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Daily Archives for November 23, 2017
The future of plastics: reusing the bad and encouraging the good
Richard Whitcombe/Shutterstock, CC BY-ND
Kim Pickering, University of Waikato
Plastics have got themselves a bad name, mainly for two reasons: most are made from petroleum and they end up as litter in the environment.
However, both of these are quite avoidable. An increased focus on bio-derived and degradable composites as well as recycling could lessen pollution and, in fact, plastics could make a positive contribution to the environment.
Plastics for bad
The durability of plastics makes them so useful, but at the same time, it turns them into a persistent (and increasingly big) blot on the landscape, or more importantly the seascape, once discarded.
Read more: This South Pacific island of rubbish shows why we need to quit our plastic habit
We’ve known for a while that bulk plastics are polluting the oceans. Converging sea currents are accumulating plastic waste in a floating island known as the Great Pacific Garbage Patch, which now covers an area larger than Greenland. The bigger bits of plastic are life-threatening to marine life and sea birds. They can strangle marine mammals or birds and build up in their stomachs and guts.
from Shutterstock, CC BY-ND
More recently, awareness of microplastics has raised concern about their ubiquitous presence in the food chain. Commentators suggest that by 2050 there will be as much plastic in the sea as there is fish. Who wants to go catch some plastic then?
Read more: How microplastics make their way up the ocean food chain into fish
Beyond that, plastic production currently relies on petroleum and that has raised issues about health hazards, generally associated with petroleum-based products during production, use and disposal.
Plastics for good
Plastics can contribute positively to the environment in the following ways:
- Reduced food wastage
Between one-quarter and one-third of all food produced is wasted through spoilage. But without plastic packaging, it would be considerably worse and have a larger carbon footprint.
Many of the recycling enthusiasts I know do not think about throwing out spoiled food that required energy in terms of planting, cultivating, harvesting and transporting and therefore will have added to greenhouse gas emissions.
- Lightweight transport
The use of plastics in transportation (cars, trains and planes) will reduce fuel consumption. Their application (along with reinforcing fibres) in aerospace as alternatives to traditional metallic alloys has brought huge gains of fuel efficiency over the last few decades.
Incorporation of fibre-reinforced plastics in the Boeing 787 Dreamliner, for example, has resulted in fuel efficiencies that are similar to a family car (when measured by kilometres travelled per person). By the way, carbon fibre, the aerospace fibre of choice, is produced from plastic.
There are good things about plastics including benefits for the environment, but is it possible to make use of the good aspects and avoid the bad?
Future proofing plastics
Plastics are, chemically speaking, long chains or large cross-linked structures most commonly made up of a framework of carbon atoms.
For a long time, we have been using bio-derived plastics – naturally occurring materials such as animal skins including leather, gut and wood. These forms of plastic are complicated chemical structures that can only be made in nature at this stage.
Some of the early synthesised plastics were made from naturally occurring materials such as casein (from dairy) that was used for simple items such as buttons. The development of petroleum-based plastics has been a major distraction from such materials.
However, in the last couple of decades, bio-derived plastics have become available that provide good replacements. These include starch-based plastics such as polylactide (PLA), which is produced from corn starch, cassava roots or sugarcane and processed in the same way as petroleum-based plastics. Such plastics can be foamed or used to make drink bottles.
From Shutterstock, CC BY-ND
Recycling plastics is another essential step towards reducing the environmental load. Let’s face it: it is people who are doing the littering, not the plastics themselves. More effort could go into waste collection and a carrot/stick approach should include disincentives for littering and a plastic tax which would exclude recycled plastics.
Incentives are also needed to encourage product development that takes account of the full life cycle. In Europe, for instance, legislation has made it compulsory in the automotive industry for at least 85% of a car to be recycled. This has had a dramatic influence on the materials and design used in the industry.
Even with best efforts, it is unrealistic that we would capture all plastics for recycling. Biodegradable plastics could be a useful tool for preventing environmental damage. PLA (polylactide) is biodegradable, though slow to break down, and there are other forms available.
This highlights the need for more research into controlling biodegradability, taking into account different applications and the need for infrastructure to deal with biodegradable plastics at the end of their life. Obviously, we don’t want our planes biodegrading during their 20 years of service, but one-use water bottles should break down within a short time after use.
The planet doesn’t have to become a toxic rubbish dump. In the short term, this will need some government action to encourage bio-derived, recyclable and biodegradable plastics to allow them to compete with petroleum-based products.
There are signs of improvement: increasing awareness of the harm plastics cause and a willingness of consumers to pay for plastic bags or to ban them. We need to stop dumping in our own backyard and remember that the environment is where we live. We ignore it at our peril.
Kim Pickering, Professor of materials science and engineering, University of Waikato
This article was originally published on The Conversation. Read the original article.
Delhi suffers second smog crisis in 12 months, as wake-up calls go unheeded
A year ago Delhi was choking, as smog in the Indian capital soared to 16 times the government’s safe limit for particulate pollution. Now the same thing has happened again.
Levels of the most dangerous particles, called PM2.5, have once again reached last November’s levels: more than 700 micrograms per cubic metre in some parts of the city. Experts say that prolonged exposure to this level of pollution is equivalent to smoking more than two packs of cigarettes a day.
Just 12 months after the record-breaking pollution that should have been a major wake-up call, Delhi is again plunged into darkness. It is a big embarrassment that authorities were not better prepared for this year’s smog season.
Read more: As another smog season looms, India must act soon to keep Delhi from gasping
In July, I released a detailed analysis of the factors that cause Delhi’s November smog.
Based on data from India’s Central Pollution Control Board and from NASA, I concluded that Delhi’s record-breaking pollution in November 2016 was largely due to slow wind speeds and prevailing northerly winds, as well as Diwali fireworks, and the widespread practice of burning crop residues. Others, including the Delhi government, reported similar findings.
But this knowledge has not stopped it happening again, much to the frustration of Delhi residents who now face a second consecutive pollution-plagued winter.
Of course, the authorities do not control the wind speed or direction. But they can and should take steps to curb the other crucial factors.
Burning issue
In Haryana and Punjab states to the north of Delhi, farmers routinely burn their croplands after the summer harvest, ridding their fields of stubble, weed and pests and readying them for winter planting.
This agricultural event coincides with Diwali, India’s festival of lights, which features three or four nights of fireworks before and after the festival, in October or early November.
This series of NASA satellite images clearly shows the pollution plume moving across the landscape during the first two weeks of November. Red dots indicate live fires.
NASA
NASA
NASA
These images show that crop burning is still continuing, especially in parts of Punjab. As the graph below shows, crop burning produced significant amounts of pollution from November 2, 2017, after an earlier pollution spike around October 20 due to Diwali.
https://datawrapper.dwcdn.net/ZHncI/1/
Other countries have taken measures to limit crop burning. In Australia, the Victorian state government strongly encourages farmers to retain crop stubble residues, although it allows sporadic burning. In some Canadian provinces, stubble burning is allowed by permit only.
There is no such legislation under consideration in India. But without a ban on crop burning, Delhi’s pollution woes are likely to continue.
It is high time that the government responded, before Delhi’s pollution gets even more out of hand. Particles in the PM2.5 size range can travel deep into the respiratory tract, reaching the lungs. Exposure to fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath.
Exposure to fine particles can also affect lung function and worsen medical conditions such as asthma and heart disease. Studies have linked increases in daily PM2.5 exposure with increased respiratory and cardiovascular hospital admissions, emergency department visits and deaths. More than a million deaths in 2015 were attributed to India’s air pollution.
What governments and residents can do
There is a range of short- and long-term options to combat the problem.
Farmers in Haryana and Punjab should be banned from residue crop burning during October and November, and should be given financial compensation for the inconvenience.
Meanwhile, Delhi’s residents should consider driving less, either by carpooling or using public transport. The city’s authorities, meanwhile, could restrict the entry of polluting trucks and heavy-duty goods vehicles, gradually phase out and ultimately ban older vehicles, and increase parking charges or restrict families to a single car.
A reliable 24-hour power supply would help to reduce the reliance on heavily polluting diesel generators in offices and factories. Subsidies for cleaner fuels or electric or hybrid cars would also help.
Read more: Air pollution causes more than 3 million premature deaths a year worldwide
Authorities also have a duty to keep the public informed of pollution levels, through daily television, radio and social media updates, as well as pamphlets warning of the effects of air quality on health. On the worst days, schools should be closed and children and older people urged to stay indoors.
In the longer terms, a “green belt” could be planted around the city, to help soak up traffic-induced air and noise pollution.
Many of these policies would involve significant upheaval. But Delhi needs action before it is too late. The alternative is to be plunged ever deeper into the murk.
Vijay Koul, Honorary fellow, CSIRO
This article was originally published on The Conversation. Read the original article.
Kevin's Walk on the Wild Side 