CenterPoint Energy Research Articles

Corporate Profiles

Subaru of America Inc. Petco Animal Supplies Inc. CenterPoint Energy Inc. Constellation Brands Inc. The Dannon Company Inc. Jarden Consumer Solutions Fifth Third Bancorp Xcel Energy Inc.

Heavy-Duty PHEV Yard Tractor: Controlled Testing and Field Results

Diesel powered tractors are used to shuttle cargo trailers from point to point within the confines of a port facility, terminal or warehouse yard. Such operations are similar to those in ground support applications at airports and in industrial warehouses with lift trucks, in that the vehicles are used as tools to move goods in a semi-regular pattern. Southern California Edison Company (SCE) and the Electric Power Research Institute (EPRI) have partnered to help electrify vehicle operations in both of those venues with great success and see good prospects for the same at port operations. However, current port operations might require large investments in infrastructure and operational changes to implement electric drive all at once. To help demonstrate the benefits of electric drive without requiring large-scale changes, a plug-in hybrid electric vehicle (PHEV) yard tractor design was proposed by EPRI and member utilities as a means to reduce operational emissions and diesel fuel use. Four member utility companies with large port customers in their service area (SCE, Southern Company, CenterPoint Energy, and New York Power Authority) agreed to work with EPRI to study the benefits and impacts of a PHEV yard tractor. In 2007 the Electric Power Research Institute (EPRI) contracted US Hybrid Corporation (USH) to design and construct a unique PHEV yard tractor. SCE agreed to test and evaluate the PHEV yard tractor for EPRI. To properly evaluate the benefits realized by the yard tractor in comparison to unmodified conventional yard tractors as well as other alternative fueled tractors, SCE had to test the tractor in controlled conditions with realistic loads in addition to field testing. SCE developed test procedures for controlled testing and for field evaluation. The field testing was conducted in four ports across the United States, each with different operating conditions and climate: Long Beach, California; Houston, Texas; Savannah, Georgia; and New York City. SCE designed a test procedure that simulates an accelerated duty cycle of cargo operations. The accelerated duty cycle has multiple starts and stops and little idle time. SCE measured the idling fuel consumption separately so it can be inserted to match the duty cycle of any particular port. The test cycle was performed with the vehicle both unloaded and loaded to profile the effects of load on system efficiencies. SCE also tested the battery and charger performance of the PHEV, and as a comparison, tested an unmodified yard tractor. In the accelerated testing, SCE found the PHEV fuel savings were as high as 60% (on a per-cycle basis) when compared to a stock diesel Kalmar tractor, and up to 35% fuel savings versus operating the PHEV tractor as a hybrid (i.e, not charging it), In charge sustaining operation, the fuel savings are as high as 40% compared to the stock vehicle. On a daily-operation basis, the projected fuel savings on a duty cycle similar to the SCE test cycle could be as low as 35% but as high as 60% with significant amounts of idling and low speed operation. The field test results show good fuel economy but are complicated by reliability issues that reduced the operational time of the prototype PHEV vehicle. Also, it was difficult to get fleet fuel use data. It was the intention in the project to compare the test vehicle’s results with the fleet average fuel use per unit time. These results will be discussed in the body of the paper. Port operators, in general, appreciated the engineoff mode’s reduced noise and exhaust. The US Hybrid prototype PHEV yard tractor has the potential to significantly reduce fuel consumption, as demonstrated in the SCE tests. Performance issues with the prototype prevented full duty in the field tests. Further testing, with a more reliable vehicle incorporating the key system improvements learned from this project, is worth pursuing to determine if the potential fuel savings can be fully realized in larger scale. Furthermore, the techniques and testing methods described can be used for other alternatively-fueled yard tractors.

Building Retro-commissioning, Texas Style

ABSTRACT CenterPoint Energy is the first investor-owned utility in the state of Texas to sponsor a retro-commissioning program for commercial and industrial markets in its service territory. CenterPoint Energy is a Houston, Texas, based company engaged in the transmission and distribution of electric power to 1.8 million customers in a 5,000 squaremile area that includes Houston, the fourth largest city in the nation. Deregulation occurred in Texas in 2001, and significantly changed how investor-owned utilities offered energy efficiency programs within their service territories. As part of deregulation, the State Legislature required that 10 percent of all new demand growth be met through utility-sponsored energy efficiency programs. In the large commercial and industrial markets, CenterPoint Energy implemented a commercial and industrial standard offer program to help meet this 10 percent demand reduction goal. After two years of implementation and a downturn in the economy, it became apparent that another program was needed to extract demand reduction from commercial and industrial markets. Through discussion with national experts and review of other building commissioning programs, CenterPoint Energy concluded that retrocommissioning would be a good candidate to supply additional demand reduction along with identifying opportunities for its commercial and industrial standard offer program. In conjunction with other Texas investor-owned utilities, a retro-commissioning program template was submitted to and approved by the Public Utility Commission of Texas in early 2003. This program has been structured to be a market transformation offering, and will continue until retro-commissioning becomes an everyday practice in the CenterPoint Energy service territory. This article will detail the development of CenterPoint Energy's retro-commissioning program, characterize the market for retro-commissioning in the CenterPoint Energy service territory, review program goals over the next three years, and discuss results to date and lessons learned.