Green the holidays. Eat your Christmas tree.

http://www.treehugger.com/lawn-garden/green-holidays-eat-your-christmas-tree.html
Sami Grover

Replanting a live tree is one of the most popular suggestions for getting a greener Christmas tree.

But what if you didn't just replant your tree? What if you ate it too?

In a special holiday episode, John Kohler of Growing Your Greens suggests several options if you really want to eat your tree. Firstly, he reminds us that pine needles are actually edible, although they are pretty much just a famine food. There are, however, other options for live, edible trees to choose from. A stone pine, for example, will eventually grow up to give you pine nuts. And many people have started using specially pruned rosemary bushes as a sustainable alternative to traditional trees.

True, neither a stone pine nor a rosemary bush are likely to provide massive amounts of nutrition. But the real idea here—as John himself explains—is to always think in terms of reuse before you think of recycling. If you have gone the route of a traditional, cut tree, then do be sure to chip it and compost it. Ultimately, once you start growing in the compost you get, you'll be eating your Christmas tree too.

Build a home in four HOURS: Engineer believes his £10,500 flat pack house could solve the UK's looming housing crisis

http://www.dailymail.co.uk/sciencetech/article-2524624/Engineer-believes-QB2-flat-pack-house-solve-UKs-looming-housing-crisis.html
By SAM WEBB

An engineer has created what he believes is a solution to the UK’s looming housing crisis - a three-storey flat pack home.

Dr Mike Page has created the QB2 ‘cube house’, which is 10ft (3m) tall and 13ft (4m) wide and can sleep up to two people.

He says the house is as easy to build as 'an Ikea Billy bookcase' and takes just four hours to erect.

THE CUBE HOUSE: WHAT DO YOU GET?

• The building is around 10ft (3m)-high, 10ft-wide and 13ft (4m) deep.
• The bedroom contains a full-sized double bed.
• There is also a 4m-long galley bathroom - complete with a full-sized shower, sink and toilet which uses a composting toilet.
• A fully functional kitchen with hob, fridge freezer, combination microwave oven.
• A dining table which can be stowed to make room for a four-seater sofa.
• A two-seater sofa and two ottomans that can be reconfigured for 4-person dining/sitting or two-person lounging.
• Low-energy lighting and appliances (including a TV and washing machine)
• Mechanical heat-recovery ventilation.
• Very efficient heating and hot water using an optional air-source heat pump.
• Solar panels on the roof providing power to LED lighting.

Despite the cube’s compact dimensions it crams in a lounge, spiral staircase, kitchen, full-size bathroom and bedroom which are spread over three floors.

It achieves this through ingenious internal design, such as a bookcase that doubles as a mini spiral staircase.

The QB2 will go on the market early next year and range between £10,500 to £45,000. 

It does not require planning permission because it is under 13ft (4m) in height.

Dr Page said: 'The QB2 is practical and fits together easily. If someone can put up an Ikea Billy bookcase then they can put this up.

'It goes together like flat-pack furniture, although when a customer buys it they will get the finished product and won’t have to put it together themselves.

'It takes around four hours to put the cube together, however it would obviously take longer when you add I’m the furniture, it depends how quickly you work.

'Most of the furniture inside is from Ikea, which I guess does coincidentally link in with how easy the QB2 is to put together.

'Inside the QB2 there is a lot of practicability, with things such as the dining table being able to move while still attached to the wall, giving more room to move around and also lounge on the sofa.

'The QB2 has everything a normal home has, except it is all scaled down, however, there is still enough room for people, with a double bed as an available feature.'

He added: 'It is quick to put up too, we can build the shell in under four hours, although obviously it would take us longer to add everything in, including the kitchen.

'I think it is great, of course I would say that, but I really do think it is and it is the only one in the world.'

The building starts at £9,495 to build yourself or £10,305.00 for Bolton Buildings to erect it for you the basic option includes foundations, floor joists, ceiling joists and wall studs.

The second option costs between £22,839 and £27,208 and adds insulation to walls, floor and ceiling, roof covering and internal birch lining to walls.

The deluxe package costs up to £47,200 and Includes a shower, furniture, LED TV, kitchen appliances, bed and mattress, lights, switches, wiring, plumbing, triple-glazed windows, chesnut cladding, cork tile flooring, and is fully painted throughout.

The QB2 made its TV debut on George Clarke’s Amazing Spaces on Channel 4 last week.

Because of the small dimensions, the structure has the same planning status of a static caravan.

Dr Page, who teaches at the University of Hertfordshire, decided to make the cube in order to teach people how they could help the environment.

He said: 'I used to be an engineer and I was looking to encourage people to be greener and make pro-environmental changes.

'I thought instead of telling people, I could show them.

'For example, if someone tells you that an LED light is better and explains why, you’ll probably go home and not do anything about it.

'However, when people would say "how is it better, and show me how", I could, all I had to do was flick a switch, it started as a way of encouraging people they could do what I have done.'

Are ideas to cool the planet realistic?

http://www.bbc.co.uk/news/science-environment-24033772
By Melissa Hogenboom

The deliberate large-scale manipulation of the Earth's environment, called geoengineering, could be one way to cool the Earth or help reduce levels of carbon dioxide in the atmosphere.

But scientists are aware that these technologies are in very early stages of development and remain untested on a global scale.

Although there are great risks in deliberately interfering with nature to cool the planet, some researchers say that if the concentrations of carbon in the atmosphere reach a critical stage, geoengineering might become the only way to take control of our climate.

On the other hand, others worry that having the technology to "reverse" climate change could be seen as a get-out-of-jail-free card and that more effort should be put on existing ways of reducing emissions.

Steve Rayner of the Oxford Geoengineering Programme, UK, says that there is no easy answer, but it would be "irresponsible for us not to explore the potential to understand the technologies as best we can".

"Throughout human history the technologies of one generation created problems for the next. We have to find some way to deal with that; it's part of the evolution of human society," he adds.

What is geoengineering?

Geoengineering refers to the deliberate large-scale manipulation of the Earth's environment to counteract climate change.

There are essentially two ways of doing this.

The first is called Solar Radiation Management (SRM) and involves reflecting more of the Sun's rays away from the planet back into space.

Cloud-whitening would aim to reflect more of the Sun's heat back into space

One proposed method of SRM involves putting sulphur aerosols into the high reaches of the atmosphere.

This mimics what occasionally occurs in nature when a powerful volcano erupts. For example,the Mount Pinatubo eruption in 1991injected huge volumes of sulphur into the stratosphere. The particles produced in subsequent reactions cooled the planet by about 0.5C over the next two years by reflecting sunlight back out to space.

Using SRM would only address the symptoms and does not tackle the issue of rising concentrations of carbon dioxide (CO2).

That is what the second option would aim to address by removing the CO2 already present. A number of ways to do this have been proposed; these approaches are known as Carbon Dioxide Removal (CDR).

This would tackle the root cause of the problem, but Prof Rayner says, it would be very slow to have any effect and would require extensive financial investment.

"The irony is the SRM is seen as being fast acting and has high leverage technically, but is probably the most difficult and distant prospect from a governance point of view."

Political dimensions

The Intergovernmental Panel on Climate Change (IPCC) has previously stated that geoengineering could provide important solutions to tackling climate change but it also says that more research is needed in the area. It remains to be seen what the latest IPCC report - known as AR5 - will have to say about the field.

A major report in 2009 by the UK's Royal Society also suggested that "CDR and SRM geoengineering methods should only be considered as part of a wider package of options for addressing climate change".

And while the idea of geoengineering seemed to have gained traction several years ago, proposals on a global scale have failed to take shape.

For many years now, an international agreement, the Kyoto Protocol, has set targets for industrialised countries to cut their greenhouse gas emissions. In 2012, the UN climate talks in Doha extended the protocol.

Prof Rayner sat on two previous IPCC assessment panels and believes such targets will be impossible to meet. He says that regardless of greenhouse gas reduction efforts, and even if supplemented by geoengineering technologies, some level of adaptation to climate change will be necessary.

"The geoengineering technologies are seen as potential additional tools in the kit for dealing with climate change, not as substitutes for either adaptation or greenhouse gas mitigation," he told BBC News.

He adds that documents compiled by the United Nations Environment Programme (Unep) and the IPCC suggest that it will not be possible to meet the targets "without finding ways of removing carbon from the ambient air".

The proposed technologies

Solar radiation management (SRM)

• Albedo enhancement: Increasing the reflectivity of clouds or the land surface so that more of the Sun's heat is reflected back into space
• Space reflectors: Blocking a small proportion of sunlight before it reaches the Earth
• Stratospheric aerosols: Introducing small, reflective particles into the upper atmosphere to reflect some sunlight before it reaches the surface of the Earth

Carbon dioxide removal (CDR)

• Afforestation: Global-scale tree-planting efforts
• Biochar: Burning biomass (plant material) and burying it so that its carbon is locked up in the soil
• Bio-energy with carbon capture and sequestration: Growing biomass, burning it for energy and capturing and locking away the CO2 generated in the process
• Ambient air capture: Building machines that can remove CO2 directly from ambient air and store it elsewhere
• Ocean fertilisation: Adding nutrients to the ocean in selected locations to increase marine food production, which draws down CO2 from the atmosphere
• Enhanced weathering: Exposing large quantities of minerals that react with carbon dioxide in the atmosphere and storing the resulting compounds in the oceans or soil
• Ocean alkalinity enhancement: Grinding up, dispersing, and dissolving rock types such as limestone, silicate, or calcium hydroxide in the ocean to increase its ability to store carbon and directly ameliorate ocean acidification

Source: Oxford Geoengineering Programme

The most scrutinised technology so far has been ocean fertilisation,which involves using iron to stimulate phytoplankton growth in the ocean, increasing the uptake of CO2.

One study, for example, has shown that about half of a phytoplankton (algae) bloom stimulated by iron sank to the deep sea, locking the carbon away on a potential timescale of centuries.

But another showed that little CO2 was taken up by the organisms and that the potential for iron fertilisation may depend strongly on the location where it is attempted.

And some schemes have attracted controversy: In July 2012, for example, 100 tonnes of iron sulphate was deposited into the Pacific Ocean, off Canada's west coast, in an attempt to help restore salmon stocks there. The move outraged environmentalists opposed to ocean fertilisation.

While the idea continues to have its adherents, John Shepherd from the National Oceanography Centre at the University of Southampton, UK, who also chaired the 2009 Royal Society report, is doubtful about the benefits.

"Ocean fertilisation involves huge interference with the ecosystem. You have a big environmental impact with a small desired side-effect."

Progress on other projects has been hindered by factors external to their intrinsic merits. Last year, a project known as Spice, which was to have deployed a tethered balloon to disperse water into the air - as a prelude to spraying climate-cooling sulphate particles - was grounded.

Core to the decision was a patent application lodged on some of the technology, though the team cited other concerns among the reasons for the postponement.

Debating the risk

Some scientists point out that manipulating the climate in one part of the world could have consequences elsewhere. Therefore, the argument goes, any action of this sort would need to be on a global level with international agreement.

Changing another country's weather is even classed as a war crime under the Geneva Convention of 1976.

Paul Nightingale of the Science and Technology Policy Research department at Sussex University, UK, says there is currently no infrastructure in place for such decisions to be made about our global climate.

"As a consequence they will be extremely contested," he adds.

Rose Cairns, also from Sussex University, has written a report for the Economic and Social Research Council (ESRC) on the area. She says one issue is that geoengineering remains an extremely ambiguous term because the technology is so diverse.

Spraying aerosols into the stratosphere, for example, could be "highly controversial", while a global project to plant trees is likely to cause much less furore.

Danger zone?

As with any new technology, unpredictable side-effects of geoengineering cannot be ruled out.

For example, in addition to any benefits it might have, it is thought that lacing the stratosphere with sulphate aerosols could deplete atmospheric ozone and exacerbate the risk of drought - particularly in Asia and Africa where it might adversely affect the monsoon.

The injection of sulphate aerosols is designed to mimic volcanic eruptions

Again, it all comes down to the thorny subject of governance. Dr Cairns says: "Who would decide what would constitute an emergency that is serious enough to change the planet's temperature?

"Who would make that kind of decision, bearing in mind some of these technologies risk, for example, affecting monsoons and changing rainfall patterns."

Another issue is that once geoengineering becomes an option, it could curtail the momentum for reducing CO2 emissions.

"In that sense, conceptually, it's quite dangerous to even have it on the table," says Dr Cairns.

Money, money, money

Another factor would be the considerable cost of using new technologies on a global scale. While the financial cost might be outweighed by the environmental cost of inaction, Prof Nightingale says it would be better to spend money on making energy production greener.

"The thermodynamics of taking CO2 out of the air makes it much more expensive than taking CO2 out of exhausts and power stations," he explains.

"It seems such an expensive, complicated and risky set of technologies to be thinking about when we've got a lot of technologies that are environmentally benign."

Echoing these points, Lord Rees, English Astronomer Royal and former president of the UK Royal Society recently said that geoengineering would be a political nightmare with unintended side-effects.

A tangible timeline?

For now, only small-scale geoengineering tests can take place as long they do not affect biodiversity, a rule agreed by the UN Convention on Biological Diversity in 2010.

Analysis

There is far more talk than action and opinions vary widely. There are some people who are enthusiastic - for example to save the Arctic sea ice - and others who think that it's far too soon to contemplate doing anything other than some limited research.

We don't know enough about any of the proposed techniques to even contemplate deploying them anytime soon, so I see it as being several decades away.

The worst thing that could happen is if people think this is going to be an easy way out and then try to do something on a large scale prematurely, which goes wrong.

Professor John Shepherd, National Oceanography Centre, University of Southampton, UK.

The limitation was in part achieved from heavy lobbying by campaigners from the ETC group. They said that their foremost concern was "the international control of planetary systems: our water, lands and air".

They also expressed concern that wealthy states could see it as a "quick, cheap fix for climate change" leaving no resources to tackle the current climate issues.

Andy Ridgwell, a professor of Earth system modelling at the University of Bristol, UK, counters by pointing out that we are already affecting biodiversity by "stuffing carbon into the atmosphere".

But he says it is more likely that "we will keep adapting" than embark on large-scale geoengineering projects anytime soon.

"Unless ice sheets collapse, I can't see a point at which we've passed a fundamental threshold where enough of the major emitters suddenly agree we'll have to do something," Prof Ridgwell says.

"Given that geoengineering would need international agreement, I suspect that [temperatures] will keep creeping up and people will have to adapt."

Prof Shepherd agrees that we're a long way from doing anything "other than talking and researching". But he adds that geoengineering could be the only way to actually reverse climate change.

"Emissions control will never reverse it. We are making what is essentially an irreversible change to the climate on human time-scales. The planet is still out of balance, the oceans are still warming," he says.

HUMAN ROLE IN GLOBAL WARMING

Human role in warming 'more certain' - UN climate chief

http://www.bbc.co.uk/news/science-environment-24204323

By Roger Harrabin

Scientists are more certain than ever that greenhouse gases from human activities are heating the planet, the head of the UN's climate panel says.

Rajendra Pachauri made the comments in an interview with BBC News.

The panel is due to deliver its latest report on the state of the climate later this week in Stockholm, Sweden.

Its last report was criticised after an error on glaciers unveiled other flaws, but Prof Pachauri said procedures had been reformed and strengthened.

He also dismissed suggestions of a slowdown in global warming.

"There’s definitely an increase in our belief that climate change is taking place and that human beings are responsible,” he told me.

"I don't think there is a slowdown (in the rate of temperature increase). I would like to draw your attention to the World Meteorological Organization which clearly stated on the basis of observations that the first decade of this century has been the warmest in recorded history.

"And I think the rest will be brought out by the report itself when it’s released."

Prof Pachauri’s insistence that warming has not slowed hints at a focus of debate this week in Stockholm: Global temperatures have not been increasing as fast as scientists predicted, and several governmentsinsist that this puzzle is properly addressed in the final summary.

Have computer climate models overestimated the sensitivity of the planet to increasing CO2? Or has excess heat been stored up in oceans whence it will emerge to super-heat the planet in decades to come? Or both?

Or just perhaps it could be something else.

Unprecedented change

The draft says a doubling of CO2 concentrations in the atmosphere above pre-industrial levels (expected by mid-century) is likely to result in a temperature rise globally of between 1.5 and 4.5C.

Any rise above 2C could risk major changes on Earth, according to projections, but the results of recent modelling involves a downward tweak at the bottom of the range, offering the tantalising prospect to politicians that if humans are very lucky, they could get away with rising CO2 emissions for a bit longer than previously expected.

The panel is struggling to offer a definitive answer as to why warming is not happening at the rate previously projected. But it will be anxious to ensure that the likelihood of a fortunate escape for humanity should not be overplayed.

It is expected to say that greenhouse gas emissions from human activities have already warmed the ocean, melted snow and ice, raised sea levels and increased climatic extremes.

It will also warn that unless emissions are cut soon, we are likely to suffer severe changes in the climate unprecedented for hundreds of thousands of years.

Prof Pachauri’s leadership of the panel has been strongly supported by developing countries, although he has faced criticism in the West. He told me he had no plans to retire after the forthcoming report.

He said the panel enjoyed massive support, with 3,000 people volunteering to act as authors, 831 of whom were selected.

Tightening procedures

In the detailed text of its last report, the UN panel made a controversial mistake on glaciers.

Prof Pachauri said: "We made one mistake about the glaciers melting by 2035 - for which we have apologised. That was totally out of character because we always give a range for these things and it somehow slipped through.

"But it wasn’t included in the technical summary or the summary for policymakers, it just somehow escaped attention.

“What we did say about the glaciers was in substance not all that wrong – the glaciers are melting across the globe so that is something we stand by.

“This time we have been doubly careful... [that] we don’t have any mistake of that type. And I hope that [the report] will reassure everyone that human influence is having a major impact on the Earth's climate.”

Prof Pachauri said he anticipated attempts to discredit the panel. But he claimed evidence of extreme events was persuading more and more people, especially in the US, that humans were taking a risk with the climate.

Indeed, the report is expected to say it is very likely that manmade climate change has produced higher precipitation in America.

"Hopefully,” he said, “there are enough sane and sensible people in the public who will ultimately prevail."

The broader question is whether science itself will prevail over politics. Whatever the pronouncements of the UN panel, emissions are expected to continue to increase into the foreseeable future as politicians weigh risks to energy bills and competitiveness against risks to the planet.

The UN Secretary-General Ban Ki-moon has re-confirmed that he will invite world leaders to a climate summit next year in an attempt to galvanise action.

Climate: Growing certainties on warming and human role

http://phys.org/news/2013-09-climate-certainties-human-role.html

Over the past 23 years, UN scientists have issued progressively stronger assertions about climate change.

They have moved from a sketchy warning that heat-trapping carbon gases emitted by fossil fuels will cause a "greenhouse" effect to the conviction that this effect is now having an impact on Earth's climate.

Following are extracts from the Intergovernment Panel on Climate Change's assessment reports, the latest of which will be published from Friday.

First Assessment Report (1990)

"... emissions resulting from human activities are substantially increasing atmospheric concentrations of greenhouse gases...

"These increases will enhance the greenhouse effect, resulting on average in an additional warming of the Earth's surface."

Second Assessment Report (1995)

"Most of these studies have detected a significant change and show that the observed warming trend is unlikely to be entirely natural in origin...

"... the balance of evidence suggests that there is a discernible human influence on global climate.

"... the average rate of warming [in projections for the 21st century] would probably be greater than any seen in the last 10,000 years, but the actual annual to decadal changes would include considerable natural variability."

Third Assessment Report (2001)

"There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.

"... the projected rate of warming is much larger than the observed changes during the 20th century and is very likely to be without precedent during at least the last 10,000 years, based on paleoclimate data."

The report said the global average temperature had risen by 0.6 degrees Celsius (1.08 degrees Fahrenheit) between 1901 and 2000.

Human activity was "likely" to be the cause of warming, a term meaning a probability of more than 66 percent.

Fourth Assessment Report (2007)

"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

"Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic [man-made] greenhouse gas concentrations."

The report said that warming over the previous 100 years was 0.74 C (1.33 F), and 11 of the previous 12 years had been the warmest on record.

Human activity was "very likely" the cause of warming, meaning a probability of more than 90 percent.

Fifth Assessment Report (draft version seen by AFP)

"In the northern hemisphere, the period 1983-2012 was very likely the warmest 30-year period of the last 800 years and likely the warmest period of the last 1,400 years.

"....Greenhouse gases contributed a global mean surface warming likely to be in the range of 0.5-1.3 C [0.9-2.3 F] over the period 1951-2010."

"...There is high confidence that this has warmed the ocean, melted snow and ice, raised global mean sea level and changed some climate extremes in the second half of the 20th century."

Human activity was "extremely likely" to be the cause of this warming, meaning between 95 and 100 percent probability.

The draft attributes an observed slowing in warming from 1998 to 2012—a phenomenon cited by skeptics as evidence that warming is not man-made—to a temporary cooling cycle in the weather system and lower-than-expected solar activity.

Temperatures since 1901 have risen by 0.89 C (1.6 F), it says.

Additional warming this century is estimated to range from 1.0 to 3.7 C (1.8-6.6 F), and sea level rise from 40 to 62 centimetres (16-24.8 inches), according to four projections based on how much carbon is emitted.

As in past reports, these estimates are an average. Each projection gives a wide margin of variation either side of the figure.

Evidence mounts for human role in climate change

http://horizon-magazine.eu/article/evidence-mounts-human-role-climate-change_en.html

by Ben Deighton

Complex computer models have helped the IPCC make climate forecasts. © UPSCALE | Credits: Natural Energy Research Council (NERC) and UK Met Office Joint Weather and Climate Research Programme (JWCRP).

Scientists are more certain than ever that humans are the cause of global warming, the Intergovernmental Panel on Climate Change (IPCC) said in its most authoritative report to date, drawing on millions of scientific observations - many of which were gathered by scientists in Europe.

The data used to compile the report includes that gathered by the EU-funded airship PEGASOS, which has been measuring the air quality over Europe to link air pollution to climate change, and RECONCILE, which helped find the first ever observed hole in the ozone layer in the Arctic region.

In its fifth assessment report, released on 27 September, the IPCC concluded that there is an at least 95 % likelihood that humans are the dominant cause of global warming. That makes them the surest they have ever been that humans are causing climate change.

Scientists are able to be so categorical because of the number of research papers that have been taken into account in producing the report. It cites over 9 200 scientific publications, more than three quarters of which have been published since the previous assessment in 2007, and bases its conclusions on millions of observations.

‘Up to now it is the only endeavour of this kind of science in the world,’ said Dr Anastasios Kentarchos, the deputy head of the Climate Change and Natural Hazards Unit at the European Commission’s Directorate-General for Research and Innovation, who was present during the discussions in Stockholm running up to the publication of the report. ‘This is a huge pool of scientists that on a voluntary basis are giving their brains and their minds for five years to do this work,’ he added referring to the IPCC report.

Unprecedented in 800 000 years

Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800 000 years, the report said.

The EU’s in-house science service, the Joint Research Centre, has provided critical data on worldwide emissions through its EDGAR database, which models emissions of greenhouse gases and air pollutants.

The rise in greenhouse gases is likely to mean that global temperatures will increase by over 1.5 degrees Celsius by the end of this century, when compared to the 1850 to 1900 period, according to all but the lowest scenario considered by the report.

‘Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system,’ said Thomas Stocker, the co-chairman of the IPCC group that assesses the physical science basis for climate change.

Climate models

Complex computer models, such as those developed by the EU-funded ENSEMBLES project, are required to allow the panel to make such forecasts. The project has modelled the simultaneous activity of the oceans, land and the atmosphere to show that the world will experience further measurable climate change.

The European airship PEGASOS. © PEGASOS

Other research groups concentrated on specific aspects, like Ice2Sea, which forecasts that by 2100 storm surges along Europe’s coastline could be up to 1 metre higher than they are today, presenting challenges to flood defences and natural habitats.

However, more data is needed to improve the accuracy of the models, for example by understanding the role of the permafrost, the permanently frozen layer of soil, in the Arctic regions on greenhouse gas levels. That's now being done by the EU-funded PAGE21 project, which brings together permafrost researchers from Europe, Canada, Russia, the US, and Japan.

‘The more observations you build, the better you understand the drivers of climate change and you can validate more accurately the next generation of climate models,’ said Dr Kentarchos. 

Future research should concentrate on improving the capacity of climate models to make forecasts on a regional scale, providing data that is useful for farmers as they plan how best to use their land, or governments as they decide where to invest money to protect their citizens from climate change.

‘The models are useful to stakeholders when they give you trustworthy information at the right regional or sub-regional scale,’ said Dr Kentarchos.

How Electric Cars Work

http://www.howstuffworks.com/electric-car.htm
by Marshall Brain

Image Gallery: Electric Cars The Subaru R1e electric car can be charged overnight on household current. It has a range of 50 miles and a top speed of 62 miles per hour. See more electric car pictures.

STAN HONDA/AFP/Getty Images

Electric cars are something that show up in the news all the time. There are several reasons for the continuing interest in these vehicles:

• Electric cars create less pollution than gasoline-powered cars, so they are an environmentally friendly alternative to gasoline-powered vehicles (especially in cities).
• Any news story about hybrid cars usually talks about electric cars as well.
• Vehicles powered by fuel cellsare electric cars, and fuel cells are getting a lot of attention right now in the news.

An electric car is a car powered by an electric motor rather than agasoline engine.

From the outside, you would probably have no idea that a car is electric. In most cases, electric cars are created by converting a gasoline-powered car, and in that case it is impossible to tell. When you drive an electric car, often the only thing that clues you in to its true nature is the fact that it is nearly silent.

Under the hood, there are a lot of differences between gasoline and electric cars:

• The gasoline engine is replaced by an electric motor.
• The electric motor gets its power from a controller.
• The controller gets its power from an array of rechargeable batteries.

A gasoline engine, with its fuel lines, exhaust pipes, coolant hoses and intake manifold, tends to look like a plumbing project. An electric car is definitely a wiring project.

In o­rder to get a feeling for how electric cars work in general, let's start by looking at a typical electric car to see how it comes together.

An Electric Car Example

The electric car that we will use for this discussion is shown here.

This electric vehicle began its life as a normal, gasoline-powered 1994 Geo Prism. Here are the modifications that turned it into an electric car:

• The gasoline engine, along with the muffler, catalytic converter, tailpipe and gas tank, were all removed.
• The clutch assembly was removed. The existing manual transmission was left in place, and it was pinned in second gear.
• A new AC electric motor was bolted to the transmission with an adapter plate.
• An electric controller was added to control the AC motor.

The 50-kW controller takes in 300 volts DC and produces 240 volts AC, three-phase. The box that says "U.S. Electricar" is the controller.

The vacuum pump is left of center.

An automatic transmission shifter is used to select forward and reverse. It contains a small switch, which sends a signal to the controller.

The water heater

The 120/240-volt charging system

The Magna-Charge inductive paddle charging system

The "gas gauge" in an electric car is either a simple volt meter or a more sophisticated computer that tracks the flow of amps to and from the battery pack.

• ·         A battery tray was installed in the floor of the car.
• ·         Fifty 12-volt lead-acid batteries were placed in the battery tray (two sets of 25 to create 300 volts DC).
• ·        Electric motors were added to power things that used to get their power from the engine: the water pump, power steering pump, air conditioner
• ·         A vacuum pump was added for the power brakes (which used engine vacuum when the car had an engine).
• ·         The shifter for the manual transmission was replaced with a switch, disguised as an automatic transmission shifter, to control forward and reverse.
• ·         A small electric water heaterwas added to provide heat.
• ·         A charger was added so that the batteries could be recharged. This particular car actually has two charging systems -- one from a normal 120-volt or 240-volt wall outlet, and the other from a magna-charge inductive charging paddle.
• ·         The gas gauge was replaced with a volt meter.
• ·         Everything else about the car is stock. When you get in to drive the car, you put the key in the ignition and turn it to the "on" position to turn the car on. You shift into "Drive" with the shifter, push on the accelerator pedal and go. It performs like a normal gasoline car. Here are some interesting statistics:
• ·         The range of this car is about 50 miles (80 km).
• ·         The 0-to-60 mph time is about 15 seconds.
• ·         It takes about 12 kilowatt-hours of electricity to charge the car after a 50-mile trip.
• ·         The batteries weigh about 1,100 pounds (500 kg).
• ·         The batteries last three to four years.
• ·         To compare the cost per mile of gasoline cars to this electric car, here's an example

Electricity in North Carolina is about 8 cents per kilowatt-hour right now (4 cents if you use time-of-use billing and recharge at night). That means that for a full recharge, it costs $1 (or 50 cents with time-of-use billing). The cost per mile is therefore 2 cents per mile, or 1 cent with time-of-use. If gasoline costs $1.20 per gallon and a car gets 30 miles to the gallon, then the cost per mile is 4 cents per mile for gasoline.

Clearly, the "fuel" for electric vehicles costs a lot less per mile than it does for gasoline vehicles. And for many, the 50-mile range is not a limitation -- the average person living in a city or suburb seldom drives more than 30 or 40 miles per day.

To be completely fair, however, we should also include the cost of battery replacement. Batteries are the weak link in electric cars at the moment. Battery replacement for this car runs about $2,000. The batteries will last 20,000 miles or so, for about 10 cents per mile. You can see why there is so much excitement around fuel cells right now -- fuel cells solve the battery problem (more details on fuel cells later in the article).

Inside an Electric Car

A simple DC controller connected to the batteries and the DC motor. If the driver floors the accelerator pedal, the controller delivers the full 96 volts from the batteries to the motor. If the driver take his/her foot off the accelerator, the controller delivers zero volts to the motor. For any setting in between, the controller "chops" the 96 volts thousands of times per second to create an average voltage somewhere between 0 and 96 volts.

The heart of an electric car is the combination of:

• The electric motor
• The motor's controller
• The batteries

The controller takes power from thebatteries and delivers it to themotor. The accelerator pedal hooks to a pair of potentiometers(variable resistors), and these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.

The controller normally dominates the scene when you open the hood, as you can see here:

The 300-volt, 50-kilowatt controller for this electric car is the box marked "U.S. Electricar."

The potentiometers hook to the gas pedal and send a signal to the controller.

Heavy cables (on the left) connect the battery pack to the controller. In the middle is a very large on/off switch. The bundle of small wires on the right carries signals from thermometers located between the batteries, as well as power for fans that keep the batteries cool and ventilated.

The heavy wires entering and leaving the controller

An AC controller hooks to an AC motor. Using six sets of power transistors, the controller takes in 300 volts DC and produces 240 volts AC, 3-phase. See How the Power Grid Works for a discussion of 3-phase power. The controller additionally provides a charging system for the batteries, and a DC-to-DC converter to recharge the 12-volt accessory battery.

The heart of an electric car is the combination of:

·         The electric motor

·         The motor's controller

·         The batteries

The controller takes power from thebatteries and delivers it to themotor. The accelerator pedal hooks to a pair of potentiometers(variable resistors), and these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.

The controller normally dominates the scene when you open the hood, as you can see here:

In this car, the controller takes in 300 volts DC from the battery pack. It converts it into a maximum of 240 volts AC, three-phase, to send to the motor. It does this using very large transistors that rapidly turn the batteries' voltage on and off to create a sine wave.

When you push on the gas pedal, a cable from the pedal connects to these two potentiometers:

The signal from the potentiometers tells the controller how much power to deliver to the electric car's motor. There are two potentiometers for safety's sake. The controller reads both potentiometers and makes sure that their signals are equal. If they are not, then the controller does not operate. This arrangement guards against a situation where a potentiometer fails in the full-on position.

The controller's job in a DC electric car is easy to understand. Let's assume that the battery pack contains 12 12-volt batteries, wired in series to create 144 volts. The controller takes in 144 volts DC, and delivers it to the motor in a controlled way.

The very simplest DC controller would be a big on/off switch wired to the accelerator pedal. When you push the pedal, it would turn the switch on, and when you take your foot off the pedal, it would turn it off. As the driver, you would have to push and release the accelerator to pulse the motor on and off to maintain a given speed.

Obviously, that sort of on/off approach would work but it would be a pain to drive, so the controller does the pulsing for you. The controller reads the setting of the accelerator pedal from the potentiometers and regulates the power accordingly. Let's say that you have the accelerator pushed halfway down. The controller reads that setting from the potentiometer and rapidly switches the power to the motor on and off so that it is on half the time and off half the time. If you have the accelerator pedal 25 percent of the way down, the controller pulses the power so it is on 25 percent of the time and off 75 percent of the time.

Most controllers pulse the power more than 15,000 times per second, in order to keep the pulsation outside the range ofhuman hearing. The pulsed current causes the motor housing to vibrate at that frequency, so by pulsing at more than 15,000 cycles per second, the controller and motor are silent to human ears.

In an AC controller, the job is a little more complicated, but it is the same idea. The controller creates three pseudo-sine waves. It does this by taking the DC voltage from the batteries and pulsing it on and off. In an AC controller, there is the additional need to reverse the polarity of the voltage 60 times a second. Therefore, you actually need six sets of transistors in an AC controller, while you need only one set in a DC controller. In the AC controller, for each phase you need one set of transistors to pulse the voltage and another set to reverse the polarity. You replicate that three times for the three phases -- six total sets of transistors.

Most DC controllers used in electric cars come from the electric forklift industry. The Hughes AC controller seen in the photo above is the same sort of AC controller used in the GM/Saturn EV-1 electric vehicle. It can deliver a maximum of 50,000 watts to the motor.

Electric-car Motors and Batteries

Electric cars can use AC or DC motors:

• If the motor is a DC motor, then it may run on anything from 96 to 192 volts. Many of the DC motors used in electric cars come from the electric forklift industry.
• If it is an AC motor, then it probably is a three-phase AC motor running at 240 volts AC with a 300 volt battery pack.

DC installations tend to be simpler and less expensive. A typical motor will be in the 20,000-watt to 30,000-watt range. A typical controller will be in the 40,000-watt to 60,000-watt range (for example, a 96-volt controller will deliver a maximum of 400 or 600 amps). DC motors have the nice feature that you canoverdrive them (up to a factor of 10-to-1) for short periods of time. That is, a 20,000-watt motor will accept 100,000 watts for a short period of time and deliver 5 times its rated horsepower. This is great for short bursts of acceleration. The only limitation is heat build-up in the motor. Too much overdriving and the motor heats up to the point where it self-destructs.

AC installations allow the use of almost any industrial three-phase AC motor, and that can make finding a motor with a specific size, shape or power rating easier. AC motors and controllers often have a regenfeature. During braking, the motor turns into a generator and delivers power back to the batteries.

Right now, the weak link in any electric car is the batteries. There are at least six significant problems with current lead-acid battery technology:

• They are heavy (a typical lead-acid battery pack weighs 1,000 pounds or more).
• They are bulky (the car we are examining here has 50 lead-acid batteries, each measuring roughly 6" x 8" by 6").
• They have a limited capacity (a typical lead-acid battery pack might hold 12 to 15 kilowatt-hours of electricity, giving a car a range of only 50 miles or so).
• They are slow to charge (typical recharge times for a lead-acid pack range between four to 10 hours for full charge, depending on the battery technology and the charger).
• They have a short life (three to four years, perhaps 200 full charge/discharge cycles).
• They are expensive (perhaps $2,000 for the battery pack shown in the sample car).

In the next section we'll look at more problems with battery technology.

Battery Problems

Y­ou can replace lead-acid batteries with NiMH batteries. The range of the car will double and the batteries will last 10 years (thousands of charge/discharge cycles), but the cost of the batteries today is 10 to 15 times greater than lead-acid. In other words, an NiMH battery pack will cost $20,000 to $30,000 (today) instead of $2,000. Prices for advanced batteries fall as they become mainstream, so over the next several years it is likely that NiMH and lithium-ion battery packs will become competitive with lead-acid battery prices. Electric cars will have significantly better range at that point.

When you look at the problems associated with batteries, you gain a different perspective on gasoline. Two gallons of gasoline, which weighs 15 pounds, costs $3.00 and takes 30 seconds to pour into the tank, is equivalent to 1,000 pounds of lead-acid batteries that cost $2,000 and take four hours to recharge.

The problems with battery technology explain why there is so much excitement around fuel cells today. Compared to batteries, fuel cells will be smaller, much lighter and instantly rechargeable. When powered by pure hydrogen, fuel cells have none of the environmental problems associated with gasoline. It is very likely that the car of the future will be an electric car that gets its electricity from a fuel cell. There is still a lot of research and development that will have to occur, however, before inexpensive, reliable fuel cells can power automobiles.

Just about any electric car has one other battery on board. This is the normal 12-volt lead-acid battery that every car has. The 12-volt battery provides power for accessories -- things like headlights, radios, fans,computers, air bags, wipers, power windows and instruments inside the car. Since all of these devices are readily available and standardized at 12 volts, it makes sense from an economic standpoint for an electric car to use them.

Therefore, an electric car has a normal 12-volt lead-acid battery to power all of the accessories. To keep the battery charged, an electric car needs a DC-to-DC converter. This converter takes in the DC power from the main battery array (at, for example, 300 volts DC) and converts it down to 12 volts to recharge the accessory battery. When the car is on, the accessories get their power from the DC-to-DC converter. When the car is off, they get their power from the 12-volt battery as in any gasoline-powered vehicle.

The DC-to-DC converter is normally a separate box under the hood, but sometimes this box is built into the controller.

Of course, any car that uses batteries needs a way to charge them.

Charging an Electric Car

Any electric car that uses batteries needs a charging system to recharge the batteries. The charging system has two goals:

• To pump electricity into the batteries as quickly as the batteries will allow
• To monitor the batteries and avoid damaging them during the charging process

The most sophisticated charging systems monitor battery voltage, current flow and battery temperature to minimize charging time. The charger sends as much current as it can without raising battery temperature too much. Less sophisticated chargers might monitor voltage or amperage only and make certain assumptions about average battery characteristics. A charger like this might apply maximum current to the batteries up through 80 percent of their capacity, and then cut the current back to some preset level for the final 20 percent to avoid overheating the batteries.

Jon Mauney's electric car actually has two different charging systems. One system accepts 120-volt or 240-volt power from a normal electrical outlet. The other is the Magna-Charge inductive charging system popularized by the GM/Saturn EV-1 vehicle. Let's look at each of these systems separately.

The normal household charging system has the advantage of convenience -- anywhere you can find an outlet, you can recharge. The disadvantage is charging time.

A normal household 120-volt outlet typically has a 15-amp circuit breaker, meaning that the maximum amount of energy that the car can consume is approximately 1,500 watts, or 1.5 kilowatt-hours per hour. Since the battery pack in Jon's car normally needs 12 to 15 kilowatt-hours for a full recharge, it can take 10 to 12 hours to fully charge the vehicle using this technique.

By using a 240-volt circuit (such as the outlet for an electric dryer), the car might be able to receive 240 volts at 30 amps, or 6.6 kilowatt-hours per hour. This arrangement allows significantly faster charging, and can fully recharge the battery pack in four to five hours.

In Jon's car, the gas filler spout has been removed and replaced by a charging plug. Simply plugging into the wall with a heavy-duty extension cord starts the charging process.

In this car, the charger is built into the controller. In most home-brew cars, the charger is a separate box located under the hood, or could even be a free-standing unit that is separate from the car.

In the next section we'll look at the Magna-Charge system.

The Magna-Charge System

Photo courtesy Jon Mauney

Photo courtesy Jon Mauney

Photo courtesy Jon Mauney

The Magna-Charge system consists of two parts:

·         A charging station mounted to the wall of the house

·         A charging system in the trunk of the car

The charging station is hard-wired to a 240-volt 40-amp circuit through the house's circuit panel.

The charging system sends electricity to the car using this inductive paddle:

The paddle fits into a slot hidden behind the license plate of the car.

The paddle acts as one half of a transformer. The other half is inside the car, positioned around the slot behind the license plate. When you insert the paddle, it forms a complete transformer with the slot, and power transfers to the car.

One advantage of the inductive system is that there are no exposed electrical contacts. You can touch the paddle or drop the paddle into a puddle of water and there is no hazard. The other advantage is the ability to pump a significant amount of current into the car very quickly because the charging station is hard-wired to a dedicated 240-volt circuit.

The competing high-power charge connector is generally referred to as the "Avcon plug" and it is used by Ford and others. It features copper-to-copper contacts instead of the inductive paddle, and has an elaborate mechanical interconnect that keeps the contacts covered until the connector is mated with the receptacle on the vehicle. Pairing this connector with GFCI protection makes it safe in any kind of weather. Jon Mauney points out the following:

An important feature of the charging process is "equalization." An EV has a string of batteries (somewhere between 10 and 25 modules, each containing three to six cells). The batteries are closely matched, but they are not identical. Therefore they have slight differences in capacity and internal resistance. All batteries in a string necessarily put out the same current (laws of electricity), but the weaker batteries have to "work harder" to produce the current, so they're at a slightly lower state of charge at the end of the drive. Therefore, the weaker batteries need more recharge to get back to full charge. Since the batteries are in series, they also get exactly the same amount of recharge, leaving the weak battery even weaker (relatively) than it was before. Over time, this results in one battery going bad long before the rest of the pack. The weakest-link effect means that this battery determines the range of the vehicle, and the usability of the car drops off. The common solution to the problem is "equalization charge." You gently overcharge the batteries to make sure that the weakest cells are brought up to full charge. The trick is to keep the batteries equalized without damaging the strongest batteries with overcharging. There are more complex solutions that scan the batteries, measure individual voltages, and send extra charging current through the weakest module.

In the next section, we'll walk through a conversion step by step.

Doing a Conversion

A majority of the electric cars on the road today are "home brew" conversion vehicles. People with an interest in electric cars convert existing gasoline-powered car­s to electric in their backyards and garages. There are many Web sites that talk about the phenomenon and show you how to do it, where to get parts, etc.

A typical conversion uses a DC controller and a DC motor. The person doing the conversion decides what voltage the system will run at -- typically anything between 96 volts and 192 volts. The voltage decision controls how many batteries the car will need, and what sort of motor and controller the car will use. The most common motors and controllers used in home conversions come from the electric forklift industry.

Usually, the person doing the conversion has a "donor vehicle" that will act as the platform for the conversion. Almost always, the donor vehicle is a normal gasoline-powered car that gets converted to electric. Most donor vehicles have a manual transmission.

The person doing the conversion has a lot of choices when it comes to battery technology. The vast majority of home conversions use lead-acid batteries, and there are several different options:

• Marine deep-cycle lead-acid batteries (These are available everywhere, including Wal-mart.)
• Golf-cart batteries
• High-performance sealed batteries

The batteries can have a flooded, gelled or AGM (absorbed glass mat) electrolyte. Flooded batteries tend to have the lowest cost but also the lowest peak power.

Once the decisions about the motor, controller and batteries are made, the conversion can start. Here are the steps:

1. Remove the engine, gas tank, exhaust system, clutch and perhaps the radiator from the donor vehicle. Some controllers have water-cooled transistors, while some are air-cooled.
2. Attach an adapter plate to the transmission and mount the motor. The motor normally requires custom mounting brackets.
3. Usually, the electric motor needs a reduction gear for maximum efficiency. The easiest way to create the gear reduction is to pin the existing manual transmission in first or second gear. It would save weight to create a custom reduction gear, but normally it is too expensive.
4. Mount the controller.
5. Find space for, and build brackets to safely hold, all the batteries. Install the batteries. Sealed batteries have the advantage that they can be turned on their sides and fitted into all sorts of nooks and crannies.
6. Wire the batteries and motor to the controller with #00 gauge welding cable.
7. If the car has power steering, wire up and mount an electric motor for the power steering pump.
8. If the car has air conditioning, wire up and mount an electric motor for the A/C compressor.
9. Install a small electric water heater for heat and plumb it into the existing heater core, or use a small ceramic electric space heater.
10. If the car has power brakes, install a vacuum pump to operate the brake booster.
11. Install a charging system.
12. Install a DC-to-DC converter to power the accessory battery.
13. Install some sort of volt meter to be able to detect state of charge in the battery pack. This volt meter replaces the gas gauge.
14. Install potentiometers, hook them to the accelerator pedal and connect to the controller.
15. Most home-brew electric cars using DC motors use the reverse gear built into the manual transmission. AC motors with advanced controllers simply run the motor in reverse and need a simple switch that sends a reverse signal to the controller. Depending on the conversion, you may need to install some sort of reverse switch and wire to the controller.
16. Install a large relay (also known as a contactor) that can connect and disconnect the car's battery pack to and from the controller. This relay is how you turn the car "on" when you want to drive it. You need a relay that can carry hundreds of amps and that can break 96 to 300 volts DC without holding an arc.
17. Rewire the ignition switch so that it can turn on all the new equipment, including the contactor.

Once everything is installed and tested, the new electric car is ready to go!

A typical conversion, if it is using all new parts, costs between $5,000 and $10,000 (not counting the cost of the donor vehicle or labor). The costs break down like this:

• Batteries - $1,000 to $2,000
• Motor - $1,000 to $2,000
• Controller - $1,000 to $2,000
• Adapter plate - $500 to $1,000
• Other (motors, wiring, switches, etc.) - $500 to $1,000

For more information on electric cars and related topics, check out the links on the next page.