- The Promise of Hydrogen (1.1)
- Five Types of Fuel Cells (1.3)
The Promise of Hydrogen (*Written in 2000)
Dr. Robert J. Wilder
President, The Hydrogen Fuel Cell Institute
* Note: While the following was written back in 2000, updated only lightly since, and has been overtaken by more recent news, it may be of some background interest.
There’s much divergence of ways that one might possibly envision a hydrogen (H2) fuel cell future. Seen most optimistically, H2 could in theory be seen as a possible future energy carrier: in that very hopeful dream, cost-effective fuel cells might draw near even to high-performance batteries potentially helping to transform energy systems.
Consider on the other hand an intellectually robust, critical and quite contrary view. It holds that FCs (fuel cells) are now and will long be uncompetitive such as in cars and small devices – especially compared to advanced batteries which can already bring electric vehicles (EVs) swiftly to the fore. This proclaims that it is uninformed to champion use of FCs over pure batteries for cars; that the small numbers of H2 ‘fool cell’ cars that are being released despite very few H2 filling stations may be in part to forestall the advance of better, battery electric vehicles. In short this harsh contrary view calls the optimistic H2 FCs idea ‘baloney’ (to put it nicely).
There’s without doubt much to be said for the latter view. Advances in battery chemistries have made them the welcome, efficient solution for many applications – far superior to competing H2 FCs in most all but niche uses.
Plus this latter view notes hydrogen as an energy carrier is almost non-existent today. Look seriously at steep costs & difficulties making, distributing and using H2 to meet demands, think of hydrogen’s lack of power density as a gas, prohibitive costs of fuel cells, fact renewable sources like wind or solar sparsely make any H2 now, and it’s easy to conclude visions of hydrogen as a key energy carrier are an idealistic dream unlikely this century. One may say absent several technology breakthroughs coming nearly all at once, the ‘Hydrogen Economy’ ideal is only a mirage.
There’s arguably a third view however between the two above (though leaning towards the latter). It starts by accepting hugely vexing technical problems must first be overcome decades ahead for H2 & FCs. These will be immense — insurmountable perhaps. Undoubtedly batteries are a winning solution near-to-mid-term (other than niche applications like say, FCs in fork lifts parked nightly at one location). Yet, never say never. Engineering efforts in clean H2 FCs — even if never successful, arguably are worth an effort, and might improbably bear fruit. One shouldn’t dismiss inventive genius of humankind, even for H2 FCs. That’s a position suggested here.
Looking decades ahead - if somehow abundant inexpensive firm ‘power’ could be had from renewable-H2, and also somehow be distributed and stored for fuel cells in cost effective ways, then that could potentially be a real advance outside of batteries.
What is clear, is that 1) ‘hydrogen fuel cells’ mustn’t be allowed to hinder the advance of Electric Vehicles using fast-improving battery chemistries; and 2) this Battery Storage will soon be Opening Underappreciated, Immense Opportunities.
Hence energy & power dense batteries can be potent and capable technologies for the next decade and beyond. These can & should open up whole vistas for innovations in building electric cars, bikes, trucks, boats, large ships, even jets. Developments in say Lithium Cobalt Oxide (LCO) batteries, safer Lithium Iron Phosphate (LFP), Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Nickel Cobalt Aluminum Oxide at the cathode (NCA) – or Titanate at the anode are important advances.
So this 3rd view strongly embraces pure battery electric cars (We Love Batteries!) with a nod to a possibility of clean H2 & inexpensive fuel cells however unlikely. The following brief text looks at that nod, and to the in-theory benefits FCs may conceivably bring – in future. Note too it comes from a confirmed believer in, and lover of solar powered battery electric cars as THE smartest & best answer ahead.
So let’s first posit that many technologies evolve in the long run, and get cheaper – and unlike many unproven technologies, a leap of faith isn’t needed to see H2 & FCs ‘working’ in the first place in unique energy storage systems where cost is no object. Even vociferous critics of a Hydrogen concept acknowledge yes, the H2 fuel cells do ‘work’ in ways fairly-well understood albeit often with relatively poor efficiency. (In fact, a working small H2 FC unit sits next to me now. Instead it is high costs, many problems making, storing, using H2, and many inefficiencies relative to BEVs that are key problems noted below). It’s because they do work and in ways intriguingly different from fossil-fuels + engines, that their future is a bit captivating.
H2 & FCs are often thought-of as most useful put together. Producing hydrogen requires first taking energy from elsewhere to release this most-common element H2 from for instance, water. The function of hydrogen is hence to store desired ‘power’ in form of an energy carrier; the fuel cell can then convert H2 to electric power at will wherever it’s needed — and will do so as long as H2 is supplied to the FC.
Put aside for a moment exorbitant costs today of many H2 FC systems, and the fact H2 itself requires much energy in order to be produced/cracked from say H2O and that it should be made in sustainable ways from ‘green’ renewable sources like wind or solar. As a way to store and later use power – using hydrogen combined with fuel cells is notable. Yet fuel cells are hardly new. Invented in 1839, they were long seen as a novelty for working electrochemically, rather than by combustion.
Ever since FCs have found only sporadic uses, in cases where high cost is not an object, including in spacecraft – or where high-quality firm power is necessary – or to make portable power longer than past conventional batteries. What helped drive the several past crazy bouts of investor hype & mania, was a leap of faith that FCs might be made at costs so attractive, they potentially could be competitive. (That clearly has NOT panned out – meanwhile batteries surged forward in their abilities).
Are great price reductions possible so FCs might one day be far less than a tenth the cost of early prototypes? And can viable green H2 distribution built as well? If so, it is still a ways off. The fuel cell bubble already inflated and burst. Batteries meanwhile did not stand still. Whether hope for disruptive advances in H2 FC leads again to irrational exuberance some time soon is unknown. But it is likely to be short-lived; in the meantime we can sketch what future H2 FCs could in theory, bring.
First observe that future FCs might be brought to market running on more convenient fuels than (gaseous) hydrogen. Candidates may include liquid proprietary fuels, perhaps involving (not green) methanol, or butane or for large systems gaseous fuels like propane or natural gas. Small FCs in personal electronics including cell phones might conceivably use liquids with electrolyte. Larger FCs in stationary settings could provide backup like for hospitals or computer centers by utilizing natural gas lines. To give some hard data for costs (1990s) one manufacturer claimed a megawatt class field test at $8,000 per kilowatt in the late 1990s – a real reduction from the $20,000 per kilowatt in prior trials, but pricey at near 20 cents per kilowatt/hour (kWh).
While there may be hope (written in the late 1990s) to one day reach installed costs under $2,000 per kilowatt, or <10 cents/kWh along with long life and green fuel, that’s a strikingly lofty goal. And the cost bar is high, with prices around the U.S. ranging in 1998 from 10-12 cents or higher, to cheapest at about 4 cents per kWh.
Ways it may be sustainably achieved far ahead are impossible to say today and importantly still science-fiction: perhaps some combination of proprietary hydrogen-rich liquid fuels, inexpensive electrolyte, nanotechnology, photobiological means for H2 production and storage, and other unimaginable advances, but we’ll ponder that (unlikely) hypothesis.
Possibilities? Still Science-Fiction Today
Look far ahead and there might be conceivable paths for expensive FCs. (As there might be for say, vanadium flow batteries but that is another story). Think of where advanced batteries can’t meet demands of personal electronics, or continuous FC power can be advantageous… imagine then, if a first-mover FC is adopted and it penetrates some ‘cost is no object’ market like military or specialized applications — later it grows practical as many technical ‘glitches’ are ironed out… next, imagine the state of the art decades later -- after billions more research, improvements, and economies of scale that go from R&D to commercial manufacturing. That far off end-point helps explain some past exuberance, despite justifiably strong skepticism.
Put aside for a moment the ecological question of whether a green way to make H2 can be found (so not from Natural Gas) — which could be major obstacle here — the operational characteristics at least merit thought. A ‘common’ fuel cell can utilize hydrogen, plus oxygen easily taken from air, to make desired electricity; there also is some water and heat produced but nothing else. This is elegantly simple. In a typical cell (of late 1990s) a catalyst splits hydrogen into two constituent parts: protons or hydrogen ions - and electrons: these protons pass through a membrane to the other side and combine with oxygen to make water. Meanwhile this membrane forces the electrons in an external circuit to the other side: that’s electric power.
Five main FCs ‘currently’ lend themselves to many applications – this commentary is written in 2000 so many advances are certain in years & decades ahead. The present 5 are distinguished by electrolyte which determines operating temperatures of the fuel cell: often the hotter ones are more efficient and fuel-flexible, but high temperatures introduce thorny issues They are the 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 the solid oxide fuel cell (SOFC) both at 800 degrees C.
Other types may be refined like the direct methanol FC (although methanol itself is toxic), and regenerative FCs, if interest grows. Think of possible benefits that might come from beginning to substitute distributed fuel cell power in place of centralized utility power plants. (It must be inserted here that many benefits equally flow from batteries!). Note that buildings account today for some ~two-thirds of U.S. electricity consumption. To conceivably move towards “distributed generation” (DG) should make it possible to better current efficiencies and by quite a lot. Also the high-quality waste heat byproduct is good for building tasks of heating and cooling.
Compared to modern coal-fired power plants, where much energy (including heat) is still wasted at the source, and fails to reach customers, these fuel cells if ever actually clean and economical could start with an advantage. Fuel cells might in theory compound efficiencies for they are scalable from micro through massive stationary applications, especially suitable to decentralized power.
This idea of localized, distributed power means it can be made by appropriate-sized sources located near to need. Place an early round stationary fuel cell where easiest to initially compete on favorable economic terms — if the existing grid is overloaded, expansion expensive, in rural areas with no power grid, in a closed microgrid that’s terrorism-proof, or if high-quality power is necessary — and exceedingly high costs could be a bit less of an issue. That said there’s no doubt FCs are (in 2000) wildly expensive. And as emphasized batteries are the better solution for a foreseeable future – including flow batteries that work as between a battery and fuel cell.
Generating power closer to where needed may help eliminate huge costs associated with trenching, of putting in miles of expensive wires on the grid. That constraint has been an issue for example in wind power; hence in distant future Storage by making H2 at wind farms and transporting it might make some sense. It would be helpful to address transmission losses and costs of power delivery, which in 1996 averaged 2.4 cents per kilowatt-hour. And they can be flexible – though very dirty; the molten carbonate FC can use hydrocarbons like natural gas, methanol, diesel, even coal gas — although as stated ‘green hydrogen’ is ecologically the only way forward.
So why aren't fuel cells powering homes, offices, phones or cars around the world? Because simply their costs are wildly high – hence batteries are a clear choice as they work well and are getting ever better. And batteries today are a sound choice no matter what fuel is used … and of course there’s no infrastructure yet to transmit H2. Moreover FCs may still require gobs of pricey catalysts like platinum and degrade too quickly. Clearly, while well-proven technology, H2 FCs do not come out on top.
Real cost reductions in some FCs could occur when used say in forklifts or portable power with unprecedented mass manufacturing. Engineering refinements can work down costs, and economies of scale may be realized. But it’s a very tall order. And only FCs run on green fuel make sense — a tough challenge. So moving towards renewable low-cost hydrogen in the first place is a distant but invigorating prospect.
There are some cases where small numbers of FCs are being used in EVs, for vehicle propulsion (along with a debut of small numbers of limited hydrogen stations). This shows advances since the 1990s in lowering FC costs, since they were much too dear. ‘Eye-watering’ prices have been brought down quite far – some progress is happening. But note Battery EVs are progressing faster still, do not suffer from lack of hydrogen transport – and more basic is the fact that going from electricity, to storing H2, and back to electricity is inefficient. In sum battery EVs will come out ahead.
Yes, to depart from the conventional wisdom, sometimes can be well rewarded. Think of a hybrid gasoline-electric car like the Toyota Prius: before that car was introduced, many analysts claimed (wrongly) the hybrid idea wouldn’t work - let alone ever be more efficient than gasoline-only vehicles. Yet, look at how hybrids have advanced in a few years and grabbed market-share. H2 FCs for car propulsion is a daunting idea technically, and it does garner a lot of imaginative attention.
To augment a case for BEVs, consider that FC cars (like BEVs) will one day require 60+ kW generating capacity. Because cars are habitually parked at home, or work, they could become mobile power plants where you might plug in your car — not to charge its battery — but to help power your home or office (Vehicle to Grid, V2G). And net metering will mean you can sell excess power. FC cars (like BEVs) accelerate faster, go farther, last longer with fewer moving parts, and are safer, than present oil-fired cars. Of course all this can be said for BEVs and V2G once battery life goes over say 5,000+ cycles; increasing cycles in newer Li batteries can make this feasible.
Given present very low costs of rival highly-refined Internal Combustion Engines (ICE) some future may be in FCs as Auxiliary Power Units (APUs) powering robust electrical systems. APUs may one-day make on-board power say for big rig tractor-trailers, or extend range in EVs. Again this is all contingent upon vast strides being made in reducing FC costs; so much that they begin to near speedier advances in batteries including somewhat similar flow batteries, but the concept is valid.
Over decades it *may be* possible to greatly reduce FC costs including 'balance of plant' supporting fuel cell stack itself. And it’s conceivable some fuel cells might be solid state: like a revolution from tubes to transistors, this could improve reliability and add in elegance. If there ever is clean H2 for inexpensive FCs - joining with powerful batteries and renewables - then oil as a source of power could in theory (like steam power of a century ago) be made largely a thing of the past.
Vexing ecological issues of climate change, greenhouse gases, ocean acidification, or loss of marine biodiversity may be addressed by fuel cells (only) if the H2 is clean. The key is prevention is better than cure. For instance avoiding oil in a first place helps prevent CO2 and movement of oil at sea with operational and accidental discharges; it avoids too contaminants from tailpipes ending up in the sea.
Given sparse industrial demand today for hydrogen that’s used such as in cooling large motors - compared to what could be using H2 as an energy carrier, little attention has been paid to finding ways to make this ‘fuel’ from, for instance, water. Over 90% of H2 comes still from steam reforming natural gas. However, should we begin adopting fuel cells, then past inattention might change. New means for storing & moving H2 safely and cheaply might one day be found, including by carbon nanotubes.
Possibilities include arrays of inexpensive solar PV or wind farms for green terawatts. (To be sure such huge renewable farms directly charging advanced Li batteries would be much better in the first place! But this Commentary gives a brief nod to H2 FCs). Other novel ideas over the horizon might include algae to make H2 photo-biologically, carbon nanotubes to store it safely and efficiently for use anywhere, or massive ramping-up of renewable energy overall, with hydrogen used for firm power.
Of course to re-emphasize batteries are well ahead of the game here – rightfully so; batteries are what should power cars in coming decades as the efficient solution. Yet whatever the means, sensibilities demand we keep an eye on even distant ideas: in that case it’s green hydrogen that may render fuel cells an energy option and only a sustainable, clean energy carrier for FCs would do.
In sum if severe problems in making green H2, storage & distribution, and high FC costs are ever solved then its possible hydrogen might make sense and no longer be perpetually relegated to a "fuel of the future – and always will be." But that's still many, many years away and much will yet depend upon technological improvements to make systems greener, simpler, accessible and easy to use. Hardest of all surely will be catching up to advanced batteries, which are viable today.
We welcome comments on the above Commentary 1.1.
Dr. Rob Wilder
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