Annex 3. Hydrogen
blended CNG (HCNG for buses)

 

Use of hydrogen-blended CNG
(HCNG) in commercial buses in Delhi NCR

Indian Oil Corporation Limited (IOCL)

03 August 2017, New
Delhi

 

Background

CNG as an auto fuel, originally was
introduced in Delhi?NCR as a legislative direction. Subsequently it has
registered significant growth owing to its advantages in terms of lower
emissions and better fuel economy. However, cities like Delhi need further
cleaner alternatives in order to reduce the vehicular emission inventories for
improving the ambient air quality. Blending of hydrogen in CNG (known as HCNG)
can result in further lowering of exhaust emissions from CNG vehicles due to
improved combustion characteristics of the resultant blend.

 

Benefits of using 18% HCNG blends:

 

1.  Light duty vehicles

Under a project funded by MNRE on
“Use of HCNG blends for Light duty vehicles”, Indian Oil R&D
conducted joint studies with SIAM on a fleet of vehicles including 3–wheelers, passengers’
cars and LCVs Annexure–I, A3. The studies established the following:

·     
18
v/v % (or ~2.7% by mass) of hydrogen in CNG is the most optimal blend ratio for
Indian vehicles

·     
reduction
of 45% in CO and 35% in HC emissions could be achieved with 18% HCNG

·     
NOx
emissions may increase or decrease depending upon the engine design and tuning

 

2.  Heavy duty engines

Indian Oil R embarked
upon another collaborative program with Ashok Leyland and Tata Motors to
validate the use of HCNG in heavy duty engines / vehicles Annexure-II, A3.
The studies indicated that;

·        
HCNG
can be used as a fuel for heavy duty CNG engine after minor engine optimization

·        
The
Specific Fuel Consumption of HCNG engine is lower than CNG by 2 to 3%.

·        
In
Ashok Leyland HD engine, CO, CH4 & THC emissions got reduced by 28%, 20%
& 20%, respectively while NOx emissions increased by 48% respectively.

·        
Studies
conducted on Tata Motors HD engine indicated a reduction of CO, CH4 & THC,
emissions by 31%, 6.7% & 6.5% respectively while an increase in NOx
emissions by 32.5% was observed.

·        
The
NOx emission with HCNG fuel can be reduced through optimization of engine which
may result in the penalty on engine power output.

·        
No
adverse impact of HCNG on vehicle components and engine performance was
observed.

 

 

 

 

 

Production of HCNG through IOC R’s patented
Compact Reformer technology

Conventionally, HCNG is
produced by physical blending of CNG and Hydrogen. However, this approach
involves onsite production of neat hydrogen through electrolysis of water,
followed by its compression, storage and blending with CNG at high pressures
using complicated mass flow control technology. The resultant blend is much
more expensive than CNG due to presence of multiple energy intensive steps.

In order to overcome the this
challenge, IndianOil R&D developed a low severity single step compact Steam
Methane Reforming process for HCNG production from natural gas. A demonstration
unit of 2.5 Nm3/h (~1.6 kg/h) HCNG capacity has been installed at IndianOil
R&D and the performance of the process has been successfully validated by
dispensing 18% HCNG in the demonstration vehicles. The cost of production of
HCNG by above process is significantly lower as compared to physical blending

 

Proposal

At 43 bus depots of Delhi Transport
Corporation (DTC), 7200 commercial CNG buses are running in Delhi NCR. Hence,
on an average 180 buses are present in a bus depot. Assuming one bus runs 200
km/day, amount of CNG requirement of a bus depot to fill the buses is 9 TPD.
Therefore, a single stage compact reformer plant of capacity ~4TPD would be
sufficient to supply H-CNG to the 50% bus fleet of a depot.

As a part of ‘Cleaner Air
Better Life’ initiative, it is proposed to set-up a 4 TPD single stage compact
reformer plant in a commercial bus depot of DTC to significantly reduce the
emission inventory from CNG buses by using 18% HCNG. Based upon the success of
this demonstration, same process can be replicated for other bus depots also.   

 

Cost Estimates

A typical heavy duty CNG bus
with 6 cylinders of 74 L capacity each can accommodate a total of ~ 52 kg HCNG
at 200 bar while delivering an average fuel economy of 4 km/kg. Therefore, a
250 Nm3/hr capacity HCNG plant can fill up 3 buses per hour i.e. 72
buses per day considering single filling in a depot operational on 24 hour
basis.

IndianOil R&D has prepared a Basic
Design Engineering package (BDEP) of single stage compact reformer suitable for
bus depot with following specifications:

o  Capacity : 250 Nm3/hr i.e., ~
165 kg/h (4TPD)

o  Skid dimension : 4 m (L)X10
m(W) X 9 m (H)

o  CAPEX of compact reformer = INR
11.56  crore 

o  Estimated OPEX is INR 6.8/kg
of product 

 

 

 

 

Issues related to
Commercialization of HCNG

  i.    HCNG as an automotive fuel
needs to be notified by Ministry of Road Transport & Highways (MoRTH)

 ii.   
HCNG
Fuel specifications need to be notified by Bureau of Indian Standards (BIS)

iii.   
Approval
by Petroleum & Explosives Safety Organization (PESO) for using Type 1
cylinder to store 18% HCNG in vehicles

·     
It
is pertinent to mention that IndianOil R&D submitted a report to PESO
highlighting the findings of the health assessment study undertaken on Type 1
cylinder used for filling 18% HCNG fuel after covering 20,000 km. The tests
based on chemical analysis of used cylinder, corrosion, tensile strength,
impact, hardness and micro-structural analysis established that 18% HCNG can be
used in existing CNG storage cylinder Annexure-III, A3.

·     
Further,
a BIS sponsored study conducted by ARAI had established the compatibility of
18% HCNG with fuel supply system components of the vehicle (except cylinder)
Annexure-IV, A3.