Wednesday, 29 February 2012

Challenging misperceptions around clean energy Part 2

Mercury Falling (apologies to Sting)

You may have read Emma's incisive comment on my previous post, questioning the relevance of US mercury emissions from power generation to the safety of CFLs here in Britain.  I agree!  The objective of my post was to put the case that the climate change resulting from (global) greenhouse gas emissions is a much greater threat to our safety than the trace amounts of mercury present in compact fluorescent lamps.  However, I used American data that didn't answer the question of how CFLs contribute to mercury pollution in Britain.

To put this right, I have examined the mercury emissions arising here in Britain from the Government's Carbon Emissions Reductions Target (CERT) programme, that funded the free distribution and subsidised retail sale of CFLs.  Rightly or wrongly, I am excluding any mining and manufacturing emissions of mercury in the production of these bulbs, since that took place outside the UK.

Compact fluorescent lamps (CFLs) of up to 20 watts contain under 5 milligrams (mg) of mercury, the metal vapour that emits ultra-violet light when the bulb is running.  This U-V light excites the white phosphor coating inside the tubes of the CFL, causing the phosphor to fluoresce, and that's how fluorescent lighting works, in a nutshell!  The typical quantity of mercury in a modern CFL is around 4mg mercury, commonly described as "enough to cover the writing tip of a biro".

Up to 350 million compact fluorescent lamps were distributed under CERT between 2008 and 2010, containing around 1.4 Tonnes of mercury in total.  Each is expected to last up to 10 years and to be recycled appropriately at end of life - in which case there is no mercury leakage from CFLs.  In practice, some of these lamps break and many are thrown in the bin when they stop working, releasing their trace of mercury to the environment.

To estimate the release of mercury from these 350 million CFLs, I have assumed that (1) 10% of them fail each year, for 10 years, giving an average working life of 5 years, and (2) HALF these CFLs are broken or binned, rather than being recycled properly.  In this case, 17.5 million of those CFLs supplied under CERT will be broken each year, for 10 years, releasing around 70 kg of mercury a year to the environment.

How does this compare with other sources of mercury emissions here in the UK?  The 2009 National Atmospheric Emissions Inventory  shows that 7.35 Tonnes of mercury were reported to be released in that year.  Some of the sources were: 3.9 T from manufacturing and chemical industries, 1.5 T from cremation and clinical waste incineration, 1.3 Tonnes from power generation and 360kg from landfill.

So the amount of mercury released each year from the CFLs distributed under CERT represents just under one percent of the total annual emissions of this toxic metal in Britain.  We are all exposed to this pollution, principally through our diets - because mercury enters the foodchain - and particularly if we eat the top marine predators like tuna and swordfish.  But the quantities we ingest are minuscule and the risk they present to most of us is, frankly, trivial in comparison with the certain dangers of manmade climate change for us and our descendants.

We live in a 4-bedroom detached house.  Shockingly, it has around 120 bulbs installed!  I first surveyed the energy use of lighting in our home five years ago, when we had 34 energy-saving CFLs and 92 incandescent lights - including halogen lamps.  We now have about 80 CFLs fitted and have replaced almost all the remaining incandescent bulbs with clean, bright LED lighting.  Our electricity usage has halved over the same period, largely through fitting energy-efficient appliances including lighting.

I also have a small, medical thermometer containing mercury, that we used to put in our babies' mouths when they were unwell.  The thermometer contains 2 - 3 times as much mercury as all the CFLs in my house.  I am sad to say that climate change is a far greater threat to my grown-up babies' wellbeing than that thermometer ever was.

Monday, 27 February 2012

Challenging misperceptions around clean energy

Which are the greater threat, heavy metals or greenhouse gases? 

Most people are happy to agree that LED lighting is clean, efficient and the way forward - when the balance of quality, performance and price becomes acceptable for mainstream customers in our high streets and retail parks.  Until then, we can get along with the current generation of energy-saving lights, known as compact fluorescent lamps (CFLs).  In recent years they have been given away by energy companies, and sold for pennies in supermarkets, under the Government's Carbon Emissions Reductions Target (CERT) programme.  Those days are gone, however, as you will know if you have had to buy any CFLs recently - they cost anything from £2 to £6 each, which is pretty much what they should cost - they last many years and save many times their own cost in electricity over their lifetimes .

There are some downsides with CFLs:

  • they can take a long time to reach full brightness
  • their colour rendition is usually less attractive than that of old-fashioned tungsten incandescent bulbs and halogen lights
  • their brightness can fall substantially over their lifetimes
  • they contain traces of mercury and, at the end of their life, they need to be disposed of through suitable recycling facilities.
These issues have led some green campaigners to argue that we should not have banned traditional bulbs, or subsidised distribution of CFLs in recent years, because it was the wrong technology: instead, we should have waited until now - or even until 2014, when the performance and price of LED lighting will really be ready to compete with incandescent bulbs.  Their feeling is that long warm-up times and poor quality light from CFLs have turned consumers against low-energy lighting, so that the adoption of great LED lights will be held back by people's bad experiences of CFLs.  

More concerning, they oppose CFLs because of the presence of trace amounts of mercury in these bulbs.  Some bulbs will be broken in the home, exposing families to traces of mercury vapour, and many will be disposed of through household waste, potentially venting their heavy metal waste to our atmosphere or soil.  In response to this, should we all be so concerned about mercury in our CFLs that we insist on keeping our incandescent lightbulbs, stockpiling them from online retailers before they run out forever?  Well, NO.  That would be a disproportionate reaction to a misunderstood threat.

The US Environmental Protection Agency (EPA) website sets out the origins and consequences of mercury contamination, here.  The principal manmade source of mercury contamination is from burning coal.  The coal is burned in order to generate electricity, to power our homes and businesses.  In Britain today, lighting accounts for about 20% of electricity demand (source).

Here's a decent analysis of the mercury released through using a traditional, incandescent light and an energy-saving compact fluorescent lamp.  The CFL contains about 5 milligrams of mercury.  Generating the power to run it for its typical lifetime of 7,500 hours releases a further 3.5mg mercury.  That gives a maximium total mercury release of 8.5mg, if the bulb is not properly recycled when it stops working.  

How about the old-fashioned, tungsten incandescent lamp?  It will only last 1000 hours.  Powering a succession of these bulbs, with the same brightness as our CFL, for 7,500 hours will release 13 mg mercury from coal.  From this, we can conclude that (a) it's important to recycle CFLs (and all fluorescent lights) properly and (b) old-fashioned lightbulbs cause much more mercury to be released into the environment than CFLs, through their inefficient use of electricity.

Emissions of carbon dioxide and other greenhouse gases are much more significant for our future wellbeing than traces of mercury.  Dr James Hansen of NASA has written, in "Storms of my Grandchildren" (2009), that the greenhouse gases emitted from a large coal-fired power station over its operating lifespan of around 25 years will be responsible for driving 400 species to extinction, through climate change.  

CFLs have been available for about 20 years and, by using them since the mid-nineties, we have reduced emissions of both mercury and carbon dioxide from Britain's power stations.  They have been unarguably a good thing in the battle against manmade global warming.

There is no doubt that LEDs are a cleaner, greener, brighter solution for the future of lighting but they are only now beginning to challenge CFLs as the low energy lighting solution of choice, in terms of performance, quality and cost.  I have adopted LED lighting in my home as widely as I can but the great majority of my lights are compact fluorescents and I still depend on these to keep my energy bills and carbon footprint low while providing warm, welcoming lighting in almost every room of the house.  The LEDs to replace these are nowhere near competitive yet and I shall be loving my CFLs until the new lighting technology can beat them on performance, quality and total lifetime cost.  

Tuesday, 14 February 2012

The thorny (or should that be bony?) subject of what we eat

I was recently told by a colleague that, "we were born to eat flesh". As a biologist, I would beg to differ.  Our dentition, evolved from an omnivorous diet, combines cutting and grinding actions.  While our canines and incisors can tear into meat, our molars enable us to chew fibrous plant material in much the same way that ruminants do.  We are well adapted to a diet of fruit, vegetables and grains - supplemented with meat when we can get it.  Our short alimentary canal indicates that, rather than being born to eat meat, we were born to cook.  The combination of farming and fire provides plentiful calories in our diet that are much more readily absorbed than the resistant flesh of raw animal and plant tissues.  Steve Jones, Professor of Genetics at University College, London, observes wryly that anyone trying to live exclusively on raw food would die of malnutrition within 90 days.

This led onto the subject of fish because my colleague felt "more strongly about the waste involved with eating fish than with cows, sheep, pigs, chicken, etc."  On the day of this exchange, I happened to be cooking sea bream for dinner.  Whenever we buy whole fish, I boil up the leftovers with a few vegetables and a drop of lemon juice or vinegar to produce a richly-flavoured broth.  Left to chill, the broth sets to a loose jelly which forms the base for another delicious meal, such as risotto or paella.  The only waste is the guts and a handful of sharp fishbones that can be composted.

Of course, there can be waste a-plenty in the supply chain.  Hugh Fearnley-Whittingstall's "Fish Fight" campaign has raised our awareness of the appalling practice known as discards, where perfectly edible, dead fish are thrown back into the sea because the vessel has exceeded its fishing quotas.  At the same time, Greenpeace campaigned against the use of purse-seine nets and Fish Aggregating Devices (FADs) to fish for tuna, as these methods result in carnage for other species including shark, dolphins and endangered sea turtles.  This incredible campaign resulted in the immediate end to these fishing practices by all the major producers and retailers of tinned tuna.

No such consumer revolution has yet been sparked against the rape of tropical peatland rainforests in Indonesia and Malaysia, which are home to all three species of orangutan, in pursuit of the latest gold rush.  Palm oil is present in about a quarter of all grocery products.  It is widely used in toiletries and cosmetics.  Most insidious is its inclusion, by law, as biodiesel in our transport fuel, under the Renewable Transport Fuel Obligation (RTFO). Liquid biofuels, including palm oil, produced from clearing virgin rainforest have a carbon intensity that is many times that of the fossil fuels they are intended to replace.  Yet that is not stopping Eric Pickles and his Department for Communities and Local Government from granting planning consent for palm-oil fired power stations in Britain, under the deceptive claim that biofuels are a central component of Britain's plans to decarbonise our energy infrastructure in the coming decades.

Industry moves to secure sustainable supplies of palm oil, through the Round Table on Sustainable Palm Oil (RSPO) are a figleaf, however well intentioned, that is allowing the continued destruction of remaining orang-utan habitat.  Most of the major retailers and brands supplying our consumer goods have pledged to use only sustainably-sourced palm oil by 2015.  In the meantime, deliveries of RSPO-certified sustainable palm oil to the UK remain unsold because so few of the major players are yet prepared to take the competitive hit of paying more for this ethical ingredient while they can still get the cheap oil, whose by-product is deforestation, leading directly to gargantuan greenhouse gas emissions, biodiversity loss and the deaths of our few remaining cousins, whose name comes from the Malay language and means "people of the forest".

So what are the most sustainable and ethical foods in our diets? Allotment-holders, by their toil, earn the right to eat fresh, healthy, seasonal vegetables with no food miles whatsoever.  Those of us with less time, talent and tenacity continue to depend on the supermarket for our weekly shop.  The best we can do there, I believe, is to buy locally-grown food that is in season, avoiding the need for fossil fuels to heat greenhouses and to fly ripe produce to our tables from around the world.   Meat and dairy products are among the most carbon-intensive foods we can buy and so it makes sense to eat less of these foods.

Instead, consider the point made by Colin Tudge in his excellent study of the history and future of food production, "So Shall we Reap" (2002).   Traditional combinations of staple foods (carbohydrate-rich grains and roots) with vegetables or pulses have developed as regional cuisines around the world.  The blend of proteins in each of these combinations provide all the essential amino acids we need to remain healthy.  Tudge's examples include rice and tofu (bean curd) in the Far East, rice and peas in the West Indies, tortillas (maize) and frijoles (beans) in Mexico - and even baked beans on toast (wheat)!  We have all experienced other, traditional combinations of carbohydrate and vegetables, from pasta and beans to potatoes and peas.

The message to take away is that meat and dairy products are not the core of a sustainable, ethical and healthy diet.  That role is reserved for the rainbow varieties of peas, beans, pulses and vegetables which we can combine with our staple foods, transforming them from monotonous carbs into delicious, nutritious and aesthetic cuisine.  And if there WAS a take-away serving that, I'd be the first to order a home delivery from their carbon-neutral rickshaw service!