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As environmental awareness of port operations has steadily increased in recent years, air emissions have emerged as one of the most serious negative impacts from operations. More and more ports worldwide are implementing policies that aim to reduce air emissions with a “zero emission” terminal being hailed as the holy grail of the industry.
Efforts to reduce air emissions typically fall into three broad categories:
• Do everything possible with electric power
• Generate as much renewable power on site as possible
• Make the terminal, especially the non-electric parts, as efficient as possible
Electric power is compelling for many reasons. Equipment running on electric power generates zero local emissions. The emissions of health risk related pollutants such as nitrogen oxides and hydrocarbons are far lower at stationary power plants, even coal fired power plants, than from mobile sources like ship engines, so switching to electric power results in a large net reduction in these types of pollutants.
Electric powered machines use far less energy for the same amount of work than diesel machines because they do not use power to idle, and they can regenerate power when braking, or when lowering a container. The chart below describes the electrification potential of many elements of marine container terminals and their landside connections.
Although dockside cranes, yard gantry cranes, and ships are all powered by either cables or bus bar type power transfer systems, other elements will have to depend on battery power. Yard tractors have a relatively easy duty cycle that consists of a confined operating area with low speed, little to no gradients to climb, and high fraction of idle time. This duty cycle lends itself to battery power very easily and prototype electric tractors are already in place at the port of Los Angeles.
Complete Post at:
http://www.pmmonlinenews.com/2012/04/zero-emission-container-handling.html
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