Glendoe Hydro project

In the mountains areas of Scotland west of Inverness, Scottish & Southern Energy (one of the United Kingdom’s six energy suppliers) has opened a new hydro electric plant at Glendoe. It can provide electrical power to more than 325,000 homes. It has been hailed as providing green clean renewable energy for Scotland. It does, but the energy it provides is not free from carbon emissions, although the emissions are significantly less than emissions created by conventional fossil fuelled generating stations.

Glendoe is in an area where there is plenty of rainfall. Each year 2000 mm of rain falls and is collected in a reservoir built in the mountains, protected by a concrete dam 905 metres long and 35 meters high. The stored water can be augmented with water from other areas, feeding into the reservoir through a network of tunnels.  

In order to generate the electricity the water drops through turbines. At Glendoe this drop is greater than any other UK hydro electric scheme, thus enabling greater energy from falling water to be converted into large amounts of electricity. The power of falling water enables the electricity generation to start and stop very quickly – in less than fifteen minutes, unlike fossil fuelled power stations which have to heat up water into steam before they start. The start up process for nuclear power stations is much longer. So, overall nuclear electricity provides a base load, conventional power stations provide the next level of predictable demand and hydro can provide both base load, predictable or emergency demands.

However, it cannot be said that hydro electricity projects like that at Glendoe are completely green or completely clean. They are far better than generating electricity by burning coal, oil or gas, but hydro electricity still has copious amounts of emissions associated with it, although, as I have said, not as high levels as fossil fuel.

First there is the carbon emission spike that is created by the building of the dam and associated infrastructure. When you disturb any land upon which there are growing things you release large amounts of carbon dioxide stored in the soil.

Secondly, when you flood the land, the vegetation flooded decays and releases much of its carbon dioxide through the water into the atmosphere.

Thirdly when you use concrete and cement you use a material the manufacture of which is responsible for between 5% and 6% of the world’s carbon dioxide emissions. When you make cement carbon dioxide is emitted from the calcinations of limestone and from the combustion of fuels in the kilns and from the power that the cement manufacturers consume. On average, for every tonne of cement made in the world more than two thirds of a tonne of carbon dioxide is emitted, slightly more than half of which comes from emissions in the process of manufacture and the rest from emissions from energy use in the manufacture.  

In the case of Glendoe huge amounts of concrete were used in the overall construction. The dam was built with internal stone, but concrete sprayed over it, and concrete was also used structurally in it. Concrete was also used in the extensive tunnel and infrastructure network, including in the 8.6 kilometre aqueduct tunnel, the * kilometre tunnel delivering water to the underground turbines and the 2 kilometre tunnel delivering tail race water to Loch Ness.

The power station itself is located in underground area close to the banks of Loch Ness.

The hydro electric power station delvers much greener and much cleaner energy than a conventional power station; in this case it probably used more cement and therefore more indirect emissions than a nuclear power station would need if one were built.

I cannot assess the impact that the Glendoe plant will have on the local environment; with much of it being built underground and the reservoir designed so as not to be visible from local dwellings, it seems that its impact may be only on the flora and fauna disturbed by the reservoir.

When it comes to energy were must make our choices on the basis of a least bad option. I would rank a project to generate electricity like that at Glendoe on this scale, with the most harmful first and the least harmful last:

1. Coal
2. Oil
3. Nuclear
4. Natural gas
5. Gledoe Hydro Plant
6. Large scale Wind
7. Large scale PV
8. Small scale PV

I should add that some hydro plants would not get such a good ranking as Glendoe. Hydro plants using very heavily silted rivers are relatively short lived and can have disaterous environmental consequences. Glendoe score low becasue of its reliance on rainfall (as opposed to river water) and the underground turbines. 

Of course electrical energy is only about half of the energy that Scotland needs; the other half is heat energy, so that the people may keep clean warm and healthy. Good projects like Glendoe are important; they are not the complete answer, and indeed have many disadvantages but taking this project for what it is, its disadvantages are greatly outweighed by its advantages.