Ambiente Environment Cartuja Qanat Sevilla Siviglia rendering
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Past technologies to counter climate change

A technique that originated in ancient Persia and another tested for the first time in the 1960s are helping some Spanish cities tackle the consequences of global warming.

«I'd like you to notice that I'm not wearing a tie», highlighted Pedro Sánchez during a press conference in July 2022. «We can all save energy with a small gesture [...]. This way, we will all contribute to the energy saving so needed by our country», observed the Spanish Prime Minister. Spain is, in fact, more affected than others by the effects of global warming which, during last summer, led to abnormal heat waves in multiple cities. The interesting thing is that local authorities are seeking to experiment with non-conventional technologies to tackle climate change in addition to the more traditional and far-reaching policies. We have seen it in Seville and Gran Canaria which rediscovered techniques that were used in the past to help tackle the climate crisis.

The local authorities in Seville, in the south of Spain, had been looking for solutions to counter the consequences of a further increase in temperatures due to global warming. In the summer, the Andalusian capital often reaches temperatures exceeding 40°C, which makes it one of the hottest cities in Europe. The technology they opted for, which is also found in other countries characterised by a particularly dry climate, derives directly from the so-called "qanat", i.e. special wells that were developed in ancient Persia over 1,000 years ago.

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The qanats used to be a series of vertical tunnels, similar to wells, connected by an underground canal characterized by a slight slope; the canals started from an aquifer and enabled the water to reach great distances taking advantage of gravity without losing some of it due to evaporation. The same principle was used and modernized by the engineers who developed the "Cartuja Qanat" project for the city of Seville: in this case, the purpose is to transport water to cool a large part of the city centre naturally thanks to a system of vertical openings that enable the cool air to reach the surface.

The project of the Seville municipality, 80% of which was financed by the European Union and which costs €5 million, takes inspiration from and improves an experiment tested by the city during the 1992 Expo. Thirty years ago, the water had been pumped and partly cooled using fossil fuels, while now the process uses entirely renewable sources. The part of Seville subject to this new technological experiment will enjoy a reduction in temperatures of approximately 10°C and it is estimated that the process will work up to 41°C. If the results are those expected, the local administration has expressed its intention to expand the network of modern qanats also to other areas, and has already planned a test in one of the city’s main streets - Avenida de la Cruz Roja.

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Another technology of the past, recently implemented in Spain to counter the effect of climate change, comes from the 1960s. We are talking about the so-called "captanieblas", i.e. "fog-catchers". Captanieblas, also known as atrapanieblas, are plastic nets placed on structures along windy slopes and can capture the water contained in the fog with the final purpose of irrigating deforested territories. The wind facilitates water condensation, which is "captured" by the net and then drips into a container placed below the structure.

Many can be observed along slopes in Gran Canaria, the third largest island in the archipelago of the Canary Islands: Life Nieblas, one of the projects for the environment and climate actions financed by the European Union initiated in 2020, installed them in Spain as well as in some locations in Portugal. The objective of the project active in Gran Canaria is to collect 215 thousand litres of water a year in order to favour the reforestation of 35 hectares of land damaged by fire.

The first model of captanieblas was designed in Chile in the mid-1900s to be used in the Atacama desert, one of the driest regions in the world which, however, is also very foggy due to its proximity to the Pacific Ocean. It was then tested in other south American countries too. This artificial system to collect fog humidity is not suitable for use in the Mediterranean area as it is too dry, but it does work very well in foggy and windy areas such as those facing the Atlantic Ocean. That is why a similar method will also be tested in Catalonia to try to hasten the reforestation of an area that was greatly damaged by fire in 2015.

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