Volvo calculates that cargo transport will account for about 4-5% of total global carbon-dioxide emissions, based on European conditions and statistics in which passenger cars represent 60% of carbon-dioxide emissions and cargo transport for the remaining 40%.

The Volvo Group is the first vehicle manufacturer to produce seven demonstration trucks that can all be driven without emitting any environmentally harmful carbon dioxide. These trucks were exhibited for the first time today in Stockholm and are equipped with diesel engines that have been modified to operate on seven different types of renewable liquid and gaseous fuels. Volvo is part of the climate problem, but today we have shown that carbon-dioxide free transports are a possibility and that we as a vehicle manufacturer both can and will be part for the solution to the climate issue.

—Leif Johansson, CEO of the Volvo Group

Volvo carried out its own analyses of the renewable fuels that are most suitable based on seven criteria: Impact on the climate; energy efficiency; land use efficiency; fuel potential; vehicle adaptation; fuel costs; and fuel infrastructure.

We know that in the foreseeable future there will be insufficient biomass or renewable fuels to fully replace fossil fuels. That is why it is important that decisions on the production of future fuels are preceded by such comprehensive assessments—otherwise there is the risk that we focus on too many and quite simply unsuitable alternatives, which will delay the introduction of carbon-dioxide-free transport.

—Jan-Eric Sundgren, member of Volvo Group Management and Senior Vice President, Public and Environmental Affairs

Volvo is particularly optimistic about the prospects for second-generation renewable fuels produced via the gasification of biomass. While different fuels have different strengths and weaknesses, dimethyl ether produced via biomass gasification comes out as a leading alternative in these assessments. A summary of the results follow.

Indexed results for climate impact. 100 is the baseline (conventional diesel), and a lower score is better. Click to enlarge.

Impact on the climate. Volvo used a five-degree scale showing the percentage the reduction of carbon dioxide emissions compared with conventional diesel fuel: 0-25% reduction; 26 - 50% reduction; 51 - 75% reduction; 76 - 90% reduction; and 91 – 100% reduction. Non-fossil CO₂ emissions were not included since they do not lead to a net increase of carbon dioxide in the atmosphere.

Five of the alternatives—synthetic diesel, dimethyl ether, methanol, biogas and hydrogen plus biogas—reduce the impact on the climate by more than 90%. In the case of methanol, gasification of black liquor is required in order to get the highest rating. For biogas and hydrogen gas+biogas, gasification of biomass is required in order to receive the highest rating. A lower rating applies if the biogas is produced through anaerobic digestion of household waste. Results for ethanol vary between 0 and 75 percent reduction depending on the production method. Biodiesel had the lowest ranking after ethanol.

WTW energy efficiency expressed in percentage of energy reaching the wheels. Click to enlarge.

Energy efficiency. Energy efficiency is rated on a falling scale and is expressed in percent indicating the amount of energy that reaches the vehicle’s driven wheels. Current fossil diesel fuel achieves approximately a 35 percent total level of efficiency. Results may vary for the same fuel, depending on the production process used.

DME and methanol receives the highest rating, on the condition that they are produced from black liquor from the wood pulp industry. The highest rating for synthetic diesel also requires the gasification of black liquor. The rating for biogas, biogas+biodiesel and hydrogen gas+biogas apply to production with gasification and anaerobic digestion. Production of biogas via gasification of black liquor is not included in the summary. The low rating for ethanol is due to the high energy consumption for cultivation and fuel production.

Efficiency of land use expressed in km/hectare/year. Click to enlarge.

Land use efficiency. The yield per hectare for each crop has been calculated using information about average yields from good quality land. The rating scale indicates how far a heavy truck can travel per year and hectare. Growing conditions apply to Swedish conditions. Cultivation in other places leads to different results but the relationships are more or less the same, according to Volvo. Volvo reduced the amount of fuel produced by the amount of fuel/energy required for harvesting, production, transport, etc. The results may vary for the same fuel, depending on the production process used.

DME and methanol, combined with black liquor gasification get the highest rating. These fuels have high harvest yields, require little use of fossil fuels, and have high energy efficiency. Synthetic diesel has high harvest yields, requires little use of fossil fuels, but has lower energy efficiency and limited selectivity in production. Ethanol gets a low rating due to limited energy efficiency and in certain cases the need for a great deal of fossil energy. Biodiesel gets the lowest rating due to low average harvest yields and the use of a great deal of fossil energy. Biogas production via gasification of black liquor is not included in the summary.

Fuel potential in TWh. Click to enlarge.

Fuel potential. Volvo expressed fuel potential in TWh (Terawatt hours). According to a study conducted by EUCAR/CONCAWE/JRC, the potential availability of waste wood, farmed wood, and straw in the EU in 2012 is approximately 700 TWh per year while the potential for sunflower oil and rapeseed oil is estimated at approximately 80 TWh per year.

350 to 420 TWh—the highest ranking Volvo used for the fuels—are equivalent to approximately 10-12% of the expected demand for petrol and diesel in the EU in 2015.

DME, methanol, biogas, biogas+biodiesel and hydrogen gas+biogas get the highest fuel potential rating.

Synthetic diesel, DME, methanol, and biogas can all be produced from entire crops, wood feedstocks, or other biological material. However, synthetic diesel has a lower level of efficiency and provides a lower proportion of fuel that can be used in vehicles. With respect to biogas, waste material and sewage can be used in production.

Ethanol can be produced from a number of feedstocks, including waste wood or other biological materials that contain cellulose, although the level of efficiency is relatively low.

Biodiesel, which has received the lowest rating, is produced from vegetable oils such as rapeseed oil and sunflower oil. Availability is limited since rapeseed can only be grown on the same land every fourth year or every sixth year. Furthermore, only the oil in the seeds can be utilized for fuel.

Vehicle adaptation. Volvo tried to provide a collective assessment of technical complexity, including adjustments to compensate for maximal engine performance, weight increase, range between refuelling, increased space for the fuel and the need for new and more expensive components. It also encompasses the need for technology to meet future emissions requirements.

Biodiesel and synthetic diesel get the highest rating, as vehicles that are run on these fuels are essentially comparable to conventional diesel vehicles.

The lower energy content in DME results in a 50% reduction in range but it is still possible to use the fuel for long-haul transport. DME requires a unique and advanced fuel system, but also offers savings in terms of costs and weight with regard to exhaust noise damping and treatment of exhaust gases.

Ethanol’s lower energy content results in a 30% shorter range per tank of fuel.

Biogas+biodiesel offers maximal engine performance, but range is reduced by half if the gas is in liquid form. This also requires two separate fuel systems. Biogas and hydrogen gas+biogas require an Otto engine, which limits power output. The compressed gas has a low energy density, which limits range to approximately 20 percent. A complex tank system results in higher costs and increased weight.

Fuel costs relative to fossil diesel. Click to enlarge.

Fuel costs. Volvo’s assessment—expressed as a percentage of the cost of conventional diesel, exclusive of taxes, at a raw oil price of US$70/barrel—includes the costs of raw materials, fixed and variable costs in the production plants, and costs for transport, infrastructure, and energy consumption in the chain of distribution.

The comparison was made per liter of diesel equivalent. The results may vary for the same fuel, depending on the feedstock.

DME and methanol get the highest rating. When produced from black liquor, they are already competitive today in terms of costs. Production via gasification of forest products or farmed wood is more expensive.

The cost of biodiesel is some 60% higher than for conventional diesel. Biogas based on waste materials leads to the most favorable results, primarily due to low feedstock costs. For biogas+biodiesel, biogas in liquid form is approximately 25% more expensive than compressed biogas. Biogas production through gasification of black liquor is not included in the summary.

Synthetic diesel is the most expensive fuel because of high investment costs and the relatively low energy efficiency in production. Ethanol is generally expensive to produce. Production from forest products is the most expensive process.

Fuel infrastructure. Synthetic diesel gets the highest rating. Biodiesel requires certain measures due to its lower storage stability. Methanol and ethanol require corrosion-resistant material, increased fire protection measures, and a separate infrastructure if they are used as pure fuel. Methanol needs to be handled in completely closed systems due to a high health risk.

The infrastructure for DME is similar to the one that has been established for Liquefied Petroleum Gas (LPG). DME is heavier than air and can accumulate in the event of leakage, resulting in a fire hazard. Biogas is handled at high pressure (200 bar) and requires the same infrastructure as the current system for natural gas.

The infrastructure for hydrogen gas is the most expensive and complicated one.

Resources:

• Volvo Group Renewable Fuels