Assignment 2 Electrical Energy Storage Systems (MIET2131)

Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2017
· This assignment is worth 15% of your final mark in this course
· Please include your name and student number in the file name as well as the cover page of
your assignment
· Use Harvard reference citation system to reference all sources used Please submit
electronically via the MIET2131 blackboard
· Due for submission: 20 Sept 2017 (11:59 pm)
Note: The learning philosophy of this course is based on adult learning where some self-directed
learning elements are embedded in the curriculum aimed at preparing you to be lifetime learners.
In line with this philosophy, you are given such opportunities in the course (e.g. through this
assignment) to further expand the knowledge you have already obtained in the class.
1- A standalone household (no grid connection) with a daily electrical load profile as given
below this question is considering a Solar-hydrogen-battery system to supply its load.
The PV panels are installed facing north and inclined at the local latitude angle of the
place where the household is located (~38°).
Use HOMER Software tool to size the system; discuss your assumptions, and
demonstrate and discuss the technical and economic performance and the system.
(4 points)
· HOMER software is now installed on all machines in rooms 56.04.86 and 56.04.89;
you can also access through Citrix Receiver (use My Desktop when you are off
Campus). HOMER’s free trial version can also be downloaded from their website There are plenty of online tutorials and videos available
to help you (some links are provided on the blackboard).
· Household load profile
H 1 2 3 4 5 6 7 8 9 10 11 12
0.3 0.3 0.3 0.3 0.3 0.5 0.8 1.1 1.3 1.2 1 0.8
H: hour; L: Load (kW)
· For solar radiation profile, you can use Melbourne’s data as given in the appendix
(taken from the Australian solar radiation data handbook). Note that you may need
to use all or some of them.
· Make reasonable assumptions for any other data that might be required for this
analysis. Describe your assumptions when answering this question.
H 13 14 15 16 17 18 19 20 21 22 23 24
0.8 0.9 0.9 1 1.1 1.2 1.4 1.6 1.3 1 0.8 0.3
Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2017
2- 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:
a. 63.0 kWh of electricity are required to generate 1 kg of hydrogen a high pressure
electrolyser and pressurised to 350 bar suitable for on-board storage in a mobile
b. The energy content of hydrogen (HHV) is 142 MJ/kg (~40 kWh/kg)
c. The average energy efficiency of the fuel cells used is 44% (based on HHV), and that
of the electric motors 86%
d. The energy content of unleaded petrol is 34.2 MJ/litre
e. The conventional petrol car has an average energy efficiency of 20% (see the lecture
(2.5 points)
3- Use the greenhouse coefficients for fuels in Victoria (from National Greenhouse
Accounts (NGA) Factors, Australian Government, Department of Environment, August
20161) to compare the greenhouse gas emissions for the same number of vehicle km
(that is, per litre of petrol used by the conventional car) of the hydrogen and the
conventional cars as specified in question 2, when the electricity to generate the
hydrogen is obtained from the Victorian grid.
If a Battery Electric Vehicle (BEV) charged from grid electricity in Victoria had a
roundtrip energy efficiency of 77%, how would its greenhouse gas emissions compare
with those of a conventional petrol car (as in question 2), and a hydrogen car in the first
part of this question.
(1.5 points)
4- For storage options a, b, and c, what volume of storage tank for hydrogen would be
needed for a hydrogen fuel cell car to have the same delivered transport energy (that is,
total vehicle-km of travel) as a conventional car with a full 50 litre petrol tank (note that
the actual volume of the tank is more than 50 litre).
a- If the hydrogen is stored as compressed gas at a pressure of 350 bar (1 bar = 101
b- If the hydrogen is stored cryogenically as a liquid
c- If the hydrogen is stored in a metal hydride in solid form
Important assumption and information required to answer this question:
· Assume the same energy conversion efficiencies and energy contents as in
question 2.
· Note that the following gravimetric and volumetric energy storage figures are
based on 50% fuel cell energy efficiency, but the energy efficiency that you need
to use (based on question 2) in order to answer this question is 44%, HHV.
Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2017
· Assumptions for the volumetric and gravimetric electrical energy densities of
different hydrogen energy storage options based on 50% electrical energy
efficiency (HHV) for the fuel cell:
– High-pressure hydrogen at 350 bar:
0.75 kWhe/kg and 0.35 kWhe/litre
– Cryogenic hydrogen storage
1.46 kWhe/kg and 0.89 kWhe/litre
– Metal hydride
0.5 kWhe/kg and 0.5 kWhe/litre
(2 points)
5- An electrical energy storage system is based on a 30 W PEM fuel cell (mass 285 g,
efficiency based on HHV of 50%) and a number of metal hydride hydrogen storage
canisters each capable of storing up to 1.2 wt% hydrogen with an uncharged mass of
134 g (NB 100% includes mass of canister plus hydrogen here). At what minimum total
electrical energy delivery capacity would this system have a system gravimetric energy
density advantage over a battery bank based on a number of lithium polymer batteries,
each weighing 88 g and rated at 1800 mAh with a nominal voltage of 7.4 V? Assume an
80% depth of discharge for each battery and a 12% drop in voltage, linear with usage,
during discharge. Consider just whole numbers of MH canisters and batteries. At the
gravimetric energy density crossover point, how many MH canisters would the hydrogen
fuel system employ and how many batteries (rounded to the nearest whole numbers)?
(2 points)
6- Using what you have learnt in this course, the readings for and group discussion held in
the week 7 class (about the hydrogen economy strategy), and other sources, discuss
critically (in about 1000 words) the potential advantages and disadvantages of using
hydrogen in national and global sustainable energy strategies? Make sure all sources are
properly referenced using the Harvard system.
(3 points)
Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2017
Appendix: Melbourne Solar Radiation Data
Assignment 2
Electrical Energy Storage Systems (MIET2131)
Semester2, 2017

find the cost of your paper