Heat wave mitigation in urban environment as a modelling tool for water cycle and possible influence of solar energy exploitation thereon

Created by Tomas Kalisz

It might be good to drive air conditioning equipments in buildings solely with electricity produced by solar cells. Present solar technology, however, produces significant amount of waste heat that might compromise the overall urban micro-climate by enhyncing the "heat island" phenomenon. On the other hand, there is a yet unexploited option that solar technology might be upgraded so that it will produce very little instant heat, by converting the waste heat could into latent heat of water wapour instead. This way, building-integrated solar cells could substitute missing evapotranspiration function of plants that are largely missing in urban environments, especially in industrial or business areas and city centres. An experimental comparison of the influence of both classical "dry-operated" solar panels an their "wet-operated" version could, if run in parallel with respective modelling of both cases, not only clarify the potential of both approaches for heat wave mitigation in cities, but also help to prove reliability of various modeling approaches and validity of their prodictions. This might be invaluable for further solar technology development and proper implementation thereof.

#climate modelling, #evapotranspiration, #heat islands, #heat waves, #solar cell cooling, #solar energy, #sustainable electricity production, #water cycle

low efficiency

Semiconductor physics implies that solar cell efficiency decreases with teperature of the p-n junction included in the cell.

Lot of waste heat produced

In form of dry hot air

or might it perhaps make deserts green again?

A model suggests that lot of excessive dry hot air created by solar installation in Sahara desert might bring rain thereto.

Another model asserts the same conlusion for deserts along to Red Sea.

Low cost

Simplicity

Cons

might worsen "heat island" phenomenon?

experimentally

by practical comparison on a small scale

design an urban experiment?

Estalished technology

Pros:

Classical ("dry")

Currently, photovoltaic cells used for direct solar energy coversion into electricity are passively cooled by radiation + air convection.

passive air cooling

The difference may have consequences for climate

we can check/prove it

Ideally both in parallel!

the experiment could validate which models reflect truth

crucial information whether or not it can make a sense to develop the alternative solar technology can be obtained

along with more reliable hints whether or not a massive use of solar technology can pose an environmental risks

Solar cell technology

might cool urban landscapes?

depending on what is true

theoretically

by modelling

start a modelling project?

Commercially unavailable yet

Alternative ("wet")

One of the oldest and simplest means for an effective cooling is making the cooled object wet and ensure an efficient air convention around the object. Heat created in the object converts into latent heat of water vapour.

Vaporization of 1 kg water consumes ca 2257 kJ (0.627 kWh) energy.

evaporative active cooling

Cons:

Pros:

In form of latent heat of water vapor

video: jan Pokorný, Anastassia Makarieva

https://www.youtube.com/watch?v=uxEwJYNb_zA

Higher cost

Complexity

higher efficiency

might act as a substitute for "biotic pump"?

The biotic pump hypothesis asserts that water evapotranspiration by terrestrial vegetation, enhancing the small water cycle, may play a crucial role for water transport from ocean to land and thus for functionality of the entire "big" water cycle.

But still significant waste heat produced