On Monday, 8 February 2021 at 13:01:38 UTC, John Rumm wrote:
On 08/02/2021 11:06, polygonum_on_google wrote:
On Monday, 8 February 2021 at 09:11:52 UTC, S wrote:
On 08/02/2021 08:42, polygonum_on_google wrote:
Anyone convinced?

Powering up: UK hills could be used as energy 'batteries'

Engineers explore using gentle slopes rather than steep dams or
mountains to store electricity

https://www.theguardian.com/environm...ergy-batteries



RheEnergise is bringing innovation to pumped hydro storage. We call our
new solution High-Density Hydro „¢.

HD Hydro „¢ uses our proprietary HD Fluid R-19 „¢, which has 2.5x
the density of water. R-19 gives RheEnergise projects 2.5x the
power and 2.5x the energy when compared to water.

https://www.rheenergise.com/

I wonder what their proprietary HD Fluid R-19 „¢ actually is?

They claim: Our innovative fluid R-19 TM is environmentally
benign and has been engineered to be non-reactive and
non-corrosive.

I expect they say its because of PE = m.g.h

where PE is Potential energy = mass x value of gravity x hieght.

So by increasing the mass by 2.5x, you then get 2.5 x the PE.

Trouble with that is they appear to be claiming same sort of capacity
despite lower height AND gentler slope AND (from the diagram) smaller
volume. They can only get the advantage of higher density once but
their claims appear to require them to do so three or four times
over.
The slope is not really of much interest - it's the height difference
and the total mass of liquid that matters when determining the storage
capacity.

The pipe cross section has no effect on capacity, but does affect power
output - since it dictates the rate at which you can move a mass of fluid..

As usual (its the guardian, so what do you expect!) they seem to confuse
energy and power (i.e. talking about MWh and MW in the wrong contexts)

So for example in the UK our main pumped hydro stations have a total
storage capacity close to 30GWh, but a maximum power output of about
3GW. So in theory could provide 3GW of power for about 10 hours. (in
reality is not quite that good since not all of the stations have the
same ratio of capacity to power output).

The gentleness of the slope might have some importance for engineering - but agreed, none regarding capacity. In the diagram. It is difficult to discern any difference in slope.

And the huge problem that the storage and receiving "tanks" will need to change level pretty dramatically. Are they going to be open air? Or covered? How will they manage dilution by rain, if open? They are hardly going to count as amenities for fishing, sailing, swimming, etc.