Hydrogen Fuel Cells

[Jano]

Bueno estreno el foro scientifics con un tema que es muy interesante: El combustible alternativo, en este caso, el hidrogeno.

Fuente
Si quieren traducción, pidan o intenten traducir on line.
Salu2

The Promise of Hydrogen

Dr. Robert J. Wilder
President, The Hydrogen Fuel Cell Institute

At long last, a technology too long overlooked promises to transform society. Offering clean & abundant power, hydrogen-based fuel cells could soon end our reliance on oil and minimize emissions of pollution and global-warming gases. But to take advantage of what may potentially be a most useful clean energy technology, we cannot afford to wait. We need to look at clean ways to produce needed hydrogen, and make it widely available.

Over the past few years and especially the last few months, much fresh attention has been lavished on a vision of a world powered by fuel cells. As an efficient way to create electricity with little or no pollution-their promise is suddenly regarded as little short of revolutionary. Yet fuel cells are hardly new. Invented in 1839, they were mostly seen as novel by working electrochemically, rather than by combustion. Since then, they found only sporadic use where cost is not an issue, such as in spacecraft.

What is now generating such interest, are great strides lately made towards producing power from fuel cells at costs so low, they could potentially match or beat all competitors--even oil. Can continuing price reductions be found, so fuel cell power soon is made for just a tenth the cost of current hand-built prototypes? Or has the allure of a disruptive technology led to hyperbole and hopes that go far beyond what's warranted, and to irrationally exuberant stock valuations in this sector? The answer to this key question should come within five years.

The crux of fuel cell viability comes down to price, and this is why so much interest is lately being given cost-breaking technological advances that suddenly put fuel cells in a whole new light. It is also why professionals in a variety of on-the-ground jobs might-and sooner than is yet realized--be exposed to, effected by, and even begin designing for their practical use.

Importantly this alternative energy should soon prove economic in its own right. FuelCell Energy, Inc. expects a coming megawatt class field test to come out at $8,000 per kilowatt (a real reduction from the $20,000 per kilowatt in a 1996 trial) for a still-pricey 17 cents per kilowatt/hour (kWh). But within five years (of 2000), it hopes to achieve total installed costs including fuel of just $1,200 per kilowatt, for an electricity cost of roughly only 5 cents per kWh. That compares favorably to prices around the U.S. ranging in 1998 from over 10 cents in New York, to the cheapest at about 4 cents per kWh in the Pacific Northwest.

Note as well that the above figures for conventional production of electricity don't begin to reflect sizable price increases seen in 2000 and 2001, such as in California and the United States west coast. Nor do they reflect the growing need for firm high-quality power that is creating a fresh need. Those factors are only enhancing the prospects for hydrogen fuel cells.

It is plausible therefore that despite combustion1s leg-up with more than a century of refinements, only a few years from now, fuel cell rates could be very attractive. Imagine then the fuel cell state of the art twenty years hence, after billions of new research dollars and decades of improvements. Such a vision helps explain the recent enthusiasm for this sector.

Put aside for a moment the environmental advantages of fuel cells--which are certainly enormous--and still their promise is extraordinary. A fuel cell uses hydrogen, and the oxygen that is easily taken from air to make desired electricity; there also is some water and heat produced, but nothing else. They work very simply. In a typical cell a catalyst splits hydrogen into two constituent parts: protons (hydrogen ions) and electrons: the protons pass through a membrane to the other side and combine with oxygen making water. But this membrane forces electrons to take an external circuit to the other side: doing so they become power.

Five main types lend themselves to many applications and are distinguished by electrolyte, which also determines operating temperatures (often the hotter ones are more efficient, but this introduces other issues). These are proton exchange membrane (PEM, or polymer electrolyte) which operates at about 80 degrees C, alkaline fuel cell (AFC) at about 100 degrees C, phosphoric acid (PAFC) at about 200 degrees C, molten carbonate (MCFC), and solid oxide fuel cell (SOFC) both at 800 degrees C. Other types are being announced at a rapid clip, like the direct methanol fuel cell, and the regenerative cell, as interest grows.

Look at the benefits that should come from substituting fuel cells, in place of for instance the standard stationary or utility power generation in the U.S. Buildings account for about two-thirds of U.S. electricity consumption. To supply that power instead by fuel cells (combined perhaps with a turbine to capture waste heat) makes it possible to better current efficiencies by as much as 60%. Their high-quality waste heat is also excellent for key tasks of heating and cooling. When compared to oil or coal-fired power plants where much energy is wasted at the source, and so fails to reach customers, fuel cells start out with a big advantage.

Fuel cells might also greatly compound efficiencies, for they are easily scalable from micro through massive applications and so are especially well suited to decentralized power. This idea of distributed power means that electricity is generated by appropriately-sized sources located near to need. By placing the first round of stationary fuel cells where it is easiest to initially compete on favorable economic terms--such as where an existing grid is loaded and expansion is expensive, or in rural areas where there's no power grid, or where high-quality firm power is a necessity-their still-relatively high present costs become less of an issue.

Generating power where it's needed further eliminates huge costs associated with putting in miles of expensive wires on the grid. It also gets rid of related transmission losses and costs of power delivery, which in 1996 averaged 2.4 cents per kilowatt-hour. And it is flexible; the FuelCell Energy, Inc's molten carbonate unit can use varied hydrocarbon fuels like natural gas, methanol, diesel, or even coal gas--although to focus on hydrogen is ecologically best.

So why aren't fuel cells now powering our homes, offices, cell phones or cars around the world? Because until very recently their costs were far too high. Each was hand built by highly-trained Ph.Ds and many required gobs of pricey catalysts like platinum in PEM cells. While a proven technology, they could not come near an unbeatable price of King Oil.

Cost reductions could well become evident this decade, as a flowering of fuel cell companies build unprecedented manufacturing plants. Oftentimes this will require extra capitalization of joint ventures. Nonetheless and for the first time, both mass production and engineering refinements may work down the costs considerably as economies of scale are realized.

Looking ahead, imagine even fuel cell powered cars where as recently as 1998, the prototypes "engines" were quite dear, costing around $3,000 per kilowatt. Estimates by Amory & Hunter Lovins and Paul Hawken in their excellent (and highly recommended) book 'Natural Capitalism', predict costs for auto fuel cells of $500-$800 per kilowatt in 2000-2001, dropping to $100 as designs improve and production grows. They predict an eye-popping figure under $50 per kilowatt is achievable if they are produced on very large scale .

Yet lately as with so many things fuel cell, that may be too conservative. Recent reports (very optimistically) claim the Ballard Power 900 series fuel cell engine might rather soon be built for $60 per kilowatt, almost as low as a current gasoline engine mated to an automatic transmission. On the other hand such may not be realistic -- and many important hurdles will have to be overcome first -- but even getting fairly close to this figure would be a remarkable feat. The magic Honda Motors is working with their own quite elegant, prototype fuel cell car -- like several other car makers -- makes clear this FC race is now afoot.

Augmenting the switch to a hydrogen economy, note a fuel cell-powered car may have 50 kW or so generating capacity. Because cars are habitually parked at home or at work, they could become mobile power plants where you plug in your car--not to charge its battery -- but to help power your home or office! And net metering would mean you can even sell your car's excess power to the grid. To add insult to injury, new fuel cell vehicles could accelerate faster, go farther, last longer with few moving parts, be more efficient, safer, and cost less.

While automotive drivetrains will be one of the most difficult arenas of competition for the fuel cell to compete, given the present low cost of highly-refined Internal Combustion Engines, they may soon be seen as the Auxiliary Power Units powering robust new 42 volt car electrical systems. And they may sooner make on-board power for big rig tractor-trailers

In time, it should be possible to greatly reduce both the number of moving parts and size of the 'balance of plant' supporting the fuel cell stack itself. And, it is entirely conceivable that fuel cells themselves can become solid state; like the revolution from tubes to transistors, this will greatly improve reliability and add an engineering elegance. With few/no moving parts, and nothing to lubricate, a pressing need for oil can like steam power be a thing of the past.

Huge leaps in stock market valuations of companies like Ballard Power Systems, or FuelCell Energy, Inc. reflect in part the rapid lowering of costs and moves towards mass-production. But they also reflect the fact that fuel cells could surely offer far more than economic gains; their ability to create power without any pollution when hydrogen is the feedstock, is an extremely attractive solution to myriad problems of pollution including global warming.

It is not apparent at first, but vexing 'unrelated' questions such as marine oil pollution can be partly well answered by hydrogen fuel cells. The thing to note is that prevention is better than cure. For instance because they avoid so much need for petroleum in the first place, fuel cells help prevent or reduce highly polluting offshore oil exploration and drilling, transport of oil at sea with enormous operational and accidental discharges, the contaminants of oil exiting tailpipes only to precipitate back downward to the sea, and the innumerable ways that oily runoff such as from city streets washes down to the sea.

Near-term, to use methanol directly or reform natural gas are certainly fuel options. The expansive existing infrastructure for delivering gasoline even makes that dirty fuel an option, given technical feasibility of reforming gasoline to get the hydrogen (yet adding an unwanted step). But on the longer view, it is clearly best to focus on building a Hydrogen Economy.

The U.S. goal should be to create hydrogen (H2) cleanly - avoiding the pollution that comes from relying on a carbon fuel as the energy carrier. Given so few demands now for hydrogen, sparse attention has been paid to finding ways to release this most attractive of fuels from, for instance, seawater. So today about 95% of all hydrogen comes from reforming natural gas. However as we begin adopting H2 fuel cells widely, that inattention should change. And practical means of storing and moving the hydrogen safely and cheaply must soon be found.

Possibilities include solar or wind power to split water where needed, this closes energy flows and builds soft energy paths--or regenerative fuel cells that use, and make, pure water. Exciting novel means are also on the horizon to generate and store hydrogen. They include green algae that produces hydrogen photo-biologically, and carbon nanotubes that could store it safely and efficiently for use anywhere. Whatever the means, ecological sensibilities demand that we must keep our eye on the prize with fuel cells: it is this hydrogen fuel that renders them an amazing option, and in the long run, no other fuel source will do.

[pablo]

muy largo para leerlo, resumilo

[Jano]

lee lo subrayado

[pablo]

gracias
muy interesante

[Jano]

si es interesante.. antes pensaba que el hydrogeno era una alternativa muy buena para el petroleo. Si agarras las cosas que hoy necesitan petroleo y las cambias por hydrogeno tenes: mucha menos contaminacion y una energia mas accesible.

pero tambien lei que decian por ahi (creo q Hobsbawm) que el uso de una nueva fuente de energia era cualquiera porque significaba su mal uso e ineficiencia, que antes habia llevado a la fuente de energia predecesora a su final...

no se

[DAC]

Alguien hace un resumen ?

[<*~*[Vuoso]*~*>]

lo peor de eso es que los autos salen fortunas, aunque en españa ya se este usando (poco pero si)..

[P340]

el mio anda a alcohol con nafta. sale fuego del caño de escape,
y cuando aprestas el botoncito del alcohol el 28 vuela..

edit: no es alconafta es la variante ke puedo usar para no comprar nitrogeno

igual, esos autos con hidrogeno no anda nada.
aka en argentina ya hay un prototipo , si lo encuentro lo posteo

[Herr Mannelig]

Eso no se usa, porque todavía hay combustibles fósiles. Sacar hidrogeno y oxígeno puros del agua es una pelotudez, con una electrólisis chota ya está. El tema es que para eso necesitás electricidad, y ni idea cuanta electricidad se necesita para obtener determinada cantidad de hidrogeno.

De todas formas, para obtener hidrogeno para usar con los autos calculo que sería una opción posible, no ya obviamente para generar electricidad, no?

Habiendo autos que funcionan con gas natural, sólo con una modificación pedorra en un motor diseñado para andar con nafta, no veo porqué no se pueda hacer lo mismo con el hidrógeno...

Todas las cosas nuevas salen fortunas, cuando se empiezan a producir en masa, el precio baja hasta niveles normales. Se acuerdan de las grabadoras de DVD?

[<*~*[Vuoso]*~*>]

men el hidrogeno juntandose con oxigeno hace mas energia que el crudo es de 2 a 1 asi que no me digan que no andan porque es una cosa que se hace porque rinde y hace bien al medio ambiente......