Provide water for urban gardening that does not need a grid connection.
Suited for small-scale apartment urban farming, the idea is to lower threshold in providing fresh produce to inner-cities.
Think - hanging gardens or planters that "never need watering".
Very similar to the thermo-electric de-humidifiers.
Current idea - solar powered thermo-electric condenser to draw water from the atmosphere. Battery to be able to operate at night, microcontroller and sensors to determine most efficient period of operation (ie. during time of day with the smallest dew-point depression).
Limitations - Small units would only have limited output (less than 1L a day).
Device would need sunlight for PV charging, or access to a suitable power source.
Myself (background in Electronic Engineering, currently a medical doctor),
Wife (background in Biomedical Science, currently a medical doctor),
Bachelor Number 3 (background in CS, currently working in systems engineering)
Thermoelectric device, also known as a heat-pump. DC current causes one side to get hot while the other gets cold. Capable of up to 70C temperature differential. Supposedly operates at about 10% efficiency.
Probably an arduino with sensors (cheap and easily available): Temperature (ambient, hot-side, cold-side), Humidity (ambient). For power management and scheduling activity during optimum periods
"bent bit of plastic and aluminium" - This is the tricky bit. There will need to be suitable air through-put to yield adequate moisture, ideally the cool-dry output air will be ducted over the hot-side heat-sink to improve efficiency.
Solar PV power-supply
Power-supply to make the device truly portable and off-grid. It would be easier to have this run from the grid, but making it solar will result in it being suitable for austere/impoverished environments, top of sky-scrapers, pot-plants in strange places...
LED pathway lights, vibration generator to scare off snakes, ultrasound to scare off rodents... yeah,... feature creep...