Critical Discussion on Advantages and Disadvantages of Hydrogen in Sustainable Energy Strategies

Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2018

Q.1 - A standalone household (no grid connection) with a conservative daily electrical load profile
as given below this question is considering a Solar-hydrogen-battery system to supply its load. The
household has been assumed to have a passive design with no heating and cooling load. Use
HOMER software tool to size the system; discuss your assumptions, and demonstrate and discuss
the technical and economic performance and the system.
Solution:
Here the assumption consider are load detail provided of the residential domain, same load
is considered throughout the year. Heating and cooling loads are not considered here in
isolated home which is supplied only by PV means with no interconnection with main grid
or microgrid. Temperature of Melbourne considered by default value.
Figure 1 Schematic and Load detials in Homer

The power factor of load considered is 0.3, and no specifications are provided we assume
that PV is connected with the battery as energy storage and the converter is use to convert
the DC power from the battery to AC is coupled in between. Assumed temperature is 38o C.
and maximum PV capacity of 1.2 kW. Other parameter is kept as default. Results are
attached in result.csv file.
Q2. How much electricity (in kWh) would be needed to produce the hydrogen to power a
hydrogen-fuel cell car for the same total vehicle km as one litre of petrol in a typical
conventional car?
Assume:
1. 63.0 kWh of electricity are required to generate 1 kg of hydrogen a high pressure
electrolyze and pressurized to 350 bar suitable for on-board storage in a mobile
application.
2. The energy content of hydrogen (HHV) is 142 MJ/kg (~40 kWh/kg)
3. The average energy efficiency of the fuel cells used is 44% (based on HHV), and that
of the electric motors 86%
4. The energy content of unleaded petrol is 34.2 MJ/litre
5. The conventional petrol car has an average energy efficiency of 20% (see the lecture
materials).
Solution:
t1 litre of petrol = 34.2MJ of energy. But the energy efficiency is 20% => 1 litre of petrol
effectively = 20/100* 34.2 MJ = 6.84 MJ
Let x be MJ of energy that comes from Hydrogen. Then taking efficiencies into account, x*
0.44*0.86 = 6.84
=> x= 6.84/ ( 0.44*0.86 ) = 18.07MJ
1Kg of Hydrogen gives - 142 MJ => 18.07MJ is obtained from 18.07/142 = 0.1272Kg
to generate 1Kg of Hydrogen - 63 kWh of electricity is needed
To generate 0.1272Kg of Hydrogen - 0.1272* 63 = 8 kWh of electricity is would be
needed