Oil and gas production handbook An introduction to oil ... - ABB Group

9.1.8 Hydrogen
Although not a hydrocarbon resource, hydrogen can be used in place of or
as a complement to traditional hydrocarbon-based fuels. As an "energy
carrier,” hydrogen is clean burning, which means that when hydrogen reacts
with oxygen, either in a conventional engine or a fuel cell, water vapor is the
only emission. (Combustion with air at high temperatures will also form
nitrous oxides).
Hydrogen can be produced either from hydrocarbons (natural gas, ethanol,
etc.) or by electrolysis. Production from natural gas is often done via syngas
(see chapter 9.1.5) with up to 75-80% efficiency. Its advantage over
methane gas is that carbon dioxide can be removed and handled at a central
location rather than by each consumer, providing a cleaner energy carrier.
Hydrogen is also produced from water by electrolysis with an efficiency of
about 25% at normal conditions, to about 50% in high temperature, high
pressure processes, or in various recycling processes in the chemical
industry. (e.g., hydrochloric acid recycled in the polyurethane process). The
energy supply can then come from a renewable source such as
hydroelectric, solar, wind, wave, or tidal, where hydrogen acts as an energy
carrier replacing batteries, to form a fully clean, renewable energy source
supply chain.
In both cases, the main problem is overall economy, distribution and storage.
Hydrogen cannot easily be compressed to small volumes, and requires quite
bulky gas tanks for storage. Also, hydrogen produced from electricity
currently has an end-to-end efficiency that does not compare well with
gasoline or electrical battery vehicles.
9.2 Emissions and environmental effects
The production, distribution and consumption of hydrocarbons as fuel or
feedstock are globally the largest source of emissions into the environment.
The total annual world energy supply of 11,000 million TOE is based 81% on
fossil fuels, and releases some 26,000 million tons of carbon dioxide plus
other gases, e.g., methane into the atmosphere.
The most serious effect of these emissions is global climate change. The
Intergovernmental Panel on Climate Change (often called the UN Climate
Panel) predicts that these emissions will cause the global temperature to rise
from between 1.4 to 6.4 ºC by the end of the 21 st century, depending on
models and global scenarios.
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