With oil near $50 a barrel, alternatives to gasoline are attracting more attention - including fuel cells, devices that convert hydrogen into electric current with no waste products except heat and pure water.

Fuel cells have found their way into power systems for laptop computers and into many experimental cars. The main drawback to automotive use of fuel cells, though, has been their cost, which at $100,000 can be 25 times the $4,000 for a gasoline engine of equal power. Lately, some companies, including Honda, have been trying to come up with cheaper versions of the most expensive part of a fuel cell: the membrane that takes the hydrogen fuel and separates it into protons and electrons.

This morning, a California company, PolyFuel, plans to announce that it has achieved a breakthrough in fuel-cell membranes by using an alternative material: a hydrocarbon that it says costs only about half as much per square meter.

Compared with the fluorine compounds that are the most commonly used for membranes in fuel cells now under testing, PolyFuel says that hydrocarbon membranes allow production of more electricity per square centimeter of membrane. That could mean that a fuel cell could produce the same power as a fluorine-membrane version, but would be smaller and lighter, further adding to efficiency, according to the company.

The blackout that left 50 million North Americans without power in August 2003 had an unexpected benefit - the air became cleaner.

As power plants were turned down in south-east Canada and the north-east and mid-west US, levels of pollutants fell, says meteorologist Russell Dickerson.

Environmentalist Paul Ehrlich has proved himself to be a stupendously bad prophet. In 1968 he declared: "The battle to feed all of humanity is over. In the 1970s, the world will undergo famines--hundreds of millions of people are going to starve to death." They didn't. Indeed, a "green revolution" nearly tripled the world's food supply. In 1975, he predicted that, by the mid-1980s, "mankind will enter a genuine age of scarcity," in which "accessible supplies of many key minerals will be facing depletion." Far from it. Between 1975 and 2000 the World Bank's commodity price index for minerals and metals fell by nearly 50%. In other words, we abound in "key minerals." Naturally, Mr. Ehrlich has won a MacArthur Foundation genius award--and a Heinz Award for the environment.

For scientists studying climate change, the past is often a key to understanding the future. Dake Chen at Columbia University's Lamont-Doherty Earth Observatory recently used more than a century of climate data to successfully test an improved model of ENSO, the El-Niño/Southern Oscillation that scientists believe is behind climate change in many parts of the world.

Chen and his colleagues report in the April 15 issue of the journal Nature that an improved climate model, known as LDEO5, for the first time predicted every major change in the temperature of the tropical Pacific Ocean over the past 150 years with up to two years of advance notice.

The Earth's magnetic field takes an average of only 7000 years to reverse its polarity, but the switch happens much more quickly near the equator, according to the most comprehensive study yet of the last four reversals.

"It's important to get an idea of how fast or slow this process is because it ends up controlling our idea of how the field is generated in the first place," says study author Bradford Clement, an earth scientist at Florida International University in Miami, US.

Previous studies have reported a bewildering range of transition times, from a few thousand to nearly 30,000 years. So Clement scoured the published data on the most recent reversals to set the record straight.

He used data from 30 cores drilled from the beds of lakes or seas, whose minerals clearly recorded the magnetic field as sediments in the water slowly solidified into rock. The cores were taken from latitudes ranging from 46 degrees south to 60 degrees north and from a wide range of longitudes.

Clement found that the duration of the transitions varied with latitude, from 2000 years near the equator to 11,000 years nearer the poles. This result concurs with a much smaller study he conducted 20 years ago using just 10 cores.

An exploding star may have destroyed part of Earth's protective ozone layer two million years ago, devastating some forms of ancient marine life, according to a new theory presented at this week's meeting of the American Astronomical Society.

The new theory brings together puzzling clues from several different fields of research, including paleontology, geology, and astronomy.

Narciso Benitez, an associate research scientist in astronomy at Johns Hopkins University, said the "missing smoking gun" that brought the clues together was the revelation that a stellar cluster with many large, short-lived stars prone to producing supernovae had passed near Earth's solar system several million years ago.

New underwater turbines could be cheap and eco-friendly.

A British company has invented a simple tidal power system that is relatively easy to install and has little impact on its environment. The device could soon be added to our range of renewable energy resources, and be used to bring power to remote seaside locations.

The TidEl system uses floating turbines that are anchored to the seabed by chains. The underwater windmills drift back and forth with the tide, so they point in the best direction to get power from the spinning blades.

Power capacity generated by the wind surged by more than a quarter last year, mainly thanks to an expansion in Germany and other European countries, according to industry figures released Wednesday.

Wind generators installed around the world by the end of 2003 had the capacity to produce 39,294 megawatts, an increase of 8,133 MW, or 26 percent over 2002, they said.

The future of manufacturing will be built on industrial-strength ecology, says architect William McDonough. The first step: Turn Ford's legendary River Rouge plant into a lean, green profit machine.

A sign up ahead reads WARNING: SLAG HAULER CROSSING. Sitting in the back of a sedan, architect William McDonough is riding through Ford's aging River Rouge factory complex in Dearborn, Michigan. At 1,100 acres, it's the largest industrial site of early- to mid-20th century America, a testament to the scale of Henry Ford's vision. The Armani-clad McDonough surveys the ruins strung along the dark, slack river, cruising past eye-level piles of black, powdery ash heaps, a spindly gas tower, and the proto-industrial blast ovens. A red oxygen furnace belches as it haltingly refines coke into steel.

It hardly looks like the site of the next industrial revolution, yet that is exactly what McDonough intends to make it. In late 2000, the Ford Motor Company hired McDonough, a designer cum environmentalist, to blueprint the site's 20-year, $2 billion redesign. The centerpiece will be a vast but energy-efficient truck assembly plant, not far from a new low-emission paint plant. Company CEO William Clay Ford Jr., Henry's great-grandson, says that the goal is nothing less than transforming River Rouge into "the model of 21st-century sustainable manufacturing."

Green architecture is an emerging field, and McDonough, who was trained at Dartmouth and Yale, spent most of the '80s experimenting with it. His highly lauded Herman Miller factory in Zeeland, Michigan, and Gap corporate offices in San Bruno, California, are designed to maximize natural lighting and air circulation. At Oberlin College, in Ohio, he built a solar- and geothermal-powered facility for the environmental studies department designed to generate more energy than it uses.

A new report commissioned by the government suggests that it will be difficult to completely prevent genetically engineered plants and animals from having unintended environmental and public health effects.

The report, released yesterday by the National Research Council of the National Academy of Sciences, says that while there are many techniques being developed to prevent genetically engineered organisms or their genes from escaping into the wild, most techniques are still in early development and none appear to be completely effective.

Iron fertilization of the surface ocean layer has been considered as a possible strategy for reducing the burden of atmospheric CO2; this would mitigate greenhouse gas buildup and global warming. The idea is that CO2 would be removed from the atmosphere by sequestering it as new ocean production in "high nutrient--low chlorophyll" regions, where biological production is limited by the scarcity of iron. This approach might have other consequences, however, including the increased production and atmospheric concentration of N2O, another powerful greenhouse gas.

"No house should ever be on a hill or on anything. It should be of the hill. Belonging to it. Hill and house should live together each the happier for the other." - Frank Lloyd Wright