Hydrogen Lecture 8 PDF

Japan’s Hydrogen Plan “Toyota, Nissan and Honda formed a joint venture with major gas and energy firms to build 80 new hydrogen stations in the next four years to add to the roughly 100 such stations already in operation in Japan.” https://www.dw.com http://undiscovered-japan.ft...

Japan’s Hydrogen Plan “Toyota, Nissan and Honda formed a joint venture with major gas and energy firms to build 80 new hydrogen stations in the next four years to add to the roughly 100 such stations already in operation in Japan.” https://www.dw.com http://undiscovered-japan.ft.com/articles/driving-a-revolution/ https://arena.gov.au/blog/hydrogen-future-australian-renewables  Hydrogen ME 4180 – Energy Systems and Sustainability Prof. Mario Medina Department of Mechanical Engineering Sept. 23, 2020 Agenda Objective Understand the advantages and limitations for hydrogen as an energy carrier Agenda Motivation for hydrogen Challenges with hydrogren Production methods Hydrogen storage Distribution infrastructure On-board reforming H2 motivation Global reaction for combustion and fuel cell applications for H2: H2 + ½(O2 +3.76N2) = H2O + 1.88N2 Hydrogen could be a path for zero carbon emission and zero petroleum vehicles Why design for ICE? Singh M., A. Vyas and E. Steiner, Argonne National Laboratory, VISION Model: Description of Model Used to Estimate The Impact of Highway Technologies and Fuels on Energy Use and Carbon Emissions to 2050, (December 2003), ANL/ESD/04-1 H2 motivation Hydrogen has the highest energy density on a per mass basis of all the fossil and renewable fuels. H2 will only produce water as product → no UHC, CO, CO2, soot H2 has the highest Tad → high efficiencies, but can lead to high NOx emissions; fuel lean equivalence ratios may address this issue and/or dilution Higher flame speed (faster by 5-10 times than HC’s) © Wooldridge, University of Michigan H2 challenges Hydrogen has the lowest energy density on a per volume basis of all the fossil and renewable fuels. H2 does not occur naturally in the environment. We need H2 carriers. Higher flame speed (faster by 5- 10 times than HC’s) → Safety concern for a wide flammability limits. © Wooldridge, University of Michigan The energy map The bar for transportation fuels is high. © Wooldridge, University of Michigan H2 production There are several ways to make H2: a) Chemically C(any source) + H2O → H2 + CO (steam reforming) CO + H2O → CO2 + H2 (water gas shift) b) Electrically electrolysis to decompose water 2H2O → 2H2 + O2 - costly compared to steam reforming - requires lots of electricity - but electricity could come from nuclear, wind, solar energy (zero carbon emissions) c) Thermally thermal decomposition of H2O (T > 2000°C) thermal cycles under 1000°C using I/H2SO4/H2O, or Br/Ca/H2O H2 storage There are several ways to store H2: System Weight Volume a) Compressed as a gas 50 kg 330 L P = 5000 psi heavy but prolific b) Compressed as a liquid 45 kg 190 L Cryogenic liquids Requires open systems due to evaporation Large volume reduction, but costly c) Reversibly chemically bonded 200-600kg 180 L Metal hydride 2M + H2 ↔ 2MH + heat Metal alloys (Mg, Ni, Ti, etc.) Costly and heavy d) Irreversibly chemically bonded 50 kg 70 L Gasoline Great infrastructure H2 distribution On-demand uses already have distribution Otherwise, there is a need for an infrastructure Possibilities include: Adapting the natural gas pipeline On-board reforming for vehicle applications Cryogenic high-pressure tanker system Hydrogen refueling stations On-board reforming for vehicles Pros: use exiting fuel supply infrastructure Cons: complex design, control, integration & packaging. From methanol: CH3OH → 2H2 + CO CO + H2O ↔ CO2 + H2 (water gas shift) After CO removal, fuel: 72% H2, 25% CO2, 3%N2,