Research Watch: Fuel cell breakthrough - Environmental Science


Research Watch: Fuel cell breakthrough - Environmental Science...

0 downloads 71 Views 3MB Size

glacial termination estimates may be similarly in error. They are awaiting the availability of yet more data to persuasively confirm this suspicion.

Fuel cell breakthrough An improved solid-oxide fuel cell (SOFC) design greatiy advances the prospect of using fuel cells for onboard power generation in transportation applications requiring the use of conventional fuels. The system, which consists of only one gas chamber in which both anode and cathode are exposed to the same mixture of fuel and air, eliminates the need for using a reformer to first convert alcohols and hydrocarbons to hydrogen before they can be used as fuel. The Japanese scientists who developed the novel SOFC for use with hydrocarbon-air mixtures report that it has several significant advantages over more commonly used polymer electrolyte fuel cells (PEFCs). The latter devices exhibit high power densities at low temperatures but

A better bug beater

Recycling's dark side

Pesticide use could be cut dramatically, and perhaps soon, if new research findings reported by a group of French scientists can be rapidly exploited. The scientists have found a simple way to reduce droplet rebound, a major problem in industrial pesticide applications mat ultimately results in overuse of the toxic chemicals. Although 4.5 billion pounds of pesticides were used for agricultural and other purposes in the United States in 1997, much of this went into the environment without its intended purpose being realized.

The German system for promoting recovery of packaging waste from consumers may successfully remove materials from the waste stream, but not without environmental consequences, says Eric Neumayer, a lecturer in environment and development at the London School of Economics and Political Science. According to Neumayer, the system prioritizes innovative development of recycling technologies at the cost of neglected opportunities for avoiding waste generation in the first place. This locked-in emphasis on recycling is an unfortunate choice, Neumayer contends (Eur. Environ. 2000, 10 (3), 152-163). He argues that avoidance saves the full material and energy content of packages, but recycling only favors partial recovery of the resources and energy embodied in the waste. Neumayer sees analogous problems emerging with the European Union's Packaging Waste Directive which has similarities to the German packaging waste

Pesticides use could be cut significantly by adding polymers to formulations prior to application.

Fuel cells could reduce on-road emissions.

The significant wastage occurs when droplets in sprayed-on pesticide formulations hit the hydrophobic surfaces of plant leaves and bounce back off, taking their chemical cargo with them. Often, more than 50% of the amount of sprayed pesticide can be lost in this manner. As a result, much more pesticide has to be used than would be needed if the droplets consistently stuck to the surfaces of the leaves onto which they were applied.

TTlflTIFKJPTTlPTlt" *JVit"PTn

The German management system was established in 1991 under the German Packaging Ordinance at a time when the country was facing a severe landfill shortage. Packaging waste accounted for 30% by weight and 50% by volume of the waste stream (Environ. Sci. Technol. 2000, 34 (7), 170A-175A). The ordinance requires producers of all kinds of packaged products to either individually take back their packaging or join the Duales System Deutschland an industry organization whose consortium manages packaging waste for producers

l



,

P

who participate in the system

long, IICAIUIC puiyiiicis, sucii do puiy m e n p e r f o r m d i i c e wheii conveii-

ethelyeneoxide, to aqueous SOlULlollS. T y p i C d l i y , d U U U l iUU p p i l l Ul

p l d l l l l U I I l d S HO r C r L i O i t l l U S I d U l l C d -

doing this markedly reduced the

l.lOi 1 v^oolo d i e l u W c L 1 l i e 11CW OVJl^vj

duiiny ui Liiese dLiLiiterdieLi t n o u o LO

design is also compact and takes up less space. That advantage, combined with no longer needing an onboard fuel reformer, makes the system very attractive for transportation applications. Test results, reported m Science (2000, 288 (5473), 2031-2033), indicate that ethane and propane can be used successfully and that liquefied petroleum gas or even butane should perform well.

rebound on a hydrophobic sunace, without diiecting oilier desirable charactenstics of the spray. l ne study, reported in Nature (2000, 405 (6788), 772-775), supports a theory that reduced rebound occurs as a result of changes in the elongational viscosity of the applied droplets, a property that affects droplet reformation and rebound after surface impact.

Recycling ignores waste avoidance opportunities.

OCTOBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 4 1 9 A