The Royal Society of Edinburgh
at Lockerbie Academy
Harvesting Earth’s Energy from Wind, Water and Waves
Professor Geoffrey Boulton OBE FRS FRSE,
Regius Professor of Geology and Mineralogy, University of Edinburgh
Tuesday 9 November 2010
Report by Kate Kennedy
Dumfries and Galloway has a rich natural heritage. The waterways and climatic
conditions have long played a key part in the economy, culture, history, landscape
and the regeneration of the region. This lecture explored the importance of wind,
water and waves to Scotland and discussed how recent developments in renewable
energy technology will help us achieve carbon reduction targets.
The energy in wind, water and waves is derived from the Earth’s rotation and solar
heating. Humans have harvested the energy from these sources from time
immemorial and will continue to do so in future. The landscape of Dumfries and
Galloway is an important resource in the drive to increase the production of
renewable energy and lower Scotland's carbon footprint. It is important that its
development is managed properly, recognising and harnessing the contribution it can
make in a way that benefits local communities and is sustainable for the future.
Our energy originates from two sources, both nuclear. The first is from the nuclear
fusion reactor of the Sun and the second an internal nuclear fission reactor in the
centre of the Earth. The evidence for the latter is evident in the landscape around us
in the form of extinct volcanoes such as Ailsa Craig and Ben More on Mull.
The work of Isaac Newton in the 17th Century was the basis on which our subsequent
understanding was built. We now recognise kinetic, potential, thermal, electromagnetic, chemical and nuclear energy. One form of energy can be readily converted
into another. For example, in the swinging of a pendulum, potential energy is
converted into kinetic and then back to potential energy. If there were no friction and
air resistance in the system, the pendulum would swing forever. Energy cannot be
lost, but is transformed into another form that can range between highly energetic
and localised forms to very weak and dispersed forms. For example, by pulling atoms
apart, massive quantities of energy are released.
If the Earth receives more energy from the Sun than is radiated back into space, the
Earth will get warmer and vice-versa; if the Earth gives out more energy, then the
planet becomes progressively colder. Thus, to maintain a constant temperature, the
heat that the Earth receives from the Sun must be lost to space at exactly the same
rate as it receives energy from the Sun. The clouds and gases in the atmosphere
play an important role in regulating what this steady temperature will be. The surface
temperatures of the planets of the solar system depend on their distances from the
Sun, but also on the gas composition of their atmospheres. Over the last 25 years,
satellite imagery shows that the Earth’s temperature has risen slightly, although the
complex manner in which energy fluctuates across the surface, turbulently
transforming energy between light, heat, sound and other forms, can make it difficult
to distinguish these trends at any one locality.
We now know a tremendous amount about how the energy/heat regime of the Earth
has changed dramatically in the past. Some of the best evidence comes from the
Earth’s great ice sheets. From Antarctica, radio-echo images show the depth of ice
over the mountain ranges and valleys varying between 1 km and 3 km, whilst closer
analysis of the chemistry of the layers of ice and gases in small bubbles within it
provides much information on the climate over the last million years.
About 150 years ago, James Croll from Perthshire had a theory of climate change
which was only shown to be correct some 100 years later. His theory, refined by a
Serbian mathematician called Milankovitch, predicted, and subsequent observations
confirmed, a strong correlation between changes in the Earth’s orbit around the Sun
and the Earth’s climate. A Belgian mathematician then calculated that the fluctuations
of global temperature arising from this should be a maximum of half a degree
Celsius, but geological reconstructions have shown actual differences of around six
degrees Celsius between the coldest part of the last Ice Age, 20,000 years ago, and
the present day. The amplification of the solar signal is attributed to atmospheric
carbon dioxide levels, noting that the oceans give out CO2 in warmer temperatures,
thus exacerbating the climate change effect.
At end of the last Ice Age over Scotland and Europe, the landscape was bare and
devoid of trees and animal life; covered by raw mineral soils much like areas of
northern Greenland and Iceland from which glaciers have recently retreated. Using
the evidence of pollen grains, insects and carbon dating of peat particles, we can
create a picture of environmental evolution since that time. This shows that broadleaved forests expanded in importance until about 6000 years ago, and then declined
dramatically to be replaced by herbs and grasses. This latter reflected the first largescale human clearances of the forest to create space for agriculture.
One of the unintended consequences of deforestation is that flooding has become
more frequent and more devastating. The reason is simply because the speed of run
off is determined by the amount of vegetation which physically obstructs the flow of
water to the rivers. Trees also absorb the water and transpire rainfall back to the
atmosphere, thus reducing further the amount of rainfall reaching the rivers.
The extent of human progress has been largely determined by the extent that we are
able to take energy from the Earth. This has increased through time from early tool
making, to early agriculture, to efficient agriculture in the mediaeval period, to the
industrial revolution and to today’s technologically-intensive world. Energy
consumption has increased dramatically throughout this evolution, taken up in food,
heating, devices (e.g. computers, television) and transport, and because of the large
growth in population. Consequently, we abstract from nature much more energy than
we did in the past, although this only represents a small amount of the total energy
available in the Earth’s system.
As fossil carbon has been the dominant fuel behind this development, global carbon
emissions can be considered a proxy for the amount of real energy being used. This
is illustrated by viewing a map showing the irradiance over the globe now compared
with one for 15 years ago, which has much more of India, China, other parts of Asia
and South America lit up as a result of globalisation. At the same time, most oil
experts are persuaded that we have passed peak oil supply and resources will
decline quite quickly, depending on population growth and global economy. Indeed
many analysts now presume that by 2050 there will be a real scarcity of oil and
prices will rise even more sharply than they currently are. The burning of fossil fuels
results in an increase in CO2 emissions and other greenhouse gases in the
atmosphere such that there is now a CO2 concentration of 380ppm compared with
270 ppm in previous periods when the Earth has been similarly warm. Furthermore,
global temperature data over the last 130 years shows a strong rise and, whilst many
variations are due to natural causes, the overall trend in the last 30 years in particular
is highly likely to be due to human activity. There is also considerable variation
between countries in terms of levels of atmospheric pollution, with the UK ten times
higher than the Democratic Republic of Congo; half as much as the US and Canada.
Qatar is “off the scale”, with the highest figures per person. It is a very contentious
issue politically.
The use of energy involves conversion processes and transitions; for example,
chemical energy is burnt to produce heat energy, often in a machine as mechanical
energy or used as electrical energy. At each one of these transitions, there are
losses of energy in forms that we don’t use, reducing the amount of energy available.
Consequently, for greater efficiency, the ideal would be to reduce the losses in these
transitions, or indeed to minimise the number of transitions. One answer is to use
renewable energy, e.g. wind/solar/geothermal/wave/water/biomass.
Dumfries and Galloway is well placed for wind, wave and tidal energy. With regular,
strong tides in the region, the latter is a reliable energy source, whereas wind is less
predictable. There is also a significant opportunity for hydro power.
But there is also much ‘hot air’ in talk about the potential of renewable energy
sources. For example, if there were wave devices all along 750 km of the west coast
of Scotland, the raw power would be the equivalent of 16kWh per person, which after
inefficiencies would drop down to 4 kWh per person, a fraction of the 195 kWh per
person that we typically use. Tidal barriers would be slightly better, but after allowing
for inefficiencies, would still only be around 11 kWh. At best, these systems might
support small communities, but could never meet the needs of national and global
economies. Similarly with wind, even with exaggerated assumptions on numbers of
wind farms, at best they might yield just about half the power currently used to run
our cars. For hydro, harnessing every drop of water in Britain would provide just
seven kWh/person.
A fundamental problem with renewable sources is that they have a large footprint
when compared with conventional power stations. For example, wind generates 2
Watts per m2 whilst a power station gives 1000 Watts per m2. As such renewable
initiatives have to be on a massive scale and in combination to make a significant
contribution, they tend to be subject to NIMBY (“not in my back yard”) reactions.
If we look at all the options, a ‘Green Plan’ would maximise all the renewable options,
in particular wind and solar power in deserts, whilst an ‘Economists Plan’ would focus
strongly on nuclear, with renewables making a small contribution. However, the
social current questions are: who chooses, and indeed is there any political drive to
take action when we have so much else on our minds?
Another important element is the transmission system for transporting energy. Whilst
there may be plans for major networks that go beyond national boundaries, political
factors also come into play, making the achievement of such networks more difficult
in practice. In principle, the larger the scale the better. For example, solar power from
desert areas of North Africa could provide the energy requirements for one billion
Europeans in ways that would benefit both supplier and receiver countries.
Britain could create a system of energy generation that would serve our current
needs using a combination of bio-fuels, major power stations, enhancement of hydro
and solar power from the deserts. To maximise this will require a network that
operates with maximum efficiency and minimal losses. However, any strong drive to
create such an integrated solution will be difficult to mobilise whilst so many remain
highly sceptical of the reality of anthropogenic climate change.
Nevertheless, the climate changes that are being anticipated are unprecedented and
can be considered as presenting significant challenges on a similar scale to the
challenges associated with the Industrial Revolution. Given that energy is going to be
more expensive and less available, and the fact that energy is a key requirement for
all our social and cultural development, changes will impact on almost all of us, and
therefore will require a political coherence and consistency of the type we haven’t yet
known, if we are to successfully address these issues. Like the engineering
achievements that brought about the Industrial Revolution, and contributed heavily to
our current problems, we need another heroic age of engineering to engineer into the
environment in ways that are clever, sensitive, intelligent and coordinated. Certainly,
there is no going back to the simple life with a global population of its current size.
Opinions expressed here do not necessarily represent the views of the RSE, nor of its Fellows
The Royal Society of Edinburgh, Scotland’s National Academy, is Scottish Charity No. SC000470