Analysis of Trends in Commuter Rail Energy Efficiency
Commuter rail systems are widely regarded as an effective transportation alternative to reduce energy consumption and emissions in large urban areas. Use of commuter rail systems in the United States is on the rise, with annual ridership increasing by 28 percent between 1997 and 2007 [1]. With growing concerns about the sustainability and environmental impacts of transportation, modal energy efficiency is increasingly considered amongst the metrics to evaluate the benefits and costs of transportation systems and justify future investment. To gauge the relative long-term efficiency trends for rail as an urban transportation mode, this study analyzes historic trends in energy efficiency metrics for US commuter rail systems. Commuter rail systems receiving, or benefiting from, Federal Transit Administration (FTA) grants are required to report operations and energy consumption data on an annual basis to the National Transit Database (NTD). NTD data on energy consumption, operations, and services supplied from 1997 to 2011 are analyzed to determine historic trends in various energy efficiency metrics for the commuter rail mode as a whole. The data analysis and comparison of the results with the highway mode is complicated by the use of electric traction by some commuter rail operators. These operators report energy consumption in purchased electricity (kWh) instead of gallons of liquid fuel. The different approaches that can be employed to compare these two forms of propulsion and their intrinsic efficiencies and energy sources are discussed. Energy efficiency of each commuter rail system and its relationship to individual system characteristics during the study period are also analyzed. Finally, case studies of historic energy efficiency of individual commuter rail systems with longer operating histories and reporting data over the majority of the study period are contrasted against more recent start-up systems. While many systems outperform the energy efficiency of a typical light-duty vehicle, there are others that, due to a variety of system parameters and characteristics, fail to achieve a load factor great enough to make them more attractive than the highway mode on a gross average level. It is hoped that highlighting trends and variation in commuter rail energy efficiency will allow policymakers to make more informed decisions regarding the environmental benefits of rail as an urban transportation mode.Copyright © 2014 by ASME
An Overview of U.S. Commuter Rail
Planners view commuter rail as a means of managing urban sprawl, stimulating economic development and reducing the environmental impacts of transportation. Commuter rail systems, which use shared rights-of-way to connect suburban hubs with downtown urban centers, are beginning to have a large impact on the way people and freight move through United States cities. Currently, there are 26 commuter rail systems operating in 29 major U.S. metropolitan areas. However, there is confusion among the general public and disagreement among transportation organizations as to what constitutes a commuter rail system and how to classify some rail systems. This research establishes a complete and definitive list of U.S. commuter rail systems, situates commuter rail in the context of U.S. rail systems at-large and establishes a 'new start' and 'legacy' classification for commuter rail. Included in this report are profiles of all U.S. commuter rail systems, highlighting governance, financing, ridership and service area demographics. This research also traces the historical development of commuter rail and the best practices employed by 'new start' commuter rail systems. This includes highlighting shared-corridor acquisition practices and highlighting policy mobility practices.
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.