Patrones de Diseño

Agricultural production is optimized for food and fodder production in Central Europe but now has to meet the demand for sustainable, innovative, renewable energy production. The question arises whether net renewable energy can be produced with the given agricultural tools.

The challenge was to find a high yielding site-specific energy crop and crop rotation system that is capable of providing the high quality biomass needed for renewable energy production for different modern conversion technologies. Energy cropping must be environmentally benign to ensure sustainable production. The following points must be considered when examining the results obtained in the five papers:

− One energy crop can best be produced for one energy type and the corresponding conversion technology.

− On the basis of the chosen conversion technology, the energy crop can be optimized for its quality.

− Agricultural practices must be adapted to the renewable energy production need, and not continued in the current manner with the imposition of agriculture to produce energy.

The perennial lignocellulosic crops willow and miscanthus combine high biomass and energy yields with low input parameters such as nitrogen fertilizer and pesticides. The production of perennial crops can be designed to be environmentally benign and at the same time to sequester carbon. Switchgrass, a C4 plant like miscanthus, might be better cultivated on marginal land where no other energy crops can compete. Lignocellulosic biomass can be used for combustion or converted into liquid biofuels via the Fischer-Tropsch-Synthesis. The latter conversion technology produces biofuels, which are second generation technologies. It is thought that these technologies will be competitive with fossil fuels in the short to middle term.

C4 plants are advantageous because of their high biomass yield potential. This has also been shown to be true of the annual energy crop maize. Maize is currently the highest yielding energy crop but simultaneously demands high levels of inputs. High yields imply efficient land use. Maize is often produced in continuous systems, which have considerable ecological impacts. These impacts can be minimized through the cultivation of undersown crops or catch crops with the aim of having the soil covered nearly year-round.

Environmentally benign and sustainable energy cropping includes the cultivation of crop rotation systems, which allow for synergistic effects such as lower infestation pressure and nutrient accumulation. Intensive crop rotation systems imply good site conditions and crop management (water and nutrient supply). Crop rotation systems using no-till techniques contribute to carbon sequestration, but they are not energy saving. Site-specific energy cropping is possible when site conditions are known and can be responded to.

Usually, annual energy crops are lower yielding in Central Europe compared to perennial crops, but their production methods are widely known. They can be easily converted into first-generation biofuels and distributed through existing infrastructure. Grain crops can contribute to the rising need for biomasses for combustion or for anaerobic digestion. Wet biomass produced by annual energy crops can be efficiently converted into heat and power via anaerobic digestion in biogas plants. Two prerequisites for efficient methane production are high yields and a suitable chemical composition.

The quality of biomass can be determined through dry matter content and chemical composition. Both quality parameters can be influenced by crop management (choice of species and variety, fertilization, harvest date). Influences from site and year must also be considered. All crop management procedures can be performed without jeopardizing the main target, which is a high biomass and net energy yield.

For a comprehensive overview of renewable energy production from agricultural land, additional aspects must also be considered, which could not be covered by the present study.

They include the following questions:

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What is the long term perspective for farmers – perennial or annual energy crops?

Perennial crops will determine the land use for 15 to 20 years, whereas annual energy crops can be changed annually.

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Site-specific energy cropping is demanded but what can be produced from marginal land alongside switchgrass? Are there crops that can be grown? Is it cost and energy-efficient to irrigate energy crops when water is the limiting factor?

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Breeding of energy crops has only recently begun. Are there further features to be expected that will substantially improve renewable energy production?

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What will the effect be on biodiversity of the increased production of a few crops?

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If global warming continues to proceed rapidly, then the climate in Central Europe will probably change to a more subtropical type with a generally warmer climate throughout the year. Thus, additional energy crops that need warmer climates to produce high yields

can be considered. Plants with a C4 photosynthetic pathway, which have been identified as having the potential to be high yielding at appropriate sites, will be one way to meet future challenges.

Agriculture can contribute to the production of renewable energy without significantly changing its tools. Energy farming has the potential to produce crops for all energy types in an environmentally benign and sustainable way. Crop rotation systems contribute to the sustainability of agriculture. The basis of successful renewable energy supply is very efficient production.

In document Analisis y Diseno del Modulo Sumario del proyecto Sistema de Gestion Fiscal (página 38-44)