Muhaimin Iqbal
Author

Waste Heat Energy (WHE), the Elephant in the Eyelid

Advanced Renewable

Mon , 06 May 2024 17:35 WIB

This enormous new energy source could be right before our eyes, simply because it is so close - like the proverbial elephant in the eyelid that cannot be seen, the potential of this new energy has not yet been widely exploited. The new energy I mean here is waste heat energy (WHE).

This waste heat is everywhere on a very massive scale, both in industrial and commercial activities, there are two sources, namely from endothermic processes - processes that require heat, but the heat supply exceeds requirements due to in-efficiency factors which almost inevitably occur in every heat process, then this excess heat becomes waste heat.

The second source is even more interesting, namely from exothermic processes - where the process itself emits heat. So far, we generally know that heat is the result of combustion, namely fuel that is reacted with oxygen - the result is heat. The exothermic process does not necessarily involve combustion or oxidation with oxygen, but it also produces heat.

For example, if we react CO gas with H2 to produce hydrocarbon fuel (CxHy) plus water (H2O), this process is very exothermic, the heat energy value that becomes waste heat is approximately half of the energy value contained in the hydrocarbon product. This would certainly be huge if we could catch and process it.

Imagine if we produced fuel in this way - the reaction is called Fischer Tropsch Synthesis (FTS), the reactor form is like the one I uploaded yesterday here: https://lnkd.in/e9Nyqp55, for every ton of fuel we produce, there is the potential for waste heat which is equivalent to 1/2 ton of oil!

The next question is how can we utilize this waste heat effectively? One way is to use a Waste Heat Energy (WHE) system like the picture below. The WHE we designed operates using Organic Rankine Cycle (ORC) technology, which can be arranged in cascades to capture waste heat from various temperature ranges. The initial waste heat is captured by ORC 1, ORC 1 waste heat is captured again by ORC 2 and if necessary it can reach ORC 3 - depending on the initial temperature of the existing waste heat.

With the concept of producing fuel and electricity at the same time with the same basic energy source - in this case biomass or charcoal, it will be possible to elevate the selling value of biomass/charcoal so that processing all our waste into energy will be feasible and attractive, our cities will be clean and energy cost will be cheap.

Another use, heat and electricity energy which does not need to be burned with oxygen and even produces waste in the form of water, could also be a solution for special missions where oxygen and water are scarce or must be highly conserved. Examples are travel into outer space and into the depths of the sea/earth by submarine, both of which need mastering in energy, oxygen and water cycles, this WHE can serve this purpose.