What happens with the water: plants, cooling, hygiene, hydrogen. These building blocks consume water instead of supplying it.
Electrolysis (hydrogen)
What is it? Electricity splits water into hydrogen and oxygen. Turns electricity into a storable fuel – and consumes very pure water doing so.
How does it work?
Electricity splits water into hydrogen and oxygen. It needs very pure water and a lot of electricity; the hydrogen can be stored and later turned back into electricity. By calculation, one kilogram of hydrogen contains about nine litres of water, plus losses and cooling. A lot of energy is lost along the way.
- Needs
- sun, wind or a grid connection
- rain, fog, dew, a well, a tap or an air-water generator
- a treatment step, mains water or an air-water generator
Hydroponic tower
What is it? Plants grow without soil in a vertical loop of nutrient solution. Needs far less water than a bed producing the same harvest.
How does it work?
Plants grow without soil in a tower; the roots stand in a nutrient solution of water and dissolved fertiliser salts that a pump circulates. The water stays in a loop, so consumption is much lower than in field cultivation; some evaporates through the leaves. It needs electricity (pump, often light), nutrients and monitoring of pH and nutrient content.
- Needs
- sun, wind or a grid connection
- rain, fog, dew, a well, a tap or an air-water generator
- a water tank
Aquaponic tower
What is it? Hydroponics with a fish tank: the fish fertilise the plants, the plants clean the water. More yield, but also more care.
How does it work?
Fish farming and plant growing in one loop: fish excrete ammonium, bacteria convert it into nitrate, which the plants take up as fertiliser. That way the plants clean the water for the fish. A pump circulates the water. The system is sensitive – feeding, temperature and water values must be right – but needs little fresh water.
- Needs
- sun, wind or a grid connection
- rain, fog, dew, a well, a tap or an air-water generator
- a water tank
Drip irrigation
What is it? Hoses deliver water drop by drop straight to the root. Loses far less to evaporation than watering or sprinkling.
How does it work?
Hoses with small emitters release water slowly straight to the roots. Little water is lost to evaporation or runoff, so drip irrigation saves a lot of water compared with sprinklers. It works at low pressure; filters against clogged emitters are important.
- Needs
- rain, fog, dew, a well, a tap or an air-water generator
- a water tank
Evaporative cooling
What is it? Air passes over wet surfaces and cools down as water evaporates. Works only in dry air – and the water is gone afterwards.
How does it work?
Water evaporates and in doing so draws heat from the surroundings (evaporative cooling), like sweating. Warm, dry air flows over a damp material and becomes cooler and more humid. That cools with little electricity, but works well only in dry air and consumes water.
- Needs
- sun, wind or a grid connection
- rain, fog, dew, a well, a tap or an air-water generator
- a water tank
- Needed by
- Cold storage (PCM)
Handwashing station
What is it? Basin, tap and drain for washing hands. The most common reason a place needs water at all.
How does it work?
A simple washing point with a water supply and a drain. Washing hands with soap markedly reduces the risk of infection. It needs only a little water per use; what matters is a reliable supply and a clean drain.
- Needs
- rain, fog, dew, a well, a tap or an air-water generator
- a treatment step, mains water or an air-water generator
Household electricity
What is it? The electricity a household uses over the year: light, cooking, washing, devices. Spread over the day the way real households were measured.
How does it work?
You enter the annual consumption, ideally from your electricity bill. Droply spreads it over the hours using the BDEW standard load profile H25: little at night, a peak in the morning and a bigger one in the evening, more in winter than in summer. That is exactly why solar power alone never covers everything – there is no sun in the evening. The profile is an average over many households; a single household has higher peaks.
- Needs
- sun, wind or a grid connection
Heat pump
What is it? Heats with electricity but takes most of the heat from the air or the ground. On average 1 kWh of electricity yields a good 3 kWh of heat.
How does it work?
A heat pump works like a fridge in reverse: a refrigerant picks up heat outside, a compressor raises it to heating temperature. The seasonal performance factor says how much heat comes out per kilowatt-hour of electricity – in measured existing homes 3.4 on average for air, 4.3 for ground source. Droply still spreads the electricity evenly over the year. In reality almost all of it is needed in winter, when solar panels deliver least.
- Needs
- sun, wind or a grid connection
Wallbox (EV)
What is it? Home charging station for an electric car. The electricity demand follows from distance driven and the car's consumption.
How does it work?
A wallbox charges the car faster and more safely than a normal socket. Droply works out the demand from kilometres per year and consumption per 100 km (19.7 kWh on average in the ADAC test, charging losses included). It assumes charging in the evening after getting home. Charging at home during the day lets you use far more solar power directly.
- Needs
- sun, wind or a grid connection
