6D - green hydrogen

Question 1

Green hydrogen

Answer 1

form of hydrogen fuel that is produced through the process of electrolysis using renewable energy sources.

Question 2

Benefits of Green Hydrogen

Answer 2

Clean, sustainable fuel for:
Transportation
Industry
Power generation

Helps reduce greenhouse gas emissions.

Essential in transitioning to net zero.

Question 3

Challenges of green hydrogen

Answer 3

High cost of renewable energy.

Electrolysers still have limited efficiency.

Technology is improving – costs expected to fall

Question 4

Electrolyser cell design features:

Answer 4

• The electrodes -> covered with platinum catalyst -> increases
  rate gas production.
• Gas diffusion layers [gold-lined, titanium and carbon paper] help
  distribute reactant gases evenly across electrode surfaces
• Bipolar plates - prevent build up of current -provide mechanical support

Question 5

PEM design functions in electrolyser cell

Answer 5

selectively permeable [plastic polymer] -> only allows H+ ions to move between cathode and anode

prevents mixing of O2 and H2

ensures h2 and o2 are produced separately -> ensures efficiency and safety -> reduces contamination possibility

Question 6

reactions in electrolyser

Answer 6

Anode (oxidation):
2H₂O(l) → 4H⁺(aq) + O₂(g) + 4e⁻

Cathode (reduction):
4H⁺(aq) + 4e⁻ → 2H₂(g)

Overall Reaction:
2H₂O(l) → 2H₂(g) + O₂(g)

Question 7

overall uses of PEM

Answer 7

catalysis, designing safer chemical, prevention of waste, use of renewable feedstock

acid cells are used in cars and renewable energy storage systems.

Question 8

photovoltaics

Answer 8

conversion of solar energy -> electrical energy

Question 9

articifical photosynthesis

Answer 9

uses artificial materials to split h2o into h2 and o2
uses semi conductors and catalysts to facilitate c reactions

Question 10

steps of artificial photosynthesis

Answer 10

Light harvesting – absorbs sunlight, excites electrons.

Water oxidation (anode)
2H₂O → 4H⁺ + O₂ + 4e⁻

Proton reduction (cathode)
4H⁺ + 4e⁻ → 2H₂

Overall:
2H₂O → 2H₂ + O₂

Question 11

artificial
photosynthesis is required to

Answer 11

create energy rich industrial fuels. Hydrogen is the primary solar fuel produced (oxygen is also produced)

Question 12

hydrogen may be used to

Answer 12

liquid energy source for fuel cells

fuel source for combustion engines

reduce co2 to methanoic acid, methanol or methane in the presence of a catalyst

reduce nitrogen gas to ammonia in the presence of a catalyst.

Question 13

advantages of creating fuels through artificial photosynthesis

Answer 13

no ghg
no use of fossils
may remove co2 from the atmosphere
produces o2 as a by product )
can create green ammonia (reacting hydrogen produced with
N2(g) from air, which is used to manufacture fertilisers.