Archive for the ‘Environment’ Category

The 2011 World Solar Challenge has been run and won

October 20, 2011

They started under clear skies and blazing heat and finished in steady rain, but the winner of the 2011 World Solar Challenge has been decided. After 4 days of travelling, Tokai University (Japan) crossed the finishing line north of Adelaide today in the lead.

Tokai University's car crossing the line surrounded by team members

In the closest finish in the history of the WSC, mere minutes separated Tokai and second placed Nuon Solar Team from the Netherlands. Third placegetters University of Michigan (USA) were themselves only a short distance behind. The close finish is remarkable given the distance travelled and time spent on the road. Ashiya University, of Japan, and Team Twente, also of the Netherlands, are further behind vying for fourth place and expected to finish Friday, as is Team Aurora of Australia, not far behind Ashiya and Twente.

The World Solar Challenge is an epic 3000km solar car challenge, running down the length of Australia from Darwin to Adelaide. With unlimited regulations it is likely all the cars would be able to exceed the road speed limit and run for extended periods of time. Instead, the regulations deliberately limit battery sizes and solar collection area to prevent the ability for the cars to run at maximum speed for hours on end and hence to help promote the development of more efficient solar collector units and motors.

The main differentiator between the cars is the ability of the solar cells to collect energy from the sun and convert it into electricity. With limited battery sizes, the energy which can be held on board the car isn’t enough to allow unrestricted running. Instead, the speed of the car is dictated by the combination of the amount of energy being collected from the solar panels, and the efficiency of the motor using that energy. The faster a car runs, the more energy it uses and hence the more energy it needs to collect to replace that used. Quite simply, if a car’s solar panels aren’t efficient in collecting energy to replace that being used, the car will run out of electricity. So a balance needs to be found between energy collection and expenditure, with cars more efficient at collecting and using energy able to run at higher speeds.

Further adding to the challenge, running of the cars is restricted to certain hours of the day, with cars required to hold at positions overnight. To ensure that the cars do maintain these hold positions, and stay within the legal speed limits, a sophisticated tracking system is employed to monitor the progress of each team. This ‘Mission Control’ was this year based in the Science Exchange in Adelaide.

This year’s race was never going to break any records with the challenge suspended for several hours due to bushfires close to the race route. There was also another dramatic development on day 4 when a car from Team Philippines, having been parked for repairs to its battery system, suffered an explosion in its battery packs. Thankfully, no one was injured.

Another challenge faced by the teams competing in the World Solar Challenge are the outsized road trains which Australian highways are famous for. These extremely long and wide trucks normally require traffic coming the other way to pull off the highway to allow the truck to pass. However, according to Bruno Moorthamers from Nuon in an interview with The Register, a solar car’s steering doesn’t allow this manoeuvre. Instead, Bruno said he has to drive “a little under” the overhanging loads of the trucks.

Despite crossing the official finishing line Thursday afternoon, a late developing fault meant that Nuon would not enter Adelaide city until the following day, meaning that celebrations in the Victoria Square ceremonial finishing line were reserved for Tokai. Dutch supporter groups hoping to cheer home Nuon and Twente were left instead to congratulate the victorious team and wait for their teams to arrive on the Friday. Tokai certainly celebrated in the rain, and definitely showed their excitement at having won such a hard-fought challenge.

Tokai team members celebrating at the finish

Celebrating with sake

Zoz Brooks from the Discovery Channel meets the driver who brought the Tokai car across the line.

The winning Tokai University team

The team celebrates by jumping into the Victoria Square fountain.

The Tokai team congratulate each other

Team Twente supporters at the finishing line

Supporters of Nuon Solar Team at the finishing line

Tokai celebrate in the Victoria Square fountain

Getting the sustainability message out through film

August 21, 2011

Over the past few weeks I’ve been involved in the organisation of public screenings for the 2011 SCINEMA Festival of Science Film.  The festival showcases science dramas, docos, animations and shorts, and in 2011 SCINEMA received over 400 entries from 35 countries including entries from professional filmmakers, amateurs, and student-groups, making it one of the foremost science film festivals in the world.



For me three films in particular stood out, and this blog post is based on their message – that we are way too wasteful, and unless things change things are going to get far worse.  Worse not only in terms of resource availability, but also in an economic sense that we’re getting ripped off by some very shrewd business people.



It is no secret that we are a wasteful society.  Humans now produce more waste than ever before, and while much of this can be recycled and reused, much is not.  Take for example metal, and iron in particular.  In 2008 the worldwide crude metal consumption was 1.4 billion tons, twice what it was in the 1970’s and nearly seven times the level of the 1950’s.  That makes sense, populations are increasing and just from an infrastructure point of view more metal needs to be used to support these increases.  However, despite the fact that metals can be recycled indefinitely around 70% of metals are used only once then discarded.  As a result of this rate, after 5 cycles only 0.25% of metal is still in circulation.  The rest forms the billions of tons of scrap metal around the world.



Such is the extent of our disposal of metal, we throw away enough iron and steel to supply all the carmakers in the world on a continuous bases.  Aluminium however – Americans dispose of enough to be able to rebuild their air force every 3 months.  When looking at environmental and energy efficiency, aluminium which is recycled uses 95% less energy than making the metal from scratch, meaning 20 aluminium cans can be made from recycled material for the energy cost of a single can being made from new material.



Taking all that into account, surely it makes sense to recycle metals more than we currently are. It doesn’t make sense to keep mining and refining all this metal given we already have so much available and able to be reused.



But why is our consumption increasing so quickly? Well partially it is a result of planned obsolescence.  Believe it or not, the lifespan of a light bulb in 1920 was longer than it was in 1950.  The humble light bulb was the originator of planned obsolescence, when manufacturers make products wear out quickly so that people have to purchase more.  In fact during the 1920’s and 30’s, there was an international cartel of light bulb manufacturers who banded together and deliberately set a limit on the lifespan of the light bulb for this very purpose.  Should any of the member companies exceed this life span they were fined heavily.  This cartel also controlled distribution and sales, increasing prices and ensuring competitors would not gain market share.



There is another type of planned obsolescence though, not through technical means like artificially shortening lifespans, but through marketing means.  Quite often manufacturers seem to release new model products with little or no improvement over the outgoing model, and through marketing convince the consumer they need to upgrade to this newer product.



This is done purely for economic purposes, to boost sales and company income.  However it has the flipside of increasing the production of waste.



So what can we do about increasing recycling?  It requires both an industry action to reuse more metals in manufacturing processes, and also consumer action to recycle and provide more access to materials which can be recycled.  In Australia only around 50% of recyclable waste is actually recycled.  However, in South Australia that level is closer to 80%, with the reason being that SA has a recycling deposit scheme – consumers are paid to recycle.  Manufacturers have previously fought against such schemes, and recently when SA increased their scheme several multi-national companies resisted the move.  However, it cannot be argued that providing a minor incentive does improve public behaviour.  50% of our recyclable waste is a considerable amount of needless landfill. Surely being smarter about what we throw away is only a benefit?



We as people can do so much to reduce consumption and landfill.  Just improving our own recycling and disposal of goods can make a huge difference, and it takes minimal effort and little or no cost.  But increasing sustainability can also go beyond just what we throw away, and again it is only beneficial.  Growing a small amount of vegetables or herbs will be cheaper than buying them from the supermarket, and will probably be tastier too, while the effort to maintain them will probably be less than having to duck out to the supermarket when you realise you’ve forgotten to buy something.



The public can make a significant effort through making basic changes to our lifestyles.  However these changes won’t take us backwards, in fact they’ll take us forward into a society where we have the same quality of life but produce less waste and spend less money.  Surely that is an improvement.



So which three films from SCINEMA did I find particularly interesting and were the inspiration for this blog post?



The winner of the 2011 SCINEMA Best Film was The Light Bulb Conspiracy, by Cosima Dannoritzer of-Spain.  An investigative piece, LBC details how “planned obsolescence” is incorporated into just about every product we buy.  This includes not only a technical planned obsolescence – where products deliberately have a limited lifespan to make customers purchase more and more products, but also a psychological planned obsolescence, where customers are induced to buy the newest product, despite being in some cases no better than their old product.



Going right back to the 1920’s and using the humble light bulb as an example, LBC follows planned obsolescence throughout its history, and shows how manufacturers are contributing to the wastefulness of society solely to make money, including revealing insights from one of the Philips family members – the family which established the Philips electrical goods manufacturers.  But, as LBC shows, the public is starting to fight back.



Trailer:





Despite not winning any prizes, Waste Not by Ruth Hessey of Australia, is a fantastic film about recycling and sustainability in our everyday lives. With some fantastic cinematography – they even make the processing of rubbish a visual spectacle – this 25 minute short film talks with people involved in every step of the sustainability movement, from scientists and policy advisors, to the garbo’s who collect our household rubbish and those people who actually work at recycling plants, and even the head chef from one of Australia’s top restaurants, Tetsuya’s.  The overriding message from all of those people is that we need to improve the way we recycle and reuse, because what we’re doing at the moment is just so wasteful, and making those improvements does not have to be difficult, or expensive.  As one of the interviewees remarks, “saving the planet is not about going back and living in a cave… this is actually about progress.”  And while documentaries on this topic in the past have been, to be honest, boring, Waste Not is captivating; the story is told by regular people and really does inspire the viewer to make a change.



Not taking anything away from the sheer power in the way it delivers its message, or the winner for Best Cinematography at 2011 SCINEMA (Where the Wild Things Were, Amber Cherry Eames, Scotland), this would in fact have been my pick for that award.



Trailer:





Another film which hits hard and delivers its message particularly powerfully is 99% Rust, by Nenko Genov of Bulgaria.  Using a very simple narrative style, black and white photographs with captions and haunting music courtesy of New Order, it rams home how wasteful society is.  Just why do we have so much scrap metal lying around when it could easily, cheaply and efficiently be recycled and used indefinitely?


99% Rust by Nenko Genov

99% Rust from Nenko Genov on Vimeo.


……………………………………………………………………………….


On a completely unrelated topic, one of the most popular films shown during our screenings was Worm Hunters, produced by Chris Carroll of Australia, and winner of the Special Jury Prize.  Taking a light hearted look at several groups of scientists, the film follows the groups as they travel the world literally hunting worms, hoping to find species that have never been seen before.  While that may sound dull, we received more comments from filmgoers about this film than any other, it comes together into a really great fun film which children in particular enjoyed immensely.

New ways to communicate science – Science-Rap

June 17, 2011

This fortnight I thought I’d do something a little different. Rather than a normal article, I thought I’d draw your attention to a group of science communicators who definitely have their own style. These people are part of a burgeoning group of science rappers.


Oort Kuiper
Jon Chase, aka Oort Kuiper, is a science communicator from the UK. Often working with another communicator Mark Brake, Jon takes his unique way of communicating science into the public by performing at schools, libraries and other community centres. Jon has been commissioned by organisations such as NASA to create science raps, and has performed at notable institutions such as the London Science Museum, the Royal Society, and the Royal Institution (GB).



With a background in aerospace, science and science fiction, his raps tend to focus more on human’s place in the Universe and how life relates to it. He gained some exposure for his 2008 rap Astrobiology, commissioned by NASA.





His other notable works include Life – An Autobiography, a six and a half minute journey through life on Earth.



A Better View reveals the world we live in through science and technology.



However Jon’s discography also includes topics as diverse as rain and genetics.



Alpinekat
One of the most well-known science rappers is Kate McAlpine, otherwise known as Alpinekat. The Michigan State University graduate was working as a science writer at the Large Hadron Collider in Switzerland when she first recorded Large Hadron Rap, featuring her and a number of CERN colleagues rapping and dancing as only scientists can. After being posted on YouTube, Large Hadron Rap has gone on to be viewed over 6.6 million times.





Despite initial scepticism from CERN management, Kate received permission to perform and record the video in and around the LHC. After viewing the finished product however, they were won over. “We love the rap, and the science is spot-on”, CERN spokesman James Gillies told National Geographic.



AlpineKat has gone on to make more science rap videos, including Rare Isotope Rap, and Black Hole Rap, below.




Tom McFadden
Tom, an instructor from Stanford University in California, approaches his science rapping a little differently. Not afraid to use technical details, his raps contain many more scientific terms and jargon, so they do require some prior knowledge. This makes them more useful for university students and scientists than the general public.



Nevertheless it is impressive he manages to rap around the jargon, and for those with a cell biology background, they’re quite entertaining.



For example, Put Some ACh Into It explains the two sides of the autonomic nervous system – the signalling system that the body uses to unconsciously control the body. The autonomic nervous system controls things such as heart rate, digestion, breathing rate and perspiration, as explained in the video.



Get Taq explains several commonly used biotechnology tools, such as replicating DNA, connecting pieces of DNA together, producing custom proteins, and even genetically modifying mice to investigate what role particular proteins play in an animal.



These three artists aren’t the only exponents of science rap, but they’re amongst the ones to keep an eye on. And as science communicators forever look for new ways to engage with the community, they’re the ones at the forefront of a new way to connect with the public.



Check out Jon, Kate and Tom’s raps, plus others at scienceraps.co.uk.

Nuclear Power – Dealing with waste and carbon emissions

March 4, 2011

Last article looked at how a nuclear power plant produces electricity. However, one problem with nuclear power stations is the production of nuclear waste, a highly toxic, highly radioactive substance made up of the spent fuel rods. Part 2 looks at dealing with nuclear waste, and looks at just how carbon friendly nuclear power really is.

 

Nuclear waste

After removal from a nuclear reactor, the spent fuel rods are stored in deep pools of water for several years to literally cool off and allow some decay of the radioactivity. These waste fuel rods are then removed, and there are two possibilities. They can either be transported and stored as is, or processed to remove any useful remnants. While processing occurs in Europe and Japan, at the moment there is no waste processing in the US.

 

A spent fuel rod will normally contain somewhere in the region of 0.8% Uranium-235, which, along with the Uranium-238 in the rod, can be extracted and reused to make new fuel rods. The waste also contains radioactive materials which are useful in medicine which can also be extracted and used. However, reprocessing fuel rods does allow the extraction and concentration of Uranium-235 and plutonium, another particularly reactive atom, which could be then used for weapons. The reprocessing of spent nuclear fuel is extremely technical and requires highly specialised equipment, including itself a particular type of nuclear reactor. As a result very little reprocessing is done with France, one of the highest fuel re-processors, only recycling around 28% of its yearly fuel. Due to this special type of nuclear reactor and other specialised equipment and processes the extraction and reuse of Uranium for nuclear fuel is very expensive, and is only viable when the prices of uranium are high.

 

On average, a nuclear power station produces between 20 and 200 tons of waste per year. Due to its toxicity and radioactivity, it needs to be stored in a location which effectively removes it from the environment. At present however, most waste is believed to be stored at the individual power stations, although there have been suggestions for centralised repositories. A centralised facility would bring all the radioactive waste into one ideal location separated from population centres. The United States conducted feasibility studies on storing waste underground in the Yucca Mountains however abandoned the idea. Australia has also considered locations for nuclear waste storage in the deep outback

 

Nuclear waste in storage

A central storage site would normally be in a remote area far from water sources to provide protection to the population in case of a leak of radioactive material. The Australian outback option is also in an area of geological stability, meaning there is not likely to be any major earthquakes which may affect the containment of the waste, and underground storage provides shielding at ground level from radiation. Such a facility would likely involve the digging of a large pit which is then lined with concrete to act as containment for any leaks. Waste canisters would be placed in the pit, and the pit filled in. A location such as the Australian Outback would limit the exposure of the canisters to moisture such as rain, and as a result corrosion of the containers would be minimal. However, should there be any leaks, the waste would theoretically be contained within the concrete-lined pit.

 

The Swedish system for disposal of nuclear waste uses caves 500 metres underground. Firstly, the radioactive waste is stored at the nuclear station for up to 30 years, after which it is placed in an iron capsule. This iron capsule is then encapsulated using copper. An 8 metre deep hole is drilled in the cave, into which the copper capsule is placed, and the hole then filled with bentonite clay which will soak up any leaks. The combination of copper, which will not corrode, and clay should prevent any toxic waste from escaping into the environment. When the storage cave is full the entrance is permanently sealed.

 

A Swedish copper canister for storing nuclear waste

When stored properly, radioactive waste is not something to be as fearful of as some people would have you believe. It may surprise you to know that at any given time, there is radioactive waste stored in most universities and major hospitals worldwide, waiting transport to a long-term storage facility. As long as the means of storage are secure, it actually poses little risk to the surroundings.

 

Nuclear waste does have a long life-span however. It takes at least 1000 years for the Uranium-235 in radioactive nuclear waste to reach the radioactivity levels of natural uranium, and sometimes up to 10,000 years for it to reach levels which are no longer toxic. However, only about 3% of Uranium-235 will be radioactive for that long time, with most waste no longer being hazardous from radioactivity after tens of years. However, there are other radioactive components in nuclear waste which remain radioactive for much longer periods. In fact it has been recommended that storage for up to 1 million years may be required before it can be considered completely safe. This problem is not only confined to the nuclear industry however, other industrial waste from non-nuclear industries includes heavy metals such as cadmium or mercury, which remain hazardous indefinitely. Radioactive waste only forms around 1% of toxic waste in countries with nuclear power.

 

The mining of uranium also produces large quantities of toxic waste. The extraction of uranium from the mined ore requires toxic chemicals such as sulphuric acid and hydrogen peroxide, for example. Additionally, the waste products from the extraction process include large quantities of radioactive water. Currently these are stored at the mine site in large dams; however spills from the dams are known to have occurred at Ranger in the Kakadu National Park.

 

Due to its extremely long life span, there are questions however about how securely the waste products from uranium mining and fuel use will be stored in the future. In particular, breakdown of the container holding the waste may allow the waste to seep out, polluting the nearby area. Sweden stores its waste in copper canisters believing the stable nature of copper will prevent any breakdown and release of waste.

 

Carbon friendly?

One of the major reasons given for a change to nuclear power stations is to reduce carbon dioxide emissions into the atmosphere. In the battle to reduce the effects of human-induced climate change, any technologies which reduce CO2 output are seen as valuable.

 

A recent study which combined the results from over 100 earlier studies examined the greenhouse gas emissions of several energy production technologies over their lifecycle. The results are shown in the table below.

 

Technology

Carbon emissions (grams CO2 per kilowatt hour)

Onshore wind farm

10

Hydroelectric reservoir

10

Solar photovoltaic panel

32

Geothermal “hot rocks”

38

Nuclear

66

Natural gas

443

Coal

960-1050

 

Nuclear produces around 66 grams of CO2 for every kilowatt hour of energy produced, compared to around 1000 grams of CO2 for coal fired plants, over their entire lifecycle. Geothermal power, which uses hot rocks deep below the Earth’s surface to heat water and produce steam to turn generators, emits around 38 grams of CO2 for every kilowatt hour of energy, while wind turbines emit around 10 grams of CO2 for every kilowatt hour. These figures take into account the mining of coal or uranium, construction of each of the power stations, any waste disposal and decommissioning of the station at the end of its lifetime.

 

From these results it is obvious that even with the carbon emissions associated with mining of uranium, building the power station and disposing of the waste, nuclear power still emits far less greenhouse gases than coal or natural gas powered stations, the major forms of power generation in Australia. Renewable resource-powered stations such as wind, hydroelectric or geothermal still do emit less greenhouse gases however. So while there would be a considerable effect on carbon emissions by replacing coal or natural gas fired power stations with nuclear, further savings could potentially be made by developing new renewable powered stations.

 

So nuclear power stations do produce less CO2 than a coal fired plant, but what about radiation levels? Possibly contrary to popular belief, nuclear power stations release effectively no radiation. In fact a nuclear power station releases less radioactive material into the atmosphere during operation than a coal power station. The ash produced from burning coal contains small amounts of uranium and thorium, another radioactive substance, which is emitted into the atmosphere and can contaminate nearby land and water. This ash results in a coal fired power station releasing at least 100 times more radiation into the environment than a nuclear plant producing the same amount of electricity. However, to put it in context, the amount of radiation a human would be exposed to in a year of living near a coal power station is around 1/180th the levels that humans are exposed to each year normally just in background radiation. In other words, there is effectively no risk from radiation by living near either a coal plant or a nuclear plant.

 

There are many economic questions over nuclear power, and new more carbon friendly power generation technologies are either currently in development or coming online. Whether it is viable to go nuclear in Australia depends on these and other factors, including the requirement for extremely large amounts of water during the mining of uranium. One new technology which may be promising as an energy source is hydrogen power; however there are some pitfalls to that too. In the near future I’ll be blogging about one of the new technologies being developed which may make hydrogen power more attractive as an option.

 

Nuclear waste

After removal from a nuclear reactor, the spent fuel rods are stored in deep pools of water for several years to literally cool off and allow some decay of the radioactivity. These waste fuel rods are then removed, and there are two possibilities. They can either be transported and stored as is, or processed to remove any useful remnants. While processing occurs in Europe and Japan, at the moment there is no waste processing in the US.

 

A spent fuel rod will normally contain somewhere in the region of 0.8% Uranium-235, which, along with the Uranium-238 in the rod, can be extracted and reused to make new fuel rods. The waste also contains radioactive materials which are useful in medicine which can also be extracted and used. However, reprocessing fuel rods does allow the extraction and concentration of Uranium-235 and plutonium, another particularly reactive atom, which could be then used for weapons. The reprocessing of spent nuclear fuel is extremely technical and requires highly specialised equipment, including itself a particular type of nuclear reactor. As a result very little reprocessing is done with France, one of the highest fuel re-processors, only recycling around 28% of its yearly fuel. Due to this special type of nuclear reactor and other specialised equipment and processes the extraction and reuse of Uranium for nuclear fuel is very expensive, and is only viable when the prices of uranium are high.

 

On average, a nuclear power station produces between 20 and 200 tons of waste per year. Due to its toxicity and radioactivity, it needs to be stored in a location which effectively removes it from the environment. At present however, most waste is believed to be stored at the individual power stations, although there have been suggestions for centralised repositories. A centralised facility would bring all the radioactive waste into one ideal location separated from population centres. The United States conducted feasibility studies on storing waste underground in the Yucca Mountains however abandoned the idea. Australia has also considered locations for nuclear waste storage in the deep outback

 

A central storage site would normally be in a remote area far from water sources to provide protection to the population in case of a leak of radioactive material. The Australian outback option is also in an area of geological stability, meaning there is not likely to be any major earthquakes which may affect the containment of the waste, and underground storage provides shielding at ground level from radiation.

 

The Swedish system for disposal of nuclear waste uses caves 500 metres underground. Firstly, the radioactive waste is stored at the nuclear station for up to 30 years, after which it is placed in an iron capsule. This iron capsule is then encapsulated using copper. An 8 metre deep hole is drilled in the cave, into which the copper capsule is placed, and the hole then filled with bentonite clay which will soak up any leaks. The combination of copper, which will not corrode, and clay should prevent any toxic waste from escaping into the environment. When the storage cave is full the entrance is permanently sealed.

 

 

 

IMAGE

A Swedish canister for storing nuclear waste

 

 

 

When stored properly, radioactive waste is not something to be as fearful of as some people would have you believe. It may surprise you to know that at any given time, there is radioactive waste stored in most universities and major hospitals worldwide, waiting transport to a long-term storage facility. As long as the means of storage are secure, it actually poses little risk to the surroundings.

 

Nuclear waste does have a long life-span however. It takes at least 1000 years for the Uranium-235 in radioactive nuclear waste to reach the radioactivity levels of natural uranium, and sometimes up to 10,000 years for it to reach levels which are no longer toxic. However, only about 3% of Uranium-235 will be radioactive for that long time, with most waste no longer being hazardous from radioactivity after tens of years. However, there are other radioactive components in nuclear waste which remain radioactive for much longer periods. In fact it has recommended that storage for up to 1 million years may be required before it can be considered completely safe. This problem is not only confined to the nuclear industry however, other industrial waste from non-nuclear industries includes heavy metals such as cadmium or mercury, which remain hazardous indefinitely. Radioactive waste only forms around 1% of toxic waste in countries with nuclear power.

 

The mining of uranium also produces large quantities of toxic waste. To extract the uranium from the mined ore, toxic chemicals such as sulphuric acid hydrogen peroxide. Additionally, the waste products from the extraction process include large quantities of radioactive water. Currently these are stored at the mine site in large dams; however spills from the dams are known to have occurred at Ranger in the Kakadu National Park.

 

Due to its extremely long life span, there are questions however about how securely the waste products from uranium mining and fuel use will be stored in the future. In particular, breakdown of the container holding the waste may allow the waste to seep out, polluting the nearby area. Sweden stores its waste in copper canisters, believing the stable nature of copper will prevent any breakdown and release of waste.

 

Carbon friendly?

One of the major reasons given for a change to nuclear power stations is to reduce carbon dioxide emissions into the atmosphere. In the battle to reduce the effects of human-induced climate change, any technologies which reduce CO2 output are seen as valuable.

 

A recent study (INSERT LINK http://www.nirs.org/climate/background/sovacool_nuclear_ghg.pdf) which combined the results from over 100 earlier studies examined the greenhouse gas emissions of several energy production technologies over their lifecycle. The results are shown in the table below.

 

Technology

Carbon emissions (grams CO2 per kilowatt hour)

Onshore wind farm

10

Hydroelectric reservoir

10

Solar photovoltaic panel

32

Geothermal “hot rocks”

38

Nuclear

66

Natural gas

443

Coal

960-1050

 

Nuclear produces around 66 grams of CO2 for every kilowatt hour of energy produced, compared to around 1000 grams of CO2 for coal fired plants, over their entire lifecycle. Geothermal power, which uses hot rocks deep below the surface to heat water and produce steam to turn generators, emits around 38 grams of CO2 for every kilowatt hour of energy, while wind turbines emit around 10 grams of CO2 for every kilowatt hour. These figures take into account the mining of coal or uranium, construction of each of the power stations, any waste disposal and decommissioning of the station at the end of its lifetime.

 

From these results it is obvious that even with the carbon emissions associated with mining of uranium, building the power station and disposing of the waste, nuclear power still emits far less greenhouse gases than coal or natural gas powered stations, the major forms of power generation in Australia. Renewable resource-powered stations such as wind, hydroelectric or geothermal still do emit less greenhouse gases however. So while there would be a considerable effect on carbon emissions by replacing coal or natural gas fired power stations with nuclear, further savings could potentially be made by developing new renewable powered stations.

 

So nuclear power stations do produce less CO2 than a coal fired plant, but what about radiation levels? Possibly contrary to popular belief, nuclear power stations release effectively no radiation. In fact a nuclear power station releases less radioactive material into the atmosphere during operation than a coal power station (INSERT LINK http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste) . The ash produced from burning coal contains small amounts of uranium and thorium, another radioactive substance, which is emitted into the atmosphere and can contaminate nearby land and water. This ash results in a coal fired power station releasing at least 100 times more radiation into the environment than a nuclear plant producing the same amount of electricity. However, to put it in context, the amount of radiation a human would be exposed to in a year of living near a coal power station is around 1/180th the levels that humans are exposed to each year normally just in background radiation. In other words, there is effectively no risk from radiation by living near either a coal plant or a nuclear plant.

 

There are many economic questions over nuclear power, and new more carbon friendly power generation technologies are either currently in development or coming online. Whether it is viable to go nuclear in Australia depends on these and other factors, including the requirement for extremely large amounts of water during the mining of uranium. One new technology which may be promising as an energy source is hydrogen power; however there are some pitfalls to that too. In the near future I’ll be blogging about one of the new technologies being developed which may make hydrogen power more attractive as an option.

Breaking News: Cyclones

February 1, 2011

Given the approach of Tropical Cyclone Yasi towards the Queensland coast, I have delayed publishing Part 2 of the UV and skin series in order to present this rapid article on cyclones.

Information specific to TC Yasi is accurate at time of publishing but should not be used to plan evacuation from affected areas.

Cyclones mainly form along a belt near the equator where the temperature of the water is warmer. The minimum water temperature needed for a cyclone to form is 26.5 degrees Celsius, however already formed cyclones can travel over areas of cooler water temperatures, but will lose intensity.

Map of cyclone areas worldwide. Orange areas are regions where conditions are suitable for cyclone formation. Image courtesy of NASA

The warm moist air above this warm water rises, resulting in a local low air-pressure area near the ocean surface. Surrounding air is literally sucked into this low-pressure area, which then too become warm and moist and rises. As this process repeats, fed by the warmth from the ocean and water evaporation, the air begins to swirl around the low-pressure area (the same effect as water swirling as it drains into a plug hole), and as the warm moist air cools away from the ocean surface it forms clouds. The combination of the swirling winds caused by the low-pressure area and cloud formation forms the characteristic spinning cloud.

Cyclone formation. Air swirls the area of low-pressure before rising upwards from the ocean surface. Image courtesy of Geoscience Australia

The swirling of air around a low-pressure area is caused by the Coriolis Effect, a result of the earth’s rotation. The direction of the Coriolis Effect depends on the hemisphere, in the southern hemisphere a cyclone will always spin clockwise.

The category of tropical cyclone is determined by wind strength. In Australia the minimum category of a tropical cyclone is reached when sustained wind speeds exceed 63km/h.

Australian Region – Tropical Cyclone Intensity Scale
Category Sustained winds Gusts Expected damage
Tropical Low <34 kts
<63 km/h
<49 kts
<91 km/h
 

 

One 34-47 kts
63-88 km/h
49-67 kts
91-125 km/h
Negligible house damage. Damage to some crops, trees and caravans. Craft may drag moorings 

 

Two 48-63 kts
89-117 km/h
68-89 kts
125-164 km/h
Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings. A Category 2 cyclone’s strongest winds are DESTRUCTIVE winds
Three 64-85 kts
118-159 km/h
90-121 kts
165-224 km/h
Some roof and structural damage. Some caravans destroyed. Power failures likely. A Category 3 cyclone’s strongest winds are VERY DESTRUCTIVE winds 

 

Four 86-107 kts
160-200 km/h
122-151 kts
225-279 km/h
Significant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures. A Category 4 cyclone’s strongest winds are VERY DESTRUCTIVE winds
Five >107 kts
>200km/h
>151 kts
>279 km/h
Extremely dangerous with widespread destruction. A Category 5 cyclone’s strongest winds are VERY DESTRUCTIVE winds 

 

Table adapted from BoM


Cyclone Intensity

There are two main factors which affect cyclone intensity – the warmth of the water and wind conditions. Warm water is required for cyclone formation, and cooler waters will degrade the intensity. In the case of Yasi it is encountering warm north Queensland waters caused by the La Nina climate.

High winds surrounding the cyclone can also reduce the cyclone’s intensity. The cyclone requires the swirling winds caused by the Coriolis Effect, high incidental winds can disrupt this swirling pattern, literally tearing the cyclone apart. Yasi is encountering only mild winds which have very little affect on the cyclone formation.

The shape of Yasi is also described as being very efficient, with good ventilation at both the top and bottom, allowing a very efficient formation of the low-pressure system which cyclones form around, and high wind velocities.

Storm Surge

As the air surrounding the low-pressure area swirls it pushes water towards the centre of the storm, literally forming a mound of water. This mound is the “storm surge”, which when reaching landfall effectively acts like a tsunami and causes significant flooding of the coastal areas. A storm surge will be greater in areas where the ocean floor slopes gradually towards the coastline, such as the areas around north Queensland.

Storm surge. The top imageis normal conditions. The lower image is the rise in sea levels caused by a storm surge at high-tide. Image courtesy of BoM

Storm surges typically measure around 60-80 kilometres across, meaning areas more than 30 km from the crossing point of the cyclone can become flooded. A category 4 cyclone will produce a storm surge approximately 4-6 metres higher than normal tidal levels.

The actual height of the storm surge depends on the tides. If the storm surge hits the coast during low tide, destruction will be minimal. However if it hits during high tide, the effective height and reach of the surge will be greater.

Cyclones and climate effects

Cyclones are more common in Australia during La Nina climate periods than during El Nino periods. La Nina is characterised by a large scale cooling of water temperatures across the Pacific, except near the north Australian coasts where there is a gathering of warm ocean waters. This area of warm water and changes in wind patterns during La Nina periods together contribute to the increased numbers of cyclones during these periods.

The La Nina period being experienced by Australia at the moment is one of the strongest on record and was also a cause of the Queensland floods.

Cyclone paths

Not all cyclones are unpredictable; their path is determined by the environment around it. Yasi is situated in a well characterised belt of easterly winds which are carrying it towards the Queensland coast. While it can be said with some certainty Yasi will strike the Queensland coast because of these winds, there is still some variability in exactly where on the coast it will hit. Latest BoM predictions are that it will reach landfall at Cairns.

The spread of Yasi has been estimated by the Bureau of Meteorology to be around 800km, stretching along the coast from Cooktown to Sarina.

Predicted path of Tropical Cyclone Yasi. Orange areas are regions of high impact. Image courtesy of BoM

Inland reach

Cyclones require warm water to maintain intensity, so once the cyclone makes landfall it will begin to lose intensity. However given its size and high intensity, Yasi may take a long time to degrade. This means it may reach as far inland as Mt Isa, however it will have likely degraded into a tropical storm by this time and not a categorised cyclone.

Floods

The wetness of the catchment areas affects the amount of runoff from rains and storm surges. Simply, the wetter the ground, the less water that can soak in, increasing runoff and the potential for flooding. Townsville and Cairns have had slightly above normal rains this season, but it is hard to tell if it will cause abnormal flooding.

Yasi no longer appears to be headed for areas affected by the January Queensland floods, so it is less likely serious weather events will affect those areas.

Cyclones and Climate Change

At the moment the BoM and World Meteorological Organisation cannot draw certain conclusions about the effect of climate change on cyclones. There is no clear evidence of long-term trends in the numbers of cyclones, and limitations in knowledge and technical limitations limit the ability to predict changes in cyclone frequency. However, they expect little or no change in global frequency of cyclones, nor significant changes in the regions affected by cyclones.

Increases in the economic damage and disruption by tropical cyclones have been caused mainly by increased population centres in coastal areas.

However, rising sea levels may increase the effects of storm surges. This is particularly of concern as historically the primary cause of death during cyclones has been due to flooding.

Satellite Images of Yasi:

NASA Earth Observatory

http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=49043

University of Wisconsin Cooperative Institute for Meteorological Satellite Studies

http://cimss.ssec.wisc.edu/tropic2/real-time/imagemain.php?&basin=austeast&prod=wvbbm&sat=gms

(links at the top change image type)

 

Thanks to Jim Davidson, Regional Director Queensland at the Bureau of Meteorology and Andrew Western from the University of Melbourne for providing their expertise.


References and further information

Geosciences Australia, http://www.ga.gov.au/hazards/cyclone.html

Magdalena Roze, Weather Channel, http://magdalena-roze.blogspot.com/

Dick Whitaker, Weather Channel, http://passingparade-2009.blogspot.com/

Bureau of Meteorology, http://www.bom.gov.au/cyclone/about/

Statement on tropical cyclones and climate change, Bureau of Meteorology, http://www.bom.gov.au/info/CAS-statement.pdf