When raising concerns about the proposed hydro scheme SavetheConwy often hears the comment “well it’s better than a coal fired power station”. RWE made a claim at the recent talk about hydropower in Snowdonia that schemes like this would prevent “catastrophic climate change”. SavetheConwy is no fan of coal fired power stations and is fully aware of the problem of man-made climate change. However reduction in carbon emissions must be balanced with damage to local habitats. A coal fired power station would obviously be far more damaging locally and through carbon emissions than the Conwy Falls hydro scheme, but it would also produce far more power. But how much more?
Let us start by making some assumptions:
From the RWE website
“We anticipate the £12m scheme could have a capacity of up to 5 megawatts (MW), and be capable of generating up to 13,000 megawatt hours (MWh) of electricity each year – enough to supply the average annual domestic requirements of over 2,700 households”
Now let’s assume that this power is produced evenly throughout the year when required, not just when it’s lashing with rain on autumn nights. Let us also assume that RWE’s sums are correct for its’ yearly production and won’t be affected by a dry summer or frozen winter.
Now let’s take a coal fired station. The largest in the UK (also with the most accessible published figures is Drax in Yorkshire.
Drax has an installed capacity of 3960 MW but not all this capacity is used full time. In 2013 Drax sold 26.2 TWh to the grid http://www.drax.com/media/32643/fyr-results-2013-final-.pdf
So Drax produced in 2013 26,200,000 MWh
26,200,000/ 13,000 = 2015.4
Therefore Drax produced over 2000 time more power than the Conwy scheme and not just when it rains.
So yes a hydro scheme is far better than a coal fired power station, but is it 2000 times better?
It is difficult to know how many sections of river there are like the Fairy Glen on the Conwy with the gradient and flow suitable for diverting through a pipe to produce power. You could take this list of rivers http://rainchasers.com/river-levels
These are all the river sections in the UK thought to have sufficient flow and gradient to be of interest to whitewater kayakers for which the Environment Agency collects flow data. The Conwy Falls or Fairy Glen section of the Conwy is listed amongst them. Some are larger but most are smaller but let us assume the Fairy Glen is an average. There are 173 sections of river on that list.
So if we dammed every section of river in the UK of suitable length and gradient, put the water in a pipe to produce electricity and if the rain fell conveniently and evenly throughout the year. It would still produce less than a 10th of one coal fired power station.
When making judgment on the Conwy hydro scheme we cannot say “but it’s better than a coal fired power station” it is an unfair comparison.
The question should be “is building a hydro scheme on every suitable section of river in Wales, England and Scotland, all 173 of them, 10 times better than one coal fired power station?”
This article is not advocating coal as a suitable fuel for electricity production but simply trying to put the small amount of power that a run of river hydro scheme produces into context. Run of river hydro schemes that lack a large impoundment (reservoir) having no real place in the production of electricity for the grid in the UK. Our rivers are too small with too low and irregular flows to make any real contribution, but mostly the few wild stretches of river that remain untouched are too precious a resource to be squandered in this way.