Can renewable energy run out?

What happens when renewable energy runs out?

Sounds daft, doesn’t it? It’s the question asked by a politico from UKIP (See the Independent- Feb 20th) that’s currently all over twitter and news sites, and forums (and annoying me because I’m getting buried by flyers from various parties at the moment and I don’t want to think about politics until April…) with people saying how daft it is. By definition renewable resources don’t run out, right?

And yet it’s not a stupid question.

Poorly phrased maybe, but it does raise a valid issue.

The issue is that there are only so many ways to obtain energy from renewable resources, there’s a limited amount available at any one time, and obt aining it can involve severe damage to the environment.

Salmon Fish Ladder
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The Pitlochry Hydroelectric dam (see my lens here) is a wonderful piece of engineering. The dam provides 15MW per year. However, building it required the construction of a fish ladder to allow salmon to reach their spawning grounds and the flooding of a valley with consequent loss of animal habitats and wildlife. It is still an area of remarkable natural beauty and supports many species, but making sure that remained the case was due to a lot of planning and work by the engineers and designers, all of which takes additional funds.

Regarding limits, renewable energy is large but not infinite. If you take a tidal river as an example, there is only so much force in each 24-hour tide which we capture by obstructing that tide. This produces consequences for a river estuary, and also means that you can’t just build dams up the length of a river: each dam will remove energy, and if the tide has less energy it will not reach as far upstream, making those further upstream less efficient. The tide failing to reach as far upstream will have effects on riverside plants, habitats and even erosion patterns and the course of the river.

Tidal Power
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Finally given the limits of modern technology, and the amount of energy available there is currently a finite cap on how much energy renewable resources can produce in a time period. If we want to avoid destructive use of it – windfarms in bird’s migratory paths, solar panels built with rare elements, tidal barriers affecting fish – that limit becomes a lot lower.

Wiki places the actual limit on hydroelectric power in the UK at our current “1.65 GW” plus another possible “146 to 248 MW for England and Wales, and up to 2,593 MW for Scotland“.  The same source gives total energy use as “35.8GW on average, and 57.490GW at its peak.” Comparing the figures, there’s a huge shortfall between the available energy and our energy use.

Do I have an answer? No, but I have noticed that limits and consequences are something they don’t tend to teach in schools when they cover renewable resources. It’s basic physics: Energy cannot be created or destroyed. If you remove energy from a system it will affect other parts of that system. Wind power affects air currents, tidal power slows the earth (noticeable in *ahem* million years)…everything has a consequence. Some are just less damaging than others.

Hydroelectric Turbine, 19th Century
Science Photo…Giclee Print
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What do I think they should do? How about using what we already have?

• There are Victorian tidal tunnels in the Thames originally built for barges, now abandoned. The daily rise and fall is nearly twelve feet, and yet no one has put a generator in?
• Looking online there are over a hundred functional watermills available to buy right now in the UK. These have been part of the environment for years, have millponds, why aren’t they being used for generation? The Gants Mill site in Surrey generates 12kw for the national grid and is still a scenic location. (There’s more details and working examples here: Using Watermills to generate electricity) Some are also windmills, offering two options.
Solar power is a little difficult in Britain given the weather, but there are other options: geothermal springs, etc.

As you might notice, these aren’t new ideas. There have been studies in this direction for years, for example: UK Hydro-Resource England and Wales Resource Study Oct 2010 (PDF). There are funds available: Rocs and Fits among others. So the question that must be asked, is why isn’t this being implemented further?

And I’ve just realised I’ve written five hundred words driven by a question from a politician that I probably put more thought into than she did.

And I’m a little disappointed. Instead of talking about the shortfall between energy use and available resources, or the failure to develop alternate resources, this morning the same per son stated she meant renewable energy subsidies (Guardian 20th Feb 2015)…oh well. Bureaucratic concerns over hard facts and engineering? That’s about what I should have expected.


*Adblock users miss the picture of the fishladder, the nineteenth century water turbine and the tidal powerstation diagram.

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This blog has now moved to http://www.rablogs.co.uk/tirial, where the original article can be found.  Can renewable energy run out? - http://rablogs.co.uk/tirial/2015/02/20/can-renewable-energy-run-out/ was published on February 20, 2015 at 11:18 am.