Environment Issues and Global Warming

Air: What’s a Tree Got to Do with It?

2009-06-05T21:37:00.001+05:30

Air: What’s a Tree Got to Do with It?

by Adam Downing

Everyone knows that trees clean the air. But do you know how they do it? Dave Nowak, a researcher with the USDA Forest Service in the Northeast has studied the effect of trees on air quality extensively. Trees clean the air in basically four different ways and Dr. Nowak has organized these as an easy to remember acrostic. T R E E.

“T” is for Temperature. Who hasn’t sought the cool air under a shade tree or enjoyed the coolness of a walk in the woods? Transpiration from trees (that is the process of moisture evaporating, primarily from leaves) and the canopies themselves not only affect air temperature directly, but also heat storage, wind speed, relative humidity, surface roughness and more. These factors work together to reduce mid-day air temperature under trees in a lawn type setting by almost 2ºF cooler than the same lawn with no trees. In effect, trees create a different, i.e. cooler, micro-climate.

So, cooler air is nice, but how does it help air quality? The emission of many pollutants and/or ozone-forming chemicals increases with temperature. A great example of this takes place in parking lots every day. You know how hot your car is after just a few minutes of sitting in the open sun? Well, hot seats and door handles are not the only undesirables happening at that moment when you get in and crank up the AC.

Trees help clean our air in a multitude of ways. (Diagram courtesy of USDA Forest Service)

Forest Service researchers in Davis, California found trees in parking lots made air 3ºF cooler. Those few degrees difference reduced vehicle surface temperatures up to 36ºF, inside (cabin) temperatures by 47ºF and, importantly, gas tank temperatures by 7ºF! Fewer hydrocarbon emissions result from gas that evaporated out of tanks and hoses with reduced temperatures. At present, most of our parking lots are a place where high temperatures increase pollutant emissions and thus the formation of smog and ozone. Gives new meaning to “made in the shade” doesn’t it?

“R” is for Removal of air pollutants. Trees are able to remove both gaseous pollutants and airborne particles. Gaseous pollutants include ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide. These are taken out of the air by trees primarily through leaf stomata. Stomata are small “windows” on green leaves which let carbon dioxide in and oxygen out. Thankfully, these stomata also accept gaseous pollutants in small amounts where it diffuses into spaces between leaf cells and from there is handled various ways.

Airborne particles, or particulate matter, is removed (at least temporarily) from the air by mechanical interception, primarily on leaf surfaces. While these bad guys float around in the air, their microscopic size enables them to be breathed deep into our lungs, potentially causing serious health problems or just a temporary irritation. In either case, reducing the amount of airborn particles and gaseous pollutants in areas above the acceptable level is a good thing.

“E” is for Emission of Volatile Organic Compounds (VOCs) and tree maintenance emissions. You may remember some time ago, trees were reported to contribute to ozone formation. This misleading fact contains only part of the truth. Most trees do emit biogenic VOCs such as isoprene and monoterpenes which can contribute to the formation of ozone and carbon monoxide. The other side of this story is that in areas with low nitrogen oxide concentrations, such as more rural areas, VOCs are believed to remove ozone. Additionally, since trees lower air temperature, the net effect of increased trees in urban areas is an overall lowering of VOC emissions and therefore ozone formation.

Trees in urban areas require energy inputs for planting, maintaining and removing. Because we burn fossil fuels (which emit CO2, SO2, N, CO and VOCs) in all these activities, we also need to factor that into the Trees + Air equation. In this case, it tips the scale a bit to the net loss side… but not for long!

“E” is also for Energy effects on buildings. Well-placed trees can significantly lower temperatures in buildings by shading them. On the other hand, poorly placed trees can increase energy needs by shading in the winter or blocking summer breezes. For trees to have a net positive effect on energy usage in buildings, proper placement is critical. With proper placement, however, the savings are quite significant. In fact, it is a double win. Homeowners get a lower energy bill while we all benefit from the reduced energy demand. When energy demand decreases, pollutant emissions from the power plants supplying that energy also decreases, and that generally improves air quality.

When we put all these letters back together we get the whole word. Likewise, we must consider each of these effects as cumulative and interactive to understand the overall impact of trees on air pollution.

The research on trees and air pollution is rather new and still ongoing. Currently, the best picture we can get is by running simulation models. The general conclusion is that increasing urban tree cover reduces ozone concentration. Economically, it’s probably one of the most efficient ways to do so. And that’s to say nothing of the many other benefits these aesthetically appealing air cleaners provide.

Biofuels: Green energy or grim reaper?

2008-02-25T22:55:00.002+05:30

Biofuels could end up damaging the natural world rather than saving it from global warming, argues Jeff McNeely in the Green Room. Better policies, better science and genetic modification, he says, can all contribute to a greener biofuels revolution.

Europe intends to adapt Brazil's experience with bioethanol

With soaring oil prices, and debates raging on how to reduce carbon emissions to slow climate change, many are looking to biofuels as a renewable and clean source of energy.

The European Union recently has issued a directive calling for biofuels to meet 5.75% of transportation fuel needs by 2010. Germany and France have announced they intend to meet the target well before the deadline; California intends going still further.

This is a classic "good news-bad news" story.

Of course we all want greater energy security, and helping achieve the goals (however weak) of the Kyoto Protocol is surely a good thing.

Little wonder that many are calling biofuels "deforestation diesel"

However, biofuels - made by producing ethanol, an alcohol fuel made from maize, sugar cane, or other plant matter - may be a penny wise but pound foolish way of doing so.

Consider the following:

The grain required to fill the petrol tank of a Range Rover with ethanol is sufficient to feed one person per year. Assuming the petrol tank is refilled every two weeks, the amount of grain required would feed a hungry African village for a year

Much of the fuel that Europeans use will be imported from Brazil, where the Amazon is being burned to plant more sugar and soybeans, and Southeast Asia, where oil palm plantations are destroying the rainforest habitat of orangutans and many other species. Species are dying for our driving

The expansion of biofuels would increase monoculture farming

If ethanol is imported from the US, it will likely come from maize, which uses fossil fuels at every stage in the production process, from cultivation using fertilisers and tractors to processing and transportation. Growing maize appears to use 30% more energy than the finished fuel produces, and leaves eroded soils and polluted waters behind

Meeting the 5.75% target would require, according to one authoritative study, a quarter of the EU's arable land

Using ethanol rather than petrol reduces total emissions of carbon dioxide by only about 13% because of the pollution caused by the production process, and because ethanol gets only about 70% of the mileage of petrol

Food prices are already increasing. With just 10% of the world's sugar harvest being converted to ethanol, the price of sugar has doubled; the price of palm oil has increased 15% over the past year, with a further 25% gain expected next year.

Little wonder that many are calling biofuels "deforestation diesel", the opposite of the environmentally friendly fuel that all are seeking.

With so much farmland already taking the form of monoculture, with all that implies for wildlife, do we really want to create more diversity-stripped desert?

Others are worried about the impacts of biofuels on food prices, which will affect especially the poor who already spend a large proportion of their income on food.

Biotech boost

So what is to be done? The first step is to increase our understanding of how nature works to produce energy.

Amazingly, scientists do not yet have a full understanding of the workings of photosynthesis, the process by which plants use solar energy to absorb carbon dioxide and build carbohydrates.

Some environmentalists are worried that altered trees will cross-breed with wild trees, resulting in a drooping forest rather than one that stands tall

Biotechnology, its reputation sullied by public protests over GM foods, may make important contributions. According to the science journal Nature, recombinant technology is already available that could enhance ethanol yield, reduce environmental damage from feedstock, and improve bioprocessing efficiency at the refinery.

The Swiss biotech firm Syngenta is developing a genetically engineered maize that can help convert itself into ethanol by growing a particular enzyme.

Others are designing trees that have less lignin, the strength-giving substance that enables them to stand upright, but makes it more difficult to convert the tree's cellulose into ethanol.

Some environmentalists are worried that these altered trees will cross-breed with wild trees, resulting in a drooping forest rather than one that stands tall and produces useful timber and wildlife habitat.

In the longer run, biotech promises to help convert wood chips, farm wastes, and willow trees into bioethanol more cheaply and cleanly, thereby helping meet energy needs while also improving its public image.

Public stake

But that is not nearly enough; bioenergy is too important to be left in the hands of the private sector.

Many of the social and environmental benefits of bioenergy are not priced in the market, so the public sector needs to step in to ensure these benefits are delivered.

An easy immediate step would be to mandate improved fuel efficiency for all forms of transport, beginning with the private automobile. A 20% increase in fuel-efficiency standards is feasible using current technology, and would save far more energy than Europe's biomass could produce.

Biofuels:the next generation

Governments also need to provide leadership in the form of economic incentives to minimise competition between food and fuel crops, and ensure that water, high-quality agricultural land, and biodiversity are not sacrificed on the altar of our convenience.

Calculations of energy return on investment need to include environmental impacts on soil, water, climate change, and ecosystem services.

The bottom line is that biofuels can contribute to energy and environmental goals only as part of an overall strategy that includes energy conservation, a diversity of sustainable energy sources, greater efficiency in production and transport, and careful management of ethanol production.

Biofuels 'will not lead to hunger'

2008-02-25T22:54:00.000+05:30

VIEWPOINT
Peter Kendall

British farmers can meet the nation's demand for both food and fuel crops, argues Peter Kendall, president of the National Farmers' Union. In this week's Green Room, he says UK agriculture already has enough capacity to fill fuel tanks and dining tables.

Fields of gold: Farmers can grow food and fuel crops, Mr Kendall says

Farmers in the UK see the opportunity to provide the feedstock to biofuel producers as a way to deliver secure, low-carbon fuel to the nation's motorists.

But we also understand that the development of biofuels should also be part of an overall strategy that includes energy conservation, a diversity of sustainable energy sources, greater efficiency in production and transport, and careful management of bioethanol production.

Some commentators raise objections to the development of biofuels because, they argue, it would increase pressure on valuable arable land that is needed to meet the growing demand for food crops. This is not a problem in the UK.

The area of land required to produce sufficient bio-diesel and bio-ethanol to meet the targets set out in the UK's Renewable Transport Fuel Obligation (RTFO), which requires 5% of all petrol and diesel sold on forecourts to be biofuel by 2010, can be found without prejudicing food production capacity.

The 3.5 million tonnes of feed wheat that is currently surplus to requirements and has to be exported will account for the bio-ethanol.

And using the UK's 750,000 hectares of set-aside to grow oilseed rape will comfortably take care of the bio-diesel requirement.

What is more, it is a pre-condition of the RTFO - entirely supported by the NFU - that biofuel crops are produced sustainably.

Developed in a sustainable way, in the context of a wide-ranging strategy for alternative crops, biofuels offer society a win, win, win solution

Send us your comments

British farmers are uniquely well placed to deliver this, thanks to the widespread adoption of farm assurance schemes. We intend to use these frameworks to ensure that fuel crops are produced without damage to the environment, just as food crops are.

Home grown

That is something that cannot, of course, be said of imported sources of biofuels, such as sugar cane from Brazil or palm oil from South East Asia.

This makes it even more important that as much as possible of our biofuel crop requirements are home-grown.

We agree with the World Conservation Union's chief scientist Jeffrey A McNeely (Green Room - Biofuels: Green or grim energy?) that the demand for biofuels will tend to lift prices for cereals and oilseeds.

But is that a bad thing? What has been holding back agriculture in the developing world is not a shortage of land, but the rock-bottom prices caused by the fact that world markets have been swamped by surplus grain, from both the EU and US.

If the demand for biofuels helps to change that, directly by lifting prices and indirectly by mopping up the surpluses, then it will give Third World farming the biggest single boost it has ever had.

That, in turn, will do more to alleviate starvation in Africa and elsewhere than all the food aid programmes put together.

Biofuels: the next generation

Developed in a sustainable way, in the context of a wide-ranging strategy for alternative crops, biofuels offer society a win, win, win solution.

Achieving the UK RTFO target will reduce CO2 emissions by two million tonnes (the equivalent to taking one million cars off the road), even after allowing for the carbon burnt in growing, transporting and processing the crop.

It will also create a greater equilibrium in grain and oilseed markets, benefiting not only food producers but food production, too.

And provided the raw materials for the biofuels are grown sustainably in the UK, their production will mean a better managed, more attractive countryside; and contribute significantly to the viability of the rural economy.

Biofuels look to the next generation

2008-02-25T22:52:00.000+05:30

By Mark Kinver
Science and nature reporter, BBC News

Click here to find out more on biomass and non-food crops

Biofuels are being hailed by politicians around the globe as a salvation from the twin evils of high oil prices and climate change.

The boom in biofuels in the US stems from President Bush's drive to reduce dependence on imports of foreign oil; in Europe it has a more environmental dimension.

Transport is responsible for a quarter of the UK's total emissions; four-fifths of that quarter comes from road vehicles.

Realising this could threaten to undermine efforts to meet Kyoto Protocol commitments, the UK government announced earlier this year the introduction of a Renewable Transport Fuel Obligation (RTFO).

It requires fuel companies to add 5% biofuel to all petrol and diesel sold on their forecourts by 2010.

Environmental concerns

When the plant-derived biofuel is burned in an engine, the CO2 released is offset by the amount of the gas absorbed by the plants when they grew.

It is, in principle, approximately carbon neutral; though the energy needed to plant, tend, harvest, process and transport the finished product can make the equation less favourable.

The scientific principle behind biomass is the carbon cycle

As they grow plants absorb carbon dioxide (C02)

The carbon (C) builds tissues and feeds the plant while the oxygen (02) is released

When plant material is burned the carbon re-combines with oxygen

The resulting carbon dioxide is released back into the atmosphere

The contribution of biomass to the greenhouse effect is therefore far less than for traditional fossil fuels

The two main players in the market, bioethanol and biodiesel, are made from crops such as cereals, soybean, rape seed oil, sugar cane and palm oil.

While governments embrace what they see as a key player in a low-carbon future, there are concerns over some potential unwanted consequences.

Demand for land to grow these crops could put pressure on valuable ecosystems such as rainforests, and reduce the area available for subsistence food crops in developing countries.

Jeremy Tomkinson, chief executive of the UK National Non-Food Crop Centre (NNFCC), shares these concerns.

"If you are chopping down huge areas of rainforest in order to grow palm oil, not only is the palm oil not very environmentally friendly, think of the damage to the area's biodiversity.

"This is a problem with some biodiesel, but the fuel we are using now is only a transitory thing."

The next generation

Mr Tomkinson predicts that within a decade, current biofuel production methods could be replaced by "second generation" fuels.

"To me, this is the answer," he says. "It opens up a whole new ball game."

"What we are calling second generation, when it comes to gasoline, is the use of lignocelluloses.

Because we are going to break everything down anyway, we can look at a whole new range of crops that really are energy crops

Jeremy Tomkinson, NNFCC

"Lignocellulose is a clever, technical way of saying biomass - it means anything that comes out of the ground."

Mr Tomkinson says it will more than double yields: "Instead of just taking the grain from wheat and grinding that down to get starch and gluten, then just taking the starch, we are going to take the whole crop - absolutely everything."

Second generation fuel will also have a smaller carbon footprint because the amount of energy-intensive fertilisers and fungicides will remain the same, he adds, for a higher output of useable material.

Because the technology will allow biofuel to be produced from any plant material, there would be no conflict between the need for food and the need for fuel.

"We can let the lads who grow wheat grow it for nutritional value, and we can have another sector that is growing non-food crops for fuel, chemicals and pharmaceuticals," Mr Tomkinson suggests.

"Because we are going to break everything down anyway, we can look at a whole new range of crops that really are energy crops, not short-rotation coppice crops that we are using now."

He says two possible energy crops are sunflowers and fodder maize.

Early days

Oil giant BP is investing $500m (£266m) in an "energy bioscience institute", which will be based in either the UK or US.

"There have been major improvements to food yields and productivity by applying plant science to agriculture," says spokesman David Nicholas, "but it has not been done yet in terms of applying that science to the yielding of energy crops."

BP is also investing money into research in India, where it is looking at whether it can derive biodiesel from plants that can be grown on soil not suitable for food crops.

"Biofuels are a reality and will become an increasing part of our industry, but we are at the early stages of what are the most efficient and advanced biofuels," Mr Nicholas observes.

Second generation biofuel production is much more expensive

There are two sizeable barriers that need to be tackled before second generation biofuels arrive at the pumps - technology and cost.

"It is technically far more complicated than current production methods," says Mr Tomkinson. "All the different [sugars] in the plant need their own enzymes to break them down.

"A number of companies are looking at something called 'cellulose accessing packages' that will allow us to take a bag of enzymes and pour it on to lignocellulose and ferment the whole lot," he explains.

The NNFCC is about to carry out a feasibility study to find out whether the UK could have a Biomass-To-Liquid (BTL) processing plant, which can produce the fuel.

Mr Tomkinson believes a BTL plant will require a serious amount of investment: "For a world-scale BTL plant, you are looking in the region of £200m ($375m).

"Currently, a 250,000-tonne biodiesel plant costs about £50m ($94m), so that is a big difference for the same amount of fuel.

But because of its environmental advantages, Mr Tomkinson says governments all over Europe are paying close attention to this technology "because BTL really could be the way forward".

Source: BBC

Quick guide: Biofuels

2008-02-25T22:49:00.000+05:30

What are biofuels?

Biofuels are any kind of fuel made from living things, or from the waste they produce.

This is a very long and diverse list, including:

wood, wood chippings and straw

pellets or liquids made from wood

biogas (methane) from animals' excrement

ethanol, diesel or other liquid fuels made from processing plant material or waste oil

In recent years, the term "biofuel" has come to mean the last category - ethanol and diesel, made from crops including corn, sugarcane and rapeseed.

Rudolph Diesel: biofuel pioneer

Bio-ethanol, an alcohol, is usually mixed with petrol, while biodiesel is either used on its own or in a mixture.

Pioneers such as Henry Ford and Rudolph Diesel designed cars and engines to run on biofuels. Before World War II, the UK and Germany both sold biofuels mixed with petrol or diesel made from crude oil; the availability of cheap oil later ensured market dominance.

Ethanol for fuel is made through fermentation, the same process which produces it in wine and beer. Biodiesel is made through a variety of chemical processes.

There is interest in trying biobutanol, another alcohol, in aviation fuel.

Are biofuels climate-friendly?

In principle, biofuels are a way of reducing greenhouse gas emissions compared to conventional transport fuels.

Burning the fuels releases carbon dioxide; but growing the plants absorbs a comparable amount of the gas from the atmosphere.

However, energy is used in farming and processing the crops, and this can make biofuels as polluting as petroleum-based fuels, depending on what is grown and how it is treated.

A recent UK government publication declared that biofuels reduced emissions "by 50-60% compared to fossil fuels".

Where are biofuels used?

Production of ethanol doubled globally between 2000 and 2005, with biodiesel output quadrupling.

Biofuels: the next batch

Brazil leads the world in production and use, making about 16 billion litres per year of ethanol from its sugarcane industry.

Sixty percent of new cars can run on a fuel mix which includes 85% ethanol.

The European Union has a target for 2010 that 5.75% of transport fuels should come from biological sources, but the target is unlikely to be met.

The British government's Renewable Transport Fuel Obligation requires 5% of the fuel sold at the pump by 2010 to be biofuel.

In the US, the Renewable Fuels Standard aims to double the use of biofuels in transport by 2012.

What are the downsides?

From the environmental point of the view, the big issue is biodiversity.

With much of the western world's farmland already consisting of identikit fields of monocultured crops, the fear is that a major adoption of biofuels will reduce habitat for animals and wild plants still further.

Asian countries may be tempted to replace rainforest with more palm oil plantations, critics say.

If increased proportions of food crops such as corn or soy are used for fuel, that may push prices up, affecting food supplies for less prosperous citizens.

The mixed picture regarding the climate benefit of biofuels leads some observers to say that the priority should be reducing energy use; initiatives on biofuels detract attention from this, they say, and are more of a financial help to politically important farming lobbies than a serious attempt to cut greenhouse gas emissions.

There are few problems technically; engines can generally cope with the new fuels.

But current technologies limit production, because only certain parts of specific plants can be used.

The big hope is the so-called second-generation of biofuels, which will process the cellulose found in many plants. This should lead to far more efficient production using a much greater range of plants and plant waste.

Airline in first biofuel flight

2008-02-25T22:44:00.001+05:30

Sir Richard and a coconut hail the "historic" flight

The first flight by a commercial airline to be powered partly by biofuel has taken place.

A Virgin Atlantic jumbo jet has flown between London's Heathrow and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts.

Environmentalists have branded the flight a publicity stunt and claim biofuel cultivation is not sustainable.

Earlier this month, Airbus tested another alternative fuel - a synthetic mix of gas-to-liquid.

Virgin boss Sir Richard Branson said the flight marked a "vital breakthrough" for the entire airline industry.

"This pioneering flight will enable those of us who are serious about reducing our carbon emissions to go on developing the fuels of the future," he said.

But he said fully commercial biofuel flights were likely to use feedstocks such as algae rather than the mix used on the passenger-less flight.

Virgin's Boeing 747 had one of its four engines connected to an independent biofuel tank that it said could provide 20% of the engine's power.

Instead of looking for a magic green bullet, Virgin should focus on the real solution to this problem and call for a halt to relentless airport expansion

Dr Doug Parr, Greenpeace

The three other engines were capable of powering the plane on conventional fuel had there been a problem.

The company said the babassu tree, native to Brazil, and the coconuts did not compete with staple food sources and came from existing mature plantations.

Both products are commonly used in cosmetics and household paper products.

'Gimmick'

One problem with flying planes using biofuel is that it is more likely to freeze at high altitude.

The Boeing 747 was partly fuelled by coconut and Brazilian babassu

The technology is still being developed by companies GE and Boeing, but Virgin believes airlines could routinely be flying on plant power within 10 years.

Kenneth Richter, of Friends of the Earth, said the flight was a "gimmick", distracting from real solutions to climate change.

"If you look at the latest scientific research it clearly shows biofuels do very little to reduce emissions," he said.

"At the same time we are very concerned about the impact of the large-scale increase in biofuel production on the environment and food prices worldwide.

"What we need to do is stop this mad expansion of aviation. At the moment it is the fastest growing source of greenhouse gases in the UK, and we need to stop subsidising the industry."

Greenpeace's chief scientist, Dr Doug Parr, labelled the flight a "high-altitude greenwash" and said less air travel was the only answer.

BIOFUELS

They are any fuels made from living things

Commonly means fuel made from crops including corn

Pioneers such as Henry Ford designed cars to run on biofuels

Quick guide: Biofuels

"Instead of looking for a magic green bullet, Virgin should focus on the real solution to this problem and call for a halt to relentless airport expansion."

Airbus ran its test using the world's largest passenger jet, the A380.

The three-hour flight from Filton near Bristol to Toulouse on 1 February was part of an ongoing research programme.

Source: BBC Website

Will biofuels power tomorrow's planes?

2008-02-25T22:36:00.003+05:30

On Sunday, a Virgin Airlines Boeing 747 took off from London's Heathrow Airport en route to Amsterdam. This short flight may prove to be a giant leap forward for the aviation industry.

The aircraft did not carry passengers - but it was the first commercial aircraft to fly partly under the power of biofuels.

One of the aircraft's four engines ran on fuel comprising a 20% biofuel mix of coconut and babassu oil and 80% of the normal Jet A aviation fuel.

Biofuels - principally ethanol and diesel made from plants - are one of the few viable options for replacing the liquid fuels derived from petroleum used in transport, the source of about one quarter of the human race's greenhouse gas emissions.

Existing engines

The airline industry is being increasingly criticised for its perceived part in global warming, as more and more people take advantage of cheap tickets on aircraft powered by kerosene. Environmentalists claim it is a major carbon producer, fuelling rising world temperatures.

Airlines and aircraft designers have been feeling the heat. Plane-makers Boeing and aircraft engine manufacturers General Electric have been working with Virgin to cut down their flights' carbon footprints.

What is exciting the aviation industry is the fact the aircraft is completely unchanged, using the same engines as any scheduled, passenger-carrying flight. Only the fuel is different.

The flight follows a journey made by an Airbus A380 earlier this month using another alternative fuel - a synthetic mix of gas-to-liquid - in one of its four engines.

It flew from Filton in the UK to Toulouse in France, a journey of some 900km (560 miles), and was in partnership with Rolls-Royce and Shell.

Air New Zealand is also working with Boeing and Rolls-Royce to mount a test flight powered partly by biofuels later this year.

These are the first tentative steps in breaking the aviation industry's reliance on kerosene. But it is likely to be decades before aircraft are able to take to the skies powered entirely by something other than fossil fuels.

One industry analyst told the BBC News website there were several problems to overcome.

Jet A fuel, one of the standard aviation fuels, has a stable energy content and a low freeze point - meaning it is suited to the very low temperatures encountered by high-flying aircraft.

Biofuels cannot be relied upon to operate as reliably in the same temperatures.

Jet A fuel also burns consistently, which means it provides a reliable and safe fuel source for long flights.

Environmental drawbacks

Airlines also want a biofuel which can be burnt in existing engines - rather than having to replace every engine in their fleets.

There are other issues surrounding biofuels. There are concerns widespread planting and use of biofuel crops could threaten natural ecosystems and raise food prices. It could also mean the deforestation of rainforests, which absorb massive amounts of carbon.

Virgin remained tight-lipped about where its biofuel comes from until the day of the flight but said it would be a "truly sustainable type of biofuel that doesn't compete with food and fresh water resources".

Some environmentalists are sceptical. They believe the secret to cutting down aviation's share of the carbon is cutting the amount of flights we take.

Kenneth Richter, Friends of the Earth aviation campaigner, said: "Biofuels are a major distraction in the fight against climate change. There is mounting evidence that the carbon savings from biofuels are negligible.

"If Virgin was really serious about reducing the aviation industry's impact on the environment it would support calls for aircraft emissions to be included in the Climate Change Bill."

Green Party councillor and former chemist Andrew Boswell said: "Richard Branson is making a huge mistake backing biofuels.

"It means a huge amount of fuel we've got to produce."

Mr Boswell, who campaigns for the lobby group Biofuel Watch, said it was unsustainable to try and replace transport's share of fossil fuel consumption with biofuels - there is simply not enough arable land to grow fuel crops and food.

Sunday's flight may herald a new direction in aviation. But any massive change in the way we power our planes is unlikely, analysts say, to be just around the corner.

Source: BBC Website

Ice keeps New York office towers cool

2008-02-24T22:02:00.000+05:30

NEW YORK :- As the summ er swelters on, skyscrap ers and apartments around the city will crank up air conditioners and push the city's power grid to the limit -- but some have found a cool alternative.

Some skyscrapers in New York City are using ice to keep office workers cool this summer.

Some office towers and buildings are keeping their AC use to a minimum by using an energy-saving system that relies on blocks of ice to pump chilly air.

"If you take the time to look, you can find innovative ways to be energy efficient, be environmental and sustainable," said William Beck, the head of critical engineering systems for Credit Suisse.

The systems save companies money and reduce strain on the electrical grid in New York, where the city consumes huge amounts of power on hot summer days.

Ice cooling also cuts down on pollution. A system in Credit Suisse's offices at the historic Metropolitan Life tower in Manhattan is equal to taking 223 cars off the streets or planting 1.9 million acres of trees to absorb carbon dioxide from electrical use for a year, according to the New York State Energy Research and Development Authority.

Such a reduction in pollution is valuable in a city where the majority of emissions come from the operation of buildings. Officials said there are at least 3,000 ice-cooling systems worldwide.

Because electricity is needed to make the ice, water is frozen in large silver tanks at night when power demands are low. The cool air emanating from the ice blocks is then piped through the building. At night the water is frozen again and the cycle repeated.

Ice storage can be used as the sole cooling system, or it can be combined with traditional systems to help ease the power demands during peak hours.

At Credit Suisse, for example, the company must cool 1.9 million square feet of office space at the historic Met Life tower.
How it works
# Air conditioning can be very expensive and use a lot of electricity, so some buildings are turning to ice cooling.

# Imagine a fan blowing cool air from a block of ice, only on a larger scale. Water is frozen in huge silver tanks and the cool air emanating from the ice blocks is then piped throughout the building.

# Officials say replacing traditional air conditioners with the ice-cooling system in one Manhattan office tower is as good for the environment as taking about 220 cars off the streets.

Source: AP

In the basement, three main cooling rooms house chilling machines and 64 tanks that hold 800 gallons of water each. Credit Suisse has a traditional air conditioning system, but engineers use the energy-saving system first.

Construction on the system took about four months, and company engineers say it is extremely efficient.

"When you make something mechanical, it can break, but a big block of ice ... isn't going to do anything but melt," said Todd Coulard of Trane Energy Services, which built the Credit Suisse system.

Trane, the air conditioning arm of American Standard, also developed a system for Morgan Stanley's Westchester County offices and just completed a new system for its offices on Fifth Avenue. A new Goldman Sachs headquarters will also have ice cooling.

Credit Suisse is considering installing the systems in offices around the globe, but nothing has been decided yet. Coulard, an expert in energy efficiency, was hired by the company four years ago to develop the energy services department.

"The idea of not only saving money for large companies, but doing something that benefits the environment, is win-win," he said. "It's doing the right thing."

Ice storage at Credit Suisse lowers the facility's peak energy use by 900 kilowatts, and reduces overall electric usage by 2.15 million kilowatt-hours annually -- enough to power about 200 homes, officials said.

At the Morgan Stanley facility in Westchester County, the system reduces peak energy use by 740 kilowatts and overall electricity usage by 900,000 kilowatt hours annually.

Both companies received incentives from the New York State Energy Research and Development Authority under a program designed to improve the power grid and help businesses reduce operating costs.

The technology is not for every office space. There has to be room to install the large tanks -- and costs are considerable. Credit Suisse spent more than $3 million to renovate its cooling system and Morgan Stanley's costs were comparable, meaning the technology is best suited to large companies.
"This is for companies that want to go green, but there (need) to be other benefits, returns on investments," Coulard said. "It works for larger companies because their cooling costs are so considerable."