Pumping Power calculator – what power is needed to pump seawater to the middle of the Gobi Desert for desalination in the SeaWater Greenhouse? – answer – not a lot

The spread sheet for calculating this, kindly provided by Wessex Water, one of the UK’s leading water supply companies, is available here:
 
 
 
This spread sheet enables you to calculate power needed to pump water any distance through any height:
 
You can see that in fact, compared to national energy consumptions, power consumed is only a very low fraction of national demand.
For example, according to the spread sheet, the energy needed to pump the entire water consumption of Wessex Water, one of the UK’s regional water companies, with  approximately 2m population, (out of UK’s population of approx 60 million),  assuming a lift of 100m, a distance of 300 miles, a 3 m a pipe, would require about 7.3 MW and cost about $10m dollars/y – which are quite small numbers in the total context when  compared to the total average power consumption of the UK which is about 37,000 MW
This shows it would be perfectly feasible to pump sea water large distances into China’s deserts, and desalinate it using cheap solar greenhouses, where the water can be used for agriculture and to stabilise the ever growing Chinese deserts.
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Also notes on pumping and pumping efficiency are at:
 

 

 

 

?H = 4fLV2 / 2dg                   (European SI Based)

?H = head loss (m)

f = friction factor

L = length of pipe (m)

V = mean flow velocity (m/s)

d = hydraulic diameter (m)

dcircular pipe = 4 x cross sectional area / wetted perimeter

(The wetted perimeter is the perimeter of the cross sectional area that is “wet”, i.e in contact with the pipe)

g = gravitational constant = 9.81 (m/s²)

The friction factor in the D’Arcy formula needs to be estimated. The friction factor depends on the Reynolds number (Re) of the flowing liquid and the relative roughness (k/d) of the inside of the pipe.

The Reynolds number may be described as the ratio of inertial forces to viscous forces and, consequently, it quantifies the relative importance of these two types of forces for given flow conditions

Re = ? V d / ? = inertia forces / viscous forces

? = density of fluid (kg/m3)

? = absolute or dynamic viscosity (Ns/m2)

V = mean velocity (m/s)

d = hydraulic diameter (m)

dcircular pipe = 4 x cross sectional area / wetted perimeter

The transition between laminar and turbulent flow in circular pipes is generally accepted to be at about Re = 2300. Avoid any pipe configuration within the range 2000 to 3000 to ensure the flow is either fully laminar or fully turbulent.

For liquids with high Reynolds number you can use the Colebrooke & White formula for turbulent flow: –

1 / f = -4log10 (( k / 3.7d ) + ( 1.255 / Re f))       (Re >3000)

k = the average height of the roughness projections
I’ve chosen a 3.0 meter diameter cast iron pipe.

As you try narrower pipes, the friction head rises sharply.

Kind Regards

M

15 comments on “Pumping Power calculator – what power is needed to pump seawater to the middle of the Gobi Desert for desalination in the SeaWater Greenhouse? – answer – not a lot

  1. Pls supply me with some guides in lifting water from ground surface to a mountain top.Pipes and pumps are to be used
    Thanks

  2. Hellow – you have asked bit of a vague question. Please be more specific in your needs.

    I expect a pump manufcaturer catalogue will answer most of your questions.

    If going very large distance upwards, you will need multiple pumping stations.

  3. jhen Said:

    Hi.. i just want to know how many hp is needed to convert a 20Hp mechanically driven pump to a motor driven pump? thanks.

    Well, if the mechanicaly driven pump, has 20 hp on it, then you need a 20 HP motor. Which is 20 x 0.746 KW.

  4. Hi guys..Im gonna pump 18m3/h from a depth of 15m (submerged in seawater). The opening in the suction pump end is 95cm2 and thereon the water should be pumped through an 100m hose and onboard a vessel. The outlet of the water will be 2 m above surface area. Does anyone know what pump this might be? Thanks a lot in advance!

  5. Hellow,
    Please help me: I need to know motor water pump I found to bay with H=30 and Q=50m3 could do me a job on 20m height and 200m lenght of pipes

  6. Easy – look up wind turbine manufacturers catalogues and see the diameter they use for wind pumps.

    You need to say if your pump is mechanically driven, in which case you need a multiblade rotor, or electrically driven in which case you need a two blade rotor.

    Assuming a multi blade make sure you are looking at a multiblade manufacturers direct drive pump.

  7. Hi, I need to choose a pump for emptying a sewage tank at about 0.1m3/s and it would only need to be lifted around 20m. Any ideas on how to find the perfect one? Thanks.

  8. Just phone any pump supplier or look in their catalogue. You will need to choose a suitable pump for sewage as otherwise it is likely to block with rags etc. When you have round one, put the details here as a comment please.

  9. DEARS
    I AM FROM THE DESERT OF LIBYA ,WISH TO KNOW THE METHOD REQUIRED FOR INTEGRATES THE WIND TURBINE INTO DESERTIFICATION PROGRAMS AS DOCTORATE THESES

    BEST REGARDS
    YOUSEF

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