BOARD MEETING DATE: October 19, 2001 AGENDA NO. 36

At its July 2001 meeting the Board directed staff to conduct a field evaluation and assessment of possible enhancements that could enable natural gas fueling stations to be compatible for future hydrogen refueling. In addition, the Board requested that a status report be provided to the Board’s Technology Committee, as well as a final report to the full Board by the August 17, 2001 meeting. At that meeting, the Board requested that staff obtain more direct input from compressor manufacturers. This report includes the direct input from selected compressor manufacturers.

Ten compressor manufacturers were asked to bid on compressor costs for three scenarios at three typical CNG stations. These three stations were selected to give a variety of applications and range of specifications from detailed (Diamond Bar) to minimal (Thousand Palms). Bid specifications were supplied via Email for planned CNG stations in Diamond Bar, Placentia and Thousand Palms. Prospective bidders were asked to bid on the compressor needed to provide: A) 4500psi CNG; B) 4500psi CNG and 6000psi hydrogen; and, C) 4500psi CNG and 10,000psi hydrogen. Bidders were also asked to include the cost of any control systems required to switch between CNG and hydrogen for scenarios B) and C) but additional equipment needed for the skid or station operation should not be included. A summary of the bids received is tabulated below.

The following Table summarizes the information received from the responding manufacturers.

Company	Response	Bid	CNG/H2Comparison
ANGI	Yes	Yes	No
CompAir	Yes	Yes	Yes
Dresser-Rand	Yes	Yes	Yes
Greenfield	Yes	Yes	Yes
Haskel Int’l	Yes	No	No
Knox Western	Yes	Yes	No
Norwalk	Yes	No	No
Pickens Fuel	Yes	No	No
Pinnacle CNG	Yes	Yes	Yes
Rix Industries	Yes	Yes	Yes
TOTAL	10	7	5

*Pinnacle provided whole system costs for a 350scfm compressor.
The other four companies provided costs for a 200scfm compressor.

1. Angi – International / Allsup Corporation
4,500psig CNG	$180,000	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	N/A	N/A
4,500psig CNG and 10,000psig hydrogen	N/A	N/A

Angi-International declined to bid on scenarios B and C since they do not have any hydrogen compression technology available for the market place.

Angi stated that a CNG facility that is being considered for future hydrogen compression should have the electric power supply oversized by 30%. Standard CNG storage and high pressure tubing is inadequate for the 6,000psig and 10,000psig hydrogen applications.

2. Comp Air
4,500psig CNG	$140,000	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	$230,000	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	$295,000	200 SCFM CNG

The above prices are budget prices only, based on Comp Air’s standard range of Gaspak compressors, with modifications required to make module compatible for compressing both CNG and hydrogen.

Comp Air stated that compressing two different gases, such as CNG and hydrogen using the same compressor unit can cause concerns when the gas is being supplied from two different sources. Factors which can affect the compressor operational reliability, efficiency and long term life are gas density, gas suction pressure, gas delivery pressure, gas inlet temperature and gas capacity. With compressors of "fixed" size cylinders, it is difficult to provide a single reliable unit for compressing two gases of different densities. The efficiency of the machine would be compromised, but, operational reliability would not be.

3. Dresser – Rand
4,500psig CNG	$215,000	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	$310,000	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	N/A	N/A

Dresser-Rand quoted the above costs for a basic system without controls. Their quote is based on a medium frame compressor. They stated that a lower cost alternative could be quoted in the future. Dresser-Rand is considered to be the world's largest compressor manufacturer and has extensive experience in both CNG and Hydrogen compression.

4. Greenfield / Henderson
4,500psig CNG	$125,100	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	$163,528	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	N/A	N/A

This is not a current design and would require implementation, design, testing and eventually pricing. Dual service switching controls were not included or quoted until these are developed manual switching valves before and after the compressor would be used.

For optimal performance, the compressor should be designed for hydrogen service but the intake valves should be designed for CNG service. CNG requires a dryer while hydrogen normally does not. Hydrogen, however, will require more extensive filtration with an additional carbon bed adsorber to ensure adequate quality. Purge design and in-line sensors will help determine the extent and duration of the changeover process.

This company did not provide any cost information. All written comments pertained to the fueling station at Placentia only.

Haskel does not suggest using the same compressor for the two different gases. The different compression ratios of the two systems is reason enough to avoid this setup. Electrical requirements would also be an issue.

6. Knox – Western
4,500psig CNG	$188,970 200	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	N/A	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	N/A	N/A

At this time Knox-Western will not offer options A and B. If the buyer is able to source higher suction pressure hydrogen and reduce the number of stages required, Knox-Western will be able to work with extra high pressure compressors and present a feasible solution.

While it is theoretically possible to use the same compressor for both hydrogen and natural gas, it is not practical for this application. Due to the difference in the compressibility of hydrogen and natural gas, compressing hydrogen from 17psig to 6,000psig requires 8 to 10 stages of compression. This will require a minimum of two machines and would require special high pressure, long stroke, low speed, single acting cylinders. Also, as hydrogen is so light, standard tandem cylinders normally used for high pressure natural gas service are not suitable at the high hydrogen pressure as the gas will leak back from the high pressure end to the low pressure end.

Norwalk Company stated that it is unlikely that gas inlet pressures in the range specified for the CNG are available without regulating from a higher pressure or boosting from a lower pressure, both of which are inefficient. Switching back and forth from one fuel to the other as described is totally impractical. There are many other factors involved like purging the compressors, mixing of gases, etc. that make it impractical as well. In addition, a piston type compressor will always have some evaporative emissions, as it is not a hermetically sealed unit. This will be from the packings on an industrial gas type unit or the crankcase on an air type unit.

Pickens has expressed concerns about using a single compressor for CNG and hydrogen. Switching requires a very thorough cleaning and purging process. Even then, we are still not sure a 99.99% purity can be achieved and maintained. From our conversations with some of the fuel cell developers, we found out that high purity hydrogen is very critical to their process. If contamination or equipment failure occurs, it could easily make the fuel cell unusable. The cost of contaminating one product with the others far outweighs any savings (if any) on a multi-use compressor.

9. Pinnacle CNG Company
4,500psig CNG	$337,000	200 SCFM CNG
	$1,011,000	1300 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	$476,500	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	N/A	N/A

This company declined to bid on the 10,000psig hydrogen scenario. Achieving a 6,000psig discharge pressure in a commercial prototype will incur $630,000 added cost for adequate testing and development of a hydrogen compatible compressor into a fully integrated system. Pinnacle has serious technical reservations about the efficiency and economic viability of hydrogen fuel delivered at the 10,000psig pressure.

10. Rix Industries
4,500psig CNG	$170,000	200 SCFM CNG
4,500psig CNG and 6,000psig hydrogen	$204,500	200 SCFM CNG
4,500psig CNG and 10,000psig hydrogen	$262,500	200 SCFM CNG

The compressor material must be selected for CNG and hydrogen service. Hydrogen service will cause the compressor to run hotter, as the K value of hydrogen is much greater than CNG. The dual use compressors should incorporate valves and design to allow for a nitrogen purge of the compressor for a period of 3-6 minutes prior to switching between the gas discharge. The discharge manifold on the hydrogen system must incorporate an activated carbon filtration system, ensuring the removal of any hydrocarbons that have carried over from the CNG gas stream. This filtration system will prevent contamination of the hydrogen for any downstream use such as to power fuel cells.

Ten compressor manufacturers were asked to bid on costs to provide hydrogen compatible CNG compressors for three typical CNG fueling stations. Nine of those companies responded to our request with six of them providing cost bids. All of the bids that included hydrogen compatibility costs (at 6,000 or 10,000psig) were specified for the Placentia fueling station location which will utilize a 200 SCFM compressor. One company did include costs for the other two locations at 4,500psig but no quotes were given for the higher hydrogen pressures. Only four companies provided CNG and CNG-hydrogen compressor costs as summarized in the table below:

Scenario*	Pinnacle**	CompAir	Dresser-Rand	Greenfield	Rix
1	$337,000	$140,000	$215,000	$125,100	$170,000
2	$476,000	$230,000	$310,000	$163,500***	$204,500
% Difference	(+41%)	(+64%)	(+44%)	(+31%)	(+20%)
3	no bid	$295,000	no bid	no bid	$262,500
* Scenario 1 = CNG@4,500psi; Scenario 2 = CNG 4,500-H2 6,000; Scenario 3 = CNG 4,500-H2 10,000 Pinnacle provided whole system costs for a 350scfm, all others provided costs for 200scfm *does not include provisions for switching to allow dual use

The ten compressor manufacturers provided a range of comments and information regarding the issue of hydrogen compatibility with CNG compressors. Hydrogen compression will require more power and upgrades to all related tubing, valves and containers downstream from the compressor to meet safety standards. Post-compression treatments for hydrogen are different from those for CNG and must be built into any dual system. Several of the bidders felt that it was impractical to use the same compressor for both CNG and hydrogen due to differences in gas properties and operating pressures. Relief valves set to the higher hydrogen pressures would not release in the CNG mode until that higher pressure was reached. The demand for hydrogen in the near future will increase very slowly. Any system designed for CNG fueling would be larger than the hydrogen fueling demand required. Some of the respondents had serious concerns about cross-contamination of the gases in a dual-use compressor and the effectiveness of purging to ensure 99.99+% hydrogen.

Specifications for three CNG fueling stations were included in the request for bids, the Placentia at 200 SCFM, AQMD Diamond Bar at 375 SCFM and Gardena 1300 SCFM. All of the cost bids received with responsive hydrogen compatibility quotes were for the Placentia location with the exception of Pinnacle which provided the quotes for a 350 SCFM compressor. Pinnacle indicated the R&D nature of the high pressure hydrogen compatibility compressor technology and it estimates that up to 2000 hours of testing are needed to firm up the technology.

The demand for hydrogen fueling will be based upon the number and availability of hydrogen powered vehicles in the area served by the station. It is most practical to plan future hydrogen fueling sites that are sized to meet the expected hydrogen needs. This will require compressors that are designed to hydrogen fueling demand and the output of the hydrogen production equipment.

Staff believes that the AQMD should be pro-active in establishing a hydrogen fueling network as soon as practicable. Staff has already pre-planned for the future installation of various hydrogen fueling equipment at the AQMD’s fueling facility on a stand-alone basis.

Based on the costs and information received from the responding compressor manufacturers, staff does not recommend funding hydrogen compatible CNG compressors at any site at this time. Staff does believe it is prudent to support the development of a Basin-wide hydrogen fueling network in the near term to ensure a smooth introduction of transition to hydrogen fuel cell vehicles as well as various hydrogen/CNG fuel mixtures for other mobile applications in the South Coast Air Basin. To that end, staff proposes the following two actions be approved by the Board to initiate a broad spectrum of support for such an hydrogen fueling infrastructure.

AQMD’s Clean Fuels Program has been active in funding the development and demonstration of low emission, alternative fuel technologies within its Technology Advancement Office. The AQMD has also supported a number of activities directed to commercialization of low-emission alternative fuel technologies. The Air Quality Management Plan (AQMP) for the South Coast Air Basin states that motor vehicles are the most significant source of air toxic and criteria pollutant emissions in the region. The use of hydrogen fuel or mixtures of hydrogen and natural gas (hythane) provides a viable, environmentally friendly option for the future. Efforts to facilitate hydrogen fueling infrastructure can provide long-term environmental benefits as well as help in meeting the requirements of the Federal Clean Air Act.

The purpose of the bid solicitation for this report was to obtain independent comparative information on compressor costs. This information will be used for reference and guidance in the solicitation of bids for hydrogen-compatible compressors for future projects. The RFP to develop a hydrogen fueling station template will enhance the design and construction of future hydrogen fueling stations with the cost for this RFP not to exceed $75,000 from the Clean Fuels Fund.

South Coast Air Quality Management District