IMPORTANCE OF HYDROGEN AND SYNGAS PRODUCTION

Clean energy and alternative energy have become major areas of research worldwide for sustainable energy development. Among the important research and development areas are hydrogen and synthesis gas (syngas) production and purifi cation as well as fuel processing for fuel cells.

 Research and technology development on hydrogen and syngas production and purifi cation and on fuel processing for fuel cells have great potential in addressing three major challenges in energy area:

(a)   to supply more clean fuels to meet the increasing demands for liquid and gaseous fuels and electricity,

(b)   to increase the effi ciency of energy utilization for fuels and electricity production, and

(c)   to eliminate the pollutants and decouple the link between energy utilization and greenhouse gas emissions in end - use systems.

The above three challenges can be highlighted by reviewing the current status of energy supply and demand and energy effi ciency. Figure  1.1  shows the energy supply and demand (in quadrillion BTU) in the U.S. in 2007.

The existing energy system in the U.S. and in the world today is largely based on combustion of fossil fuels - petroleum, natural gas, and coal - in stationary systems and transportation vehicles. It is clear from Figure  1.1  that petroleum, natural gas, and coal are the three largest sources of primary energy consumption in the U.S. Renewable energies are important but are small parts (6.69%) of the U.S. energy fl ow, although they have potential to grow.

Figure 1.1. Energy supply by sourcess and demand by sectors in the U.S. in 2007 (in quadrillion BTU)

   

Figure  1.2  illustrates the energy input and the output of electricity (in quadrillion BTU) from electric power plants in the U.S. in 2007. As is well known, electricity is the most convenient form of energy in industry and in daily life. The electric power plants are the largest consumers of coal. Great progress has been made in the electric power industry with respect to pollution control and generation technology with certain improvements in energy effi ciency.

Figure 1.2. Energy consumption for electricity generation in the U.S. in 2007 (in quadrillion BTU)

What is also very important but not apparent from the energy supply – demand shown in Figure  1.1  is the following: The energy input into electric power plants represents 41.4% of the total primary energy consumption in the U.S., but the electrical energy generated represents only 35.5% of the energy input, as can be seen from Figure 1.2.

The majority of the energy input into the electric power plants, over 64%, is lost and wasted as conversion loss in the process. The same trend of conversion loss is also applicable for the fuels used in transportation, which represents 28.6% of the total primary energy consumption.

Over 70% of the energy contained in the fuels used in transportation vehicles is wasted as conversion loss. This energy waste is largely due to the thermodynamic limitations of heat engine operations dictated by the maximum efficiency of the Carnot cycle.

Therefore, the current energy utilization systems are not sustainable in multiple aspects, and one aspect is their wastefulness. Fundamentally, all fossil hydrocarbon resources are nonrenewable and precious gifts from nature, and thus it is important to develop more effective and effi cient ways to utilize these energy resources for sustainable development. The new processes and new energy systems should be much more energy effi cient, and also environmentally benign.

Hydrogen and syngas production technology development represent major efforts toward more effi cient, responsible, comprehensive, and environmentally benign use of the valuable fossil hydrocarbon resources, toward sustainable development.

Hydrogen (H₂) and syngas (mixture of H₂ and carbon monoxide, CO) production technologies can utilize energy more efficiently, supply ultraclean fuels, eliminate pollutant emissions at end – use systems, and signifi cantly cut emissions of greenhouse gases, particularly carbon dioxide, CO₂.

For example, syngas production can contribute to more effi cient electrical power generation through advanced energy systems, such as coal - based Integrated Gasifi cation Combined Cycle (IGCC), as well as syngas - based, high - temperature fuel cells such as solid oxide fuel cells (SOFCs) and molten carbonate fuel cells (MCFCs). Syngas from various solid and gaseous fuels can be used for synthesizing ultraclean transport fuels such as liquid hydrocarbon fuels, methanol, dimethyl ether, and ethanol for transportation vehicles.