It is highly doubtful that industrial biohydrogen processes will be the entry points for the widespread use of H2 as a fuel. Despite a number of major national and inter­national initiatives and research programs, fossil fuel-based and alternative energy processes are widely considered to be essential before 2030, or even as late as 2050. Of these nonbiological technologies, H2 production by coal gasification is clearly the worst alternative in terms of fossil energy use and greenhouse gas emissions (figure 7.8).93 Nevertheless, gasification and electricity-powered electrolytic routes to H2 offer the promise of production costs rivaling or even less than those of conventional gasoline for use in fuel cell-powered vehicles with an anticipated fuel economy approximately twice that of conventional internal combustion engines (figure 7.9). As a carbonless production route, the internationally accepted “route map” is the sulfur-iodine cycle based on the three reactions:

H2SO4 ^ SO2 + H2O + /O2 [850°C]

I2 + SO2 + 2H2O ^ 2HI + H2SO4 [120°C]

2HI ^ H2 + I2 [220-330°C]

The high temperatures required for the first reaction have prompted research pro­grams investigating solar-furnace splitting of sulfuric acid, for example, in the five — nation project HYTHEC (HYdrogen THErmochemical Cycles), involving research teams from France, Germany, Spain, Italy, and the United Kingdom in the “search for a long-term massive hydrogen production route” that would be sustainable and independent of fossil fuel reserves (www. hythec. org).

Electrolysis (wind)

The enormous added bonus of biohydrogen would be the use of other highly renewable resources as well as avoiding undue reliance on nuclear technology (an alternative means of providing the power for very-high-temperature reactors), highly persuasive rationales for the continuing interest in biohydrogen energy in the twenty-first century as exemplified by the International Energy Agency’s Hydrogen Implementing Agreement whose Task 15 involves Canada, Japan, Norway, Sweden, the Netherlands, the United Kingdom, and the United States in four R&D areas:94

• Light-driven H2 production by microalgae

• Maximizing photosynthetic efficiencies

• H2 fermentations

• Improving photobioreactors for H2 production

In Japan, all the major automobile manufacturers are active in the development of fuel cell-powered vehicles: Toyota, Honda, Nissan, Mazda, Daihatsu, Mitsubishi, and Suzuki.94

In Europe, HYVOLUTION is a program with partners from 11 European Union countries, Russia, and Turkey, funded by approximately $9.5 million, and aiming to establish decentralized H2 production from biomass, maximize the number and diversity of H2 production routes, and increase energy security of supply at both local and regional levels (www. biohydrogen. nl/hyvolution). The approach is based on combined bioprocesses with thermophilic and phototrophic bacteria to provide H2
production with high efficiencies in small-scale, cost-effective industries to reduce H2 production costs to $10/GJ by 2020 — with production costs in the $5-7/GJ range, biomass-derived H2 would be highly competitive with conventional fuels or biofuels.95 Principal subobjectives for HYVOLUTION include the following:

• Pretreatment technologies to optimize biodegradation of energy crops

• Maximized conversion of biomass to H2

• Assessment of installations for optimal gas cleaning

• Minimum energy demand and maximal product output

• Identification of market opportunities for a broad feedstock range

Based in Sweden, the SOLAR H program links molecular genetics and biomimetic chemistry to explore radically innovative approaches to renewable H2 production, including artificial photosynthesis in manmade systems (www. fotmol. uu. se). Japanese research has already explored aspects of this interface between industrial chemistry and photobiology, for example, incorporating an artificial chlorophyll (with a zinc ion replacing the green plant choice of magnesium) in a laboratory system with sucrose, the enzymes invertase and glucose oxidase, together with a platinum colloid to photoevolve H2.96

The size of the investment required to bring the hydrogen economy to fruition remains, however, daunting: from several billion to a few trillion dollars for several decades.97 The International Energy Agency also estimates that H2 production costs must be reduced by three — to tenfold and fuel cell costs by ten — to fiftyfold. Stationary fuel cells could represent 2-3% of global generating capacity by 2050, and total H2 use could reach 15.7 EJ by then. There are some appreciated risks in these prognos­tications, with governments holding back from imposing fuel taxes on H2 but impos­ing high CO2 penalties being strongly positive for increasing the possible use of H2, whereas high fuel cell prices for automobiles will be equally negative (figure 7.10).