A Question of Properties

Trees and grass, leaves and straw – sounds like idyllic countryside and fresh air. But what is amazing: This is actually where the production of fuel begins. We are, however, talking about biofuel that is produced from so-called energy plants, from leftover wood, green waste or straw, for example. In the long run, these resources will gradually replace fossil energy carriers in fuel production. The aim is to reconcile mobility and environmental protection better in the future.

In Germany, biofuels have already replaced at least three percent of conventional fuels in road traffic. It was only at the start of March 2007 that the EU heads of state and government committed themselves to increasing the share of biofuels to ten percent by 2020. Above all, synthetic fuel on the basis of biomass (BtL), like so-called SunFuel, can make an important contribution to reaching these EU aims.

In order to use the potential of the existing biomass to the full in the future, the Clausthal Institute for Environmental Technologies (CUTEC) with the support of Volkswagen and the Agency of Renewable Resources (FNR) is investigating its economy in the area of fuel production. The aim of the research project was to define the minimum requirements for biomass and provide economic planning data. The results are above all directed at potential biomass farmers and future operators of biofuel refineries. The final report provides farmers with reference points about requirements for the plants or the preparation techniques and storage. This will allow producers to adjust to the set requirements at an early stage. Potential facility operators are shown which measures will help make operation profitable.

Biomass – a heterogeneous starting product

As an energy carrier, biomass should not be seen as a single plant group. On the contrary, biomass covers a wide range of fast-growing and unassuming plants. In addition, bio waste materials like straw, wood or organic waste are used. For this reason biomass has greatly varying properties. On the one hand, this concerns the chemical structure and physical properties and, on the other, for example, cultivation and harvesting methods or storage techniques. To produce biofuel, it is important to know that different chemical compositions can lead to different reactions when biomass is processed. As a result, specific requirements are placed on facility technology that have to be met for fuel production.

Volkswagen supports the investigation of such requirements as part of the science collaboration “Biomass for SunFuel” under the patronage of the German states of Brandenburg, Hesse and Lower Saxony. A research project completed under the guidance of the CUTEC Institute aimed to investigate technical and economic questions from the viewpoint of farmers and facility operators. In the long-run, this should provide the basis for large-scale and economic production of SunFuel.

All biomass is suitable for SunFuel

In the project, it was possible to take the experiences with traditional power plants, waste incineration plants and biomass power plants as a basis. This showed that the properties of the biomass, with which a facility is operated, have a great influence on the further processing. In addition, information on problems that occur frequently was available. Past difficulties were, for example, caused by a high chlorine content that can lead to corrosion in the facilities. Also problems that are caused by the phosphor or mineral content of the plants were already recognised and checked before the project started.

The CUTEC Institute has produced an interesting result for potential facility operators. In terms of facility technology, there are no significant limitations resulting from the chemical and physical properties of biomass. This means that biofuel facilities can process all types of biomass almost without any problems. Some properties, for example, a low chlorine or sulphur content, do prove to be particularly favourable. This can, however, be taken into consideration during the facility planning from the beginning to avoid problems. No additional costs arise for the facility operator in the long term as a result. There are slightly higher costs for the new construction, but the operator can then benefit from a wider range of biomass qualities, i.e. for example, also buy the respectively cheapest biomass without having to pay any particular attention to its composition.

The research project has also provided an important discovery for biomass farmers. Even if the facility technology can easily process different biomass qualities, the significance of the chemical properties of the plants is very different for the economy of the fuel facilities. The influence of the mineral content has been investigated in particular. This varies considerably with different plant species. When biomass is processed, minerals occur in the facilities as ash. The CUTEC Institute has proven a clear connection between the ash content and the economy of fuel production. Plants with the lowest possible mineral content are thus recommended.

Size and form of the biomass determine the economy

Therefore the lower the mineral content, the easier higher profits can be reached. To a limited extent, this can be influenced by the soil fertilisation – if there is at all freedom of choice for individual farmers. A further analysis of the combustion process is worthwhile for refinery operators with regard to the ash that occurs. Their aim should be to create ash that, for example, can be used as a raw material by fertiliser producers. In this way, the residual material ash can, on the one hand, close the mineral cycle of the ground and, at the same time, increase profits for facility operators.

A special mixture of produced biomass is important for farmers to maximise their returns. Fuel facilities need to be supplied all year round in order to work profitably. Potential biomass farmers should be prepared for this. Therefore they will be able to sell their product at a profit not just during specific harvest times, but also all year round.

The transport costs and the composition of the supplied biomass were also investigated. The transport route has only very small effects on the costs. The quantity or form of the biomass is very different, however. As costs for energy use and the corresponding plant technology are incurred when the plants are cut up, this has a great influence on the economy. It has thus become clear that cutting up is only worthwhile if we can work at high efficiency – i.e. with low energy consumption. Processing into so-called pellets has been assessed critically in particular. The volume of the biomass can actually be reduced greatly in this way which makes it very easy to transport later on. The incurred costs are estimated as excessively high, however.

One of the most important research results is significant for potential facility operators. The size of the planned facilities has a great influence on the economy of the later operations. Operators of larger facilities can pay high prices for the required biomass. If the size of the fuel facility decreases, the possible purchase price is also reduced considerably. Conclusion: Economy can only be achieved at all above a certain facility size.

Incentive for further research

The researchers have come to the conclusion that biomass facilities can currently only operate economically if the price of diesel is high. According to the calculations, the purchase price for SunFuel would be over €1.15 per litre. It is decisive here that various costs like the added value and a possible fuel tax or the distribution are not yet included in this price. In comparison: Car drivers currently pay between €1.15 and €1.40 per litre for conventional diesel in Germany – as a fixed final price including all costs incurred.

At the same time, the investigation also shows the opportunities in the further development of biomass processing. Both biomass farmers and also future biofuel facility operators have been given specific recommendations on how they can increase their economy in the future. By using improved cultivation and preparation methods as well as further developed facility technology, fuel made from biomass can, in future, play an important role in sustained energy supply – and also be produced in an economic way.