Waste heat delivered in a container
A recent project led me to the task of quantifying amounts of waste heat emitted by US industries and the assessment of opportunities for its recovery. As one would expect, excess heat in the form of hot gases, steam or liquids produced by energy intensive industries such as oil refineries, chemicals and steel is plenty. Trillions of Btu’s are (British Thermal Unit with 1 Btu = app. 1kJ) are released to the environment each year, enough to cover for Denmark’s and Croatia’s combined annual energy demand. Considering such the large amount of wasted energy it is easy to understand why its recovery also stands for a significant economic opportunity. This opportunity however, is strongly linked to conditions of economic feasibility, with two key requirements being the low costs of equipment as well as the readily available use for the recovered heat. Interesting, while heat recovery equipment fulfilling the requirement of relatively low initial costs, is available and already widely in use, finding readily available use for the recovered heat can be a challenge difficult to tackle. This is particular the case for industries such as cement where plants are banned to remote areas due to high noise and pollution levels and where in addition is little use for recovered heat on site due to a lack of processes and sub-processes. Thus, the questions of how to get the heat recovered from a plant to the end-user, in an economic viable fashion is a key aspect to waste heat recovery. As recently announced, in the German industrial city of Dortmund a physicist, an information scientist and an investor demonstrated what could be a solution to the problem – a container, a container which enables to carry heat from various industrial processes to sites where it can be used. Moreover, a fist project has already been realised for a local swimming pool. The container with the heat, which was recaptured from a plant outside town, is connected to the heating system of the swimming pool and now provides it with heat. The storage technology, which was developed at the German Aerospace Center (DLR), is based on a so-called latent heat and surprisingly simple: With the recovered heat, a sodium acetate, which is also used for the curing of meat is brought to melt and the resulting stored energy is later during crystallization released again. It is the same effect that is already being used on a small scale: for example, hand-sized heating pads that can be put into a jacket pocket. With the pilot project seemingly being a success, its inventors are joined by officials at the German Environmental Protection Agency in predicting a great potential for this technology. Critics referring to the container as an eye-sore with little chance of being installed without objections of the public have been silenced as the use of the container is planned for public buildings, including swimming pools, schools and hospitals rather than residential buildings. Objection that the environmental benefits of heat recovery are undermined by the carbon miles used for the transport of the container have also been refuted by the fact that the fuel used for the transport is fractional to the energy in the container. Besides, the use of bio-diesel could be considered. The real challenge, so experts, is in the logistics of delivering heat ‘just in time’ as this is crucial to the projects commercial viability. To find further ways of optimizing the ‘loading and un-loading’ of energy, the project owners have teamed up with the local municipality’s utility provider. While the developers admit that significant improvements in this field may take up to two years time, they point to the fact that an anticipated rise of energy prices may help their cause in the meanwhile. So, what to make of this ‘energy on wheels’? A brilliant solution of delivering trillions Btu’s that are wasted in industrial process to places where it is needed? A great investment opportunity? Well, its technical feasibility seems proven, if the prove of its economic feasibility follows, it may become considered as a serious option of reducing waste heat in the industrial sector. Admittedly, it would be one option of many, however considering the scale of industrial waste heat losses, enough for its inventors to get very excited about.