T HE FUTURE OF THE HYDROGEN ECONOMY : BRIGHT OR BLEAK ?

Abstract

In the past, many have considered the production and use of hy-
drogen, assuming that it is just another gaseous fuel and can be handled
much like natural gas in today’s energy economy. With this study we
present an analysis of the energy required to operate an elemental hydro-
gen economy, with particular reference to road transport. High-grade
electricity from renewable or nuclear sources is needed not only to gen-
erate hydrogen, but also for all the other essential stages. However, be-
cause of the molecular structure of hydrogen, the infrastructure is much
more energy-intensive than in an oil and natural gas economy.
In a “Hydrogen Economy” the hydrogen, like any other commer-
cial product, is subject to several stages between production and use.
Hydrogen has to be packaged by compression or liquefaction, trans-
ported by surface vehicles or pipelines, stored, and transferred to the end
user. Whether generated by electrolysis or by chemistry, and even if pro-
duced locally at filling stations, the gaseous or liquid hydrogen has to
undergo these market processes before it can be used by the customer.
Hydrogen can also be derived chemically at relatively low cost from
natural gas or other hydrocarbons. However, because there are no ener-
getic or environmental advantages, we do not consider this option.
In this study, the energy consumed by each stage is related to the
true energy content—the higher heating value (HHV)—of the delivered
hydrogen. The analysis reveals that much more energy is needed to oper-
ate a hydrogen economy than is required for fossil energy supply and
distribution today. In fact, the input of electrical energy to make, package,
transport, store and transfer hydrogen may easily exceed the hydrogen energy delivered to the end user—implying a well-to-tank efficiency of
less than 50%. However, precious energy can be saved by packaging hy-
drogen chemically in a synthetic liquid hydrocarbon like methanol or
ethanol. To decouple energy use from global warming, the use of “geo-
carbons” from fossil sources should be avoided. However, carbon atoms
from biomass, organic waste materials or recycled carbon dioxide could
become the carriers for hydrogen atoms. Furthermore, energy intensive
electrolysis may be partially replaced by the less energy intensive chemi-
cal transformation of water and carbon to natural and synthetic hydrocar-
bons, including bio-methanol and bio-ethanol. Hence, the closed natural
hydrogen (water) cycle and the closed natural carbon (CO 2 ) cycle may be
used to produce synthetic hydrocarbons for a post-fossil fuel energy
economy. As long as the carbon comes from the biosphere (“bio-carbon”),
the synthetic hydrocarbon economy would be far better than the elemen-
tal hydrogen economy—both energetically and thus environmentally