11 Hydrogen Economy Flashcards
Products of Hydrogen combustion
Mainly water. (steam)
Also NOx if temp becomes too high when burning. (higher NOx emissions than CO2!!)
How much more damaging is NOx than CO2 to atmosphere?
NOx is orders of magnitude more damaging than CO2.
Can hydrogen be used for energy storage?
Yes. Its atomic bonds offer an efficient energy storage medium which can be exploited over long periods of time.
Uses of hydrogen
Combustion
Fuel cells
Heating
Cooling
etc
Examples of Hydrogen sources
Fossil fuels
biomass
green renewable energy (wind/turbine/solar/etc)
nuclear energy
What makes hydrogen fuel competitive?
Produced at large scales due to lower costs of equipment/process. Fossil fuels need carbon capture.
Difficulties of hydrogen flames
H flames are difficult to handle
They exhibit extremely high temps
Sometimes invisible flames
Can leak through fittings
Main advantage of using hydrogen in gas turbines
produces low emissions
Why do you need to be careful when using hydrogen in gas turbines?
If temps aren’t controlled they could reach high levels that are possible of producing NOx emissions.
Challenges of using hydrogen in gas turbines
no technology is flexible enough to use hydrogen in current systems
How to reduce temps during hydrogen combustion in gas turbines?
Inject steam or water to reduce temps whilst producing higher output powers
What are fuel cells?
Electrochemical energy converters that produce electrical and thermal energy from the chemical energy of the fuel without moving parts or combustion.
They allow the use of hydrogen at lower temps.
fuel cells don’t store energy (unlike batteries); they PRODUCE it.
(although they’re called fuel cells, nothing burns within them)
Hydrogen fuel challenges
- storage (methods and cost)
- volumetric energy density
- diffusivity
- leakage distribution
- explosivity
- flame speed
- adiabatic temp
- unstable combustion regimes
- lack of infrastructure for distribution
