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By Professor Colin McInnes
Scotland has ambitious plans to become a world leading low carbon economy. But to deliver on this ambition will take some clear thinking about how we will generate energy in the future. More importantly, we need to learn from our past and recognise that we have been decarbonising our economy for nearly 400 years.
The beginning of the substitution of coal for wood during the Elizabethan era was our first transition to a low carbon economy. Surprisingly, coal is a
low carbon fuel since per unit of energy produced it releases less carbon than wood. This decarbonising of energy production has continued through waves of energy transitions from coal to oil, methane and now nuclear fission. Each new fuel has a higher energy density and a lower carbon content than the last, particularly so for carbon-free nuclear energy. For example, one kilogram of coal can power a light bulb for 4 days, one kilogram of methane for 6 days and one kilogram of uranium for a remarkable 140 years.
These continuous improvements in energy density have led to better energy utility, falling energy costs and wonderfully, greater energy use. Of course our growing energy use has led to an overall increase in carbon emissions. But let's not forget, this growth in emissions correlates strongly with the extraordinary improvements in human well being since the industrial revolution.
In the Elizabethan era, coal was seen as a dirty and polluting fuel. Some thinkers such as agricultural writer Arthur Standish advocated simply growing more trees to meet rising energy demand and so avoid the use of coal at all costs. Writing in 1615 Standish claims “there may be as much timber raised as will maintain the kingdom for all uses forever”. Such a national energy policy would no doubt have led to a sustainable society based on renewable biomass, but it would never have led to the marvels of the industrial revolution and the liberating and civilising effects of cheap energy. Later, with the advent of coal driven steam power through the innovations of James Watt, energy costs fell while prosperity rose for the first time in human history. Carbohydrate fuelled human labour was replaced with hydrocarbon fuelled machines. This is human progress.
Wood is a diffuse energy source and required much human labour to gather and use. As practical wood resource limits were reached in the neighbourhood of population centres, easily transportable, energy dense coal slowly became the fuel of choice for warmth and emerging industries. Such was the shortage of wood in central Scotland during the reign of James VI it was quipped that, “if Judas had repented in the king's native land [Scotland], he would have been hard put to find a tree on which to hang himself”. The growing use of coal helped end the Elizabethan energy crisis (which peaked between 1570 and 1630) and allowed an escape from the Malthusian trap of medieval subsistence.
The transition from low energy, carbon rich wood from forests to low carbon, energy rich coal from the ground which began in the 17th century was our first step in de-coupling energy production from the environment. Due to its poor energy density wood required vast areas of forest to be levelled for energy production, demonstrating the strong coupling between the environment and energy production from diffuse sources. In comparison, energy dense coal could be extracted from compact punctiform mines, while oil from the ground would start to replace oil from whales later at the end of the 19th century.
This important coupling between energy density and environmental impact can be seen again in the steady growth of wind farms across Scotland to exploit diffuse renewable energy.
Current plans are for the 5 TW-hr of energy produced by onshore wind in 2008 to grow to almost 20 TW-hr by 2030. At the same time the 14.3 TW-hr of nuclear energy produced by Huntertson B and Torness in 2008 will vanish by 2030. The sole result of this energy transition is that we will have substituted 15 TW-hr per year of compact, base-load nuclear energy for the same quantity of diffuse, intermittent wind energy. In the process we will have expanded onshore wind farms fourfold and disfigured many unique Scottish landscapes.
The long history of energy production in Scotland, from Elizabethan era woodland to Victorian lowland coal, North Sea oil and gas and now nuclear fission shows a slow substitution of fuels with energy transitions coming in waves. In terms of its long-term historical market share, coal is in its twilight years while methane and uranium are in the ascendancy. The beginning of the large-scale use of civil nuclear energy in Scotland since the opening of the 1200 MW Hunterston B plant in 1976 (currently operating at 870 MW) is simply the most recent wave in a 400 year journey along a path of improving energy density and falling carbon intensity.
In a strong parallel to the Elizabethan aversion to coal, some now advocate avoiding the use of uranium at all costs by returning entirely to the large-scale use of diffuse and intermittent energy sources such as wind. While the wind, waves and sun are of course free, the massive infrastructure to gather low grade, diffuse renewable energy, turn it into to high grade, concentrated electrical energy and deliver it along lengthy transmission systems to urban population centres is not. Renewable energy such as wind requires immense quantities of materials, principally steel and concrete. In comparison, per unit of energy produced, compact nuclear plants are vastly more efficient in their use of materials due to the energy density of their fuel and their long design life of 60 years compared to 20 years for renewables.
Support for renewable energy is provided through renewable obligation certificates. The key word is obligation. There is a legislated requirement to continually grow renewable energy production to meet entirely arbitrary European targets. Renewable energy is growing, not because it is a more productive means of generating energy, but because government has mandated it and is providing extremely generous incentives.
For example, the 322 MW Whitelees wind farm at Eaglesham generated 676,133 MW-hr of fluctuating electrical energy last year, supported by renewables obligation certificates worth £37.5 per MW-hr. This amounts to £24M of revenue, or some £480M over the 20 year life of the wind farm, paid for through higher energy bills. This is a seriously good return on a £300M capital investment, and that's before revenue from the sale of electricity. It should be no surprise that developers have been queuing up for a slice of Scotland. Ambitious plans for 11,000 MW of offshore wind will require some £30B of capital and potentially up to £57B of renewable obligation costs over the 20 year life of offshore plant. This will be exceptionally expensive energy. It is not clear who will buy such energy in an export market, or what will be the result of a reduction in renewables obligation certificate support if the economy struggles to provide such resources.
Strong investment in research is required to improve the competitiveness of renewable energy, but the proposed level of support for future large-scale commercial renewable energy generation through higher energy bills is questionable. Expensive energy is socially regressive and impacts on the poorest first and most affluent last. We should not forget that the end result of the Elizabethan transition from wood to coal was that energy became cheap and so human labour became expensive.
Nuclear power is projected as being the lowest cost means of generating electrical energy, and by far the cheapest way to displace carbon from energy production. Our vast potential for offshore wind is projected to cost 15-21 p/kW-hr, onshore wind 8-11 p/kW-hr compared to 6-8 p/kW-hr for nuclear and 6-11 p/kW-hr for methane. These are levelised costs which include decommissioning for both nuclear and offshore wind, but do not include offshore connection costs. Published claims that Scotland can depend entirely on renewable energy are missing a thick appendix on costs. If we can deliver socially progressive low cost energy and environmentally progressive low carbon energy, then our transition to clean energy production will be far more likely. This is a no regrets policy.
Worryingly, some are actively disseminating plain disinformation concerning nuclear energy. Spurious claims are made that a nuclear plant has the same level of emissions as a methane-fuelled gas plant. This is simply untrue. For example, the full life-cycle carbon emissions of the Torness nuclear plant are only 7 gCO2/kW-hr, similar to that of wind and less than 1% of coal at approximately 900 gCO2/kW-hr.
Similar disinformation can be found elsewhere. As a result of the 1974 decision to pursue nuclear energy, France brought on-line over 63,000 MW of nuclear power and now produces nearly 80% of its electrical energy from carbon-free nuclear plants. However, in their G8 Climate Scorecard the World Wildlife Fund for Nature (WWF) places France a lowly third. On reading the small print of their methodology it transpires that “WWF does not consider nuclear a viable policy option” and actual French carbon emissions for electrical energy generation are artificially inflated by a factor of 4 as a penalty, dropping France from clear first place to third. This is entirely unhelpful spin that would blush the cheeks of Malcolm Tucker. The effective use of light water reactors in France, and elsewhere, shows the way forward for large-scale decarbonisation of an industrial economy.
If we’re serious about displacing carbon from energy production we would be well advised to accelerate our journey along the historical path of improving energy density, away from coal and ultimately oil and towards methane and uranium. Methane has a carbon content about half that of coal and is easy to both store and transport. Due to its lower carbon content, methane offers perhaps a more realistic prospect for large-scale carbon capture. While many worry over, or in some cases naively welcome, the depletion of oil reserves, so-called peak oil, in future utilisation of low carbon methane is likely to grow as high carbon oil prices eventually rise. Hydrocarbon fuels will be with us for quite some time to come and casual talk of a post-carbon economy is entirely premature. It ignores the historical dynamics of the long waves of global energy transitions.
Previously unexploitable shale gas fields are now being tapped using technical innovations in seismic imaging and horizontal drilling to allow hydraulic fracturing of deep shale bedrock.
Some predict that the world will be awash with shale gas in future. It will therefore be difficult for expensive renewable energy to compete with cheap methane if gas prices remain low for the long haul.
Compressed or liquefied methane can be an almost direct substitute for oil in transportation using conventional internal combustion technology, and is particularly useful for fleet vehicles such as those used in public transport. Electric vehicles may also come to fruition once their high price and poor performance improves, but they will require a growing, reliable source of clean base-load energy for overnight charging.
Moving to higher energy density again, the use of nuclear fuels can grow significantly to offer energy for the deep future. Some dismiss nuclear energy as unsustainable since uranium is seen as a finite resource. This echoes Elizabethan agricultural writer Arthur Standish who bemoaned “there is no assurance how long they [coals] will last” at the beginning of the transition from wood to coal. In fact, nuclear energy has the almost magical quality that it can potentially breed its own fuel, while spent nuclear fuel (wrongly classified as waste) still has copious quantities of latent energy that can be extracted rather than buried.
Future so-called fast reactors, pioneered in Scotland at Dounreay, but now being aggressively pursued by China and India can convert this spent fuel into yet more clean energy leaving extremely small volumes of short-lived waste products. Contrary to received wisdom spent nuclear fuel is a valuable asset. If we really must bury it, vitrification and deep geological storage are well understood, while the quantity of spent fuel is remarkably small. For comparison, each year a city-powering 1000 MW coal plant will dump 7.5 million tonnes of carbon dioxide as a gas directly into the atmosphere and produce approximately 400,000 tonnes of fly ash. An equivalent nuclear plant will produce 27 tonnes of spent fuel in solid form which can be easily separated from the environment, equal in volume to a box of side less than 3 meters.
Through dogmatic opposition to nuclear energy, orthodox environmental thinking is blocking one of the most pragmatic and lowest costs means of displacing carbon from energy production. Compact base load nuclear plants are a direct substitute for base load coal plants. The sole result of historical opposition to nuclear energy has been that we have continued to burn more coal. Those who oppose nuclear energy should think carefully about the consequence of their actions. Simultaneously campaigning for firm action on climate change and against nuclear energy are entirely incompatible goals. The unseemly haste of Energy minister Chris Huhne’s recent and rapid conversion to nuclear advocacy was the result of being faced with the stark realities of real national energy and climate policy.
Nuclear energy is often claimed to be yesterday’s technology. In fact, it is one of the key energy technologies of tomorrow. Future high temperature reactors can co-generate electricity and hydrogen for industry and transportation, or can desalinate seawater in developing nations. We have only scratched the surface of what is possible with energy dense uranium, and later vast untapped global reserves of thorium to help deliver a genuinely sustainable supply of clean, high-grade energy. Thorium is virtually unknown outside the world of energy analysts but utilises a fuel cycle which has many advantages over uranium, producing abundant energy and small quantities of short-lived waste products. It offers a compact source of clean, dependable energy so enormous as to be essentially unlimited, but only if we have the will and ambition to exploit it. Peak uranium worriers should take note.
To deliver both a low carbon and prosperous Scotland we need to quickly dispense with dogmatic views on nuclear energy and so ensure a balanced energy policy which is based on methane and uranium with a measured and appropriate use of renewable energy. We will then turn the corner on carbon emissions when our historical journey towards fuels of greater energy density overtakes growth in energy demand.
At present we are betting on renewable energy at any cost, economic or environmental, simply to eradicate nuclear energy from Scotland. We also need heretical greens who are prepared to challenge failed orthodox environmental thinking and embrace compact nuclear energy as the most effective means of decoupling human energy needs from the environment. It has a lower cost, a vastly smaller physical footprint and requires significantly less material than diffuse renewable energy. By any measure nuclear energy is green. Along with the growing use of methane, it represents one of the next waves in our long historical journey of energy transitions from Elizabethan era forest and Victorian coal to cleaner fuels of greater energy density.
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Colin McInnes is Professor of Engineering Science at the University of Strathclyde. Other articles can be found at Perpetual Motion.
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