Biomass benefits
There is nothing wrong in theory or in practice with the plan to burn biomass in power stations and sequester the carbon dioxide. There is also no problem about scale when more reasonable assumptions are made than those of Sam Little (7 April, p 20).
It is realistic to suppose that replacing 20 per cent of the UK’s electricity supply 鈥� as much as is currently generated by nuclear power 鈥� with biomass. It is unrealistic to suppose that we will rely on any single energy source for all of our electricity.
It is also reasonable to assume greater efficiencies than the levels achieved by the coal-fired Drax power station, where about 70 per cent of the energy is lost as waste heat. Modern gas-fired stations (combined-cycle gas turbines) lose 50 per cent of the energy, while the exploitation of waste heat in combined heat and power stations (for example supplying district heating schemes) reduces the lost energy to 35 per cent.
Even assuming less than the best efficiency, about 1.6 million hectares (around one-third of the UK’s agricultural land and 15 per cent of the UK’s combined forest and agricultural land) is then needed for biomass production for 20 per cent of the UK’s electricity.
The UK used to have a hydrogen economy. Most houses were supplied with town gas that had hydrogen as its major component. Town gas was produced by the gasification 鈥� steam reforming 鈥� of coal. This tried-and-tested method not only makes it possible for biomass to fuel a combined-cycle gas turbine but also has the twin benefits of reducing the need to dry the biomass and producing hydrogen as an energy source.
Hydrogen can be transported without significant energy loss, whereas distributing electricity in the national grid loses 7 per cent of the total electricity generated in the UK. Accounting for this increase in the efficiency of energy distribution reduces the amount of land required for biomass production. Further reductions can be achieved from increased biomass production per unit area from improved agronomy and higher-yielding varieties, and by using waste biomass from agriculture, industry and households.
Hydrogen is a valuable fuel and feedstock. It can be used to power fuel cells and to replace the natural gas used as a source of hydrogen for the annual production of the 70 million tonnes of urea essential to feed the planet’s population. The use of biomass with carbon sequestration is the only carbon-negative way of producing energy using present-day technology. Biomass energy is already economically viable and is made much more attractive by a market for carbon offsets. Richard Branson should consider spending his prize money to promote the wider use of an existing method of carbon-negative energy production rather than trying, perhaps vainly, to invent new ones.
Group observation
How does being part of a group affect individual behaviour (l4 April, p 42)? Some 30 years ago I ran a group workshop for the Open University summer school at York.
Eighty students were divided into four groups. I asked each group to find an identity for themselves, to give themselves a name. After that I asked them to discuss ways and means to relate to other groups and how they felt about that.
I recorded their conversations and discussions, which I later played back to them. They were amazed to hear themselves, their hostility to the other groups, their difficulties in making any kind of peaceful contacts, and the arguments that followed between the ones that wanted to make contact and others that vehemently did not.
One group went so far as to kidnap someone from another group, much to their delight and entertainment. One young woman, a pacifist by conviction, persuaded her group to relate by peaceful means. The group’s energy visibly dropped: they had no idea how to deal with that.
Say again?
Alison Motluk mentions a study which reported that people using cellphones drive no better than drunks (7 April, p 31). She concludes that the speaker who is not in the car is unaware of the hazards facing the driver. This may, however, be only the beginning of the distraction. Consider that in their pursuit of profits, telephone companies reduce the bandwidth used by each call to the absolute minimum, leaving us straining to differentiate certain sibilants and plosives without the benefit of any frequencies greater than 3 kilohertz. This strain, when we drive through a patch of low reception, multiplies, and takes a good deal more of our processing power automatically into our audio realm, away from our driving prowess.
From Jonathan Wallace
I read with interest Alison Motluk’s article on how the human brain copes with multitasking (7 April, p 28). It called to mind a phenomenon I have noticed.
As many do, I often listen to the radio while driving and find that in normal traffic conditions I can happily follow a political interview or a drama. By contrast, when I manoeuvre around even the most straightforward of junctions, I am left with no recollection at all of what has been said in the programme when I emerge the other side.
Clearly, my brain is happy to multitask when the two tasks are relatively low-level. When one task becomes more critical, an involuntary switch shuts down the less important task.
Newcastle upon Tyne, UK
Plane problem is passengers
It seems as though the aviation industry is being continuously misrepresented in New 杏吧原创 as both negligent and naive 鈥� most recently by Martin Allen (31 March, p 22).
The reality is that conventional civil aircraft configurations are not optimum for performance. The resistance to change comes from airlines’ unwillingness to risk buying aircraft that the public might not trust, rather than lack of efficient technology.
Passenger demands drive design where they really shouldn’t: for example windows are unnecessary, require extra structural weight and increase drag, but if they were designed out, the manufacturer would go out of business.
The “wacky designs” are the best way to minimise weight, drag and fuel burn 鈥� far more than could be saved by scrapping duty-free or flying more slowly. Civil airliners already fly at a speed which is optimum for the combination of aerodynamic and propulsive performance, regardless of powerplant type, and jet streams are used where possible. The propulsive efficiency of turbofans will increase with speed, whereas turboprops peak at around 550 kilometres per hour 鈥� so perhaps this is the way forward.
Metamorphosis
Arthur Shapiro says that losing populations of established butterfly species is “like discovering that cockroaches are becoming extinct in cities” (14 April, p 46). In what way would that be a bad thing?
Dangerous and at large
It was quite a shock to open my copy of New 杏吧原创 and see the murderer of my wife and child staring out at me (14 April, p 8). My contribution to the debate about the Mental Health Bill now being considered by the British parliament is as follows.
Existing UK law permits violent people with mental health problems to be detained. The man who was convicted of killing my wife and 6-year-old daughter in a cornfield in Kent in 1996 was diagnosed as having an “untreatable personality disorder”. He was classed as “bad” but not “mad”.
So he was free to roam the streets, even though he was a known violent criminal, had told his therapists that he wanted to “kill children in the woods”, and was begging to be treated for his disorder. If the new law had been in place, he could have been compelled to receive “appropriate treatment” even had he not been seeking it. Or he could have been detained 鈥� in which case I believe that my wife and child would still be alive today.
I think risk assessments that are subject to review, with input from doctors, drug counsellors, police, probation officers, social workers and so on, could be consistent and reliable. I also believe that the provision of dedicated secure accommodation with modern therapeutic capacity could help to better manage the hard core of violent and dangerous people who are currently free in the community, and for whom it is only a matter of time before they injure or kill innocent members of the public.
Falsifying warming
In applying Karl Popper’s philosophy of science, Roger James implies that only a falsifiable hypothesis is a scientific one, and that theories linking such things as greenhouse gas emissions to climate change are “outside science” (14 April, p 23). There are, however, other measures of a theory beyond Popper’s.
The science of epidemiology, for example, hypothesises links that cannot be tested in a Popperian framework.
It is well accepted that smoking causes lung cancer, despite instances of lung cancer in people who have never smoked, and smokers who never succumb to lung cancer.
Legal systems introduce burdens of proof. In British criminal law, conviction requires that defendants be guilty beyond any reasonable doubt; in civil law, issues are decided on the balance of probabilities.
Where does climate change sit? Where does smoking sit?
There are expert witnesses on both sides, but the preponderance of scientists knowledgeable in these subjects have lined up to say that smoking causes cancer, and man-made greenhouse gas emissions are contributing to climate change.
I wouldn’t say that the climate change case is proven beyond a shadow of doubt, but surely it is proven on the balance of probabilities. This level of proof has been sufficient for governments to exert some control over tobacco companies, and it should now be sufficient for governments to institute controls on climate-affecting industries.
From Gregory Bradley
The test lies in the name of the phenomenon: “greenhouse effect”. All it would take to falsify it is an experiment conducted under controlled conditions that did not produce a temperature rise resulting from adding accepted greenhouse gases into the atmosphere.
In fact, all such experiments have shown a greenhouse effect.
In addition, we know humans are releasing large amounts of greenhouse gases; our measurements show levels of greenhouse gases in the atmosphere to be rising; and temperatures are also rising.
All these factors tally with the theory being true, so the onus of proof would seem to be on those proposing alternative explanations for the heating to explain why the additional greenhouse gases are not causing it.
Man-made greenhouse gas emissions are the simplest explanation for the observed phenomena.
Logan, Queensland, Australia
From Martin Parkinson
Climate scientists are proper scientists; they have heard of falsifiability; there is no growing body of evidence throwing doubt on man-made warming.
Bristol, UK
For the record
鈥� An editing error had Rachel Nowak implying that birth rates in the US have fallen below the rate needed to maintain the population (7 April, p 13). In fact, the US is one of a handful of western countries to have bucked the trend of declining birth rates 鈥� for reasons that include high birth rates in some segments of the population offsetting low birth rates in others.
鈥� We said that Stanley Milgram’s electric shock experiment was published in 1974 (14 April, p 42). That was his book Obedience to Authority; the experiment was published in 1963 in the Journal of Abnormal and Social Psychology, vol 67, p 371.
Back to the future
Apparently the earliest Ediacaran fossils “left no ancestors” (14 April, p 34). The question is, did they leave any descendants?
Logical flaw
Michael Brooks writes: “If information is always physical in some way, all physical processes can be seen as a form of information processing,” (31 March, p 30). This seems to me to be false logic, yet a lot about the existence of quantum gravity computers depends on it. “All buses are red” would not mean that “all red things are buses”.
It's in the can
You report Marko Hekkert of Utrecht University as saying that soda is no longer sold in cans in the Netherlands (7 April, p 37) While this is true for smaller outlets such as gas stations, cans of soda are still sold in supermarkets. In fact, they are the cheaper option.
Axis of not-so-evil
There are indications that the cosmic “axis of evil” is real and “won’t be written off any time soon” (14 April, p 10). Is it is time to choose a more appropriate name for it, without the connotations of badness and malice? Any good suggestions?
Carbon capture caveats
Recent articles have discussed the future potential of carbon dioxide capture and storage: for example, your editorial on 17 March (p 5). They focus mainly on two questions: Is it possible to capture CO2? Will the storage be reliable in the long term? The answers are “yes”, and “don’t know”.
There are in addition major issues that these discussions neglect. CO2 capture is energy intensive. On a life-cycle basis, it will reduce the effective output of a coal-fired power plant by 25 to 40 per cent, depending on the distance to the storage area. Capturing sulphur dioxide, to mitigate acid rain, reduces output by about 10 per cent.
CO2 capture imposes a huge waste-management challenge. The volume and weight of wastes is greater than the volume and weight of the coal being burned. This issue is unavoidable, because of the carbon content of coal: 70 to 80 per cent, compared with 1 to 2 per cent sulphur.
Very few of the world’s coal-fired plants are scrubbing SO2 emissions, because of the efficiency penalty and waste-management challenge, so how many would be prepared to take on the much greater burden imposed by CO2 capture?
Assume, however, that CO2 capture technologies will become affordable and that reliable long-term storage proves possible. We will then have to recognise that the life-cycle emissions factor of a “clean coal” plant will remain high. A realistic CO2 capture rate will be about 85 per cent, not 100 per cent. Moreover, emissions due to extraction, processing and transportation of coal would not be captured. If the energy penalty of CO2 capture is 30 per cent, 30 per cent more coal will have to be extracted, processed and transported to provide the same final service.
These factors have been reported in numerous life-cycle assessments of CO2 capture. The key is to put them together to give a complete picture of what the options are.
The editor writes:
鈥� This letter expresses a personal view, but Gagnon points out that he is Senior Advisor, Climate Change, for Quebec-Hydro.
Offset optimism
Carbon offsetting seems to me an easy way out for many, letting them avoid addressing the amount of carbon dioxide they produce in their daily lives. I find it hard to believe, however, Fred Pearce’s contention that the planting of trees in a forest restoration programme could make matters worse (10 March, p 38).
Trees become woodlands, and woodlands become immense carbon sinks.
Sheep, on the other hand, strip hillsides bare and stop any regeneration. If trees were planted where once there was a bare hillside, a complex environment rich in biodiversity would develop.
I would love to know how many millions of tonnes of carbon could be stored on all the hillsides that are at present used for sheep farming in the UK.
The government needs to use offset money to encourage sheep farmers to be foresters instead. Forests that are sustainably managed can also be a source of biofuel and of material for houses and furniture, which are in themselves carbon sinks.
Forest continuously regenerates itself if allowed to do so, and must surely be more or less carbon-neutral.
Thus so as long as it is not clear-felled, forest stores carbon indefinitely.
Pearce suggests that carbon-offset forestry projects kick indigenous people off their ancestral land. Surely the biggest cause of this is clear-cutting of primary forest.
The black lion tamarin conservation programme in Brazil, run by the Institute for Ecological Reasearch (Instituto de Pesquisas Ecol贸gicas), is a great example of how offset money could be used to conserve endangered species while also benefiting local communities. It provides previously landless people with resources to help them make a living on the land, while planting forest corridors in an environment denuded by cattle ranching.