Solar Power Volcanic Risk

Iceland has been in the news several times in recent months as volcanic eruptions have forced the evacuation of the town of Grindavik and threatened the electricity generation system. This threat continues, with lava flows from the vent now two miles long. In recent years, unrelated volcanic activity elsewhere in Iceland has caused entirely different problems. Between March and June 2010 a series of volcanic events at Eyjafjallajökull caused small lava flows, but sent pumice dust emissions high into the atmosphere. These caused enormous disruption to air travel across Western Europe for several weeks.

The ejected tephra and an ash plume rose to a height of around 10 km (30,000 ft), and the incident was rated as a 4 on the Volcanic Explosivity Index. The scale has a maximum of 8, a level that is 10000 times more powerful than a 4.

We have been fortunate in the UK that although situated only a few hundred miles from this region of regular volcanic activity in Iceland, it has rarely disrupted normal life. There is a risk however that we are making ourselves more vulnerable as we increase the renewables into our energy supply system. This is because volcanoes – even those thousands of miles away - could also cause significant damage. We need to be aware of this risk. The threat may seem very remote, but a recap of the substantial historical evidence puts it into context. The Laki event in Iceland in 1783 was a large eruption and caused many deaths amongst the people and animals but few problems in the UK. We have been affected by eruptions in more distant countries.

Most of the dates in the list below may mean little to people in this country, but they contain hidden evidence that needs to be recognised ever more seriously by the public and our political leaders.

The dates are all connected with powerful volcanic events that caused multiple local fatalities plus damage extending hundreds or thousands of miles from the source. Were anything similar happen today. the damage to our advanced society – that is so dependent upon electricity and communications - could be devastating. In part, it is our increased dependence upon renewable sources of electricity – particularly solar power - that is increasing the dangers.

The events listed above encompassed a wide range of volcanic threats and were spread both geographically and chronologically, showing that the concerns are not restricted to Iceland. All had serious consequences not only for populations in the immediate vicinity, but often on a global scale, even causing deaths thousands of miles from the source. They are not rare events that can be easily dismissed, but must be recognised.

Significant scientific data has been recorded with those that occurred in the last 300 years and video evidence is readily available from Mount St Helens and Pinatubo. The evidence from those in the more remote past has been deduced from archaeological and geological records and our understanding of the movement of airflows in the troposphere and stratosphere. Vesuvius and Krakatoa in particular have become legendary disasters in history, but they were not the greatest. Many of the more obscure are long forgotten but the scale of the catastrophe has been estimated from the ice records enabling temperature changes to be calculated. After Krakatoa, there are many paintings recording the changes to the atmosphere and weather.

Those rated at Explosivity level 7 – close to the top of the scale of volcanic events - will continue to represent the greatest plausible threat. Such events have reduced temperatures by a degree or more in weeks or months, causing multiple authenticated reports of crop damage and harvest failures. One of the least well known but most significant was Tambora (in what is now Indonesia) 1815 - explosivity index of 7. The year immediately following has been called the Year without a Summer. Columns of gas; dust and debris were blown many miles upwards into the upper atmosphere where they circulated for months, reducing the incoming solar radiation thousands of miles away in Europe and North America, with low temperatures producing frosts in mid-summer, local famines and mass starvation.

Records of ash fall from close to Tambora are sketchy, but the adverse effects felt in Europe and North America were caused not by heavy ash fall, but by the smallest particles and acidic gases carried around the Earth by high level winds. This could happen again after an explosion in the Far East and could last longer in the UK than any direct ash deposits from the volcanoes in Iceland.

Deep deposits of ash from eruptions like Vesuvius of AD79 and Pinatubo of 1991 are unlikely to be experienced by the UK, but atmospheric scientists around the world, have estimated that the event caused a global temperature decrease of about 0.5 degree Celsius (0.9 degree Fahrenheit) over the ensuing year. This would be enough to change weather patterns significantly.

Volcanoes are distributed widely. There has recently been increased activity at Sakurajima in Japan and Popocatapetl in Mexico is beginning to erupt and active. In both cases and at sites like Etna and Stromboli, the regular small eruptions release the pressures and usually reduce the risk of a catastrophic explosion.

Volcanic eruptions with heavy ash deposits and atmospheric pollution materialise as dramatic events every few decades. They can happen on such a scale that even our greatest human efforts are inadequate to overcome their effects. In addition to the threats to food; farm livestock and human life, our society has introduced new areas of vulnerability. We have constructed massive areas of solar panels and large wind parks in recent years. The former are highly vulnerable to ash deposits only a few centimetres deep reducing output to an insignificant level. They can also show a massive reduction in output if there is high level atmospheric pollution and solar radiation is blocked. Electricity is needed with 100% security of supply. Renewables are recognised as intermittent and are routinely backed up by reliable generators, but the loss of swathes of solar and wind power would force the use of more fossil fuels . The threat from volcanic debris is yet another factor underlining the folly of an advanced society becoming dependent upon weather-driven power plants.

Wind power is also vulnerable since the turbines depend upon steady conditions that could be disrupted by alterations to the Jetstream and equivalent air movements south of the equator. The appearance of frosts in summer indicates that the normal weather was altered during the 1815 disaster. The limited records do not know which parts of the world were affected most. The crucial point is that the energy in the atmosphere was reduced by a significant percentage with lower wind speeds and reduced output. It is particularly worrying that solar and wind power could both fail at the same time – common mode failure affecting diverse systems… a very dangerous weakness.

Renewable power is highly dependent upon the behaviour of the natural world. That was part of the motivation for the development of fossil fuel power in the industrial revolution. We are re-introducing the risks from nature that could prove very dangerous to our society with its delicate technical balances.

Paul Spare
MSc CEng FEI FIMechE

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