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OFD-Chapter2-H2-Applications

Hydrogen Applications

Introduction

Hydrogen applications, or end-use technologies, can be grouped by sectors:

  • Transport
  • Stationary (industrial and residential)
  • Portable

Transport applications, especially cars and buses, seem to be of highest priority but due to stringent performance and cost targtes, significant market penetration is not likely to occur before two decades. Stationary applications are not believed to play a relevant role for the hydrogen energy consumption in Europe before 2020 neither. However there could be significant development of niche markets in transport, stationary, and portable applications, which would positively contribute to further technological progress and public acceptance, despite their marginal impact on the total energy use.

Hydrogen can be used to power vehicles my means of internal combustion engines (ICEs), fuel cells (FC) or gas turbines. FCs have a higher useful energy conversion efficiency than simple ICEs and they are therefore often used in automotive applications. ICEs are, however, well established technology that is relatively easy to convert from conventional liquid fuels to hydrogen, so some car manufacturers are also working on ICEs specifically for hydrogen. Gas turbines are today much too large to be used in road vehicles, but there are R&D development in countries including Germany and the USA aiming at developing smaller units, which when used with other energy conversion technologies in hybrid cycles, might improve the effectiveness (RisoEnergyReport:3:2004).

Like any vehicle the driving range of a hydrogen vehicle depends on the amount of fuel, in this case hydrogen, that it can carry. Hydrogen has a lower volumetric energy content, especially in the gas phase, than conventional fuels such as gasoline, and storage of hydrogen on the vehicle is therefore a challenge. The storage system itself also includes a considerable weight and volume – thick walled vessels needed for gaseous high pressure storage (pressure 250 – 700 bar) or insulation and a boil-off management system for storage of liquefied hydrogen at cryogenic temperatures, see also figure 1. Several large R&D projects are in progress to solve these challenges and to address alternative solid storage techniques, e.g. metal hydrides. The low volumetric energy content and the limited infrastructure for hydrogen refuelling has also encouraged vehicle manufacturers to study the use of more conventional liquid fuels (e.g gasoline and methanol) that can be converted to hydrogen-rich gas mixtures by a “fuel processor” in the vehicle. However, it seems as if most vehicle manufacturers today focus on direct use of hydrogen for propulsion, and for most projects gaseous hydrogen is used instead of liquid hydrogen. Fuel processing may have a more significant role to play as auxiliary power units (APU) in, for example trucks.

For on-board reforming in Fuel cell vehicles, methanol has been considered because it operates at lower temperatures and is more tolerant to intermittent demand. Gasoline or LPG reforming would even be more practical, since this infrastructure is already existing and could allow the introduction of respective vehicles even at a lower number. R&D activity on on-board reforming for passenger vehicles has significantly diminished in consideration of the intrinsic complexity and cost compared to the limited impact on CO2 emissions compared to direct use of hydrogen. Still on laboratory scale, but highly promising is the OTM (Oxygen Transport Memebrane) technology.

References:

Riso National Laboratory (2004) Riso Energy Report 3. {\tt http://www.risoe.dk/rispubl/energy\_report3/ris\-r\-1469.pdf}.(BibTeX)
!!! Transport From 1967 to 2003 about 110 FC powered prototype cars and light trucks have been developed world-wide as well as some 36 ICE cars. Counting the vehicles of which more than one example has been built, a total of 230 FC and 66 ICE hydrogen vehicle prototypes have been put on the road. Most of these vehicles were built after 1995. For the propulsion of passenger cars and light trucks hydrogen may be used in internal combustion engines as well as in fuel cells. Whereas in cars driving on urban cycle patterns the FC seems to be the preferred drive system, ICE with hydrogen could be competitive for long-distance motorway-type driving modes in terms of efficiency and in the transition phase to a wider use of hydrogen as a vehicle fuel Invalid BibTex Entry!. Figure 1 shows the power train of a simple FC vehicle. The fuel cell generates electricity, which drives an eclectric motor.

Examples showing a FC and a ICE vehicle are given below. A FC vehicle is illustrated by a Nissan X-Trail Fuel Cell Vehicle (figure 2) and an ICE vehicle by a BMW 750h (figure 3).

At the core of the X-Trail FCV is the Nissan-exclusive Super Motor. In an ordinary motor, a rotor fitted with permanent magnets rotates around electromagnets (stator) to generate power that is output through one shaft. The Super Motor incorporates a new technique of applying compound current to the electromagnets and has two rotors positioned both on the inside and outside of one stator, allowing power to be delivered through two shafts.

The Super Motor can achieve improvements in compactness and efficiency compared with the use of two motors. Additionally, it controls the power of each shaft separately, making it possible to drive right and left independently, enhancing dynamic performance and stability. One motor package also incorporates the dual functions of a motor and a generator. The Super Motor can be utilized in a wide variety of applications, including on fuel cell vehicles and hybrid vehicles, which benefit from the use of its generator function.

Powering the Super Motor are high-output lithium-ion batteries that utilize a laminated lithium-ion cell in place of the conventional cylindrical shape. The use of a laminated cell as an automobile battery, which has a high current rate, requires larger terminals. The sealing performance of the cell also becomes an issue because of the gas produced by repeating charging and discharging cycles.

BMW focus their development solely on ICE driven vehicles fuelled by liquid hydrogen. According to BMW an evolution of the existing ICE technology offers much better power density and propulsion efficiency as compared to fuel cells. One example of a BMW hydrogen vehicle, the 750h, is shown in figure 3.

The 750h is powered by a 5.4-liter V12, featuring bi-VANOS variable valve timing, Valvetronic variable intake runners, and a fully variable intake manifold. The 750h can use either hydrogen or premium unleaded gasoline. Running on hydrogen, the 750h produces 150kW/200hp and can achieve a top speed of 215 km/h. The cruising range is 300 km. Added to the 640 km range of the normal fuel tank, the 750h can go 960 km between fill-ups. An Auxiliary Power Unit (APU) runs the 750h's power-consuming features. The APU operates on a 5kW Polymer Electrolyte Membrane (PEM) fuel cell that is independent of the engine, thanks to a direct hydrogen feed from the trunk-mounted tank. This means power accessories like air conditioning can be operated when the engine is shut off, saving 3.78 l of gas for every 280 km of city driving.

BMW has announced that they expect a wide market entry not before 2010. The development of FC powered cars by other manufacturers such as DaimlerChrysler, Ford, GM/Opel, Toyota, Honda and Nissan has also led to a number of prototype vehicles on the road in Europe, Japan and the U.S. The complexity of hydrogen drive-systems is viewed as medium for the technologies both for the FC and ICE. If on-board reforming from hydrogen containing carbon based fuels is preferred, the system complexity rises due to the complex processing hardware involved which is required for the highly dynamic operating conditions.

The technical maturity of both ICE and FC (without on-board reforming) for cars is judged as medium by the car industry as prototype vehicles are on the roads and field tests in the hundreds are imminent. Technical and economic challenges remain to be solved. For FC drive systems these are cost reduction by e.g. minimization of catalyst demand, material development towards e.g. high temperature membranes, extended driving range, storage system integration, further improvement of the onboard fuel reforming technology, cold start performance and reliability/operating life. For ICE vehicles improved fuel injection systems utilizing the refrigeration energy of liquid hydrogen and the hydrogen-mono-fuel performance have to be optimized.

References:

Invalid BibTex Entry!
!!! Transport
The market of city buses is highly prioritized for the following reasons:

  • Short daily driving distances (relatively simple high-pressure compressed hydrogen onboard storage, probably in the range of 20-35 MPa)
  • Fleet operation and centralized refuelling provides low investment costs and easy fuel accessibility
  • Local emission reduction (pollutants, noise) has high impact in inner city traffic
  • Good public visibility

These arguments foster the use of hydrogen and specifically fuel cell operated city buses even though improvement potentials for high efficiency conventional diesel-engines are within reach. A number of prototype ICE and FC powered buses have been built and demonstrated in field tests throughout Europe.

In the large European demonstration project, CUTE, 30 hydrogen operated fuel cell buses are test-driven in 9 European cities. A technical drawing showing CUTE fuel cell Citaro buses are shown in figure 2.

To store hydrogen on board the CUTE buses, new generation hydrogen storage vessels are used operating at a pressure of 350 bar. Experiences collected with high pressure storage modules by Evobus during the design of natural gas buses contributed to the structural layout of the hydrogen bus. The storage module consists of 9 cylinders each containing 205 litres of geometrical volume. The carbon fibre-wrapped aluminium-lined (Type 3) tanks can contain a total of 44 kg of hydrogen at a nominal pressure of 350 bar. The quantity of hydrogen fuel that can be stored in the cylinders at one time is deemed sufficient for the typical daily range requirements of city transit buses.

The hydrogen components are located on the roof of the bus. There are considered to be several advantages with this localization;

  • Improved safety in terms of city transit traffic accidents (seldom roof damages in such accidents)
  • Reducing the probability of intrusion of hydrogen into the passenger compartment
  • Easy access to components

The fuel cell stack modules transform the chemical energy contained in the hydrogen fuel into electrical energy used to power the bus. The direct current from the fuel cells is regulated by an electrical inverter, which creates the alternating current to power the central traction engine. This engine is designed for a maximum power of 205 kW which is sufficient to give the fuel cell bus a similar driving and acceleration behaviour as a diesel bus. All other components required for the operation of the bus. e.g. 24 volts supply, air condition compressor, air compressor or steering wheel pump are driven by this central engine.

The technical maturity for hydrogen buses is judged as medium with field tests in the hundreds in discussion such that – in combination with the simple and cost efficient refueling – a market entry is possible even before 2010. However, costs remains a significant barrier to deeper market penetration.

Transport

Other transport applications include:

  • Heavy trucks & long distance buses - Industry puts less priority on the early development of drive systems for heavy trucks and long distance buses using hydrogen as an alternative fuel. Main reasons are the high efficiency and the achievable driving range of current diesel trucks at low costs
  • Construction vehicles – so far very limited development
  • Trains – several potential applications foreseen
  • Leisure boats – several demonstration projects on the use of FC on-board suggested
  • Small ships and ferries – high interest for transport tasks close to shore due to the high pollutants of diesel. Potential European markets are Scandinavia. Iceland and Norway have developed some initiatives
  • Aircraft – feasibility studies carried out in the EQHHPP project. Development depends on price development of kerosene. Extensive R&D is necessary. EADS is investigating an emergency power supply based on a PEMFC and local gaseous storage for aircraft

Stationary

The previous chapter was dealing with mobile applications for a hydrogen economy including the necessary stationary applications to build an infrastructure to make these mobile applications feasible like hydrogen refueling facilities. The application of hydrogen driven fuel cells are also thought to be valuable in other stationary applications e.g. in households. Field tests are being performed in several countries e.g. in Germany and Norway to show the feasibility of a combined electrical power and heat supply for households utilizing e.g. PEM or SOFC fuel cells. While in mobile systems PEM cells working at low temperatures -e.g. giving fast start up times - are the most suitable solution presently, stationary systems may benefit from high temperature type fuel cells as e.g. the SOFC (solid-oxide fuel cell) systems. These are working at about 700 to 900O C and have the advantage of being less sensitive on impurities in the supplied hydrogen and being able to internally convert natural gas and other fuels. (see figure 1 and 2) (PalssonJ:2003). The higher operating temperature is in the stationary application considered as an advantage as it makes the utilization of the waste heat easier.

Fuel cell (e.g. SOFC) cannot only provide electrical power, but also can work in an inversed mode as electrolysers producing hydrogen, see also chapter 1.3.2.2. This potential flexibility would be important for a future strategy of decentralized electrical power supply, as this flexibility will help stabilizing the demand of electrical power. The role would be to act as a “power station” for periods with large demands of electricity and as a “consumer of electricity” for periods of excess production of electricity, e.g. in wind power systems. In such future systems the natural gas supply grid would be connected with the electrical power grid. It also would make it possible to establishing private hydrogen refilling stations e.g. for overnight refilling of the family car.

For economic reasons, a wide hydrogen supply infrastructure for industrial or residential applications is not expected to be in place in the foreseeable future. Until a suitable hydrogen supply infrastructure is developed, fuel cells for industrial and residential use will typically be fuelled through conversion to hydrogen of natural gas, LPG or methanol. According to the Hynet report this technology has an expected market entry of between 2006 and 2008.

Stationary applications can be divided in

  • Industrial applications (>= 50 kWel) – power generation
  • Small residential (<= 5 kWel l) and large (<250 kWel ) applications – power generation -> heating, cooking, illumination

and the general design of a fuel cell power system as described in the (IEC:TC105:2005) draft standard on stationary fuel cell systems (working group 3) shall form an assembly of integrated systems, as necessary, intended to perform designated functions, as follows:

  • Fuel Processing System - Catalytic or chemical processing equipment plus associated heat exchangers and controls required to prepare the fuel for utilization within a fuel cell.
  • Oxidant Processing System - The system that meters, conditions, processes and may pressurize the incoming supply for use within the Fuel Cell Power System.
  • Thermal Management System - Provides cooling and heat rejection to maintain thermal equilibrium within the Fuel Cell Power System, and may provide for the recovery of excess heat and assist in heating the power train during start-up.
  • Water Treatment System - Provides the treatment and purification of recovered or added water for use within the Fuel Cell Power Systems.
  • Power Conditioning System - Equipment that is used to adapt the produced electrical energy produced to the requirements as specified by the manufacturer.
  • Automatic Control System - The assembly of sensors, actuators, valves, switches and logic components that maintains the Fuel Cell Power System parameters within the manufacturer’s specified limits without manual intervention.
  • Ventilation System - Provides, by mechanical means, air to a Fuel Cell Power System’s cabinet.
  • Fuel Cell Module - The assembly of one or more fuel cell stacks, electrical connections or the power delivered by the stacks, and means for monitoring and/or control
  • Fuel Cell Stack - An assembly of cells, separators, cooling plates, manifolds and a supporting structure that electrochemically

coverts, typically, hydrogen rich gas and air reactants to dc power, heat, water and other by-products.

  • Onboard Energy Storage - internal energy source intended to aid or complement the Fuel Cell Module in providing power to internal or external loads

Most of the technologies (electrolysers, fuel cells, instrumentation, storage, compressors) are currently available or developed for commercialisation for operation with i.e. natural gas. Although several hydrogen specific end-use technologies such as gas turbines, internal combustion engines and also Stirling engines exist, fuel cells are believed to have the best chance for widespread commercialisation in stationary hydrogen energy systems as they provide highest efficiencies and a number of other structural advantages.

For specific tasks such as compression for pipeline transport, gas turbines or during the transition phase towards a wide hydrogen use, gas internal combustion engines can become viable options.

However, the future use of hydrogen entering the stationary market as a viable fuel will be dictated by infrastructure.

It is expected that in the longer term, i.e. after 2020, a hydrogen infrastructure for stationary applications could develop. The success of this will depend on a number of factors including the degree of decentralization in stationary energy markets, energy demand reduction, the need for load leveling capabilities for renewable energy and the success of competing technologies such as combining a hydrogen admixture to the natural gas in the existing grid. Additionally carbon capture schemes for large-scale centralized power generation could be based in the future on natural gas reforming or fossil fuel gasification technologies, with large scale production of hydrogen and its consumption in efficient combined cycle gas turbine (CCGT) schemes.

These different options will have to be tested, with lighthouse demonstration projects being a viable way of achieving this. A current limiting step in these demonstration projects is the lack of small reformers for fuel cells in the 1 - 10 kWel class. A possible means of bridging this technology gap could be to use local hydrogen distribution grids fed with hydrogen from either commercially available central reformers, electrolysers or from by-product hydrogen. In this way, a hydrogen infrastructure for stationary supply would evolve from local clusters.

It is not expected that the direct use of hydrogen to provide power for industrial or residential use will play an important role in the short-medium term. However, longer term, an increasing amount of hydrogen for use as an energy buffer may be required. The development of the necessary infrastructure will have to be adapted to the changing needs of the evolving decentralized energy markets. It will likely start with local and virtual hydrogen supply islands.

References

IEC-TC-105 (2005) Fuel Cell Technologies - Part 3-3: Stationary Fuel Cell Power Plants - Installation..(BibTeX)
Palsson J., Hansen J.B., Christiansen N., Nielsen J.U. and Kristensen S. (2003) Solid oxide fuel cells - Assessment of the technology from an industrial perspective. Energy Technologies for Post Kyoto Targets in the Medium Term. Proceedings of the Riso International Energy Conference, Denmark, 19-21 May 2003.(BibTeX)
!!! Portables Portable applications are small mobile power generation units. The wording portable applications describes either battery replacement systems (micro fuel cells with power below 500 W) or small mobile or remote power supply systems (portable generators with power above 500 W up to 5kW). Fuel cell types that are suitable for portable applications include:

  • proton exchange membrane fuel cells (PEMFCs) using pure hydrogen (H2-PEMFCs);
  • PEMFCs using hydrogen-rich gases from hydrocarbon or alcohol reforming (Ref-PEMFCs);
  • direct methanol fuel cells (DMFCs); and
  • high-temperature fuel cells such as solid oxide fuel cells (SOFCs) and molten carbonate fuel cells (MCFCs) using hydrocarbons directly.

micro fuel cells

The main market fuel cell based portable batteries are mobile phones, personal digital assistants (PDAs), laptop and notebook computers, cameras, medical equipment, military applications and other portable electronic devices. In comparison to batteries, fuel cells can supply much more power per unit volume or weight and also give the ability to retaure power by simply replacing the fuel cartdrige. However, they have lower output voltages and are slower to respond to transients.

DMFCs are mostly used for small units and devices in integrated systems because they use a liquid fuel with a high energy density that is easy to distribute. PEMFCs for portable generators do not differ much from the large PEMFCs used in stationary and transport applications. However, PEMFCs that are to be integrated into small electronic devices, need to be specially designed for miniaturisation.

Fuel cells for portable applications have the advantage that the cost per kW is much less important (not a barrier to market introduction) than for stationary and transport applications. They are usually only required to have relatively short lifetimes, typically of the order 2,000 hours. This makes them suitable for rapid market introduction. Fuel cells do not create new applications for portable equipment, but they can improve the practical value of existing devices. As battery replacements, for instance, fuel cells can increase the operating time of electronic and electrical equipment.

Illustrations of portable applications are shown in figures 1 - 2 below (RisoEnergyReport:3:2004):

portable generators

For fuel cells up to 5 kW, main market includes portable generators, uninterruptible power supplies (UPSs), auxiliary power units, power tools, light vehicles such as electric trolleys, lawn mowers and roadside equipment. In comparaison with conventional ICE generators, fuel cell portable genrators offer lower noise and exhaust emissions. In this marked sector it is necessary to solve the remaining problems associated with reliability and lifetime.

References:

Exploiting Synergies between End-use Sectors

When developing an infrastructure to support these applications, it would make sense to exploit any synergies between the sectors - transport, stationary and portable.

One such example is the concept of an energy station, combining power generation and hydrogen refueling at the same location. This could provide the means to manage the utilization rate of refueling sites, particularly in the early stages of vehicle introduction when demand will be limited. Such an energy station could help to establish local stationary hydrogen energy clusters for small industrial or residential use.

Hydrogen can also play a role in managing the intermittence of renewable power generation from technologies such as wind and PV (both in grid connected and off-grid schemes). One example is the demonstration project at the Norwegian Iceland Utsira, where 10 households receives electricity solely from wind turbines and hydrogen. This is conceptually similar to energy storage schemes for managing peak and off-peak supply/demand imbalances, using compressed air plants or pumped-hydro-storage. However, these current installations are insufficient for load-managing large amounts of future renewable generation. It has therefore been proposed to use the surplus electricity to generate hydrogen via electrolysis and use the hydrogen as daily and/or seasonal storage. In addition, this hydrogen could also be employed as a vehicle fuel.

One can also envisage that hydrogen fuel cell vehicles could be used to supply electricity (and heat) to residential, office buildings or recreational areas, while parked during working hours. Another option could be the establishment of cylinder-filling points at refuelling stations. Such filling points would serve as an infrastructure for portable fuel cell applications in industrial, household and recreational use.

The convergence of the sectors to a common fuel provides the opportunity to improve the economics of hydrogen distribution and supply by developing such innovative approaches to optimise the use of these novel energy conversion devices.

EU projects within Hydrogen applications

Lists of EU financed projects focused on hydrogen applications from 2002 – 2006 are given below. The topic adressed within each project is also given. The lists and additional information can be found in the report of `European Fuel Cell and Hydrogen Projects, (EuropeanCommission:EUR22398EN:2006).

References

{European Commission, Directorate-General for Research, Directorate-General for Energy and Transport} (2006) European fuel cell and hydrogen projects. RTD Info, EUR 22398 EN, Brussels.(BibTeX)


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