d5 2 final version

D5.2 |Report on technical

assessment of different

vehicle storage options

DELIVERABLE: D5.2 (REPORT ON TECHNICAL ASSESSMENT OF DIFFERENT VEHICLE STORAGE OPTIONS)

AUTHOR(S): ANTONIO FUGANTI, SILVIA DI ROSA, MARCO TASSAN (CRF) PAUL BONHAM (NCS) MRTEN AHLM (SEA-SE) RADOSAW POMYKAA (AGH-UST)

VERSION: FINAL

INTERNAL QUALITY CONTROL: STEFANO PROIETTI, ISIS

DATE: 06/08/2012

CONTRACT N: IEE/10/351/SI2.591136

STARTING DATE: 01 MAY 2011

DURATION: 36 MONTHS

COORDINATOR: STEFANO PROIETTI, ISIS

TEL: 0039 063 212 655

FAX: 0039 063 213 049

E-MAIL: [email protected]

D5.2 Report on technical assessment of different vehicles storage options

www.biomaster-project.eu page 2|46

TABLE OF CONTENT

INTRODUCTION _____________________________________________________________ 4

1 NGV CYLINDER DESIGN STANDARD DEVELOPMENT ____________________________ 8

2 OVERVIEW ON CNG VEHICLE TYPES, SYSTEM AND COMPONENTS ________________ 10

2.1 CNG VEHICLES TYPES ________________________________________________________ 10 2.2 CNG VEHICLE ADVANTAGES/DISADVANTAGES ________________________________________ 10 2.3 CNG VEHICLE: SYSTEM AND COMPONENTS __________________________________________ 11

3 COMMERCIALLY AVAILABLE CNG VEHICLES __________________________________ 14

3.1 FOCUS ON UE MARKET _______________________________________________________ 14 3.2 FOCUS ON UK MARKET _______________________________________________________ 16 3.3 FOCUS ON ITALIAN MARKET ____________________________________________________ 18 3.4 FOCUS ON SWEDISH MARKET ____________________________________________________ 20 3.5 FOCUS ON POLISH MARKET _____________________________________________________ 22

4 STANDARD STORAGE ____________________________________________________ 24

4.1 TYPE I CNG CYLINDERS - ALL METAL ______________________________________________ 26 4.2 TYPE II CNG CYLINDERS - HOOP WRAPPED COMPOSITE _________________________________ 27 4.3 TYPE III CNG CYLINDERS - FULLY WRAPPED COMPOSITE WITH METAL LINERS __________________ 27 4.4 TYPE IV CYLINDERS - FULLY WRAPPED COMPOSITE WITH NON-METALLIC LINERS ________________ 28 4.5 OTHER COMPONENTS _________________________________________________________ 28

5 INNOVATIVE STORAGE SYSTEMS __________________________________________ 32

5.1 CRYOGENIC/LIQUID STORAGE ___________________________________________________ 32 5.2 METHANE/HYDROGEN BLEND STORAGE ____________________________________________ 35 5.3 ADSORBED NG TECHNOLOGY ___________________________________________________ 37 5.4 METAL-ORGANIC FRAMEWORKS (MOF) ____________________________________________ 39

6 BENCHMARKING ON VESSEL SUPPLIERS AVAILABLE IN UE COUNTRIES ____________ 42

7 CONCLUSIONS _________________________________________________________ 44

REFERENCES ______________________________________________________________ 45



BIOMASTER IN A NUTSHELL

BIOMASTER intends to prove that biomethane for transport can be an operational and viable option in spite of the regulatory and fiscal barriers that hamper its replication. The 4 participating regions, Maopolska Region (PL), Norfolk County (UK), Skne Region (SE) and Trentino Province (IT), are ready to exploit the potential of biomethane production and use for transport to overcome the current impasse and bring the key components of the biomethane chain into a joint initiative, stimulating investments, removing non-technological barriers and mobilising action for uptake. The qualifying characters of BIOMASTER are the commitment of a "waste-to-wheel partnership, the set-up of networks to involve local stakeholders, the intention to address the potential sources of biomethane production, the potential for total production and use, the available distribution modes, and the legal, organisational and financial barriers. A key ambition of the project is to focus on biomethane grid injection. The goal is to bridge the knowledge and operational gaps fragmenting the biomethane chain and to establish local alliances of stakeholders to foster open dialogue and create a mutual understanding which will facilitate an increase in actions along this biomethane chain.

BIOMASTER is a project, co-funded by the Intelligent Energy Europe-Programme and is composed of 17 partners, coming from Austria, Italy, Poland, Sweden and the United Kingdom. It will run from 01 May 2011 until 30 April 2014. The sole responsibility for the content of this document lies with the authors. It does not necessarily reflect the

opinion of the European Union. Neither the EACI nor the European Commission are responsible for any use that

may be made of the information contained therein.



Introduction NGVs Market overview

Compressed natural gas has been used as a vehicle fuel since the early 1940s and the number of vehicles running on the road across the world is reaching 35 million in 2015 (Figure 1).

Figure 1: NGVs Growth Worldwide

Growth in the coming years will be driven by emerging markets in Asia (especially in India, China and Thailand) and some South American countries (e.g. Venezuela); among other top markets Iran, Pakistan, Brazil and Argentina have started to recover after the 2009 fall in volumes. There remains uncertainty for the European markets where the development of alternative vehicle fuels and vehicles is highly dependent on governmental incentives.



Figure 2: Overview NGVs Europe 2011 (source: NGVA)

Around Europe, before 1995 the NGV market was basically limited to Italy. Since then, the number of NGVs in Europe has started to grow steadily. During the last five years the market growth for NGVs in Europe picked up significantly and NGVA Europe even expects it to be much higher in the near future due to the current EU Policy on alternative/renewable fuels and GHG emissions. In particular, in the White Paper for Transport1, providing the EU vision on transport for next decades, the European Commission has confirmed the necessity to reduce dramatically Europes dependence on imported oil and cut carbons emissions in transport by 60% based on 1990 levels by 2050. CNG (and biomethane) are mentioned to be one of the possible alternatives to achieve this target, especially for medium and long distance road transport, being large fleets of urban buses, taxis and delivery particularly suitable for the introduction of alternative propulsion systems and fuels. The natural gas Roadmap to 2050 published by EUROGAS2 gives an outlook of the future role that natural gas might assume in the future foreseeing that the transport sector should reach 13% and 33% respectively for passenger and freight, representing a volume of 33 bcm (billion cubic metres) in 2050 (actually only 1 bcm of natural gas is used in transport).

1 European Commission, WHITE PAPER Roadmap to a Single European Transport Area Towards a competitive and resource efficient transport system 2 http://www.eurogas.org/uploaded/Eurogas%20Roadmap%202050%20-%20summary.pdf, 2011



Figure 3: Primary Energy consumption of natural gas in EU27 by 2050

In this sense a stable strategy of national incentives both on the purchase of NGVs and on the development of gas refuelling infrastructure is needed in order to ensure an adequate European NGV marked development for the achievement of the foreseen targets.

Gas Cylinders Overview

Initially the high-pressure cylinders used to store the natural gas for transport were manufactured and tested in accordance with the industrial cylinder standards, but this resulted in cylinders that were far heavier than they needed to be. Moreover with the development of high strength steel and aluminium alloys and the increasing acceptance of composite cylinder technology, authorities identified the need for standards to adopt the new materials so that lightweight, strong and safe cylinders could be approved for use.

Figure 4: Cylinder Technology



The global demand of high pressure cylinders (~8.3 mln units in 2009) for natural gas is about 2.4 millions (29% of the market) and mainly located in Asia (~46% of the market).

Figure 5: Cylinders Global Market (source: Faber Cylinders)



1 NGV Cylinder Design Standard Development In the lasts 40 years many countries has developed different standards for NGV vehicles gas cylinders. The most common and used standards, within the EU and in the world, are described below3. NZS 5454: New Zealand published the first standard dedicated to CNG service (this was mainly focused on steel). CSA B51-1995: Canada released this standard in 1991, expanded on NZS 5454 requirements by including requirements for metal-lined composite-wrapped designs based on industrials standards for transportable cylinders. After failures of composite- wrapped cylinders happened in US and Canada, it has been reissued as the CSA B51-95 standard. NGV2-2000: This standard has been developed in 1992 by US and it included different regulations (US DOT 3AA regulation for steel, the 3AL regulation for aluminum, the draft FRP-1 standard for fully-wrapped designs and the draft FRP-2 standard for hoop-wrapped design). The 4 basic types of cylinder currently used are defined within this document are the following: Type 1 metal (aluminum or steel) cylinders; Type 2 metal-lined hoop-wrapped cylinders; Type 3 metal-lined fully-wrapped cylinders; Type 4 plastic-lined fully-wrapped Cylinders. ISO11439: It has been issued in the September 2000 and it represents the required standard for "Gas cylinders. High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles". This standard is not yet adopted by any country but it is very important as a starting point from which many other national standards have been developed within various countries.

ECE R110. This regulation was issued in 2000 by the United Nations to define Uniform Provisions concerning the Approval of Specific Components of Motor vehicles using Compressed Natural Gas (CNG) in their Propulsion System. As the title suggests, this document considers all of the components in the fuelling system of Natural Gas Vehicles, including the CNG cylinders. The UNECE R110 covers specific components for vehicles using CNG and aims to ensure all components in contact with Natural Gas are tested and certified by a recognised inspection body accepted by numerous countries including the EU ones. It is important to understand the various classifications with regards to working pressure and function. These are outlined as follows.

Class 0 High-pressure parts including tubes and fittings containing CNG at a pressure higher than 3 MPa (30 bars) and up to 26 MPa (260 bars);

Class 1 Medium-pressure parts including tubes and fittings containing CNG at a pressure higher than 450 kPa (4.5 bars) and up to 3000 kPa (30 bars);

Class 2 Low-pressure parts including tubes and fittings containing CNG at a pressure higher than 20kPa (0.2 bars) and up to 450 kPa (4.5 bars);

Class 3 Medium-pressure parts as safety valves or protected by safety valves including tubes and fittings containing CNG at a pressure higher than 450 kPa (4.5 bars) and up to 3000 kPa (30 bars);

Class 4 Parts in contact with gas subject to pressure lower than 20 kPa (0.2 bars).

3 Extracted and cited from: M. Trudgeon An overview of NGV cylinder safety standards, production and in service requirements; ISO BULLETIN FEBRUARY 2001 Taking new approaches in standards-development for products for new markets - The development of ISO 11439 for compressed natural gas vehicle cylinders.



There are a number of differences between R110 and the final version of ISO 11439. The differences are not very significant, but a comparison between the two documents was issued by ISO as ISO TC58/SC3 document N1036. Ultimately there will be convergence between ISO 11439 and ECE R110, as was the original intention. The original version of the ECE R110 was issued in December 2000 with a revised version issued on March 2001. This document is used to regulate NGV cylinders in the European Union, Brazil, Argentina and other countries. As yet the USA has not adopted this UN Regulation.

FMVSS 304. In the USA cylinders used for fuel on NGV have to comply with the FMVSS 304 regulation of the National Highway Traffic Safety Administration (DOT-NHTSA).



2 Overview on CNG vehicle types, System and Components

2.1 CNG Vehicles Types

Gas Storage Categories

Natural gas is one of the cleanest burning alternative fuels. At atmospheric pressure and temperature, it has an energy content of around 40 MJ/Nm3 or 50 MJ/kg, as compared to gasoline (35 MJ/L) and to diesel (39 MJ/L). In order to reach an acceptable range, gas needs to be stored in a way that increases the energy density. There are currently three technologies for this:

CNG (Compress Natural Gas); LNG (Liquid Natural Gas); ANG (Adsorbed Natural Gas).

CNG is gas that is compressed to a pressure of usually 200-250 bar, after which it is stored in cylinders; LNG is gas that has been liquefied by cooling it to below its boiling point of -163 C (at atmospheric pressure) and subsequently stored. There are two standards for dispensing LNG, i.e., saturated LNG (8 bar and -130 C) or cold LNG (3 bar and - 150 C); ANG is a new and promising technology that is not commercialised yet. The addition into the tank of a micro porous material with adsorbent capacity (e.g. activated carbon) results in an increase of the maximum volume of gas that can be stored at the same internal pressure (which results in a higher range) or in a lower storage pressure for the same amount of gas (which means lower costs for refuelling and a higher variety of options to shape the fuel tank). ANG potentially offers a higher storage capacity than CNG with lower costs and complexity than those associated with LNG, but there are still some technological barriers that require further R&D.

CNG Vehicle Categories

CNG vehicles could be divided into the following three categories:

Mono Fuel: dedicated natural gas vehicles designed to run on natural gas/biomethane only; Bi-fuel vehicles: running on natural gas/biomethane or gasoline: since natural gas is stored in high-

pressure fuel tanks, bi-fuel vehicles require two separate fueling systems;

Dual-fuel vehicles: running on biomethane/natural gas but using diesel for ignition assist. They allow users to take advantage of the efficiency of the diesel engine but without the risk of running out of gas because of the wide-spread availability of diesel. When biomethane/natural gas is available, the dual fuel vehicle can use a cleaner, more economical alternative.

Light-duty vehicles typically operate in mono-fuel or bi-fuel modes, whereas heavy duty vehicles operate in mono-fuel or dual-fuel modes. Conventionally vehicles in which an auxiliary tank for a different fuel is incorporated, but where this fuel has a capacity not exceeding 15 litres, are also considered to be mono-fuel.

2.2 CNG vehicle Advantages/Disadvantages

The biggest advantage of CNG vehicles with respect to gasoline and other conventional-fuel vehicles is that environmentally harmful emissions are significantly reduced. Natural-gas vehicles compared to gasoline/diesel vehicles show: reduction in carbon monoxide (CO) emissions; reduction in emissions of various oxides of nitrogen (NOx); reduction in reactive hydrocarbons when compared to gasoline vehicles.



CNG vehicles also perform better in particulate matter 10 (PM10) emissions, responsible for transporting and depositing toxic material through air. CNG vehicles that operate in diesel applications can reduce PM10 emissions by a factor of 10. Other advantages of NG with respect to vehicles running on conventional fuels are: NG costs are lower than gasoline and NG prices have exhibited significant stability compared to oil prices;

NG can be easily replaced by biomethane as a renewable fuel for transport; NG vehicles make less noise.

The main disadvantages are: Less space (e.g. in the luggage compartment) than conventional (e.g. gasoline) cars because space is taken

up accommodating the CNG storage cylinders (even if, today, in most cases, vehicles have a fully integrated tank system that does not reduce the available space by avoiding this problem);

CNG vessels can be expensive to design and build since safety must be absolutely guaranteed; indeed, the costs of the cylinders is a factor contributing to the higher overall costs of a natural-gas vehicle;

Limited vehicle availability; The gas infrastructure still needs to be implemented with other gas filling stations; Fewer kilometers with a tank of fuel. Therefore, in order to provide an acceptable driving range of vehicles using NG, a compromise must be found between vehicle range, weight and cost of the cylinders in order to offer a real advantage to the customer with respect to conventional fuels.

2.3 CNG vehicle: System and Components

According to the ECE R110, the CNG System means an assembly of components (container(s) or cylinder(s), valves, flexible fuel lines, etc.) and connecting parts (rigid fuel lines, pipes fitting, etc.) fitted on motor vehicles using CNG in their propulsion system.

Figure 6: Typical CNG System (source: LandiRenzo)

Always according to the same standard, a CNG system shall contain at least the following components: Container(s) or cylinder(s); Pressure indicator or fuel level indicator; Pressure relief device - temperature triggered (fitted on the container);



Automatic cylinder valve (fitted to the container); Manual valve (fitted to the container); Pressure regulator; Gas flow adjuster; Excess flow limiting device (fitted to the container); Gas/air mixer (carburetor or injector(s)); Filling unit or receptacle; Flexible fuel line; Rigid fuel line; Electronic control unit; Fittings; Gas-tight housing: it is a device which vents gas leakage outside the vehicle including the gas ventilation hose The container shall be equipped with components, which may be either separated or combined. The CNG system may also include the following components: Check valve or non-return valve; Pressure relief valve; CNG filter; Pressure and/or temperature sensor; Fuel selection system and electrical system. An additional automatic valve may be combined with the pressure regulator. Basically the CNG fuel system transfers high-pressure NG from the storage tank to the engine while reducing the pressure of the gas to the operating pressure of the engine fuel-management system. (see Figure 7).

Figure 7: Engine fuel-management system (CRF Data)

NG is injected into the engine intake air in the same way gasoline is injected into a gasoline-fuelled engine. In fact the NG engine functions like a gasoline engine: the fuel-air blend is compressed and ignited by a spark plug and the expanding gases produce rotational forces that propel the vehicle. According to ECE R100, the main requirements for the CNG system are as follows: The CNG system shall be installed such that is has the best possible protection against damage, such as damage due to moving vehicle components, collision, grit or due to the loading or unloading of the vehicle or the shifting of those loads. No appliances shall be connected to the CNG system other than those strictly required for the proper operation of the engine of the motor vehicle.



Notwithstanding the vehicles may be fitted with a heating system to heat the passenger compartment and/or the load area which is connected to the CNG system. The heating system shall be permitted if, in the view of the technical services responsible for conducting type-approval, the heating system is adequately protected and the required operation of the normal CNG system is not affected. No component of the CNG system, including any protective materials which form part of such components, shall project beyond the outline of the vehicle, with the exception of the filling unit if this does not project more than 10 mm beyond its point of attachment. No component of the CNG system shall be located within 100 mm of the exhaust or similar heat source, unless such components are adequately shielded against heat. Regarding cars, the cylinders can be fixed directly on the chassis, or fixed on a frame which is then connected to the chassis.

In order to illustrate the variation in the solutions for accommodating the pressure vessels on-board CNG vehicles adopted by different car manufacturers, Errore. L'origine riferimento non stata trovata. illustrates three different configurations of vessels and fixings of the tanks which are used on different, commercially successful, currently produced vehicles including B- and C- segment cars and an MPV (multipurpose vehicles).

Figure 8: Different solutions for mounting CNG vessels adopted by different production cars



3 Commercially available CNG vehicles

3.1 Focus on UE Market

According to Directive 2007/46/EC concerning type approval of vehicles, all petrol/gas vehicles having a petrol tank not exceeding 15 litres should be classified as mono-fuel and beyond this value the classification will be bi-fuel. However, Regulation (EC) No 443/2009 of the European Parliament and of the Council says that "in the case of bi-fuelled vehicles (petrol/gas) the certificates of conformity of which bear specific CO2 emission figures for both types of fuel, Member States shall use only the figure measured for gas". Also Commission Regulation (EU) No 1014/2010 of 10 November 2010 on "monitoring and reporting of data on the registration of new passenger cars" pursuant to Regulation (EC) No 443/2009 obliges Member States to treat mono-fuel and bi-fuel vehicles as natural gas vehicles (also important for fiscal treatment of these vehicles). 'Flex-fuel' means that up to three different types of fuel can be used. Pictures below show available models on UE market for cars, vans, buses and trucks.

Figure 9: NGV available on the market-Cars (CRF elaboration on NGVA Data)



Figure 10: NGV available on the market - VAN (CRF elaboration on NGVA Data)



Figure 11: NGV available on the market Buses (CRF elaboration on NGVA Data)

Figure 12: NGV available on the market Trucks (CRF elaboration on NGVA Data)

3.2 Focus on UK Market

The UK market is focusing on natural gas for use in commercial vehicles and it is characterised as follows:

There are 3 types of vehicles, namely dedicated CNG, dual fuel (diesel-natural gas) and bi-fuel (natural gas with petrol standby);

There are 2 forms of gas storage on the vehicle - compressed or liquefied; With the compressed system there are 2 different pressure regimes (250 bar or 200 bar); There are 4 possible types of fuel:

natural gas out of the gas grid; compressed biomethane coming from AD plant;



liquid biomethane from AD plant or landfill; natural gas from the grid but coupled with Green Gas Certificates.

In the UK, the economics of biomethane injection into the grid is good compared to direct use of biomethane as a vehicle fuel and in addition, the grid allows flexibility of filling with gas. The capital expenditure (capex) and operating expenditure (opex) associated with liquid biomethane from AD are very high and it is not believed there are any such projects underway in UK.

Original Equipment Manufacturers (OEM) Produced Vehicles

OEMs offer standard factory service and warranties for their NGV products. Dedicated or bi-fuel natural gas vehicles, including vans, trucks, and passenger cars are available from major auto manufacturers like Fiat (Iveco), Mercedes, GM (Opel/Vauxhall), and Volkswagen (VW) and a number of bus manufacturers. There are no CNG cars currently available in the UK, though there are more than 20 models available in the EU from Mercedes Benz, VW, Opel (Vauxhall), Fiat, and Volvo. MAN and Scania are also believed to be bringing dedicated CNG trucks to market in the 16 - 26 tonne range. OEM produced vans in the UK may be purchased from VW (Caddy), Iveco (Daily), and Mercedes Benz (Sprinter). These are bi-fuel the vehicle runs on CNG but if CNG runs out they run on petrol. For trucks the OEM vehicles are Mercedes Benz (Econic) and Iveco (Stralis). These vehicles are available in either tractor unit or rigid configurations and MAN are believed to be bringing their dedicated CNG truck engine into the UK market. In the bus market there is now a vehicle available from MAN and Scania with other potential CNG buses and CNG-hybrid buses including one made by Tata and approved for sale in EU.

Figure 13: UK Methane Vehicle Market overview

Vehicle Conversions

In addition to the OEM products, almost any petrol-fuelled vehicle can be converted to operate on natural gas (usually bi-fuel). Whilst petrol cars can be converted to run on natural gas and millions have been converted in South America and Asia, no companies in the UK are currently converting petrol cars to CNG. This is largely due to the absence of CNG refueling stations in the UK.



Diesel vehicles can also be converted to operate on natural gas. Diesel conversions are usually dual-fuel. In a dual-fuel vehicle, an amount of Diesel fuel is injected into a natural gas/air mixture to trigger the ignition of the fuel mix. In the truck market there are 3 dual fuel options available in the market place as aftermarket conversions along with two OEM approved vehicles. In the OEM market both Volvo and Mercedes Benz offer dual fuel (diesel/natural gas) vehicle platforms. The Volvo system is factory fitted and initially is LNG based, with potential for a CNG storage option from 2013. The Mercedes Benz is an approved conversion of its Axor and Actros trucks carried out by Hardstaff Group, available as either LNG or CNG. The dual fuel conversion companies operating in the UK market are Clean Air Power, Hardstaff Group, and Prins, with customers including Sainsburys, GIST, Warburtons and Tenens. The market leader in terms of sales in the Mercedes Benz Axor with Hardstaff conversion and this is believed to give around 55- 60% substitution of diesel with natural gas. The list of dual fuel trucks on sale in UK is below:

Figure 14: Dual fuel trucks - UK Market

3.3 Focus on Italian Market

Italy, with a very long tradition concerning the use of CNG vehicles, is still the absolute European leader with more than 750,000 CNG circulating vehicles by mid 2011, meaning an increase of + 12% compared with end of 2009.



Figure 15: CNG stations and car fleet in Italy

Figure 16: Italian Methane Vehicle Market (Source: ACI)

This high number is mainly composed of private cars and vans, which can be refuelled in any of the 900 public refuelling stations spread over the country. The number of NGVs has reached this significant level over the last 30 years, as a result of the following factors: - The availability of the small and medium-sized cars and their commercial ex-factory CNG versions; - The savings in fuel costs per Km which can reach up to 60% if compared with an equivalent petrol engine

and 33% if compared with a diesel version; - The adoption in some Italian regions of measures and economic incentives for NGVs such as the

exemption/reduction of vehicles tax for CNG and LPG cars, the economic incentives for the purchase of



new CNG cars and the conversion of traditional refuelled vehicles to CNG, free parking in some areas. This system of incentives has been stopped in the last two years, negatively affecting the very recent development of CNG market in Italy.

The availability of more new car models with ex-factory CNG options is pushing the growth of the NGV market share further. On the commercial vehicle side, Italy counts some 1,200 CNG trucks, mainly operating in garbage collection services, and 2,300 urban buses. In the Trentino Province there were at the end of 2009 about 3,000 vehicles running on natural gas (Figure 17) .

Figure 17: Trentino Methane Car Fleet (Source: ACI)

3.4 Focus on Swedish market

The first filling station for CNG and the first CNG vehicles on the Swedish market were introduced in 1995. One year later, in 1996, biogas was upgraded into biomethane and started being used in vehicles. In the years after 1996 the share of biomethane in the CNG increased and in 2006 biomethane stood for more than half of the volumes of sold CNG on the Swedish market. At the end of 2011 there are over 180 CNG filling stations and a total of about 39,000 vehicles running on CNG in Sweden of which about 60 % is biomethane. Out of these vehicles about 1,500 are buses, 550 heavy duty vehicles and the rest is personal cars and vans.



Figure 18: CNG Swedish Vehicles and Filling Stations (Data from Energigas Sverige and SCB)

Although a quite high increase in CNG vehicles, the last years they only stand for less than 1% of the total vehicles running in the country. When looking at regional figures there are 24 public CNG filling stations and about 5,000 personal cars running on CNG in the Skne region, which is also about 1% of the total number of personal cars in the region. In 2011, 2,5% of the new CNG cars were CNG cars. A majority of the buses used for public transportation in Skne are CNG buses. The actor responsible for the public transport in Skne, Sknetrafiken, have taken a strict policy for changing their entire fleets into fossil free vehicles and their main choice for road transports has been CNG vehicles running on biomethane. All of the vehicles in the city bus fleets have been changed into CNG buses and about half of the inter-city buses are now driven on CNG. Also a big share of the waste refuse vehicles in the region is CNG-vehicles. There have been different drivers for increasing the number of CNG vehicles in Sweden. The most important factors are:

Lower price on CNG than other fuels - CNG price is about 20% lower than petrol.



National clean vehicle definition - this definition was introduced in 2006 and is often used as a guideline for public actors when they purchase vehicles. Reduced fringe benefit tax Drivers who choose to use CNG-vehicles as their company official car gets a reduced fringe benefit tax with -40%.

Reduced environmental impact CNG vehicles, particularly when driven on biomethane has lower negative environmental impact both when it comes to emissions giving negative impact locally, regionally and globally.

Conversion of vehicles into CNG vehicles has not become a big business on the Swedish market, probably because of the relatively low fuel cost advantage for CNG compared to petrol and diesel and also because of a relatively good range of available OEM vehicles. Therefore the majority of vehicles sold on the Swedish market are OEM made from the main manufacturers of CNG vehicles for the European market: Fiat, Mercedes Benz, Iveco, Opel, Subaru, Volkswagen and Volvo. The CNG vehicles from Volvo and Subaru are actually being converted/ retro fitted with CNG equipment in house with full warranties and are sold at the ordinary Volvo and Subaru car dealers and can therefore be seen as OEM products.

3.5 Focus on Polish market

In Poland, the process of adaptation of law to the requirements in force in the EU has already been implemented. Nowadays, in 20 Polish cities operate the total of 310 CNG-powered buses that operate in the fleet of 22 carriers. In the greater majority, these are Poland-produced Jelcz buses with additional CNG installation, second-hand Volvo vehicles imported from the countries of Western Europe, and Solaris buses with manufacturers installation (Figure 19). Krakow city transport is returning to the use of CNG and in this city, 5 buses are gas-powered.



Figure 19: Most Common Polish CNG Public Vehicles (CRF elaboration on NGVA Data)

Poland has a small number of refuelling stations, i.e., only 30 for 2,000 vehicles (see Figure 20). It also has a small offer of NGV vehicles compared to other European countries. The manufacturers offering CNG-powered vehicles include, among others, Citron, Honda, Fiat, Ford, Mercedes, Opel, Peugeot, Volvo and Volkswagen.

Figure 20: Number of NGV vehicles in Poland (Source: cng.auto.pl)



4 Standard storage In general there is a common categorization of NGV cylinders used across the major NGV safety standards and 4 basic types of tank designs might be adopted by taking into account the following criteria4: Design depends on need to reduce weight and costs: all designs have equivalent safety, as all meet

requirements of the same standards; Design type can also determine how a tank may be handled and how it may be filled.

The main types of cylinders are represented in the figure below:

Figure 21: Type of Tanks: most common used materials

Figure 22: Cost/Weight Comparison

4 Extracted and cited from: M. Trudgeon An overview of NGV cylinder safety standards, production and in service requirements, 2005; Livio Gambone, P.Eng., CNG Cylinders 101 NG Transit Users Group Webcast September 5, 2007; FABER CYLINDERS - Presentazione per Workshop ISTUD Mediobanca - Stresa, 19 novembre 2010; http://cng-times.com/2011/12/19/f250-powerstroke-natural-gas-conversion-project- pt-2/



The relative roles of metal and composites in the four designs can be understood by comparing the portion of the pressures retained by the liner and by the overwrap (Figure 23).

Figure 23: Roles of metal and composites for different Cylinder Types

In Type I all of the internal force is contained by the metal. In Type 2 and 3, the metal and composite share the pressures. The difference between the two is the coverage of the fiberglass overwrap. Type 2 covers the center of the cylinder only, while Type 3 wraps the entire cylinder. Type 3 will have a significant decrease in the metal liner thickness. Type IV is a full composite cylinder with no metal, except for the end boss for the valve. In Figure 24 a cost/weight evaluation of the different vessel types is shown.

Figure 24: Cost/weight comparison - Different vessel materials

There are several different production processes of the different vessel types as shown in the figure below:

From metal sheet/tube/billet: cylinders of Type I; From different available composites processes: cylinders of type II, III, IV.



Figure 25: Production Processes (Source: Faber Cylinders)

4.1 Type I CNG Cylinders - All Metal

The type I includes steel cylinders, welded steel cylinders (in this case a higher safety factor is required) and aluminium cylinders that are a lightweight alternative.

Figure 26: Type I Cylinders: Examples

The most common materials used for Type 1 Cylinders is steel as shown in the figure below:



Figure 27: Type I Cylinders: Standard Steel used

Among the main suppliers of Type I cylinders there are Faber, Chesterfield cylinders, Tenaris, Gas container services and Vitkovice Milmet s.a.

4.2 Type II CNG Cylinders - Hoop Wrapped Composite

Type II cylinders are made of metal liner reinforced with composite wrap (either glass or carbon fiber) around the middle of the cylinder ("hoop wrapped"). The liner and the composite each take 50% of the stress caused by internal pressurization. These cylinders are lighter (-35%) and more expensive compared to Type 1 cylinders, but heavier (and less expensive) than Type 3 and 4.

Figure 28: Type II Cylinders: Examples

Among the main suppliers of Type 2 containers there are Faber, Mannesmann, and Luxfer.

4.3 Type III CNG Cylinders - Fully Wrapped Composite with Metal Liners

Type III cylinders have a metal liner reinforced with composite wrap (either glass or carbon fiber) around the entire tank ("full wrapped"). These tanks are lightweight, but more expensive than Types 1 or 2. Type 3 cylinders are used in a wide range of applications where weight reduction is important, for example in transit buses and delivery trucks.



Figure 29: Type III Cylinders: Examples

In the type III the whole tank is wrapped, including the ends, instead of just the middle as for the type II and this is very important for the mechanical properties of the structure. The most common suppliers of Type 3 containers are Luxfer, Dynetek, and Structural Composites, Inc.

4.4 Type IV Cylinders - Fully Wrapped Composite with Non-Metallic Liners

Type IV cylinders are made of plastic gas-tight liner reinforced by composite wrap around the entire tank ("full wrapped"). The entire strength of the cylinder is composite reinforcement. This is the most lightweight the most expensive tank in comparison to Types 1, 2 or 3.

Figure 30: Example of a high-pressure CNG Type IV cylinder for heavy-duty trucks

(Quantum Fuel Systems Technologies Worldwide Inc.)

The suppliers of Type 4 containers include Quantum, Ullit and Lincoln.

4.5 Other components

Valves and Accessories

According to ECE R110, the accessories that must be fitted on the cylinder are:

Automatic valve which shall be operated such that the fuel supply is cut off when the engine is switched off, irrespective of the position of the ignition switch, and shall remain closed while the engine in not running;

Manual valve which must be rigidly fixed to the cylinder and which can be integrated into the automatic cylinder valve;

Excess flow limiting device which is a valve that automatically shuts off, or limits, the gas flow when the flow exceeds a set design value (~_P0.2 MPa);



Pressure relief device (PRD) which is the pressure relief device (temperature triggered) fitted to the fuel container(s) in such a manner that can discharge into the gas-tight housing (if present); the pressure relief device shall be so designed to open the fuse at a temperature of 110 10 C;

Pressure relief valve-discharge valve which is that device that prevents a pre-determined upstream pressure being exceeded; the pressure relief valve shall be so designed as to withstand a pressure of 1.5 times the operating pressure (20 MPa);

Additional Safety Tap (optional) so that, if a solenoid valve is damaged or otherwise becomes inoperative, the safety tap allows safe venting of the cylinder so that the valve can be removed for servicing or replacement.

Figure 31 illustrate two examples of production cylinder valves which integrate the required function listed above.

Figure 31: Example of a series-production cylinder valve



Figure 32: Example of a series-production cylinder valve (OMB Vega)

Pressure regulator and control unit

The pressure regulator and control units govern the pressure of the gas supplied from the CNG storage system as a function of the engine demand in terms of pressure, flow rate, etc. Pressure regulators can be classified in terms of the type of actuation (piston, membrane) and of the number of pressure change stages (single or double stage). Figure 33 illustrates two examples of single-stage pressure regulators.



Figure 33: Schematic illustration of CNG pressure regulators

a) Piston-type, single-stage; b) Membrane-type single-stage

The pressure regulator is controlled via a control unit capable of converting different signals: e.g. the low sensor pressure in the rail, the engine load, pedal position etc. Apart from performance, reliability and control stability, the optimisation of the design of pressure regulators focuses on reducing the weight and costs. Of significant interest and relevance is the development of electronically-controlled pressure regulators which may also have applications for vehicles which either use H2-CH4 blends.



5 Innovative storage systems

5.1 Cryogenic/liquid storage

Liquefied natural gas (LNG) is gaining in importance as an alternative to conventional vehicle fuels (gasoline and diesel). The EU document The revision of the trans-European energy network policy (TEN-E) (October 2010) underlines the key-role that LNG will assume in next future especially for security purposes in terms of storage capacity. Because LNG consists of cryogenic liquid methane stored and transferred under pressure, its use as a vehicle fuel presents technological challenges different from those associated with conventional fuels. LNG temperatures typically range from -120 to -170 C, and pressures typically range from 0.17 to 1.7 MPa5.

Figure 34: LNG Composition (source: Internet)

LNG shows several advantages: It is a very high quality product; 1 litre LNG = 600 lt. about methane gas at standard conditions; 1.8 litre of LNG is needed to meet the equivalent autonomy as using 1 litre of diesel oil for which 5 lt of

CNG compressed at 200 bar would be required; The LNG has a weight equal to about 45% of the weight of the water, is odourless, colourless, non-

corrosive nor toxic; Having been subjected to a liquefaction process, does not contain H2O, CO2, or condensable, therefore, has

energetic qualities that best correspond to a Higher Heating Value (HHV), representing approximately 10,000 Kcal/m3.

One of the challenges that present itself to anyone managing an LNG refuelling station and a fleet of LNG vehicles is the selection and maintenance of the optimum saturation pressure in the station tank and in the vehicle tanks. The saturation pressure is the pressure at which the cryogenic liquid boils to vapour in the tank. Lower saturation pressure corresponds with lower storage temperature. Thus, the term saturation pressure describes the temperature of the cryogenic liquid. The lower the storage temperature, the longer the hold time (that is, the longer the fuel can be stored before it becomes so warm that the pressure relief valve vents vapour to prevent overpressure). Also, lower storage temperature corresponds with greater fuel density. As much as 40% more fuel can be stored in the same volume if the saturation pressure is very low (about 0.17 MPa, very cold fuel), compared with warmer fuel at a saturation pressure of about 0.83 MPa. An additional advantage is

5 https://inlportal.inl.gov/portal/server.pt/community/natural_gas_technologies/437/on-board_pressure-building_device/4369



that a very cold fuel facilitates the filling process at the fuelling station. The introduction of very cold fuel from a station tank into a relatively warmer vehicle tank causes the methane vapour in the vehicle tank to collapse to liquid, reducing the pressure there and making the vehicle tank easier to fill.

Figure 35: Cryogenic Vehicle Storage Tanks (source: Internet)

The strategy of filling the vehicle tanks with very cold fuel, however, has the disadvantage of sometimes subjecting the engine to fuel starvation. The engines fuel control system expects the fuel (methane vapour) to be delivered to the engine at a pressure of about 0.48 to 0.83 MPa, more or less, depending on the manufacture of the system. At pressures lower than this, the engine is likely to suffer from fuel starvation during acceleration or when operating against a heavy load. If the vehicle tank is filled with very cold (0.17 MPa saturation pressure) fuel, it is very likely that the gauge pressure will be at or near 0.17 MPa at times during the first few days after refuelling, low enough to cause fuel starvation The disadvantage, however, is the high cost of cryogenic storage on vehicles and the major infrastructure requirement of LNG dispensing stations, production plants and transportation facilities. LNG has begun to find its place in heavy-duty applications in places like the US, Japan, the UK and some countries in Europe.

LNG Filling Stations

LNG filling stations supplying long-distance heavy vehicles equipped with cryogenic tank on board (since it is impossible for these to use methane CNG vehicles because of excess weight and dimensions of the cylinders on board). LNG stations can also be built with a possibility to fill up vehicles with CNG this layout is called LCNG. The gas is stored in a LNG tank connected to two different dispensers. LNG can be fuelled directly in a LNG-dispenser or evaporated and pressurised in a CNG-dispenser. The evaporation process is driven by the energy in the surrounding air, so no energy has to be added to the process. With LCNG-stations fleets of personal cars can be reached with CNG in areas with no gas grid or local biomethane production.



Figure 36: LNG Stations (source: Vanzetti engineering)

The main advantages of this type of fuelling stations are:

Significant mass and space reduction on board vehicle; Reduced noise level; Significant increase in range; Accessibility to urban areas; Net saving on fuel station; Saving on fuel costs (30% less than diesel);

Excellent solution for private distributor / fleets; In Europe, there is a Program for the development of European LNG Blue Corridors).

Figure 37: LMG Blue Corridors Project

Within this project four initial pan European routes are defined with strategically placed LNG filling stations that would allow the heavy, long distance truck transport throughout Europe: Portugal-Spain to France, Netherlands, UK and Ireland; Portugal-Spain to France, Germany, Denmark, Sweden; Mediterranean arch to Italy and with another branch to Croatia; Ireland-UK to Austria.



5.2 Methane/hydrogen blend storage

Vehicle manufacturer (as for example Iveco) is testing with hydro-methane fuelled vehicles. This is a blend of two gases, methane (or bio-methane) and hydrogen (30%), which provides further CO2 emissions reductions.

Figure 38: CO2 Additional Reduction

From the viewpoint of the compatibility of the materials, it is well known that the presence of hydrogen could cause some embrittlement phenomena with aging.

Figure 39: CNG/H2 Blends: Vehicles System (source: LandiRenzo)

Hydrogen may diffuse into materials and change their mechanical properties. For example, hydrogen embrittlement of steel, leading to an accelerated growth of micro cracks, is a well recognised phenomenon. Hydrogen may also diffuse through polymers resulting in a significant loss of hydrogen. The compatibility of the most common materials with hydrogen is shown on the figure below.



Figure 40: Fatigue Cracking Phenomena and material compatibility

This may affect the integrity of the system and could also have an impact on safety.

Figure 41: Utilization of H2/CH4 Blends: Impacts on vehicle

For these reasons, even if a smoothing effect is expected thanks to the partial pressure of hydrogen in the blend, an exhaustive overview of the problem based on laboratory and durability test is needed. It is recommended to use materials with good resistance to embrittlement phenomena, mainly the parts directly and permanently in contact with blend such as gas tank (to be noted that presently used CNG Type 1 steel cylinders are not approved to handle H2 contents above 2%), pipes, fuel rail, and some details of pressure regulators and injectors.



5.3 Adsorbed NG Technology

Adsorbed Natural Gas (ANG)6 technology stores natural gas and/or biomethane, in special micro-porous material placed inside the vessel. These are sponge-like materials containing tiny nanometer sized spaces within their structures.

Figure 42: Energy contained in a tank: comparison (Elaborated Image of Chris Wilmer)

The energy contained in a tank of gasoline is significantly greater than the one in a tank of the same size filled with methane at atmospheric pressure (Figure 42). The energy density for the natural gas tank can be improved by increasing the pressure and/or filling the tank with a "spongy" material such as a metal-organic framework. Traditionally microporous materials have either been classified as the following:

Inorganic (mineral like materials such as zeolites); Carbon based (including activated graphite and carbon nanotubes for example).

This material acts as a sponge to adsorb natural gas/biomethane. ANG technology enables to store similar gas quantities as CNG under much lower pressure (40-50 bars) and decrease dramatically filling station capital and operation costs as well as reduces NG end-user cost. In addition this method opens new possibilities for non-cylindrical tanks application. Alternatively ANG in combination with higher pressure enables to increase the driving range of NGV or to reduce the size of NGV tank. Adsorbed Natural Gas (ANG) storage technology has quite a few promising advantages over both CNG and LNG. Concerning the technical aspects, The volumetric efficiency of ANG storage tanks is measured by volumetric ratio. LNG, being a lower-pressure liquid, is the most volume efficient natural gas storage option and has volumetric ratio about 615 V/V, i.e. 615 Normal cubic meters (litres, etc.) of gas are stored in one geometrical cubic meter (litres, etc.) of the storage tank. Compressed natural gas (CNG) has a volumetric ratio of 200 V/V.

6 Extracted and cited from: Prof. Y. Ginzburg, ANG Storage as a technological solution for the chicken and egg problem of NGV refueling infrastructure development 23rd World Gas Conference, Amsterdam 2006; http://www.sigmascan.org/Live/Issue/ViewIssue/443/5/metal-organic-frameworks-new-materials-without-limits/; http://newenergyandfuel.com/http:/newenergyandfuel/com/2012/05/04/a-new-break-into-carbon-dioxide-capture/mof-example-texas-am/; http://www.jptonline.org/index.php?id=1478



Generally the goal of ANG product developers is to achieve a similar volumetric ratio. The combination of adsorption and higher pressure makes it possible to increase the volumetric storage ability of ANG and bring it even to higher levels than that of CNG. In addition, low-pressure ANG tanks open new possibilities for tank designs of various forms and configurations instead of the cylindrical form of CNG high-pressure tanks. Thus, tanks could be tailored to fit odd spaces, similar to todays gasoline/diesel tanks. A non-cylindrical tank gives a significant advantage for small vehicles from a volumetric efficiency standpoint. For example, rectangular shell gives an additional 25% volume (see also in Figure 43, the green is rectangular ANG tank whereas the red is CNG cylindrical tank). This could be very important respect to the vehicle architecture and could enable innovative eco-vehicle design with optimized space utilization.

Figure 43: ANG Tank Free-shape Potential Advantage

Up to now the commercialization of ANG method was hindered due to several unsolved technological problems. The main challenges of ANG storage products development are:

Sufficient volumetric storage ability (that will be competitive with existing NG storage methods); Efficient gas filling and release from ANG tank for automotive application (this requires the control of

thermo-dynamic processes);

ANG fuelling system cost should be competitive with the cost of existing fuelling systems. ANG technology has to become comparable to already on the market NG storage systems (about costs, efficiency and so on). A re-fuelling infrastructure development has to go hand in hand with the increasing diffusion of adsorbed NG technology. It would be necessary to go beyond the traditional filling systems and to develop innovative cost efficient refueling patterns. Attempts to develop ANG automotive fuel system was done by several organizations during the last decade all over the world. Among them we would like to mention the following: AGLARG (Atlanta Gas Light Research Group, USA), Brazilian Gas Technology Center (CTGS), HONDA Research Company (Japan), LEVINGS (EU-FP5 funded project), Oak Ridge National Lab (ORNL, USA), Osaka Gas Company (Japan), University of Alicante (Spain), UNIVERSITY OF PETROLEUM (China).



Figure 44: Comparative characteristics of some ANG projects

Based on state of the art study the following short conclusion can be made: Max. V/V reached up to the present is 150, with prohibitively high cost of sorbent; Sorbents with more or less acceptable cost provide V/V=120-130,

All existing tanks were based on multicell concept that requires a sorbent block with high mechanical strength;

Due to the presence of buffer gas the volume of tank delivery is 15% less than tank uptake;

All tanks made up to the present do not include any active thermal management systems High-pressure ANG storage was researched much less than low-pressure ANG; The combination of adsorption and low-temperature storage was almost never researched. The solutions to these problems can be grouped around two aspects:

Adsorbent material with sufficient gas storage ability that is inexpensive enough to meet the requirements of automotive application

Effective design of a pressure vessel including thermal management abilities The first issue concerns with the maximization of the sorbent ability for gas uptake. All mentioned ANG projects considered activated carbon as the most suitable. Primarily it is supplied in powder or granules and needs to be compacted.

5.4 Metal-organic frameworks (MOF)

In the field of microporous materials, metal-organic frameworks or MOFs are hybrid organic-inorganic materials. MOFs contain metal atom nodes connected by organic linker units to give one-, two- or three



dimensional infinite-network structures. As well as being highly robust these regular crystalline networks or scaffolds are highly flexible and can contain a large amount of empty-space or porosity within them. Crucially, judicious choice of the metal and linker units can be used to tailor the architectural, chemical and physical properties of the resultant MOF. This has allowed scientists to prepare MOFs with some truly remarkable properties, including world-record breaking surface areas up to the area of a standard football pitch per gram of material! MOFs are currently at the forefront of research into new fuel-tanks for hydrogen and methane gas, carbon dioxide capture and storage, and as new more efficient, more selective, greener catalysts.

Figure 45: An example of a metal-organic frameworks (MOF)

(Assembled in Dr. Hong-Cai Joe Zhous lab. - Texas A&M Dep. of Chemistry)

MOFs are materials that can store different types of gas, as for example: Hydrogen in its molecular H2 form: although MOFs have been reported with high hydrogen storage

capacities, they require an additional cooling mechanism: recent breakthroughs indicate that MOFs with increased operating temperatures are not far away;

Methane: some MOFs have been shown to readily store large amounts of methane at room temperature. The record for the highest methane storage capacities ever measured for any kind of material is held by a MOF;

Carbon dioxide is also suited to storage within MOFs at ambient temperatures. This has led to speculation that MOFs can be used for the removal of carbon dioxide from the flue exhausts of power plants, currently a major source of emissions. At present carbon dioxide removal is usually undertaken by either passing the exhaust fumes through a fluidized bed of aqueous amine solution or by chilling and pressurizing the gases, both of which are costly and inefficient processes.

Commercial and industrial applications of MOFs require these materials to be prepared on much larger scales than the laboratory based syntheses currently employed. BASF is one company working on scaling up MOF production. The industrial preparation of MOF materials can be achieved by adaptation of conventionally available precipitation and crystallization manufacturing methods. This means that the capital investment required for MOF production is comparatively small when compared to other competing new technologies. Over the next 5-10 years innovations in MOF chemistry can be expected to lead to significant improvements in



their gas storage and catalytic properties as well as new applications with potential academic and industrial significance. It is not unfeasible that we will see MOFs playing a major role in the future value-added growth of industrial companies and society within the next decade. Applications of MOFs which have seen particularly rapid advancements include:

Storage of hydrogen gas for hydrogen powered automobiles and portable electronic devices Storage of methane gas for methane fuelled automobiles and portable electronic devices Carbon dioxide removal from the flue exhausts of power plants

There is a strong economic and social benefit towards the realization of new technologies in each of these above areas. Given current climate change fears and also the limited remaining world stocks of accessible petroleum oil, a move from a petroleum based society to one based on cleaner and greener fuels such as hydrogen or methane gas seems inevitable. New technologies such as MOFs will be key in facilitating this transition. There are significant economic advantages for the UK to be at the forefront of these new emerging technologies. In addition, the ability of the UK Government to meet its future climate change commitments, and indeed the future development of society, will be dependent on new green technology advances such as those promised by MOFs. In addition to these well-established gas-storage applications, MOFs have many other potential uses of scientific and economic benefit including: gas purification; gas separation; anion exchange; sensors for small molecules; phosphors; novel conducting and magnetic materials; structural templates for the formation of nano-wires and other shapes of diverse materials; drug delivery agents. There is an almost infinite number of possible combinations of inorganic metal nodes and organic linkers that can be connected together to generate MOFs materials thus leading to a myriad of potential applications, many of which are as of yet unimagined. There are already existing MOFs on the market but hydrogen storage techniques (at lower temperatures) could be a limiting factor7.

7 Prof. Y. Ginzburg, ANG Storage as a technological solution for the chicken and egg problem of NGV refueling infrastructure development 23rd World Gas Conference, Amsterdam 2006.



6 Benchmarking on vessel suppliers available in UE Countries A benchmarking about UE vessel suppliers has been done and all the available data regarding them has been collected into the table shown in Figure 46.

Figure 46: UE Cylinder Suppliers



In order to choose the most appropriate gas cylinder, an important parameter to be evaluated is potential light weighting. This is defined by the ratio Kg/l that gives an idea of how much fuel could be stored in the system for every kilo of weight. This number is function of the vessel material and generally is higher for the more innovative materials (Cylinder type III). As an example, a cylinder of 140 l of capacity is shown in Figure 47.

Figure 47: CNG Cylinders Comparison (Faber Source)

Figure 48 provides a general comparison of the different types of CNG vessels in terms of weight and cost per litre of gas stored.

Figure 48: CNG cylinder types compared in terms of weight and cost per litre stored



7 Conclusions Natural gas and biomethane are an immediately available alternative to oil in transport which would highly contribute to the achievement of the EU targets both for the reduction of the GHG and for the increase of the share of alternative and renewable fuels in transport (EU Directive 2009/28). In Europe the use of biomethane is still in the initial stages with respect to vehicle transport, but there are well-intentioned pioneers like for example Sweden, The Netherlands, Austria, Germany and Switzerland, where about a third of the natural gas used in the transport is biomethane. In many countries, a methane filling infrastructure already exists and the natural gas industry invests in a good coverage. CNG vehicles can function with either natural gas or biomethane on the condition that they meet the product specifications to be defined nationally and/or internationally. Various scenarios of development and manufacture CNG pressure vessels have been discussed and all the CNG pressure vessels (CNG-1 TO CNG-4) had their own advantages and disadvantages. The cost of manufactured and material will increased from type-1 to type-4. New solution, manufacturing process or material should be used to reduce the cost following the international standard characteristics. Not only costs but also reliability and life span of tank must be considered to developed economical and reliable tanks. In a conventional mid-size passenger car, about 20 kg of methane can be stored in under-floor vessels with nowadays storage technology at 200 bar filling pressure. This is roughly equal to the chemical energy content of 30 litres of gasoline. To achieve a sufficient range, the vehicle has obviously to be as efficient as possible. With today solutions, available passenger CNG cars or light commercial CNG vehicles achieve a range of around 300 km which is sufficient for many applications. However, one major goal in the R&D of methane vehicles is the enhancement of the range of the gas that can be stored to weaken their disadvantage compared with liquid fuel driven vehicles. An increased range can be achieved with different measures but in particular with the development of innovative storage systems that will allow to increase storage volume onboard of the vehicle and to increase the filling pressure.



References

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board_pressure-building_device/4369

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materials-without-limits/



19. http://newenergyandfuel.com/http:/newenergyandfuel/com/2012/05/04/a-new-break-into-

carbon-dioxide-capture/mof-example-texas-am/

20. http://www.jptonline.org/index.php?id=1478

21. William Harris, How Natural-gas Vehicles Work

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development GasHighWay final seminar Brussels, 1st March 2012

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(Centro Ricerche Fiat), Position Paper: Natural Gas Hydrogen Blends Technology - NGVA Europe

A position paper of NGVA Europe

d5 2 final version

Documents

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cng vehicle types

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