Exergy

A valid standard to determine the value of commodities, products and emissions is exergy. This is the maximum of energy that can be taken from a commodity, a product or an emission. It is possible to calculate the exergy for all commodities, products and emissions in an industrial process. A mayor advantage of calculated exergy values is that they are expressed in the same unit (Joule [J]). It offers the possibility to accumulate very diverse flows and processes while presenting it in a very unified output. On base of a 'exergy household' in a process, it is possible to sketch a transparent insight in the efficiency of certain systems.

In an efficient process, the energy commodities contain is almost completely transmitted to products, and only a small amount will be converted into emission. As a result, only a small percentage of energy have to be taken from those emissions so the emissions aren't harmful for ecosystems and environment. A process with a very low efficiency on the other hand will discharge 'high-exergetic' emissions into ecosystems. This sort of emissionproducts contain a lot of energy and are harmful for environment. Exergy of emissions is thus an indicator for the damageability for ecosystems, and exergetic efficiency is an indicator for the sustainability of a process.

For areas and buildings that use energy, this exergetic efficiency is highly relevant. It is possible to determine the chances of energyflows, flows nowadays too often emitted into nowhere. An welknown examples rethinking energy flows is the city heating. Heat surplus from energy-or waste treatment plants is used to heat adjacent neighbourhoods instead of dumping into rivers of lakes. But also the combination of icerink and tropical swimparadise is smart. Cooling produces a lot of heat. The combination with a tropical swimparadise is also smart since both can share central fascilities.

'Energy Potential Mapping' is introduced to find potential energy savings. With this method, all energyflows, energy produces and emitters, are visualized for a defined area. The next step is finding and creating relationships between the different systems, which will result in an optimal exergetic efficience and will minimalize emissions.

JV/AdN

Sources:

www.exergieplanning.nl
 

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