Q2. What is the main advantage of hydrogen as a fuel?
The main advantage of hydrogen as a fuel is the absence of CO2 emissions, as well as other pollutant emissions (thermal NOx) if it is employed in low temperature fuel cells.
Q3. How can the authors supply hydrogen to areas far from the general network?
In order to supply hydrogen to areas far from the general network it will be necessary to build refuelling stations able to generate hydrogen in situ, by means of electrolysers fed by renewable energies (such as photovoltaic solar panels or windmills) or biomass reformers.
Q4. What is the definition of the so-called hydrogen economy?
The so-called Hydrogen Economy is a long-term project that can be defined as an effort to change the current energy system to one which attempts to combine the cleanliness of hydrogen as an energy carrier with the efficiency of fuel cells as devices to transform energy into electricity and heat.
Q5. What is the appropriate fuelcell for the use of hydrogen?
At the present time the most appropriate fuelcells for this use are the Solid Oxide Fuel Cells (SOFC) which are fitted with non-porous ceramic electrolytes.
Q6. How long is the cost of H2 guaranteed?
Although clearly the best solution to the negative effects of energy consumption is to continue to decrease the use of fossil fuels, their use on a large scale for electricity generation and H2 production is guaranteed at least for several decades.
Q7. How much heat can be produced by the use of two parallel thermal cycles?
the use of two parallel thermal cycles in which H2 and O2 are produced separately, allows H2 to be obtained at a considerably lower temperature (<1,000ºC).
Q8. What is the favorable scenario for the development of a Hydrogen Economy?
In the most favourable situation for the development of a Hydrogen Economy (ESTEC D) in 2050 30% of the cars will be powered by hydrogen feed fuel cells and there will be a capacity of 200-300 GW in installed fuel cells to cogenerate heat and electricity in the residential sector.
Q9. What is the main reason for the increase in capacity of reformers and electrolysers?
It can also be assumed that the increase in capacity of reformers and electrolysers will lead to a further decrease in their cost and an increase in their efficiency to values close to the theoretical ones.
Q10. How many Gton of carbon will be produced by the IEA in 2050?
In a no-change scenario (Base Scenario of the International Energy Agency, IEA) CO2 emissions in 2050 can be expected to reach 14 Gton of carbon (6).
Q11. What is the common way to convert biomass to a hydrogen?
In the transition to a hydrogen economy, biomass can be employed as a clean form of energy mainly through the three conversion processes (Table 2) described below:Process 1. Transformation to bio-fuels (bio-ethanol and bio-diesel) that are directly burnt in the internal combustion engine.
Q12. What is the common type of tank used in the bus fleet?
These tanks which are built of carbon fibre are used in the bus fleet mentioned above and in some car prototypes such as Ford Focus C-Max with ICE-H2.
Q13. What are the technical barriers to the use of bio-methanol?
The technological barriers include the cost, the development of economic and appropriate materials for the experimental conditions (separation membranes and heat exchangers) and an increase in thermal efficiency of over 50%.
Q14. How much of the electricity generated by renewable sources?
The European Union expects that by 2010 these renewable sources will contribute 22% to the total amount of electricity generated (Figure 1).
Q15. What systems could be used for smaller scale storage at production points?
For smaller scale storage at production points, similar systems to those employed in vehicles could be applied (pressure tanks, liquid hydrogen tanks, hydrides, etc).
Q16. How long will the rate of consumption guarantee H2 production for transport?
For instance H2 production for transport by coal reforming, if the authors consider the rate of consumption expected in 2050 (1 Gton H2/year) will be guaranteed for 70 years if electricity and heat are produced from other energy sources (Table 3).
Q17. How much would it cost to force the energy companies to implement carbon-free energy sources?
This problem can be expressed in numbers via the worldwide CO2 emission market, in which an estimated cost of $50/ton would seem to be enough to force the energy companies along the path of implementing carbon-free energy sources.
Q18. What type of systems will be used to produce H2 and electricity?
These fuels will be transformed in cogeneration thermal plants to produce H2 and electricity (for instance in IGCC plants; integrated gasification in combined cycle) provided with CO2 separation systems (sorbents, membranes, etc).
Q19. How much is the cost of hydrogen in centralized coal gasifiers?
Currently the cost of production of hydrogen in centralized coal gasifier systems (without CCS) is more expensive than the cost of H2 from centralized natural gas reforming systems ($0.22/Lge vs. $0.13/Lge) (10).
Q20. What is the alternative to a gradual decrease in the consumption of gasoline?
the first process is the best alternative to allow a gradual decrease in the consumption of gasoline in the short-term, since bio-fuels can be mixed with standard gasoline or used alone with only minor modifications to the current combustion engines.