DfT Publishes Ricardo Report on Technology Options for Reducing CO2 Emissions from Heavy Goods Vehicles; Focus on Vehicles, Powertrains and Fuels

18 July 2009

Representation of cost vs. benefit of low-carbon HGV technologies. Source: Ricardo/DfT. Click to enlarge.

The UK Department for Transport has published a report prepared by Ricardo on the potential of various technologies for reducing CO₂ emissions that are applicable to the heavy goods vehicle (HGV) sector. HGVs (goods transport vehicles with >3.5t GVW) represent 24% and vans 12% of total UK road transport greenhouse gas emissions.

The report presents an analysis of a number of HGV technologies with carbon saving potential and evaluates these technologies in terms of CO₂ benefits, technology costs, environmental costs arising from production of the technology, safety and other limitations, and the maturity of the technology within the market. The report then summarizes which technologies are the most promising in terms of CO₂ benefits when all these other factors are taken into consideration.

The report categorizes the low carbon technologies reviewed for application to HGVs into three themes: vehicle, powertrain and fuel. For the vehicle theme, technologies lie in the fields of improving aerodynamics, reducing rolling resistance and driver behavior.

For the powertrain theme, the report identifies four main areas of low carbon technologies: engine efficiency, waste heat recovery, alternative powertrains (fuel cells and electric vehicles and hybrids) and transmissions. Engine efficiency is itself subdivided into four themes: combustion systems, friction reduction, engine accessories, and gas exchange.

For the fuel theme, the report analyzes three alternative fuels (CNG, biogas and hydrogen), and three different biofuels for diesel engines (biodiesel; biomass-to-liquids (BTL); and hydrogenated vegetable oil).

Ricardo further segmented HGVs for the feasibility analysis into medium-duty (3.5 - 15t GVW, including both rigid and drawbar trailer vehicles) and heavy-duty (>15t GVW, including both rigid and articulated vehicles) to allow for the differences in typical vehicle duty cycles (i.e., urban delivery with frequent stop-start vs. long-haul highway at high speed) and hence potential CO₂ benefit of a technology.

Results of the analysis show that:

• Aerodynamic trailers; electric bodies (electrification of the power requirements of vehicle bodies such as refrigeration and refuse vehicles); and vehicle platooning may have the greatest CO₂ reduction potential for vehicle technologies.

• For powertrain technologies, electric vehicle and full hybrids offer the best potential in the near-term. Medium-term powertrain technologies with greatest CO₂ reduction potential are fuel cell APUs, stop/start hybrid systems and heat exchangers. Long-term, fuel cells have good CO₂ reduction potential.

  Benefits are application specific, with significant lifecycle CO₂ impacts dependent on energy mix.

• Despite sustainability concerns associated with indirect effects of biofuels, first generation biofuels and biogas offer the greatest CO₂ benefit in the near-term. Fuel technologies for the medium-term include BTL, HVO, hydrogen and CNG, of which CNG offers the lowest CO₂ reduction.

The report identified seven of the technologies reviewed as potential indicative guides for CO₂ benefit due to their limited fields of application and narrow benefit ranges associated with it. An indicative guide means, if a particular technology is applied to a particular vehicle type, the CO₂ benefits are consistent, repeatable and not significantly affected by variables such as vehicle load and driving style, such that statistics about take-up of a particular technology can be translated into an estimated fleet CO₂ saving. For example:

• Aerodynamic trailers are a good indicative guide as their CO₂ saving performance is consistent and repeatable when applied to heavy duty articulated vehicles used on a constant high speed duty cycle.

• Full hybrids are a poor indicative guide, as their CO₂ improvement benefit is highly dependent on duty cycle, vehicle architecture, battery size, and environmental impact is strongly dependent on battery technology.

Even the technologies deemed as good indicative guides only act as good indicators when applied to specific vehicle applications and duty cycles, the report cautions. Very few technologies can be viewed as blanket indicative measures regardless of vehicle implementation.

The seven technologies identified as potential indicative guides include:

• Aerodynamic trailers: for heavy duty long haul applications, if no change to existing tractor unit.
• Electric Vehicle Bodies: applies to a set portion of the market.
• Air compressor: for HD applications.
• Mechanical Turbocompound: for HD applications.
• Electric Vehicles: zero tailpipe CO₂.
• CNG: if dedicated CNG engine.
• Fuel Cell: zero tailpipe CO₂.

Resources

• Review of low carbon technologies for heavy goods vehicles

• Review of low carbon technologies for heavy goods vehicles - Annex 1