01 Introduction

• small processing machines —> gaseous and liquid fuels

• More processing machines

• Higher efficiencies of the processing machines

• Lower specific investment costs of the processing machines (no steam generator)

• CO2 emissions

• Limited reach (40 - 60 years)

• Security of supply

1. Fermentation (biogas, sewage gas)

   • Substrate ferments anaerobically in big digesters

   • Low temperature process

   • Heat values till 20 000 kJ/m3

2. Thermal gasification

   • Autothermal gasification —> Lean gases till 5 000 kJ/m2

   • Allothermal gasification —> Gases till 15 000 kJ/m2

   • Tar problem

• Combustion or fermentation —> CO2 as much as they absorbed earlier

• CO2 same amount released either through rotting or composting

—> It’s CO2 free, BUT additional CO2 for transport and agricultural growing

1. Vegetable oil

2. Sugar / Starch

3. Herbaceous (cellulosic) biomass

4. Woody (lignin) biomass

Sources

• Rape

• Palm

• Camelina

Options

• Vegetable oil cogeneration units

• Tractors

• Production of biodiesel

Problem

—> Only a part of the plant’s heat values is used

Advantage

—> Used directly in oil burners and engines

Sources

• Wheat

• Triticale

• Maize silage

Options

• Production of bioethanol

• Production of biogas (fermentation)

Problem

—> Only a part of the plant’s heat values is used

Advantage

—> Used in cold conversion processes (biogas plants and ethanol production)

Sources

• Green waste (shrub cuttings)

• Straw

• Miscanthus (C4-grasses)

Options

• Production of biogas (fermentation)

• Thermal usage of electricity and heat generation

Problem

—> Bad usage < 50 % in cold conversion processes (biogas plants and ethanol production)

—> Thermal usage (ash melting behavior and chlorine content)

• Sugar, carbohydrates, fats

  —> Easily degradable by bacteria

• Cellulose (polysaccharide)

  —> Degradation is more difficult (slower) by bacteria

• Lignin (solid biopolymere)

  —> In economic time only thermal decomposable (combustion, gasification)

Photosynthesis

—> With light energy, CO2 will be absorbed and as carbon C integrated in a plant

—> C4-Photosynthesis: Faster, more efficient (maize, grasses, miscanthus)

Examples

• State solid-liquid-gaseous

• Humidity

• Elemental composition

• Density

• Low energy density —> High heat value needed (wood chips dry, humid)

• Required capacity of transporting

  • Max. 50 MWel of wood chips

  • Max. 20 MWel of biogas plant

1. Biogenic residues

   • Wood waste

   • Green waste

   • Industrial waste wood

   • Wood pellets

1. Energy plants

   • Forest wood chips

   • Fire wood

   • Short drive wood

• Fast growing timbers (poplars / willow)

• Repeated after 3-5 or 10-15 years

• High yields until 25 t/ha*a