Well-to-wheels

The vehicle also puts constraints on the choice of fuel. A combination of factors, such as the anticipated fuel and vehicle cost, both vehicular and well-to-wheels emissions and efficiency, perceived or real safety, and infrastructure will determine the choice of optimum fuel. 

The refinery will evolve to meet the market (and so, the environmental) needs. Some characteristics are easy to foresee versatility, integration from resources to final user ( well-to-wheels), intensive incorporation of computing tools (integrated and predictive modeling at all levels feedstock-process-product), large dynamic incorporation of new catalysts, chemistry driven , fast incorporation of emerging knowledge and last, but most important, environmental preservation and safe operation. 

Bossel U., Well-to-wheel studies, heating values, and the energy conservation principle, Report, 2003, http //www.efcf.com/reports/E10.pdf, 01/2007. 

Bouwman AF, Boumans LJM, Batjes NH (2002) Emissions of N20 and NO from fertilised fields summary of available measurement data. Glob Biogeochem Cycles 16 1058 Christensen S, Simkins S, Tiedje JM (1990) Spatial variation in denitrification dependency of activity centers on the soil environment. Soil Sci Soc Am J 54 1608-1613 CONCAWE (2006) Well-to-wheels analyses of future automotive fuels and powertrains in the European context. Study of European Council for Automotive R D, EUCAR, European Commission, Brussels... 

Schindler, J. and Weindorf, W. (2003). Well-to-Wheel - okologische und okonomische Bewertung von Fahrzeugkraftstoffen und -antrieben. Ludwig Bolkow Systemtechnik (LBST). www.HyWeb.de/Wissen/pdf/Nuernberg2003.pdf. 

Although in principle stationary and transport-specific energy chains can be analysed, here the assessment of the latter is explained in more detail, and is then referred to as well-to-wheel (WTW) analysis. The primary focus of WTW analysis in Europe is on global environmental impact, i.e., greenhouse-gas emissions expressed as C02-equivalents. Other issues of interest are (a) primary energy demand (which equals resource utilisation), (b) local pollutant emissions and (c) full energy or fuel supply costs. Well-to-wheel analysis covers the entire fuel supply chain from feedstock extraction, feedstock transportation, fuel manufacturing and fuel distribution to fuel use in a vehicle. 

Well-to-wheel analysis needs to be applied for all relevant time steps to understand the evolution of environmental effects and possibly costs in the short to long term. This is of specific importance when innovative processes are considered, as these are characterised by technology development and cost curves with high gradients. 

Well-to-wheel analysis is a specific form of life-cycle analysis (LCA). In contrast to WTW analysis, LCA typically also takes factors other than global GHG emissions of a product or an energy carrier into consideration (such as air pollutants), including provision of all construction materials for the necessary processing plants and, furthermore, plant decommissioning. The full detail of a general LCA analysis is not needed at the level of policy discussion to reach a broad consensus on alternative fuels or drive systems. As a subset of WTW analysis, well-to-tank (WTT) analysis is often used to separate environmental or economic effects of fuel supplies and drive systems. 

Well-to-wheel and WTT discussions are often accompanied by an assessment of further closely related issues, such as ... 

Figure 7.5. Overall well-to-wheel (WTW) primary energy requirement for different energy chains (hybrid ICE and FC vehicles, electric vehicle (EV)).

Figure 7.9. Fuel costs versus GHG emissions, Well-to-Wheel (until 2010).

GM (General Motors) (2001). Well-to-Wheel Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems. Argonne National Laboratory. 

Joint Research Centre, EUCAR, CONCAWE (JEC) (2007). Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context Well-to-Wheels Report. Version 2c, March 2007. http //ies.jrc.ec.europa.eu/wtw.html. 

Punter, G., Rickeard, D., Larive, J-F. et al. (2004). Well-to-Wheel Evaluation for Production of Ethanol from Wheat. Report by the LowCVP Fuels Working Group, WTW Sub-Group FWG-P-04-024. 

JEC (Joint Research Centre, EUCAR, CONCAWE) (2007). Well-to-Wheels... 

Wang, M. (2005). Well-to-Wheels Analysis with the GREET Model. Argonne National Laboratory. Presentation at the 2005 DOE Hydrogen Program Review, May 26, 2005. 

The efficiency and costs of the complete power production cycle or well to wheel cycle dictate the technology choices. Industrial hydrogen or ammonia synthesis are relatively high-value products compared with electricity and automotive fuel. 

As said before, the figure of 2.5-kg C02 per kg of H2 does not necessarily represent a lower limit of what can be achieved, as much of the remaining emissions still come from point sources, from which C02 could again be captured. It does indicate a sensible well-to-wheel emission level in the medium term when CCS will not be ubiquitous. 

When CCS is practiced in association with central production it also contributes in a very significant way to CO2 reduction from the transport sector. This clean hydrogen could have well-to-wheel emissions of 2.5-kg C02 per kg H2, a level at which the transport-sector emissions would be reduced by 85%, when hydrogen fuel cell vehicles replace hybrid ICE vehicles. We have shown that this emission level can be achieved both for gaseous and liquid distribution of hydrogen, and that the total costs for both distribution modes are similar, offering the possibility to adapt flexibly to local retail preferences and industrial opportunities. 

Methanol is unquestionably the easiest of the potential fuels to convert to hydrogen for vehicle use. Methanol disassociates to carbon monoxide and hydrogen at temperatures below 400°C and can be catalytically steam reformed at 250°C or less. This provides a quick start advantage. Methanol can be converted to hydrogen with efficiencies of >90 %. But methanol is produced primarily from natural gas requiring energy and it is less attractive than gasoline on a well-to-wheels efficiency (2). 

Today s mid-sized passenger cars are about 15 to 18 % "well-to-wheels" energy efficient as indicated in Figure 9-3. Despite the increased vehicle efficiency of a methanol... 

Figure 9-3 WELL-TO-WHEEL EFFICIENCY FOR VARIOUS VEHICLE SCENARIOS... 

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