ABAT in Agreement with Chinese Electric Bike Manufacturer
Michigan, Chemrec and NewPage Partner to Explore Black Liquor Gasification to Fuels Project

Demonstration of LNG Cold Ironing at Port of Oakland

PG&E, CleanAir Marine Power (CAMP) and Wittmar Engineering recently demonstrated cold ironing the first ship—APL’s 863-foot container ship the APL China—with a mobile, LNG-fueled shore-side electrical generator.

The APL China was powered at berth at the Port of Oakland by CAMP’s Dual Frequency Multi Voltage (DFMV) generator. PG&E provided the LNG (liquefied natural gas) and LNG equipment and technical expertise.

CleanAir Marine Power is a newly formed subsidiary resulting from the merger of CleanAir Logix (CAL) and Wittmar Engineering & Construction, Inc. Wittmar developed the modular DFMV generator in 2001.

Cold ironing is a process in which ships shut off their diesel-powered engines and use shore-based power for their electrical needs, preventing and/or significantly reducing harmful emissions during each port visit. At-berth ship emissions make up approximately 28% of all port emissions, according to Brad Whitcomb, vice president of customer products and services for PG&E.

The DFMV generator utilizes a trubocharged natural gas or LPG engine to generate either 50Hz or 60Hz and 380 volts to 480 volts so that it can be utilized with any ship that may call on a port complex.

The generator is mobile; positioning on the dock is not fixed, thereby accommodating ships of any length or configuration. Mobile LNG cold ironing offers quick connection to a significantly cleaner fuel source than marine diesel and precludes the need for installation of permanent infrastructure.

During the July 18, 2007 demonstration at the Port of Oakland, the APL China was cold ironed for eight hours. Natural gas provides significant emissions benefits and emits zero diesel particulate matter.

Emissions Comparison, LNG Cold Ironing of APL China
PollutantOn-board diesel power
(0.5% sulfur marine diesel)
LNG cold-ironing% reduction
NOx 1,059 lbs 56 lbs 94.71%
CO 79 lbs 34 lbs 56.96%
PM10 15 lbs .02 lbs 99.93%
SOx 72 lbs 0 100%
CO2 42,651 lbs 24,430 lbs 42.72%

Based on the success of the demonstration, the Port of Oakland is considering a plan that would use Wittmar LNG generators to cold iron every ship entering its port by 2010, 10 years in advance of CARB’s proposed regulations. In 2006, the Port of Oakland received 1,940 ship calls with an average stay of 18 hours.

An additional LNG cold ironing test is planned to take place at the Port of Richmond later this year.

The demonstration at the Port of Oakland—the-fourth busiest container port in the United States—was part of the ongoing development of technologies to meet emissions reduction targets set by the California Air Resources Board (CARB).



Would the use of electrically powered generators be just as versatile? As much as LNP lowered emissions over bunker oil usage, electrical generators would lower emissions again...specially if used in our NorthWest ports where electricity is generated with only 4% the emissions of an Internal Combustion Engine.

Max Reid

Interesting, it would be better if the ships can be powered by LNG.

Trains, Trucks and Buses are other application for LNG fuel. Whether Saudis are supplying more Oil or not, Qatar is going to supply more natgas.

Doug M

What is the incentive for the ships to use shore power? It may be more expensive, so what is the port going to do to encourage the use? Subisdies? Making it mandatory?

Does anyone have a cost breakdown?

Rafael Seidl

@ litesong -

what is an electrically powered generator? Electricity is the output, not the input.

Quick back of the envelop calculation:
duration 8 hrs = 28800 s
CO2 24,430 lbs = 11091 kg
methane: 11091 * (12 + 4*1)/(12 + 2*16) = 4033 kg
lower heating value: 34.5MJ/m^3 * 0.717kg/m^3 = 24.7MJ
engine efficiency: 50% (assumed)
engine power: 4033 * 24.7 * 0.50 / 28800 = 1730kW
=> efficiency assumption is realistic for
a genset rated at ~2000kW

If you wanted to provide this power from the grid, your infrastructure overhead would be greater (a big power drop to every berth vs this mobile unit) and thermodynamic efficiency would not be better - even if you consider the overhead of liquefying the natural gas.

Rafael Seidl

Sorry, the data for natural gas should have read:

lower heating value: 34.5MJ/m^3 * 0.717m^3/kg = 24.7MJ/kg


Sorry Rafael...you're right...I meant electric motor.


Doug M

It will of course be mandatory, however they are smoking crack if they think that all ships visiting their port will be able to cold iron by 2010. There is no way all those ships will retrofit to cold ironing in 2 years.

Max Reid

Instead of a generator, a grid based power line should be cheaper.

Whether cold ironing can be provided to all ship by 2010 ?
Absolutely yes, whole World is moving towards alternatives, US has to, otherwise we will be left behind.

See this website, developing countries like Argentina , Pakistan and Brazil have more CNG vehicles
Even Iran & Colombia are ahead of USA.

Kit P

Hey Max. I want to watch you sync a 50 hz systems to a 60 hz system. From a safe distance, that is.

And Max which is better imported oil or imported LNG?

Rafael Seidl

@ dsl987 -

the "only" modification needed is a giant socket into the on-board grid, big enough to support the electric power flow an in an externally accessible location. Power electronic switches (GTOs for example) would isolate the socket from the internal grid when its not in use.

More important is that ship owners/operators can be convinced of the safety, reliability and low cost of cold ironing. Emissions legislation will then get them to pony up for the retrofit.

@ Kit P -

the generators can deliver multiple voltages and frequencies. It's merely a question of running the genset at either 1500 or 1800 RPM. See the CAMP web site.


Rafael. Do you have any figures on the ammount of energy required to liquify a pound of n.g. and how much energy to keep it refrigerated (in a liquid state) for say , 7 days ? day temp 90 f. nite 70 f. ambient.

Rafael Seidl

@Lakewood90712 -

specific heat capacity of natural gas: 2.34 kJ/kgK
latent heat of vaporization (methane): 510.6 kJ/kg
boiling point at normal pressure: approx. -160 degC
lower heating value (natural gas): 34.5-39 MJ/kg

The exact composition of natural gas varies by reservoir, but it always mostly (>95%) methane.

So, getting 1kg (~1.4 m^3 at 1023 mbar and 0 degC) of natural gas liquefied from these standard conditions takes ~885 kJ of energy, or ~2.5% of the heating value. However, this is the theoretical minimum. Real-world refrigeration is inefficient and may therefore consume ~10% of the gas produced at the wellhead. This overhead needs to be taken into account in the well-to-wheels analysis of e.g. CNG vehicles if the grid they draw their fuel from is fed with LNG. Losses in pipelines are much lower, unless there is a leak.

LNG is shipped and stored in extremely well insulated cryotanks. To avoid a build-up of pressure, the LNG is allowed to slowly boil off. It's really like a kettle on the boil, except at a much lower temperature. The engines of LNG tanker vessels combust this boil-off; on shore, it is fed into the grid. In both cases, waste heat is used to bring the cold gas back up to standard temperature first. The boil-off rate depends on the design of the cryotank and the ambient temperature.

Some have proposed using e.g. Stirling engines to recover some of the energy expended on liquefaction. This is possible only if the boil-off rate is higher than the "natural" one implied by heat transfer through the cryotank walls. Even then, the Carnot limit for recovery at the temperatures involved is ~60% or ~530 kJ/kg. Any real-world Stirling engine would yield even less than that, roughly 1% of the heating value. Therefore, recovering the cold energy only makes sense in very large LNG installations.

If you want all this in imperial units, please perform the necessary unit conversions.


I understand that the CAMP generator reduces emissions significantly. What I am unclear about: are there any energy or monetary savings(except for the cost of the generators, etc)? That is, is it more or less expensive to run the ships on the LNG generator vs. the onboard deisel engine?

The comments to this entry are closed.