More Maths

1st April 2019

After reading Blair’s popular post last week in which he worked out that there were approximately 200000 Tonnes of snow in Coire an Lochan I realised that when it melted it would run through the Nevis Range hydro scheme and was keen to find out how much electricity it would produce.

From the hydro manager I learnt today that at a flow rate of 0.01 Tonnes/second it would produce 50 KW/hour. Multiplying the 0.01 by 60 by 60 gives a figure of 36 Tonnes/hour to produce 50 KW/hour. Getting rid of the hours and dividing 50 by 36, 1 Tonne of water produces 1.39 KW of power.

200000 Tones of snow could therefor produce 278000 KW which looks simpler written as 278 MW. An average UK home uses approximately 4000 KWh  of electricity per year so the snow in Coire an Lochan could power around 70 homes for a year.

Lots of assumptions have been made here including; the amount of snow in the Coire; that the snow all melts and there is no evaporation or sublimation; and that the snow melts at a steady rate (turbine efficiency varies with flow rate and if the snow melts too quickly, water flows over the dam rather than through the turbine). Also remember that this is  just what would be produced from snowmelt from one corrie. A lot of other snowmelt and rain water run through the hydro scheme too.

The outflow from the hydro scheme then rejoins the Allt Choille-rais which then feeds in to the hydro system for the aluminium smelter and produces more power but I don’t have figures for that one sorry.

The photos below show conditions this morning – a frozen snowpack with very isolated and shallow areas of fresh snow. Further snow fell this afternoon and more is forecast for tonight.

Nevis Range ski area while the cloud remained high this morning.

Carn Mor Dearg with Ben Nevis behind.

Coire an Lochan, Aonach Mor.

Comments on this post

  • That Guy from The Internet
    1st April 2019 5:04 pm

    Careful now, you’ll be giving people ideas. A ‘green’ energy person will be along in a minute wanting to pour concrete for a micro-hydro scheme in yet another of our rapidly diminishing wild places.

    BTW. The maths did make my head explode. A bit.

  • Mark Bull
    1st April 2019 7:57 pm

    Your units are all messed up (KW is power, KWh is energy, KW/hour doesn’t make sense) but the sums look right!

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