DAVID Watson is correct to highlight the fact that the capacity of
hydro-electric pump storage is difficult to expand significantly to provide
“base-load” back-up for a renewables-based power supply system for Scotland
(“We still do not have a solution for storing energy from renewables”,
Herald Agenda, May 26).
However, I suspect that very few people who have thought about these issues
seriously would consider that reliance on one renewable source (wind) or
one form of massive energy storage system (pumped hydro) to be practical.
While effective energy storage on a massive scale is clearly essential to a
viable future for renewables, the intermittency issue is hugely diminished
if a mix of renewable technologies is commissioned simultaneously.
Furthermore, an intermittency problem for an individual nation can be
greatly reduced by sharing technologies at the multinational level.
At a European level, for example, such sharing of resources could involve
hydro power emanating from Scotland, Scandinavia and the Alps, wind power
from the western coastal areas of Europe, wave power from Norway, UK, and
Portugal, geothermal power from Iceland, Spain, Italy, Rumania, Turkey, and
solar power from Spain and North Africa.
This transition has to be planned on a very large scale to overcome
variability issues – at least at the continental level. The switch to
renewable power for all our energy needs cannot succeed without
incorporating a wide range of technologies, including massive storage systems.
It will need to be monitored and controlled using advanced electronic
control systems probably based on satellite communications, and will
probably employ a direct current (DC) grid because of the large distances
involved. If it can be achieved, the variability issue becomes redundant.
For example, at European Community level, studies have been generated
quite recently to assess the feasibility of a DC super-grid connecting
geothermal power stations in central Europe, solar power stations in
southern Europe and North Africa, wind farms in Western Europe, wave/tidal
systems in Scandinavia and Portugal, and hydroelectric stations in Northern
Europe.
This system would be backed up by massive storage facilities based on
pumped-storage, compressed gas and hot water thermal storage using
cathedral-sized underground storage caverns, on massive flywheel farms, on
battery storage barns the size of football pitches and on huge super-cooled
magnetic storage devices. Prototype examples of all of these technologies
already exist.
Once all this is in place, we will be able to start dismantling the
fossil-fuel powered stations, but we really need to start this technology
revolution soon, in order to complete it by 2030, and so avoid creating
levels of greenhouse gases in the atmosphere which could lead to runaway
global heating.
A transfer of resources of bank bale-out proportions will be required to
implement such a massive growth in the capacity of renewable power and
storage systems. But when the health of the planet, not just the global
economy, is at risk, surely it is a small price to pay.
Alan J Sangster,
37 Craigmount Terrace,
Edinburgh.
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