here are cost- efficient large-scale thermal storage, which come at a fractional cost compared to alternative energy storage, such as battery storage. Heat recovery applications Clearly, simply capturing the waste heat is not enough; it will also need to be made available to the waste heat user at the right temperature level. Depending on the temperature level of the captured waste heat relative to the temperature requirement of the waste heat users, different temperature adaption options are available. These can be 1) direct heat exchange via heat exchanger, 2) a combination of a heat exchanger and a heat booster unit, could be a heat pump, or 3) a heat pump.
In other instances, such as subway stations, the ventilation systems can be retrofitted with simple air-to-water heat exchangers to capture the waste heat. The bottom line is that waste heat recovery is typically not complicated from a technical point of view. The complexities are generally on the organization side, where it can be narrowed down to the lack of knowledge of the potential value of the waste heat, complicated local regulations, unfavorable tax regulations, or complex reporting and documentation requirements. F) No need; decarbonized electricity is just around the corner... Which corner and at what cost? The fact is that while electrification and decarbonized electricity are very big parts of the future solution, it truly matters how electrification takes place. It can be made sustainable and cost-effective with a minimal ecological footprint, or it can be made with a major ecological footprint and high cost. Smart electrification is to utilize all available resources to minimize the final electricity demand, and by this, the investment in the generation and distribution capacity is also minimized. In this regard, waste heat sources and other renewable, low-temperature sources are immensely important. Another important aspect is ensuring as much decoupling of the electricity demand and generation as possible. In fact, decoupling is the number one measure for enabling sustainable and cost-effective electricity generation based on intermittent and fluctuating renewables. This is where district heating and district cooling come into play, as no other technology can make as cost-effective decoupling
The following section will present the general heat recovery options with district heating in mind.
Case 1: Direct heat exchange via heat exchanger In case the temperature of the waste heat is high enough to directly fulfill the temperature requirement of the district heating system, a simple heat exchanger solution should be applied:
Figure 1: An example of simple direct waste heat recovery using heat exchangers.
12 HOTCOOL no.6 2024
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