The dreaded humidity. Over wintering in the UK without a heat source is very unpleasant, mainly due to the build up of humidity inside the van. It chills you to the bone and it’s nearly impossible to get rid of it unless you have a heat source. Prolonged relentless rain and the city environment I’m currently in means that I can’t open the doors and hang out my mattress and duvet as often as I would like, further exacerbating the problem. Any further and I will be fighting with mold throughout the long dark months of winter which is quite a bleak thought.
So I’ve finally succumbed and ordered a Chinese diesel heater, which is currently travelling across the Earth at snail’s pace. Diesel heater was something I wanted to avoid but the alternatives are just not feasible at the moment. To use my 700W oil heater, which is tiny by oil heater standards, I’d need a humongous solar array that stretches beyond my roof space with a gigantic battery bank if I want it on at night. And I don’t have enough space in my vehicle to create a safe perimeter around even the smallest of wood burners. Opening windows and aerating it is meaningless when it’s pissing down with rain.
Contrary to what some readers might think, the cold isn’t such a big problem. Frosty nights are absolutely fine as long as the duvet is dry and fluffy. All I need is something that can suck water out of the air…. Surely it won’t be as energy intensive as running an electric heater?
The problem is that a standard dehumidifier uses condensation to draw moisture out of the air – by cooling it with a compressor – meaning that it just doesn’t work in colder temperatures below 15C. Great for tropical countries but absolutely useless in the UK winter.
A more recent addition called desiccant dehumidifier uses a fan to push air through a silica gel or Zeolite rotor that absorbs moisture. A portion of the rotor is then blasted with hot air (90 to 140C) to remove the humidity and reactivates the desiccant wheel’s capacity to absorb more water. This absorption is effective even at very low temperatures down to 1C and is mechanically far more simpler than a compressor type, reducing the points of failures.
The only problem is the need to heat the rotor to remove the humidity it absorbed. A moderately sized desiccant dehumidifier will still consume about 600W to do so which writes off the possibility of using one in my van.
But in a dreamy state last night, it really hit me. There must be a way to engineer a super low energy solution based on laws of nature and biomimicry.
What is Biomimicry?
Biomimicry is an approach to innovation that seeks sustainable solutions to human challenges by emulating nature’s time-tested patterns and strategies.Biomimicry Institute
Humpback whales are able to turn incredibly tight angles due to its tubercles on their fins which grips the water even at low speeds. A model of the fin tested in a wind turbine showed 32% reduction in drag with 40% increase in angle of attack. Whalepower is currently working to improve the efficiency of wind turbines with potential for application in airplanes and fans.
Recent research suggests that termite mounds acts as a natural air conditioner, able to maintain a steady internal temperature through internal air currents driven by solar heat. There are multiple high rise buildings that have a structural climate control system inspired by the termite mounds.
There is a company that imitates the ability of corals to sequester carbon dioxide to create its rigid structures. They are now able to produce carbon negative concrete which is mind boggling since current methods of making concrete is responsible for 5-8% of CO2 emissions globally.
By mimicing how schools of fish are able to move in water efficiently by using the vortices created by the fish in front, scientists were able to create vertical axis wind farms that generated 10 times more wind power.
Another research revealed how mycelium helped to grow certain grass specie in extremely hot conditions next to a hot spring in Yellow Stone Park. They applied this mycelium to seed and was able to grow 5 times more rice using half the water. Imagine the implications in the near future when droughts and water scarcity hits us full on.
More examples of biomimicry can be read here.
Biomimicry Inspired Desiccant Dehumidifier Design Idea
So back to the dreamy inspiration. What if the zeolite rotor that absorbs humidity could be spun a bit faster to use centrifugal force instead (like a salad spinner)? What if the zeolite was formed in a way that it wicked to a finer and finer concentric branching pattern, allowing the edges to reach a saturation point and drip off naturally? Perhaps the zeolite could be encouraged to shed the water by intermeshing it with hydrophobic materials mimicking the structures of lotus leaves.
The only energy used by this system would be to fan the air flow and to spin the rotor. Both of which could be run with the minimal output of my solar setup, especially if the blades mimicked the humpback whales fins to achieve 35-40% efficiency gain… The solution is structural, with the least amount of moving parts and should require very little maintenance or repairs. If the 2 motors could be made in a way that it’s removable and repairable, the product could be used almost indefinitely.
I stated in my last post that a path to an indefinitely sustainable future lies in us figuring out how to live within the boundaries of nature. A key part of that must surely come from taking inspiration from the 3.6 billion years of R&D already perfected by life, to solve problems in context with minimum energy use and to preserve the environment for the future generations. There are astonishingly elegant solutions all around us if we look closely enough.