Jun 16 2008

Utilities Tapping Green Hybrid Technologies For Overhead Repairs

Posted by: Leonard Anderson

Fuel efficient, clean energy cars and trucks were front and center in Washington D.C. last week with a hearing at the House Subcommittee on Energy and the Environment on hybrid technologies for trucks and a conference at the Brookings Institution pondering federal policies to promote plug-in electric cars. To learn more about hybrid vehicles NEXT100 visited PG&E's sprawling service yard on Harrison Street in San Francisco's Mission District to look over a new heavy duty diesel-electric hybrid bucket truck.

First, some background: For most repairs on overhead wires, transformers and other energy gear attached to power poles, the utility industry standard is to dispatch large diesel-powered bucket trucks. These trucks often must idle for long periods of time to complete the repairs, burning up fuel at a rate of about one gallon of diesel per hour of idle time. The idling engine is needed to power a hydraulic arm and maneuver the bucket hoist servicemen who make the repairs. 

Last year, PG&E was one of 14 utilities in North America to deploy diesel-electric hybrid bucket trucks developed by International Truck and Engine Corp. and Eaton Corp. for field tests to be measured against a conventional diesel truck. The benefits jump out: preliminary results indicate that the hybrid trucks cut fuel consumption by 40 to 60 percent and slash emissions by 50-90 percent by operating the bucket in battery-only mode without the engine running. With a hybrid, a truck's diesel engine may run only about one hour during eight hours of overhead work. Another plus: the trucks can generate 25 kilowatts of standby electricity, enough to power several homes and traffic lights while service is being restored.

PG&E has also acquired two Peterbilt diesel-electric hybrid trucks for its fleet designed specifically for work on live overhead wires in the electric distribution system, and Lineman Rob Galligani showed off one for us on Friday at the Harrison yard.

Galligani, harnessed and snapped inside the bucket, takes the controls and, tapping lithium ion battery power, rides the bucket atop the truck's hydraulic Terex boom to a height of about 50-55 feet before the diesel motor starts up to boost the batteries. Suddenly we can't hear Galligani well because the diesel motor is making loud growling noises along with some nasty fumes.

"With the batteries on, it's a lot easier to talk back and forth," Galligani shouts down; minutes later, the batteries kick in again and we're able to lower our voices. "This is a big safety feature for communicating between the bucket and a crew below on the street," he says, especially on the busy and crowded streets of San Francisco where traffic noise can drown out conversation. Also, repairs needed during nighttime hours can be made without keeping the neighborhood awake.The diesel-electric hybrid also drives down maintenance costs due to reduced engine use.

New hybrid utility bucket trucks offer environmental benefits and reduced fuel and maintenance costs, but vehicle costs can run 50 percent more than a conventional bucket truck.

At the House subcommittee hearing last week, Jill Egbert, manager of Clean Air Transportation at PG&E, said "in order to accelerate the procurement of hybrid trucks into utility fleets, we believe some financial incentives will be needed in either the form of grants or tax credits...At a time of historically high diesel prices, increasing concern over climate change and energy security, the time is right to accelerate the research and deployment of hybrid and plug-in hybrid electric truck technologies."

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