Twenty Myths Challenged
Our PreambleIn his recent paper "Twenty Hydrogen Myths", Dr. Amory Lovins, CEO of the Rocky Mountain Institute addresses some of the important issues regarding the proposed future "hydrogen economy"1. He describes some of the discussion that has occurred as "conflicting, confusing and often ill-informed" and claims that some issues have been raised solely as reasons for not developing a "Hydrogen Economy".
He is right on both counts but his paper adds to the problem by:
- (a) Failing to address adequately several of the key issues that render hydrogen non-viable as a fuel on both economic and technical grounds6.
- (b) Addressing a lot of his favorite issues, many of which have little to do with the viability of hydrogen and
- (c) Providing misleading and "conflicting, confusing and often ill-informed" information on some of the issues that he does address.
- (b) Addressing a lot of his favorite issues, many of which have little to do with the viability of hydrogen and
To add to the confusion, several of the "myths" that he identifies really are myths – but most are not.
This response attempts to correct some of the impressions that have resulted from Dr. Lovins' "Myths" paper. We will depend to some extent on the useful bibliography2 provided by Dr. Lovins and his colleagues while adding some references and notes of our own.
We should note here that Dr. Lovins has a financial and emotional interest in seeing hydrogen succeed as a fuel. His Hypercar concept3 requires hydrogen fuel to meet all of its objectives. Much of the consulting activity of the Rocky Mountain Institute centers on hydrogen.
We should disclose our prejudices, too. The writer has worked with hydrogen intermittently for many years, first in the former coal-gas industry and then in the oil and chemical industries and was involved in the investigation and analysis of several hydrogen-related process developments, fires and explosions. Before that, he learned first-hand about the risks and the difficulties involved in dealing with hydrogen and hydrogen-methane mixtures as fuels by working in the U.K. gas industry just before it transitioned to natural gas. Based on this experience, we consider hydrogen to be a safe and technically viable commodity for industrial use but believe that numerous economic, technical and safety considerations make it non-viable as a replacement motor fuel for public use.
Our papers on hydrogen, including this one, have all been developed at our own expense. TMG now works for its clients on alternate-fuel topics such as coal-based synthetic fuels (including hydrogen), soy-based biodiesel and biomass-to-ethanol technology and assists its clients in making conventional energy vs. alternate energy decisions.
The Responses to the "Myths"
Lovins' "Introductory Facts"
First, let's take a look at the "Introductory Facts" set out by Prof. Lovins. Unfortunately, his "facts" get mixed in with a lot of opinions and generalities that are presented as fact. Some examples:
"....unlike electricity, hydrogen.....can be stored in large amounts". On the contrary, electricity can be stored in large amounts, for example in batteries (the largest being the battery that provides backup power for the entire city of Fairbanks, Alaska – 2,000 m2, 1,300 mt, capacity 40 Megawatts for 7 minutes) or in pumped water storage reservoirs. The largest available storage devices for hydrogen are old-fashioned ambient-pressure gasholders (which leak), pressurized tanks (too small) or metal hydride systems (inefficient; not enough capacity). In principle, underground natural gas storage wells can be used but those that are suitable are all in use, can also leak and must be carefully selected for geological suitability.
"Like electricity, hydrogen is an extremely high-quality form of energy.....". We don't know what this means. By our definition, hydrogen comes nowhere near to equaling the qualities of electricity, or even methanol, that we all find so convenient.
"However, hydrogen yields a smaller share of fossil-fuel energy because its chemical bonds are weaker than carbon's". We don't know what this means, either. Hydrocarbon reforming involves a complex combination of water-splitting and (hydro) carbon oxidation with the release of all of the hydrogen in the hydrocarbon and in the water.
"Hydrogen is thus most advantageous when lightness is worth more than compactness, as is often true for mobility fuels". This may be true in extreme cases like a hypothetical hydrogen-fueled motorized glider, but not for automobiles for which the value of weight reduction is well defined at about $10/lb. of weight saved and has generally been achieved through size reduction and intelligent design using conventional materials, rather than by use of high-cost exotics. In any case, the weight and volume of the containment vessel (e.g., filament-wound aluminum) needed for the much larger volume of hydrogen (even at high pressure) that is needed to provide an adequate range more than offsets the small difference (~80lb) between a typical tank full of gasoline and the energetically equivalent amount of hydrogen. Fuel container size is a critical issue – in the current smaller vehicles used to achieve weight reduction there is already barely enough room for an adequate gasoline tank.
PEM fuel cells are much less efficient than the ~50-70% hydrogen-to-output-electricity figure used by Lovins (as we have only recently discovered). An overall figure of ~35-50% is probably more appropriate for normal use when all accessory and parasitic losses are taken into account. At the same time, the figure that Lovins uses for gasoline engine efficiency is too low for modern gasoline IC engines combined with high-efficiency transmissions; roughly 25% is closer to the real efficiency and this figure is climbing steadily. But this does not completely negate his point that fuel cells used in light-vehicle applications should offer about 50-100% better economy (not the 2-3X claimed by Lovins) than gasoline engines, especially at low load. Diesel engines, on the other hand, are substantially more efficient than gasoline engines, approaching the lower bound of the fuel cell efficiency range (35-50%) and potentially capable of much higher efficiencies. In hybrid-electric applications, they can currently offer higher efficiency with acceptable on-road performance (currently a problem with fuel cell and hybrid vehicles). If high-speed compression-ignition engines can be developed to operate at very high compression ratios and near-instantaneous combustion (offering a close approximation to constant-volume combustion), probably on gaseous fuels (and possibly even hydrogen!), much higher efficiencies are possible.
Several manufacturers of battery-powered cars are about to announce significant technical breakthroughs, hopefully to be followed by economic gains. Lithium ion battery-powered light passenger vehicles will soon offer ranges of up to 300 miles, a vast improvement over earlier efforts such as the General Motors EV-14. Li-Ion batteries offer rapid recharge capability and long lifetimes. Increased use will undoubtedly reduce their initial cost, now prohibitively high, and operating costs should be low unless utility costs rise unexpectedly. As in the case of the power used to produce electrolytic hydrogen, power to charge batteries must be generated in coal, oil or gas-fired power stations, typically at 30-35% thermodynamic efficiency, and some power is lost during the charge cycle as heat or parasitic losses. But at least battery charging does not involve the conversion of one energy carrier into another. We will shortly be publishing a number of detailed, thorough well-to-wheel analyses of the various automotive power options, including this one.
The major problem with hydrogen fuel cell use lies not with the fuel cell per se but with the efficiency loss associated with converting one energy form (e.g., natural gas or an alternative fossil energy source) via electricity into another (hydrogen). The energy "cost" of this is often not fully accounted for in Lovins' estimates. The "well-to-wheels" efficiencies of the two systems (hybrid and fuel cell), if all factors are correctly accounted for, are not that far apart5. Lovins routinely separates, in his paper, the efficiency of use of hydrogen in fuel cells from the energy losses associated with the manufacture, transportation, distribution and delivery of hydrogen. As a substitute for conventional energy generation in a distributed power scenario, fuel cells are attractive, at least on paper and if you can afford to produce and transport the fuel for them.
We also question much of the underpinning of the "hydrogen economy", although this concern is not directed at Lovins or RMI. We believe that there is substantial doubt that carbon emissions are the cause of global warming (GW). Much of the warming effect attributed to carbon dioxide is in our view due to a natural increase in solar irradiance accompanied by a related increase in atmospheric water vapor levels. The latter is more effective as a GW forcing agent than carbon dioxide (we estimate its GWP = 1.75 compared to 1.0 for CO2) and is present in the atmosphere in far greater quantities. We therefore believe that water vapor, rather than CO2 is the dominant forcing agent in global warming (with a little help from the sun and perhaps from other greenhouse gases) and that the increase in atmospheric CO2 levels is a secondary effect. Since one of the major reasons for moving to hydrogen fuel is the reduction of carbon emissions, this observation brings into question a large part of the entire underlying rationale for hydrogen.
Anyone who has actually worked with hydrogen on a commercial scale would not claim, as Lovins does, that "The....technical obstacles to a hydrogen economy – storage, safety and the cost of hydrogen and its distribution infrastructure – have already been sufficiently resolved to support rapid deployment....". To do so is irresponsible. More specifically:
Storage is far from resolved – in fact it is one of the biggest barriers to successful implementation of hydrogen-powered transportation. Current storage systems have numerous shortcomings – among them, excessive weight and size for a given task, inadequate capacity or availability, and a lack of safety in collisions and fires.
Safety has yet to be addressed, at least in terms of codes and standards, as evidenced by the many initial meetings on the topic that are scheduled around the country for later this year (2003). In the transportation industry, safety and the related topic of product liability is of enormous importance. The level of reliability required to make a complex hydrogen fuel cell system and its associated vehicle deliver 100% safety will be high indeed. The same will apply to hydrogen pipelines, distribution and delivery systems and especially the small-scale reformer-based gas-station hydrogen generating plants that Lovins believes are feasible and desirable (they are neither, but more of that later).
The cost of hydrogen in the real world remains to be determined but, notwithstanding the optimistic estimates presented by Lovins, DOE and the would-be hydrogen manufacturers for this market, we have shown that it will be more expensive on a per-mile basis in a given vehicle configuration and weight than is gasoline6.
Finally, distribution infrastructure issues are anything but resolved. We have in place in the U.S. a few hundred miles of pipeline carrying industrial-grade hydrogen operating at relatively low pressure (~1,500 psi or ~100 bar) and, separate from that, a few hydrogen refueling stations are planned, mostly for demonstrations to politicians. So far, the most prevalent attitude regarding hydrogen availability has been "the government will take care of that". Not so!
Prof. Lovins is incorrect in implying that no major technological breakthroughs are needed in fuel cells, other than those aimed at cost reduction. Major work is still required on reliability and durability (current warranties must be lengthened by up to an order of magnitude to be acceptable in a marketplace used to 50-100,000 mile vehicle warranties). Membrane life is a major unknown. Avoidance of membrane fouling requires ultra-clean air which, in turn, currently requires ultra-filtration and consequent parasitic losses. Catalyst loadings must be reduced and perhaps precious metals in the catalysts replaced with less costly alternatives while catalyst life is increased. If hydrogen is to succeed both technically and economically, significant cost-reducing breakthroughs are required in manufacturing (especially in the distributed, rather than centralized, manufacturing model preferred by Lovins), equipment for compression to pressures above 5 ksi, pumping, pipeline hardware, local distribution systems, delivery systems (for liquid and gaseous hydrogen) and numerous other areas. A massive effort will be required to reduce the energy consumed in manufacturing and transporting hydrogen. Unfortunately, the gas starts off with the disadvantage of having to be made from a primary energy source that could be used more efficiently if conversion could be avoided.
In the case of autos, Dr. Lovins must know of the many failed efforts that have been made to develop a cost-competitive ultralight, mass-manufacturable auto body (the writer managed such a program involving stampable composites in 1976-9). Notwithstanding the undoubtedly good design work at Ultracar, translating such designs into real manufacturable products that meet a wide range of engineering, cost and safety criteria and also attract the necessary large market has proven extremely difficult.
With respect to the future size of the required hydrogen industry, the current North American hydrogen industry produces about 10 million metric tons/year of hydrogen (not 15 million as Lovins estimates). To replace all of the current gasoline consumption (about 9 million barrels per day) would require about 130 million metric tons of hydrogen annually, a figure that depends on assumptions about use efficiency – a very substantial increase and not just "several fold bigger", especially in view of the completely different manufacturing technologies that are likely to be needed.
Comments on Specific "Myths"
The numbering and wording follows that of Lovins.
- A whole hydrogen industry would need to be developed from scratch.
If we cut through Lovins' obfuscating detail, he claims, based on DOE data, that the present world-wide hydrogen industry produces about 50 million metric tons, or about 500 billion cubic meters of hydrogen annually. A little under 50% of this comes from natural gas, 30% from oil and 18% from coal (but please note our earlier comments – even in the case of natural gas, at least 50% of the hydrogen is derived from water). All of these sources produce hydrogen by steam-hydrocarbon reforming, an alternative water-splitting process which in effect uses the carbon (instead of electricity) to split the water to produce the hydrogen. In this case the oxygen forms carbon oxides instead of being released as oxygen. Thus, water, rather the hydrocarbon, can be the most important source of the hydrogen. The lower the hydrogen content of the hydrocarbon (the most extreme case being coal), the more the water needed to produce the hydrogen (see also "myth" #14). For 4 mols of hydrogen product:
- For methane, including the shift reaction: CH4 + 2H2O ? CO2 + 4H2
- For carbon, representing coal: 2C + 4H2O ? 2CO2 + 4H2
Note that carbon/coal produces about twice the amount of CO2, which must then be sequestered if CO2 atmospheric emissions are a concern (but see our earlier comments about global warming). At present, only about 2% of hydrogen production comes from the electrolysis of water. Current U.S production is about 9 million metric tons/year with Canada accounting for another 1 million tons. Lovins' estimate of ~15 million tons is high, apparently because of double counting.
Lovins is correct in saying that "the industrial infrastructure for hydrogen production already exists". However, there are only some 460 miles of pipeline in the U.S., all fully dedicated to industrial users of hydrogen in Texas and Louisiana. A comprehensive infrastructure associated with centralized hydrogen production would require many thousand miles of new pipeline (natural gas pipelines are fully committed and are likely to remain that way; in any case, none were designed for hydrogen service – for a further discussion, see "myth" #5).
Professor Lovins does not like overhead electrical transmission lines but, notwithstanding the recent blackout in Midwestern and Northeastern states, they have served us very well and will continue to do so. As he rightly points out, these lines experience transmission energy losses (these can be as much as 5% and are a function of line length and construction as well as the transmission voltage), but he has his numbers wrong in the comparison with hydrogen. There is no real-world experience with pumping high-pressure hydrogen (=5,000 psi/350 bar) through long-distance pipelines but Eliasson and Bossel (see Lovins, Ref. #5) have shown convincingly that the energy losses will be substantial. Moving hydrogen at lower pressures requires a very large pipeline to move very large volumes because the energy content of hydrogen gas (or liquid) per unit volume is so low (as Lovins points out, the only time that the very low density of hydrogen may be an advantage is in space travel, and even then, as we know from experience with the space shuttle, the size of the liquid hydrogen tank presents significant design challenges).
Lovins is probably correct in saying that distributed, rather than centralized production and (of course) use of hydrogen will have to characterize any future "hydrogen economy", but this is precisely the problem – small scale production means that economies of scale are lost (however well the "reformers and electrolyzers work at small scale") and that the probabilities, and associated dangers, of equipment failure are greatly increased. Furthermore, the energy source has to be connected to the distributed reformers or electrolyzers, although this should present no more of a challenge than distributing and delivering gasoline does today. A centralized or regionally distributed system (see the comments on Myth #9) offers much greater safety. A problem with any system involving large-scale hydrogen production, whether national or regional is the lack of really large-scale storage. Suitable underground storage such as proven gas-tight former natural gas wells or even salt caverns is not usually available where it is needed.
Off-peak power may be less costly, but is likely to become much more costly as the U.S. and Canada invest in a much-needed renewal of their power generation and distribution systems. Electrical power has or will become far too costly for hydrogen production.
- Hydrogen is too dangerous, explosive or "volatile" for common use as a fuel.
The hydrogen manufacturing industry may indeed have an "enviable safety record". This writer has no statistics but recalls a few alarming incidents. Large-scale reformers are usually controlled remotely and automatically so that employee exposure is minimal. The hydrogen user industry (oil refining, ammonia production, etc.) is more prone to accidents, but many minor hydrogen-related incidents (usually compressor fires or explosions) go unreported.
Hydrogen is not inherently safe because it "rapidly disperses up and away from its source", particularly if this happens in a closed or poorly ventilated building. It easily leaks from equipment using it, especially at elevated pressure, but may not ignite at the point of egress. Any equipment using hydrogen must be equipped with hydrogen and fire detection sensors strategically located above the equipment, as must the building in which it is located.
As anyone who has been involved in large-scale hydrogen fires or has used an oxy-hydrogen blowtorch will testify, the flame is intensely hot on contact (although, as Lovins says, it is not intensely radiant) and causes a lot of damage very quickly. Notwithstanding all of the theory about lower explosive limits, in practice hydrogen both ignites and explodes easily. Hydrogen explosions, especially if the gas is at high pressure, are massively powerful (although in practice major hydrogen explosions often involve other energy sources such as gaseous hydrocarbons that are mixed with the hydrogen). The subsequent large-scale fires are often intense and very difficult to fight because the flame cannot easily be seen except in cases where hydrocarbon is present.
We agree that the Hindenburg story is irrelevant. Both airships and hydrogen technologies have made considerable progress since 1937.
As NBC Television learned the hard way, staged demonstrations of vehicle fires seldom relate to real-world experience. No one experiences much heating from an oxy-hydrogen blowtorch flame, even a big one, but hydrogen explosions at even 3,000 psi (200 bar) have been lethal and have done immense damage (e.g., that at the Esso (now Exxon) refinery in Linden, NJ in 1970).
- Making hydrogen uses more energy than it yields, so it is prohibitively inefficient.
This entire discussion is an excellent example of the smoke-and-mirrors (or perhaps apples-and-oranges) method of comparing energy sources. We will examine the claims point-by-point:
Any conversion of energy from one form to another is, indeed, costly although it is not true that such conversions "always consume more useful energy than they yield". In addition, most of our current energy resources require no conversion – just a little chemical modification and fractionation for oil and usually only moisture and sulfur removal for natural gas. This means modest well-to-tank energy consumption (10-30% of that in the original source) as Lovins correctly points out, but no conversion energy costs of the kind applicable to hydrogen.
In the case of manufacturing hydrogen by electrolysis, for example, the equivalent of the "well-to-tank" investments of energy must be made just to get the fuel (coal, oil or natural gas) to the power station. Then the power must be generated, typically at a low efficiency of ~30% or less (more if in a combined-cycle facility), and only then do we have electrical energy available for conversion into hydrogen. So far, we have an overall efficiency of about 22.5%. Now we convert AC power to DC (5-10% loss), and electrolyze water to produce hydrogen (electrolyzer losses are more like 35% in commercial operation but are improving). So far, our overall conversion efficiency is just under 14% based on the energy in the original resource.
Having made the hydrogen at ambient pressure or a little above (and we will generously assume that this happens at the point of use, thus avoiding transportation costs), we have to compress it for distribution (if needed) and delivery, a process that can easily convert the small overall positive amount of net energy available (14% of that in the energy source) into a net loss of energy. These conversion losses and costs are not tolerable. It makes no sense, in a world that will soon be resource-limited, to invest massive amounts of additional energy just to achieve a fuel that offers somewhat greater end-use efficiency.
The energy balance is a little better for the conversion of natural gas into hydrogen because the really nonsensical double conversion step – fossil fuel into electrical energy and electrical energy into hydrogen – can be avoided. Thus we have only to be concerned about energy source production efficiency (taken above at 75%, probably a little better for low-sulfur natural gas) and the reformer thermodynamic efficiency (also about 75%, lower for small units but expected to improve) for an overall efficiency for the well ? hydrogen step of ~55% (not 70% as Lovins assumes). In this case, hydrogen makes greater sense although we are much less certain about the efficiencies (and certainly the safety) of future small point-of-use reformers. We expect them to be significantly lower – perhaps 55-60% for an overall figure of 40-45%. At this point, we still have to compress the hydrogen (15-20% of total energy), so the net energy available, although positive, is not very large – and we lose all of that in fuel cell inefficiencies.
The most critical issue facing the use of natural gas reforming to make large quantities of hydrogen, at least in the U.S., is that it represents an unwise use of a rapidly-diminishing resource (see response # 12-4, below).
There have been many "well-to-wheels" analyses of the efficiency of petroleum fuel use7. When being compared with hydrogen, pessimistic assumptions are usually made about the efficiency of modern internal combustion engines. Analyses for hydrogen that are used in comparison typically ignore some of the steps involved, or make optimistic assumptions about their efficiencies, so the differences are always exaggerated. The Toyota analysis referred to by Lovins was chosen to make their Prius gasoline-electric hybrid vehicle look good relative to Toyota's conventional vehicles.
In-vehicle fuel cell efficiencies, when they are stated at all, are generally overstated. If all accessory demands such as air compression are taken into account they typically range from 30-40% at high load to 40-50% or so at low load for an average of about 35-40%, depending on usage. The drive train (more accurately a drive system) loses a small amount of additional energy, leading to an overall tank-to-wheels average efficiency of about 35%. Electrically-driven air conditioning, steering and other loads will slightly reduce overall efficiency. Thus, using the well-to-tank estimate for reformer hydrogen (55%, which may be optimistic if small point-of-use reformers are used), we obtain a well-to-wheels estimate of 19%, or about the same low figure as Lovins quotes for the gasoline engine (gasoline-electric hybrids will soon achieve better than 30%). Diesel-engine hybrids using ultra-low sulfur fuels and direct injection provide even better overall efficiencies (up to 40%) since no energy conversion is required and this advanced diesel engine is much more efficient than, and offers almost the same performance as, the gasoline engine of equivalent performance. As we have made clear elsewhere, we see the diesel-electric hybrid as a far better choice for future transportation needs (once the U.S. has low sulfur fuel available in about 2006-2008) than either gasoline-electric hybrids or hydrogen fuel cells.
We have no quarrel with Lovins' conclusions regarding fuel cells in power generation, although his efficiency figures are, again, the most optimistic that we have seen. Fuel cells are already showing their worth in peak-shaving (although more often with non-hydrogen fuels and alternate, e.g., solid oxide electrolyte, cell designs).
Regarding underground storage of hydrogen, we note here only that old gas fields that are gas-tight for natural gas are often (although not always) unsuitable for hydrogen storage – they may leak too much. The result is dependent on the local geology.
To Be Continued...
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