New Alternatives with Much Potential

Michael Millikin of Green Car Congress
June 26, 2006

Last week saw the introduction of two new alternatives to powertrains and to fuels, one announced by the US Environmental Protection Agency and Eaton, the other by BP and DuPont. Each has great promise, and both highlight that there is much potential for the future evolution of alternative solutions in each field.

The US EPA, Eaton and their development partners introduced the world's first diesel-hydraulic series-hybrid delivery truck. The hydraulic hybrid offers an improvement in fuel economy of up to 60-70% and a reduction in CO2 emissions of 40% or more compared to a conventional diesel-powered truck.

A diesel-electric series hybrid uses a combustion engine as a generator (engine/generator or genset) to produce electricity that powers the electric drive motor and to recharge the battery.

Rather than using a engine/generator, electric motor and a battery, the hydraulic series-hybrid uses an engine/pump to pressurize and to transfer hydraulic fluid to a rear drive pump/motor and/or high pressure accumulator.

The rear drive pump-motor converts the pressure from the hydraulic fluid into rotating power for the wheels, and recovers braking energy which is stored in the high pressure accumulator.

In other words, it is the pressurized hydraulic fluid that powers the pump/motor that drives the vehicle, replacing a conventional drivetrain and eliminating the need for a conventional transmission.

EPA and UPS plan to evaluate the demonstration vehicle in on-the-road service during 2006. EPA and Eaton are also developing a second UPS demonstration vehicle in a second phase of this partnership. EPA also plans to install an EPA-developed Clean Diesel Combustion (CDC) engine in the phase 2 vehicle. The CDC engine does not need NOx aftertreatment to achieve 2010 NOx standard.

BP and DuPont created a partnership to develop, produce and market next-generation biofuels, the first of which will be biobutanol. The partners will first introduce biobutanol as a gasoline bio-component in the UK in 2007.

Butanol is an alcohol that originally was produced by fermentation starting nearly 90 years ago. Butanol shifted to becoming a petrochemically-derived product in the 1950s as the price of petrochemicals dropped below that of starch and sugar substrates such as corn and molasses. Virtually all of the butanol is use today is produced petrochemically.

BP and DuPont have developed a process that more effectively produces butanol biologically--i.e., biobutanol.

Butanol's energy content is closer to gasoline than is the energy content of ethanol. Butanol is non-corrosive, can be distributed through existing pipelines, and can be--but does not have to be--blended with fossil fuels.

Butanol could be reformed for hydrogen for use in fuel cells, and the production process itself produces hydrogen.

Biobutanol's low vapor pressure and its tolerance to water contamination in gasoline blends facilitate its use in existing gasoline supply and distribution channels.

It has the potential to be blended into gasoline at higher concentrations than existing biofuels without the need to retrofit vehicles and it offers better fuel economy than gasoline-ethanol blends, improving a car’s fuel efficiency.

In other words, biobutanol offers greater benefit as an alternative fuel used in gasoline engines than does ethanol. Similarly, the hydraulic hybrid, with its 60-70% improvement in fuel economy offers a big jump in efficiency for an urban delivery vehicle.

Sustainable transportation will feature a number of different solutions that become mainstream. These two developments--the hydraulic hybrids and biobutanol--are likely to be part of that set.