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Digestate handling. Logistics of biomass for biogas Co-substrates.

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Presentation on theme: "Digestate handling. Logistics of biomass for biogas Co-substrates."— Presentation transcript:

1 Digestate handling

2 Logistics of biomass for biogas Co-substrates

3 Surplus of P in Danish agriculture P Surplus Plant Cattle Pig Mixed

4 What is this?

5 Typical composition of digestate Total N kg/ton Total P kg/ton K kg/ton Degassed slurry Liquid fraction Solid fraction Birkmose et al. (2013). Biomasse til biogasanlæg i Danmark

6 Solid Logistics of biomass for biogas Solid fraction Co-substrates

7 Value of digestate Potential Value Kr/ton Degassed slurry Liquid fraction Solid fraction True value is lower because of: 1. Difficulties and costs during storage, 2. Uncertain availability of nutrients, 3. Administrative and legistrative problems, 4. Increased demand for catch crops, 5. Odour, 6. Supply and demand Birkmose et al. (2013). Biomasse til biogasanlæg i Danmark

8 The goal Feedstock (chemical composition) Retention time Temperature Soil Precipitation Oxygen NH 3 N 2 O CO 2

9 Main environmental impacts associated with digestate handling NH 3 emissions during storage and land application Formation of the greenhouse gas N 2 O ad CO 2 after land application Nitrate leaching Phosphorus loss

10 NH 3 volatilization High pH of digestate leads to high risk of ammonia volitilization Covered storage Low dry matter content leads to fast infiltration and therefore low ammonia volatilization

11 N 2 O emission N 2 O is formed in two processes, nitrification and denitrification Nitrification requires ammonia and oxygen Defitrification require nitrate, organic matter and absense of oxygen

12 Application of fertilizer and N2O emissions Bouwman (1996)


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