Electric Ports: think globally, plug in locally

Special to World Port Development

Environmental concerns in US ports have forced authorities to look at various optionsto power their cargo handling equipment.Krystle McBride, Analyst, and Mark Sisson,head of DMJM Harris’s marine analysisgroup highlight the pressing environmentalissues that currently exist in the USA.

n recent years, awareness of various typesof pollution - and the major contributors thereto - has increased dramatically. Ports

have been targeted as one of these majorcontributors, although most of the focus hasbeen given to “local” pollutants such as particulate matter (PM) and nitrogen oxide

(NOx), one of the key ingredients of smog.One promising technique to mitigate thesetypes of pollution is to reduce the amount ofdiesel fuel used at terminals; this can be achievedby electrifying some container yard and shipoperations.There is concern, however, thatswitching to electricity may simply move thesource of pollution to the power plants thatsupply the ports with electricity.And if thesupplying power plant is fueled by coal, the switch could even increase emissions ofgreenhouse gases such as carbon dioxide (CO2).The amount of pollution resulting from electricitygeneration can differ significantly from regionto region, even within the United States. Onelocation where electrification is a significantissue is California; in recent years, port

electrification has become a prominent topicin the effort to reduce emissions at both thePort of Los Angeles and the Port of Long Beach.California has traditionally been a leader inimplementing stringent environmental regulations.As shown in figure 1, less than four percentof the electricity generated in California isproduced from the “dirty,” high-emissionsources of coal, oil, and other fossil fuels. Incomparison, these sources are used to generateover half of the electricity produced in thecountry as a whole. California’s high proportionof “clean,” renewable sources and its lowproportion of coal-generated energy result inlower-emission electricity than the nationalaverage.The following analysis uses coal-generated electricity as a worst-case standard ofcomparison due to its prevalence and highrate of emissions.

Operations today in North America are typicallya combination of wheeled and grounded storageprimarily using rubber-tyred gantry (RTG)cranes. In order to increase capacity, this systemnaturally evolves into an entirely groundeddiesel RTG operation.An alternative to thissystem is an electric rail-mounted gantry (RMG)crane operation.The photographs in figure 2show some sample layouts for low-density diesel, high-density diesel, and electric operationsrespectively. Figure 3 details some of the numericaldifferences among the three representative typesof operations. Data for the “low-density diesel”operation is similar to typical operations inSouthern California today.A high-density dieseloperation requires an RTG to handle almost allcontainers because only a small percentage

World Port Development July/August 20081

e n v i r o n m e n t e l e c t r i c p o r t s

Electrifying cargo handling

Figure 1: Sources of electricity generation (California versus US average)

Figure 2: Representative container yard layouts

I

Electric Ports:think globally, plug in locally

July/August 2008 World Port Development 2

e n v i r o n m e n te l e c t r i c p o r t s

of the containers are stored on street chassis.This results in a greater diesel consumptionper move than in a low-density diesel operation. Figure 4 compares the averageemissions per TEU for typical diesel and electric container yard operations. Clearly,electricity-powered container handling dramatically reduces NOx emissions. Emissionsof CO2 are also reduced compared to dieselcontainer handling, although to a lesser degree,unless the electricity is generated at coal-firedpower plants. Even in that worst-case scenarioof coal-produced electricity, CO2 emissionsexceed the diesel alternatives by one-third orless, while NOx emissions decrease by morethan 90 percent.

Ships are a significant source of emissions atports because of a procedure known as“hotelling.” While docked, ships must run theirauxiliary engines to power basic functions,such as lighting and refrigeration of perishablecargo.These large auxiliary engines run onrelatively dirty fuel (either marine distillate orbunker fuel).Alternatively, this power can beprovided through electricity.Using a techniqueknown as cold-ironing, ships can “plug in” toa port power supply (assuming both the shipand the port have the necessary infrastructure).Figure 5 compares hotelling using traditionalon-board fuels and cold-ironing ship emissionsfrom standard fuels and electric sources.Compared with cold-ironing, running auxiliaryengines with on-board fuel produces far greateremissions of NOx and PM - about nine timesas much as using electricity generated fromthe most-polluting source, coal. CO2 emissionsare also less with cold-ironing (substantially less in California’s clean-generation environment)except in the worst-case scenario, whereinall of the electricity would be generated fromcoal. Even in that severe case, CO2 emissionsare only one-third higher than those producedby the ships’ oil-fueled auxiliary engines.Figure 5 shows that electricity delivers anundisputable advantage over traditional fuelsfor local emissions such as NOx and PM, sinceeven the extreme case of electricity exclusivelygenerated from coal is far cleaner than dieseloutput.When it comes to CO2 emissions thedifference is much less dramatic, but electricityis generally cleaner than the traditional alternatives.As demonstrated in Figure 6,almost all states with major ports generateelectricity from fuel sources that will reduceCO2 emissions (compared to typical shipfuels).This reduction will be significant forports in locations such as the U.S.West

Figure 3: Representative differences between RTG and RMG operations

Figure 4: Emissions for typical diesel and electric container yard operations

Figure 5: Ship hotelling emission factors by energy source

Electric power to ships

World Port Development July/August 20083

e n v i r o n m e n t e l e c t r i c p o r t s

Coast states, which provide electricity fromcleaner-than-average sources.

Overall, implementing electricity-based operations and cold-ironing will enable portsto dramatically reduce their total emissions.This can be accomplished in several ways.Ports with more than one possible energyprovider can use resources such as the EPA’sEmissions & Generation Resource IntegratedDatabase (eGRID) to compare power companies and choose the one with thegreenest sources of generation. Port managerscan also participate in one of the green energy programs listed by the United StatesDepartment of Energy on its Energy Efficiencyand Renewable Energy web site under the topicof Green Power Network(www.eere.energy.gov/greenpower).Theadvantage provided by electricity can also beaugmented through implementation of morerenewable energy sources, such as installationof wind turbines or solar cells in the port.Arecent study found that mounting solar panelson the roofs of buildings as well as canopiesover wheeled reefer parking stalls andemployee parking lots could develop peakpower outputs of 1,000 - 2,000 kW. In

comparison, a ship using electric shorepower typically draws approximately 3,000kW.Furthermore, solar panel and wind turbinedesigns are evolving rapidly.The concern thatplugging ships into land-based electric power

will only shift power-generation pollutants offsite is understandable and plausible.Thoroughanalysis, however, shows that the overall benefit of substituting electric power fordiesel is clear and substantial.

Figure 6: Maritime States’ electricity generation emisson rates for CO2

Electricity versus diesel