Assignment

The question and procedures are provided in the assignment.rar file. Please refer it. 

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diesel_vs_hydrogen_smr

INDIVIDUAL ASSIGNMENT – Engineering Sustainable Development 201
Due Date : 13/09/2013
Scenario 1 – TransBus, Perth

This is a hypothetical example that we have developed for you to carry out the task

More than 95% of Australia’s transport energy comes from fossil oils. There is an
increasing awareness of health effects and environmental impacts due to emissions
from the combustion of these oils.
TransBus is one of the Perth’s largest bus companies having a fleet of 450 diesel-
powered buses covering 33 million route kilometres and transporting more than 26
million passengers annually. It employs 850 staff to manage the operations. The
company is planning to use hydrogen fuel in their new buses. The company is
committed to reduce GHG emissions and so they will use clean fuel. They have
identified Hydrogen as a clean transport fuel because the combustion of hydrogen
produces no pollutants; the only emissions are water and heat. The company will make
the decision on the basis of carbon and cost saving benefits associated with the
substitution of diesel with hydrogen fuel in TransBus buses.
Your task is to compare economic and environmental benefits associated with the
replacement of diesel with hydrogen fuel following the procedure stated in the handout
of week 1.
Please follow the steps below to the calculate functional unit:

 Calculate the GHG emissions from the production and use of hydrogen fuel in
the internal combustion where the hydrogen was produced from steam methane
reforming process. The functional unit is the number of kilometres travelled by a
hydrogen powered bus. The functional unit is calculated by multiplying 50 by
the sum of the last two digits of the student ID numbers of all students in your
group. (i.e. if ID numbers of all group members are 1432510, 1432528,
1432587, 1432506 and 1432593, the total kilometres travelled is calculated as
50x(10+28+87+06+93) = 11,200 kilometres).
 Similarly, calculate the GHG emissions from the diesel run vehicle for the same
functional unit.
 Once carbon footprints of buses powered by diesel and hydrogen are
calculated, calculate the carbon saving benefits of this substitution for a carbon
tax of $ 20.00 per tonne of CO2 e-. Following this, please calculate the total
profit, which includes carbon saving benefits and operational benefits.

Data to be used for comparison purposes

Pre-combustion takes in to account all GHG emissions released during exploration,
production, refining and delivery of the fuel while combustion emissions are the
exhaust pipe emissions produced when the fuel is burnt in the vehicle’s engine.

INDIVIDUAL ASSIGNMENT – Engineering Sustainable Development 201
Due Date : 13/09/2013
Economic/Technical Specification and Life Cycle Impact for the Average Diesel –
Powered Bus

Bus maintenance cost $ 0.50/km
$ 50,000 for replacing engine at every 1,000,000 km
Energy consumption 19.3 MJ/km (2.00 km/l diesel) – $ 0.78/km @ $ 1.57/l
Emissions (g/km) Fuel Production Stage
Combustion Stage

CO
2
emissions 0.014 kg CO2 e- / MJ
73.25 g/MJ

Economic/Technical Specification for the Hydrogen/Fuel Cell Bus

Bus Maintenance cost $ 0.60/km
$12,000 for replacing fuel cell stack at every 5,000 hrs
Energy consumption 11.99 MJ/km costing @ $ 6.5/kg

Stage of Steam Methane Reforming Method

 0.5667 kWh electricity is consumed to extract 1 kg Natural gas, where 141 m
3
of
natural gas is required to obtain 1 kg of hydrogen.
 6.556 kWh electricity per kg of hydrogen are consumed for the process at 20
bar
 0.894 kWh electricity is consumed for Compression of hydrogen into large
transport trailers at 165 bar
 0.45 L/km diesel is consumed for hydrogen distribution to fuel station via Diesel
tanker truck, where an average distance between hydrogen plant and fuel tank
is 100km.
 0.236 kWh electricity is consumed for compression of the hydrogen into
medium-term storage tanks at fuel station at 300 bar
 0.0538 kWh electricity is consumed for compression of hydrogen into buses at
350 bar

Density of hydrogen – 0.0899 kg/m
3
, calorific value of hydrogen – 121,000
kJ/kg.density of natural gas is 0.9 kg/m
3
.
\ Density of Diesel – 0.84 kg/litre, heating value of diesel is 38MJ/litre
Emission factors

 Electricity – 1.032 kg CO2 e- /kWh
 Diesel production – 0.014 kg CO2 e- / MJ
 Emissions from the combustion of diesel – 73.25 g/MJ

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