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forum hydrogenium 2003
|"The energy system compares nicely with a bicycle: When not pushed forward, it tumbles!"|
Hydrogen secondary energy is on the verge, after or in parallel to coal, oil, natural gas, nuclear fission, energy efficiency gains, and all sorts of renewable energies, of becoming the seventh energy in the heptagonal energy mix mankind utilizes, before - perhaps - nuclear fusion will become the eighth. Never was the mix in a steady state, never did a new energy addition fully replace its predecessors, the ever increasing demand needed them all; energy multiplicity grows.
What we face is an intensified multidisciplinary dispute: more arguments than before, with more areas of concern, are being exchanged on the way to the environmentally benign and climate change risk abating, hydrogen-supported, supply and safety secured energy mix of the future.
Three parameters are in the foreground: (1) The demographics of a growing world population are the overruling factor; each newly borne human adds to the world capacity requirement in North America some 10 kW/cap, in Europe 4 - 6, and in the poorest nations 0.1 - 0.3 kW/cap, in average 2 kW/cap! (2) the growing influence of efficient technologies reduces the influence of traditional primary energy raw materials; ongoing technification of the energy system, thus, turns energy policy into technology policy. Efficient energy technology becomes as good as energy. Even energy poor, but technology rich industrial nations get the chance to become - almost - energy self sufficient; hydrogen-technology-supported energy supply security is not an illusion, particularly relevant in times of increasing oligopolization of primary energy sources. And (3), the ecological factor, almost nonexistent in the historical energy discussion, has become, together with the economic and social criteria and the criterion of reversibility, an equally entitled criterion of energy sustainability.
"forum hydrogenium 2003" offers an introduction into the HYFORUM 2003 dispute held in Beijing, China, the rapidly newly industrializing country with the world's largest population. For sure, in the environmentally and climatically clean hydrogen energy economy there is a powerful alternative to the unreflected repetition of the historical development of the industrial countries. No earlier investment has to be recapitalized from prior to the introduction of hydrogen and the associated technologies - an exemplary leapfrogging on the energy HYway into the 21st century.
Up to now, there is only one industrial branch using hydrogen as an energy carrier, the space industry, which because of its comparatively rather small size is not really exemplary for the upcoming world hydrogen energy economy. The other branches, like the fat industry, the electronics industry, methanol synthesis, glass manufacturing or generator cooling, and, not least, the fertilizer industry, use hydrogen non-energetically or indirectly energetically. Lessons learned and experience gained in each branch are common knowledge, though.
Of the seven energies in use, coal, oil, gas, nuclear fission, energy efficiency gains, renewable energies, and hydrogen energy, all but nuclear fission are more or less dependent on hydrogen. The atomic hydrogen/carbon ratios of the hydrocarbons coal, oil, and natural gas, and hydrogen are H/C =< 1 : 2 : 4 : ∞ highly efficient fuel cells run on hydrogen; renewable energies rely on hydrogen for storage and transport.
The global energy trade system in place is extremely valuable, more or less reliable and experienced; it is day-to-day practice. However, it carries energy over global distances and, in parallel, the pollutants bound to it. It is up to the energy buyer to remove the pollutants in parallel to the energy usage. – Hydrogenation of the system enables the energy seller to remove the pollutants already at the mine mouth or the wellhead and to sell clean, value added hydrogen on the market; there will be no need any more to store and globally transport polluting and eventually hazardous hydrocarbons.
Essentially, the world's transportation system runs on hydrocarbons: gasoline, diesel, heavy oil or kerosene. Although environmentally clean conversion is feasible eventually, the emission of greenhouse gases will never be zero, because even the best conversion efficiencies remain well under 100 %. And capture and sequestration of co-produced carbonaceous greenhouse gases is nowhere operational. – Hydrogen or hydrogen rich compounds on board busses, trucks, limousines, ships, locomotives, or airplanes is a powerful climate change risk preventive measure; with no carbon on board, no carbonaceous greenhouse gases are in the exhaust.
The trend in the world energy mix from coal to oil and further to natural gas is obvious: coal usage decreases relatively, oil usage stagnates, and natural gas usage is increasing. Hydrogen as a gaseous energy carrier fully supports this trend, trivial to say. Not so trivial is that hydrogen enables coal and oil to take part in this trend, as long as hydrogen is manufactured from these solids or liquids, accompanied by carbon separation and sequestration in order to prevent greenhouse gas emissions. Hydrogen is utilized preferably as a gas, regardless of the solid, liquid or gaseous state of aggregation of the primary energy raw material it is made from.
On principle, electrolytic hydrogen and hydrogen from fossil fuels or biomass comes as gaseous hydrogen (GH2). It may be used directly or be enpiped into the natural gas pipeline grid up to a percentage of 10 to 15% without major technical changes, thus taking advantage of the immense investment in place. Further, it may be liquefied (LH2) with an energy investment of one kilowatt-hour for three kilowatt-hours to higher energy densities, stored in cryostores and serve in lieu of liquid hydrocarbons whenever and wherever higher energy densities are decisive, e.g., in the transportation sector.
Humans lived in energy centuries: never has the energy system of mankind consisted only of one energy, never did a new energy fully replace its predecessors, the ever increasing energy demand needed them all:
It so happened that certain indigenous energies in a country ceased to be utilized as a result of the introduction of the global energy trade, particularly with the advent of oil, natural gas, and uranium in the late 19th and the 20th centuries. Besides noncommercial energies, only hydropower survived as the representative of the renewable energy wealth of up to eight dissimilar renewable constituents (solar, wind, hydro, biomass, ambient heat, geothermal, tidal, oceanic enthalpy differences). With the triumph of mineral oil and natural gas, coal withdrew from the residential heat and transportation markets. – Now, with the advent of hydrogen storage and transport, unrestricted utilization of any renewable energy becomes possible whenever and wherever, and coal enjoys a renaissance via its gasification to hydrogen.
Countries importing large amounts of energy are industrialized countries with no, or small, or decreasing indigenous resources. A steady increase in import dependency accompanied by an increasing burdening of the national trade balance can be observed, which is not politically stabilizing. Hydrogen-supported use of indigenous sources and sources which so far have not contributed much at all, as for instance the large world potentials of biomass, puts the world market on a broader basis and, consequently, increases energy supply security. Thus, (quasi-) energy ubiquity politically stabilizes the world energy trade system.
It is observed that the world's major oil and gas suppliers concentrate in the "strategic energy ellipse" reaching from the Arabian Gulf via Iraq, Iran, and the central Asian states to as far as Siberia. From an energy security standpoint, this is politically not a comfortable situation for the world, particularly for the energy importing world. Fewer suppliers have to serve more customers with their ever higher demand. Hydrogen contributes to a renaissance of relatively neglected sources like coal via its hydrogenation, adds more sources so far not a part of the world energy system, like biomass and other renewables, and, thus, forms a powerful counterpoise to the ever stricter oligopolized energy sellers' market.
The engineer knows that, on principle, there is no absolute safety, both in general and specifically as applied to energy. Each energy has its specific safety risks; hydrogen is no different. There are positive and negative elements: hydrogen is highly affinitive to oxygen; a hydrogen/oxygen (air) mixture has a very small ignition energy and a wide ignition range. However, since hydrogen is the smallest element in the Periodic Table of Elements, its diffusivity in air is high; spilled-off hydrogen from leakages or reactants of a hydrogen reaction flow quickly upwards. Accident times are short. However, nothing about energy should be taken lightly, and that applies to hydrogen, too. Codes and standards have to define safe handling procedures, and education programs have to secure awareness, repeatedly.
In comparison to fossil fuels or nuclear fission, two overruling motives make hydrogen a safe energy. Since carbon is absent, hydrogen cannot contribute to the greenhouse effect, and humans cannot be suffocated or intoxicated from reaction fumes; and since radioactivity and radiotoxicities are nonexistent, a hydrogen energy system cannot burden humankind with potential nuclear diseases of unknown character and duration. Incidents like the burning of the hydrogen-filled Hindenburg zeppelin in the 1930s or the destruction of the Challenger shuttle riding on its LH2 central tank in the 1980s were not causally initiated by hydrogen. In both cases the ignition energy came from the outside: the zeppelin's canvas cover with a highly inflammable weathering coating was ignited by an elms fire around the pilot's aluminium window frames as a result of an extremely high airborne static electricity level; and the Challenger LH2 centre tank's polyurethane insulation layer was melted by an extremely hot exhaust gas flow venting from an improper sealed solid booster mounted aside of the tank. – Further, the hydrogen energy economy has absolutely nothing to do with the hydrogen nuclear bomb.
For industry complexes, countermeasures against international vandalism or terrorism have become no longer negligible design parameters. Installations of extremely high energy concentration grades such as nuclear power parks or refineries are much more vulnerable and alert potential vandals more than the ones with lesser grades of concentration. The former are smaller in number but much bigger in size, the latter are numerous but comparatively very small.
Millions of decentralized hydrogen energy conversion devices of the kilowatt to megawatt classes such as fuel cells in stationary application are not the preferred target of terrorists' interest. And if ever, for an absolutely secured energy supply the failure of one conversion device out of millions in a virtual power station is irrelevant, whilst the failure of a multi-gigawatt installation is not.
On principle, consumers don't need energy, they do need exclusively four energy services, safely, cleanly, and affordably: warmed or cooled rooms, lighted streets or living and working places, power support for production and transport, and communication services. Their supply is the exclusive motivation for the operation of the gigantic global energy system. All the energy conversion steps of the conversion chain which precede the provision of energy services have no motivation in themselves. Primary energy raw materials, primary energy, secondary energy, end energy, and useful energy are means to an end: providing environmentally and climatically benign energy services reliably, to cost, and in time. Hydrogen aboard automobiles, hydrogen fuelled fuel cells, hydrogen in ship bunkers or airplane cryostores provide these energy services and, thus, deserve very high consumer acceptance, of course as long as affordability is secured.
Never did a new addition join the energy mix in a jumpstart. Many decades, up to half a century, are the usual times for a first significant contribution. Take the so far latest addition to the mix, nuclear fission: Otto Hahn's first nuclear reaction was in 1938 in Berlin; today, after 65 years nuclear power stations' primary energy equivalent worldwide is 7 %. Another example: Fig. 1 shows the historical development of heat engines beginning with James Watt's steam engine with approximately 1 % efficiency up to modern combined cycles which combine gas turbines and steam turbines at almost 60 % efficiency. When, again in a few decades, a high temperature fuel cell will have been added, even 70 % efficiency is not too far fetched. Truly, the final result is convincing; however, in total, the time necessary for this achievement was more than two centuries! And, since the half-logarithmic plot is a straight line, it seems that human influence to, say, accelerate this development is rather limited.
The world energy system in place is a centralized system. It is an energy "diluting" system, since energy of very high concentration like in coal mines or oil and gas fields, refineries, or power stations at the front of the energy conversion chain is link by link consecutively diluted via electricity grids, pipeline systems, transportation and storage means finally to the minimally energy-dense energy services the consumer asks for at the end of the chain. Capacity units at the beginning are gigawatts to terawatts, at the end watts to kilowatts or, at most, megawatts.
Hydrogen joins and complements ideally electricity in the secondary energy market. Electricity and hydrogen have much in common: they can be made of any primary energy; once made, their respective entire following energy conversion chains are environmentally and climatically clean; they are predominantly grid- or pipeline-delivered; they are interrelated via electrolysis and fuel cell. – Of course, there are differences: Hydrogen can be stored, electricity cannot; electricity conveys communication, hydrogen does not. Hydrogen fuelled fuel cells allow for electric loads with stringent reliability-of-supply standards.
The hydrogen energy economy introduces and strongly supports decentralizing elements. With the hydrogen fuelled fuel cells and their characteristic unit capacities of watts to a few megawatts, highly efficient end user converters provide distributed stationary electricity and heat, and portable or mobile electricity. What is converted right on-the-spot of utilization must not be shipped from afar, sometimes over global distances. Consequently, where these growing secondary energy markets serve billions of lay persons with energy services, professionalization is urgent. Professionals have to take the basic decisions and to take over responsibility for the operation and maintenance of appliances also at the end of the chain, similarly to what they have been routinely accustomed to doing for centuries in the primary energy sectors at the front of the chain. Energy is much too precious for these decisions to remain in the hands of lay persons.
On principle, energy conversion depends on two things, primary energy raw materials and efficient technologies for the consecutive conversion of energy and matter. The primary energy raw materials can be zero, as is the case for all renewable energies; then the energy conversion chain lacks the link from primary energy raw materials to primary energy and begins with the latter. In any case, a tendency is visible for energy technologies to become much more important. Increasing technification turns energy policy more and more into technology policy. The necessity is obvious: even after more than two hundred years of industrial energy, the world energy system is only a little more than 10 % efficient, 10 kilowatt-hours of energy have to be introduced into the system in order to get 1 kilowatt-hour of energy services at the end bitter to admit. Even the best national energy systems are not much more than 30 % efficient. And these figures indicate only the energy efficiencies, not to speak of the exergy (available energy) efficiencies (energy = exergy + anergy) which at a few percent worldwide and maximally only 15 % in the best national energy system of an industrialized country are also not too convincing. The dormant virtual energy potential activated through efficiency gains by a moderate factor of 2 in industrialized countries and a factor of 3 to 4 in newly industrializing countries is technologically not at all illusive! The appropriate technologies are at hand, the goal is to bring them to market. And here hydrogen and fuel cells are key. The insightful perspective reads: "Technology is energy"!
With the exception of biomass, no renewable primary energy is transportable, many are nonstorable, too. In order to let them participate not only locally, but also in the world energy trade system, an unrestrictedly storable and transportable chemical energy carrier is needed. Electrolytic hydrogen made from renewable electricity and water can play this role. A closed material system (Fig. 2) is envisaged taking water from the water inventory of the earth, splitting it into hydrogen and oxygen, recombining them as they are turned into energy services, and giving water back to the inventory, quantitatively and qualitatively unaltered. With this vision energy sustainability is nearly achieved. Since nothing that humans do is without ecological influence, here also care is to be taken with respect to, for instance, the hydrogen transport routes over global distances, or the water vapor amounts released on the spot of recombination. - On principle though, hydrogen is key in the scheme of energies-of-light which utilizes the light of the sun (and other renewable energies), lightens the burden on the environment and climate, trades lightweight energy carriers, and sheds light into the energy future of humankind. Thus, hydrogen fits well into the ongoing Kondratieff cycle (Fig. 3) which is characterized by a trend toward weightless products or at least products of low specific weight, e.g., ceramics instead of steel, fast electrons instead of bulky letters in the information and communication business, bio-products instead of bulk chemicals, and, sunlight instead of weighty coal, or hydrogen instead of hydrocarbons: Hydrogen adds value to renewables!
The atomic hydrogen/carbon ratios of coal : oil : natural gas : hydrogen are <1 : 2 : 4 : ∞, and the atomic weights of carbon and hydrogen are 12 and 1, respectively. Hydrogen helps in switching from a carbon-rich/hydrogen-poor to a hydrogen-rich/carbon-poor energy mix. It minimizes the energy density. Fig. 4 indicates that this switch resulted over the last 100 years already in a decrease of energy-related emitted carbon tonnages by some 35 %, and the gradient is still steep. It is foreseen that at the end of this hydrogenation a good percentage of today's carbon amount will have been replaced by hydrogen. And since hydrogen is 12 times lighter than carbon, dematerialization of the energy system will be reached in parallel. Dematerialized energy has lower storage and transportation costs.
Of course, since hydrogen is a secondary energy carrier it can only be more costly than the primary energy it is made from; that is the situation at the front end of the hydrogen energy conversion chain. At the back end, however, hydrogen allows for the installation of stationary, mobile, or portable fuel cells, which in comparison to the technologies they replace (e.g., boilers, reciprocating piston engines, or batteries) are of significantly higher efficiencies and available exergy potential. Take for instance the usual home boiler system: it is energetically superb, exergetically, however, miserable. Replaced by a fuel cell, we get firsthand 35 % efficient electricity pure exergy and the exhaust heat is still sufficient to heat the home. The efficiency gain at the end of the energy conversion chain more than compensates for the efficiency loss at its beginning. Hydrogen and fuel cells are key!
The traditional energy system experienced a strong tendency to ever larger energy conversion devices (oil or gas field size, off-shore platform capacities, pipeline diameters, tanker carrying capacity, power station unit size, and the like). Economy-of-scale thinking dominated the evolution in size. Now, with the advent of the fuel cell two almost unexpected revolutionary characteristics are being introduced into prevailing energy thinking of the past: Fuel cells allow highly efficient energy conversion not only at the front end of the energy conversion chain, but also at its back end in the very vicinity of the energy service customers, and, the second characteristic, the highly exergetically efficient converter fuel cell can be small. As a consequence, competition is being introduced between the traditional kilowatt-hour from the front end of the conversion chain and the novel fuel cell's kilowatt-hour at its back end: a favorable situation for energy service customers; they have options! – And a side aspect: For centuries, the heat engine was the absolutely dominating energy converter, and it still is. Now, hydrogen introduces competition between dissimilarities: the classical heat engine and the modern, up-coming, electrochemical converters electrolyzer and fuel cell. On principle, the "learning rate", i.e. the cost reduction of millions of efficient energy converters of the watt to kilowatt classes per doubled cumulative installation capacity is much higher than that of classical converters of the accustomed megawatt to gigawatt classes.
Until the advent of oil and gas in the manufacturing, transportation, and residential/office building energy supply markets, coal enjoyed a monopoly. This has changed radically, coal has almost completely vanished from the three sectors; it is reduced to generating electric power and producing steel. Since coal, however, has by far the largest reserves of all fossil energies, and, because there is no continent where coal is not found, coal resources are almost ubiquitous; there is a powerful incentive for a coal renaissance in the secondary markets mentioned.
Hydrogen enables this renaissance. Hydrogen from gasified coal and its reaction with lime and water delivers coal the chance to become a player in the ever more important gases' markets and, thus, to provide efficient heat and electricity via the fuel cell, or serve as fuel in gaseous or liquefied form on board vehicles. One condition sine qua non, however, is capture and sequestration of co-produced carbon dioxide, in order to avoid coal's inherent risk of climate change!
Modern up-coming coal power stations with electrical efficiencies of 50% or more are a success story. Their environmental pollution is almost zero, and their contribution to the greenhouse is minimized, although there is still some climate change risk, because thermodynamically power conversion will never reach 100% efficiency.
The hydrogen supported zero-CO2 power plants may change this: gasified coal, lime and water react to hydrogen and calcium carbonate, the hydrogen is converted to electricity in an extremely efficient high temperature fuel cell, and the calcium carbonate is converted to CO2 and lime, which is recycled into the start reaction. The CO2 is sequestered and mineralized, and, thus, prevented from being released into the atmosphere. Two advantages: the CO2-free coal fired power station becomes feasible, and hydrogen enables coal to play its role in the growing gases' markets.
Nature operates a closed solar photosynthetic hydrogen-carbon-oxygen cycle with intermediate biomass production: carbon dioxide and water are solar-photosynthetically converted into hydrocarbons (biomass) and oxygen; the oxygen is immediately released into the atmosphere, and so is the biomass after its decay into carbon dioxide and water (if not carbonized to fossil energy raw material over millions of years). On principle, the material cycle is closed, and the energy system is open, exergy comes from the sun, anergy vanishes into deep space.
In five steps, anthropogenic imitation of this renewable hydrocarbon system seems possible where carbon serves as renewable hydrogen carrier: (1) Conversion of renewable energy into electricity via solar, wind or hydropower stations; (2) electrolytic generation of hydrogen from water/water steam; (3) conversion of biomass or fossil-fuel-derived carbon dioxide into carbon monoxide; (4) carbon monoxide/hydrogen synthesis to a storable and transportable renewable hydrocarbon (e.g., methanol); (5) utilization of the renewable hydrocarbon in a heat engine or a fuel cell with carbon dioxide and water given back to the aforementioned steps. The hydrocarbon can be seen as highly energy-dense hydrogen carrying renewable carbon with no greenhouse gas relevance. In an intermediate step biomass serves as the carbon reservoir; at a later stage additional industrial carbon dioxide sources of high concentration may take over that role. - For the abatement of climate change risk it may well once be heard: Burn more carbon! Renewable carbon, nota bene.
Historically, atmospheric CO2 concentration prior to the begin of worldwide industrialization in the 18th century was 280 ppm (parts per million), to date it has reached some 370 ppm. The related mean temperature in the atmosphere increases by 0.1 degree per decade. The anthropogenic influence is obvious. Energy and transport are the major fields of concern. Besides the major greenhouse gas CO2, other gases such as methane are increasing in influence. Five measures promise remedy:
Sustainability meets the requirements of the living generation without compromising the prospective needs of generations to come. Sustainability's basic characteristics are economic, ecological, social, and the requirement of reversibility. Energy sustainability is severely hurt by the traditional manner of mining, converting and utilizing energy raw materials: