Monday, March 21, 2011

The forces of nature

We engineers tame the forces of nature. We improve the human condition by our work. But we are human ourselves. Sometimes we fail.

All are chastened by the recent events in Japan. How was it possible for whole towns to be swept away before our very eyes? How could the model of a modern high-speed railway have disappeared with all its passengers? Or a cruise liner with its hundred tourists? What was a fishing boat doing, sailing across the fields and overtaking a doomed pantechnicon? How could a nuclear reactor have had its safety compromised, threatening to contaminate the region with radioactivity?

Japanese engineers have mastered earthquakes to a high degree. Tokyo emerged essentially unscathed from a tremor 8 000 times stronger than that which levelled Christchurch only a few weeks before. Yes, the high rise buildings rocked and rolled, but they did not collapse. The nuclear reactors went into a safe shutdown, just as they were supposed to. But power lines and many other services failed, so there is more work for the engineers to do, to make the infrastructure earthquake proof.

The real problem was the tsunami. We did not understand its possible magnitude. We had not realized that Aceh was merely a sneak preview. We had forgotten that, in 1883, Krakatoa caused waves 35m above normal sea level. In 1958, at Lituya Bay in Alaska, a wave reached 516m as a result of a landslide triggered by an earthquake of magnitude 8.3.

And you should not think that it is only around the Ring of Fire, the shores of the Pacific, that tsunamis strike. In 1751, an earthquake destroyed Lisbon, and the ruins caught alight. The citizens fled to the banks of the River Tagus to avoid the blaze. An estimated 20 000 died when the tsunami roared up the river.

Japan has already spent billions of dollars on anti-tsunami seawalls. They line at least 40 percent of its coastline and are up to 12 meters high. However, the March 11 tsunami washed over the top of many walls, and caused some to collapse.

Critically, it washed over the seawall at Fukushima Daiichi, a nuclear power plant. When the earthquake struck, the reactors were immediately shut down. The earthquake broke the power lines, but the emergency generators kicked in to keep the essential cooling water flowing. But 55 minutes after the earthquake, the tsunami arrived, flooded the generators for four of the six reactors, and stopped the cooling of those reactor cores. Two of the staff, who were presumably outside the reactor buildings at the time, have disappeared.

The seawalls held the tsunami at bay at the remaining two of the Fukushima Daiichi reactors, at the four Fukushima Daini reactors next door, and at the three Onagawa reactors further up the coast, even closer to the centre of the earthquake. All these reactors shut down safely, the emergency generators kept functioning, and they will almost certainly be started up again.

All four of the reactors that lost emergency cooling have suffered catastrophic damage. There has been some release of radioactivity into the surrounding environment. The release has been far less that at Chernobyl, which in turn was far less than the radioactivity spread around the globe by the atmospheric testing of nuclear weapons in the 1950’s and 1960’s.

The catastrophic damage was caused by explosions of gaseous hydrogen. Many metals react with water when they are very hot, and the reaction produces hydrogen. This caused a build-up of pressure in the reactors. The operators took the decision to reduce the pressure, by releasing the gas along with some radioactivity into the secondary containment building. The hydrogen-air mixture then exploded and destroyed the secondary containment.

It is a miracle that no-one was killed in these explosions. When the building round Reactor 1 exploded, four people were injured, none seriously. When the hydrogen from Reactor 3 blew up, eleven were injured, one of whom had to be hospitalized. None were injured in the explosions that destroyed the buildings around Reactors 2 and 4. To prevent build-up of hydrogen in the Reactors 5 and 6, the owners have improved the ventilation of the secondary containment.

The workers trying to bring the plants under control are being exposed to significant quantities of radiation. The Japanese Government has just raised the limit to 250 millisieverts per worker. To put this in context, most of us are exposed annually to about 5 millisieverts from natural sources. A single whole-body dose of 5 000 millisieverts will kill half the population, but the death rate falls off rapidly below that level. It is unlikely that any of the workers will suffer serious consequences from their exposure.

The radioactivity that has been released is detectable in food grown within 30km of the failed reactors. The activity is primarily that from the iodine isotope I131, half of which disappears every 8 days. The releases are dropping as cooling is restored, which means that the food grown in that region will be safe within about 2 ½ months, if no further significant releases occur.

At this stage, the only deaths that have occurred at the damaged reactors appear to be those who were swept away by the tsunami. This is the essential message. We should be absolutely terrified of tsunamis. They are far worse than earthquakes, in the loss of life and destruction of property they cause. They are far, far worse than any nuclear disaster.

We engineers have to learn from our mistakes. We need to bolster our defenses against tsunamis. We can now do a pretty good job of designing against earthquakes. And the recent events have shown that most nuclear reactors can survive that greatest of cataclysms called a tsunami. Some reactors were compromised, but the fix is obvious.

Thursday, March 17, 2011

That carbon tax - again

Government has just announced that it is forging ahead with a carbon tax for South Africa. A carbon tax is a crazy idea. Government's rationale, expressed in its discussion paper, is to help pay for the costs of climate change - but there are no costs readily attributable to climate change. Certainly not now, because climate change is barely detectable, and probably not for a long time to come. Another excuse is that the playing fields should be leveled, so that renewable power can compete - another way of saying that renewable power is not competitive, and we should therefore pay more for our power. However, this makes us as a country less competitive than out rivals in world trade. The only nations to have agreed to carbon taxes are in the EU. A carbon tax is a Brussels idea. Should we be the only developing country in the world to commit economic suicide in this way? Say No! to carbon taxes -No!, No!! and No! again.

Thursday, March 10, 2011

A carbon tax in South Africa?

Last year, Treasury issued a discussion paper on a possible carbon tax. It concluded that a tax of R75 per ton of CO2, with an increase to about R200 per ton CO2 (at 2005 prices) would be both “feasible and appropriate.” As a coal-fired power station emits about 1kg CO2 per kWh, the carbon tax would add between 15 and 40% to the present cost of electricity. Is such an increase merited?

Treasury’s discussion paper starts by reviewing the effects of climate change. It gets the effects wrong, and always in the wrong direction. For instance, Treasury claims “Average temperatures have increased over the past 50 years at a rate of 0.2°C per decade, largely as a result of human activity.” The HADCRUT official data, variance adjusted, gives 0.13°C per decade for 1960-2010.

Similarly, Treasury believes “the atmospheric concentration of these gases could reach 550ppm of carbon dioxide equivalent (CO2e) by as early as 2035, committing the earth to an average temperature increase of about 2-5°C.” The IPCC, which is nothing if not conservative about these matters, says that with a very gloomy view of the world (its A2 scenario), it expects an average temperature increase of about 2-5°C about 2095, not 2035! Less gloomy IPCC scenarios give 1.8-2.8°C about 2095.

Likewise, Treasury claims “Warming is expected to increase mosquito prevalence, with a concomitant rise in malaria.” The IPCC says “Climate change is expected to have some mixed effects, such as a decrease or increase in the range and transmission potential of malaria in Africa.” This is IPCC-speak for “We don’t know!”

Why was it necessary for Treasury to overstate the case in this way? Did it honestly believe we should be scared into accepting its new tax? A guide to the true impacts of climate change is the last century. There was detectable global warming, but the impacts can barely be seen. We live in a water-stressed country. Yet our own Weather Service reports “Higher temperatures will influence the rainfall, but it is still uncertain how the annual rainfall will change. It could increase in some parts of the country, and decrease in other parts.” The IPCC couldn’t have put it better!

Treasury’s Paper then considers the rationale for a tax. “Command and control regulations and market based instruments are used to control pollution.” Is carbon dioxide a pollutant? A dictionary definition of pollution is “The contamination of air, water, or soil by substances that are harmful to living organisms.” Carbon dioxide is not harmful to living organisms. To the contrary, it is the very basis of life.

The Paper then argues “Climate change and its effects are the result of GHG emissions, which are not paid for by the emitters.” That may be so, but many costs are born by society as a whole. Society can agree to build a bridge to cross a river. The costs may born by society, or the bridge may be tolled and paid for by users. The implicit assumption in the Paper is that ‘tolling’ is the only solution.

The Paper lists some issues underlying the design of a carbon tax. The first of these is “Environmental effectiveness – The ability of the tax to reduce GHG emissions.” Suddenly the rationale has moved from concern about the external costs associated with emissions to the emissions themselves.

It is futile to worry about South Africa’s emissions alone. Climate change is a global problem. Each year, South Africa emits about 125 million tons of carbon. China’s emissions are growing by an additional 200 million tons of carbon each year. South Africa could cut its emissions to nil, and the effects of climate change would still be there.

Until there is agreement on a global solution there is no purpose in placing additional imposts on our economy. A carbon tax would be a cost with no detectable benefit.

The only countries to have imposed carbon taxes are in the European Union. There is also a Canadian province, British Columbia. No developing nation has seen any merit in the idea.

This is not altogether surprising. Development demands ever more energy. There is a direct relationship between energy consumption and GDP. Over 80% of the world’s energy is derived from fossil fuels. The International Energy Agency predicts this may fall to slightly less than 80% by 2035. However, ongoing economic growth will see a 30% increase in greenhouse gas emissions by then.

Why should we slavishly follow the Europeans? There is absolutely no basis for a carbon tax in South Africa.

Tuesday, March 8, 2011

The Greenpeace Prescription

Greenpeace has urged the South African government not to get caught up with short-term political agendas, but rather to consider what scientists said was required to address climate change.

Me, I'm a scientist, and I think the past is quite a good guide to the future. The temperature rose by ~0.7 degrees C in the 20th century and there was effectively no change in any of Africa's climate indicators. There were no real regional trends in rainfall, for instance - a bit more here, a bit less there, but nothing Africa-wide.

So to address climate change, we need to do absolutely nothing - and the money saved can be used to address a real problem, like the million who die each year from a preventable disease like malaria.

If that is the message that emerges from COP 17, it will be worthwhile. Instead we will be told we need Africa to curb its emissions and preserve its forests. When Africa is about 2% of the global emissions? Purlees!