news ambientali

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Andes drought leaves Lima thirsty

By Hannah Hennessy
BBC News, Lima



The water restrictions in Lima affect eight million people
Peru has begun rationing water to its capital, Lima, following one of the worst droughts in a decade.
Millions of people in the coastal city are being left without water supplies for twelve hours every night between 1700 and 0500.

The restrictions are likely to last through Peru's winter until December.

Peru's state-run water company, Sedapal, was forced to restrict its supplies because of exceptionally low rainfall in the Andes.

Lima is on the edge of the Pacific Ocean, but the coastal strip is desert and the city's eight million people get their water from the mountains over 160km (100 miles) away.

Sedapal President Jorge Villacorta said water levels in the high altitude reservoirs had fallen to 165 million cubic metres, 120 million less than in a normal year.

Mr Villacorta said people in Lima currently used twice as much as the World Health Organisation deems necessary for personal use.

But he knows it is not just up to the city's population to reduce the amount of water they use.

Sedapal also needs to reduce its so-called non-revenue water - the 38% of its supplies that is lost mainly through leakage and illegal use.

Poor worst affected

"People need to lose less and leak less water in their houses," Mr Villacorta said.

"We need a hundred more wells and we need to build our famous new reservoir project, called Marcapomacocha 2, which will bring an additional 6.5 cubic metres a second. So we need to consolidate supply and optimise demand."


Around five million people in Lima have cisterns and tanks. This means they usually have an uninterrupted supply of water, even when the main taps are turned off during the night, when demand for water is at its lowest.

That still leaves three million people without water for twelve hours at a time. The majority of them are the city's poor.

"It's very bad for us until December. The government needs to provide us with a solution," said one resident.

"When we've got water, we mostly use it to bathe for hygiene purposes, but without water, what are we supposed to do?" asked another.

Mr Villacorta says Sedapal is planning to equip Lima with hundreds of new wells and build another reservoir to catch the rains further up the mountains.

But with more droughts predicted for next year, Lima's residents could be in for another testing time.

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Inaugurato un sistema che sfrutta le acque gelate dell'Ontario
Abbattuto l'inquinamento: è come eliminare 8 mila automobili
Toronto, addio ai condizionatori
La città si raffredda grazie al lago
Si risparmia il 75% di elettricità, scongiurando il rischio blackout
di ALESSIO BALBI


La centrale Enwave
sul lago Ontario

ROMA - L'hanno definita "l'energia del futuro, a disposizione fin da oggi". A Toronto, la più grande città del Canada, 130 edifici hanno dato l'addio ai tradizionali sistemi di aria condizionata e da ieri vengono raffreddati usando le acque del lago Ontario. Un sistema innovativo che permetterà di risparmiare fino al 75 per cento nel consumo di elettricità, riducendo l'inquinamento e scongiurando il rischio di emergenze energetiche come quelle sperimentate l'anno scorso da vari paesi occidentali.

La città di Toronto usa già il lago Ontario come serbatoio di acqua potabile. Acqua che, in profondità, si mantiene quasi ghiacciata anche d'estate. Le autorità comunali hanno avuto l'idea di convogliare il freddo del liquido, invece di farlo disperdere nel percorso dal bacino ai rubinetti delle case.

Il sistema è stato battezzato Deep lake water cooling (Dlwc). La Enwave, l'azienda municipale che lo ha sviluppato, ha scelto per l'inaugurazione l'anniversario del blackout che nel 2003 lasciò al buio il Canada e gli Stati Uniti orientali. Una scelta non casuale: il sistema permetterà di risparmiare ogni anno 59 megawatt e, a pieno regime, continuerà a funzionare anche in caso di blackout elettrico. In termini ambientali, significa 40 mila tonnellate di ossido di carbonio in meno nell'aria, l'impatto di 8 mila automobili.

Il cuore del Dlwc sono tre tubi in polietilene che pescano a 83 metri di profondità, dove l'acqua mantiene una temperatura costante di circa 4 gradi centigradi. Durante il percorso tra la centrale di filtraggio e le pompe che convogliano l'acqua verso le case e gli uffici, i tubi incontrano una stazione della Enwave, dove avviene lo scambio di calore con il circuito di condizionamento. Alla Enwave ci tengono a precisare che non c'è mai un contatto tra l'acqua e i sistemi di refrigerazione: è solo la temperatura del liquido ad essere sfruttata.


"Questa è l'energia del futuro a disposizione fin da oggi", ha dichiarato il presidente di Enwave, Dennis Fotinos. "E' pulita, rinnovabile e affidabile". Per il momento, a giovarsi dell'innovazione saranno oltre 130 edifici nel distretto finanziario di Toronto, tra i quali i quartieri generali della Royal Bank e della Air Canada. Secondo la Enwave, il sistema Dlwc ha abbastanza capacità da raffreddare 10 milioni di metri quadri, l'equivalente di 8 mila case.

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Water 'wake-up call' given by UN

By Imogen Foulkes
BBC correspondent in Geneva



Some 4,000 children die daily from illnesses caused by unclean water
The UN says the world faces a silent emergency because of the continued lack of clean water and sanitation.
A new report reveals that more than 40% of the world's population does not have even the most basic sanitation.

More than one billion people have no access to clean water sources, the document adds.

The report was prepared by the UN's children's fund, Unicef, and the World Health Organisation to assess progress towards reaching millennium goals.

A key development goal is to cut by half the number of people without clean water and sanitation by the year 2015.

We have to act now to close this gap or the death toll will certainly rise



If things continue as they are, half a billion people will still have no sanitation 11 years from now.

And while the world is on target to meet the clean drinking water goals, population growth will probably outstrip the improvements.

This would leave 2.4 billion people drinking unsafe water in 2015.

The report also says:


1.8m people die each year from diarrhoeal disease
Over 40 billion work hours are lost in Africa to the need to fetch drinking water
There has been progress - an estimated 1.1bn people now have better access to water than 12 years ago.

Political will

Unicef points out that it is the young who suffer most from continuing shortages.

"Around the world millions of children are being born into a silent emergency of simple needs," says Carol Bellamy, Unicef's executive director.






"The growing disparity between the haves and the have-nots in terms of access to basic services is killing around 4,000 children every day and underlies many more of the 10 million child deaths each year. We have to act now to close this gap or the death toll will certainly rise."

Rural regions in Africa and Asia are worst affected, but the global trend towards urbanisation is also putting more of a strain on water services in cities.

Unicef and the WHO want this report to be a wake-up call to world leaders.

Achieving clean water and sanitation for everyone will take more than money, they say.

A clear political commitment to the universal right to water is needed too. The report warns that the failure to act will have severe consequences.

Millions of people, mainly children, will die unnecessarily and millions more will be left out of the development process.

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Need for carbon sink technologies

By Carolyn Fry
in Stockholm



Scientists have watched as the melting of Greenland's ice has accelerated
Governments should consider setting lower targets for levels of CO2 in the atmosphere and investigate ways to extract surplus amounts of the greenhouse gas from circulation, say climate scientists.
Before the industrial revolution, the level of CO2 in the atmosphere was around 280 parts per million by volume (ppmv) but that has risen to around 380ppmv due to our burning of fossil fuels.

The Intergovernmental Panel on Climate Change is focusing its efforts on emission scenarios that lead to concentrations of no less than 450ppmv while the UK government is working towards a concentration target of around double pre-industrial levels, at 550ppmv.

If concentrations stabilise at 550ppmv, the corresponding global average temperature rise brought about by the greenhouse effect could still be as high as 5.5C, sufficient to melt the Greenland Ice Sheet and prompt a rise in sea level of six metres.

Fair targets

Scientists speaking here at EuroScience Open Forum 2004 said governments should be exploring the potential of Negative Emissions Technologies (NETs) which could actively remove CO2 from the atmosphere and stabilise atmospheric concentrations of the gas at much lower levels.

"The current stabilisation targets are a social construction," said Professor Christian Azar, of Goteborg University's Department of Physical Resource Theory.

"Governments are not looking at NETs because part of the cost of doing so will fall on certain industry sectors and they are powerful enough to protest."

Current CO2 emissions vary greatly between countries of the developed and developing world.

In 1998, the US released 5.4 tonnes of carbon per capita, European countries averaged around 1.9 tonnes and Africa emitted 0.3 tonnes.

To meet a global concentration target of about 350-400ppmv would require a cross-the-board emission level of no more than 0.4 tonnes of carbon per person per year.

In the developed world this would require per capita emissions to be cut to the level of Africa or Asia, while the people of the developing world would never be able to use the same amount of fossil fuels that the industrialised countries have to achieve the equivalent standard of living.

The proposal closely resembles an idea developed by the UK-based Global Commons Institute, which has gained wide support among scientists and policymakers, called contraction and convergence.

"Contraction" means cutting the world's output of greenhouse gases, and "convergence" means sharing out between countries the amount of climate pollution which scientists say the Earth can tolerate, so that by perhaps 2050 everyone in the world is entitled to emit the same amount of pollution.

Leakage rules

NETs offer a means of cutting emissions without the need for immediate extreme lifestyle changes.

They ideally involve using biomass from planted forests to produce energy and then capturing the CO2 produced, or alternatively extracting CO2 directly from the atmosphere.

Recovered CO2 would then be injected into deep underground or sub-sea stores to remove it from circulation.

Opponents of the technologies suggest such methods would be costly and that CO2 could still leak back into the environment, with unknown consequences.

However, modelling the various options for achieving emissions targets of between 350ppmv and 450ppmv between 1990 and 2200 at the least cost, Professor Azar found not only that it was feasible but that in certain cases the cost barely exceeded that of running large fossil fuel plants.

"The capture and storage of CO2 offers a great opportunity to get lower stabilisation targets at lower cost," he said.

"We need a regulatory framework on how to deal with carbon capture and storage. It should include rules for leakage and how to deal with capture from biomass.

"We also need to support technological development so that solar and other renewables can come to the marketplace and become viable options."