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Crop Plans

Rapid Turnover Projects

Fast-growing varieties of trees, like willows and poplars, have been analyzed in Germany for years in isolated demonstration and research projects. However, experiments on rapid turnover plantations have not progressed beyond the pilot stage, because there has not been any sustained demand for wood chips up to now. But there has been a commercial breakthrough in Sweden. Willow trees are grown there on approx. 16,000 ha and the wood chips from these are sold to heating works.

The fast-growing trees are usually grown in a 3 or 4-year rhythm. They are harvested in winter using an adapted corn chopper and are stacked in piles. As a result of microbe activity, the water content in these heaps falls to approx. 30% in just a few months without any further intervention.
Huge progress has also been made in cultivation techniques. Rapid turnover plantations have now become so cost-effective, when compared with other arable crops, that earnings of approx. € 50 per t of dry matter are guaranteed at many locations. Depending on the location and type of tree used, the yields normally range between 10 and 20 t of dry matter per hectare each year – i.e. approx. 30 – 80 t of dry matter per harvest.

Rapid turnover plantations have many advantages:

  • little interference with the soil balance
  • continuous humus enrichment in the soil
  • little need for nutrients
  • at most, small amounts of pesticides are required
  • nutrients from deeper soil horizons are activated
  • ideal for damp locations
  • plowing is only required at all during the first two years
  • almost undisturbed habitat for wild animals
  • little work required

Fast-growing trees are particularly suitable for producing SunDiesel®, as the wood chips from these do not require any treatment other than additional drying.

Straw and Whole Plant Crop Briquettes

A large amount of the straw produced on agricultural land is unused at the moment. Even allowing for the humus balance, i.e. the right amount of straw is left in the fields to form new humus, there is enormous potential here. For example, the State Office for Agriculture in the state of Thuringia has calculated that 60% of straw could be used for energy purposes, i.e. 1.6 million t per annum in Thuringia alone, even after allowing for an even humus balance and straw for animals.

Once straw has been processed and turned into a universal pellet or briquette, it is very suitable for SunDiesel® production. In order to make the process chain as efficient as possible, the straw can be compressed into bales and stored in piles at the edge of fields or old agricultural buildings. The straw can then be transported to briquette works or directly to the SunFuel production facilities “just in time”. The density of straw in highly compressed bales almost matches that of wood chips – but pellets or briquettes have a much lower volume. In each case it is economically and ecologically feasible to transport the materials over long distances, e.g. in trains up to 700 m long or by sea.

Of course, whole plant crops can also be used within the same process chain. This will be particularly interesting in future when scientists manage to cultivate special varieties with a higher yield from the whole plant. At the moment cereals are used, but they are really designed to produce as much grain as possible.
In each case, classical arable crops and their by-products can be used for the flow of raw materials for SunDiesel® production. Farmers can then use proven arable crop concepts without the need for any fundamental changes.

Miscanthus

Scientists here in Germany discovered several years ago that miscanthus, also known as Chinese reed, could be used as an energy plant. But disillusionment soon followed the initial euphoria when expected yields failed to materialize. Indeed, some unexpected problems cropped up. The results of leaving the young miscanthus plants in the soil during the first winter were disappointing.
The initial problems have now been solved and growing practices have been optimized. A yield of 15 – 20 t of dry matter per hectare per annum on good soil is a realistic figure. Miscanthus has several advantages: the crop only has to be planted once and can then be used each year for at least 20 years; the biomass harvest takes place in winter and has a water content below 20%; and no pesticides are required once the plant has become established. And there is still more potential for cultivating miscanthus. The type most commonly used is still a wild form of the most common variety of the plant, miscanthus giganteus.
In Great Britain miscanthus is now being grown on several plantations covering thousands of hectares.

The Idea of Planting Two Crops

Prof. Scheffer from the University of Kassel/Witzenhausen has developed the modern form of two crop harvests. In this system of maximum biomass production, two crops are grown on the same land during the same year. Both are harvested while still green and then placed in silos. The hardy crop (e.g. winter cereals, rape seed, winter peas) is sown in October immediately after the previous crop has been harvested. This is then harvested in May and a fast-growing crop like corn, sunflowers or pearl millet, which love warmth, is then sown. The complete vegetation period is fully exploited and this leads to particularly high yields of biomass. This concept has been tested on about 25 hectares near Göttingen for some years now. The yields of biomass have been between 25 and 30 t of dry matter per hectare.

However, the biomass in this system is not dry, but has a water content of approx. 65%, so some processing is necessary. The best solution here is a combination of solid combustible fuel/biogas production: a press is used to separate the liquid and solid parts in the silage. The liquid part is fed into a biogas unit and is converted into biogas in a very short time in an extremely efficient process. The biogas can then be used in a combined heat and power station to generate electricity. The electricity is fed into the public grid and attracts very favorable remuneration rates according to the EEG. The waste heat in the electricity generation process is used to further dry what is left over from the press in order to manufacture a universal solid combustible fuel. This is then available as a raw material to produce SunFuel.