Water from Air

Henk Miedema

Wetsus in Leeuwarden

April 12, 2017

Wetsus?

Wetsus

Sustainability

Wetter = water in Frisian language

Water scarcity - 2020

Where is (fresh drinking) water?

The hidden source: Atmospheric water

Just 2% but still

amounting to

13.000 km3

% water vapor in relation to relative humidity and temperature

Natural water cycle

Nature exploits the water dew point!

…and so does the Dutch Rainmaker

Participant in the WetsusResearch Program

How to improve the system?

Latent heat of condensation

Delineation energy cost of air cooling & condensation

Energy in kJ

Temperature in 0C

Total energy

Cooling air

Condensing vapor

CoolingCondensate

PhD thesis, TUe - Wetsus Daniel Bergmair, 2015

H2O

O2

N2N2

N2

N2N2 N2

N2

O2

O2

O2

O2

N2

N2

N2

N2

N2

N2

N2

O2O2

H2OH2O

N2 N2

N2

N2

H2O

H2O

H2O

H2O

H2O

H2OH2O

H2ON2

H2O

H2O

H2O

H2O

H2OH

2O s

elec

tive

mem

bran

e

H2OH2O

O2O2

N2N2N2N2

N2N2

N2N2N2N2 N2N2

N2N2

O2O2

O2O2

O2O2

O2O2

N2N2

N2N2

N2N2

N2N2

N2N2

N2N2

N2N2

O2O2O2O2

H2OH2OH2OH2O

N2N2 N2N2

N2N2

N2N2

H2OH2O

H2OH2O

H2OH2O

H2OH2O

H2OH2O

H2OH2OH2OH2O

H2OH2ON2N2

H2OH2O

H2OH2O

H2OH2O

H2OH2O

H2OH2OH

2O s

elec

tive

mem

bran

e

Cool down

60% energy savings

Just cool the water vapor!

How to do that?Hollow fiber H 2O-selective membranes

H2OH2O

O2 + N2

H2O

outlet

Humid airinlet

Humid airinlet

Simulation studies

IncreasingH2O

permeability

Humid air

Blue: Low H 2O content

Red: High H 2O content

z

z

Water-from -air harvesting system

Humid air Dry air

Permeate sideMembraneFeed side

Vacuum

Condenser

Water

We can improve the membrane but not the driving force!

pH2O

pH2O

Permeate side

- Vacuum: 5 mBar- Sweep gas- Condensation at 2 0C

Feed side

Ambient air

Membrane

Drivingforce - High selectivity membrane required:

non-condensable gasses lower vacuum- Temperature >2 C to prevent ice forming- Vacuum and membranes main operating cost

Membrane limitations

In conclusion: air harvesting from air (Dutch Rainmaker)

- Stand -alone device

- Minimal local infrastructure needed

- Minimal operating cost

- Lifespan of up to 20 years

- Affordable

- 1 Windmill per 500-1000 people

Interesting option for the military…..?

THANK YOU SO MUCH

FOR

YOUR ATTENTION!