Table 8 Energy balance and energy ratio (R) of unfertilised (F0) and fertilised (F +) Salix varieties and dairy manure (DaM) co-digestion feedstocks in the biogas system under base and heat recovery (HRE) scenario

Net energy output^*

9.43

10.19

10.42

10.22

9.85

9.24

10.04

10.41

10.33

10.32

11.10

10.95

GWh

Base scenario

 Net diesel demand

1.06

1.24

1.07

1.45

1.08

1.28

1.07

1.50

1.07

1.26

1.06

1.22

GWh

 Net heating demand

2.79

2.75

2.76

2.73

2.85

2.85

2.76

2.81

2.80

2.83

2.84

2.79

GWh

 Net cooling demand

1.07

1.11

1.13

1.11

1.09

1.06

1.09

1.12

1.12

1.12

1.17

1.16

GWh

 Net electricity demand

0.73

0.77

0.79

0.78

0.75

0.72

0.77

0.79

0.78

0.78

0.83

0.82

GWh

 Output–input ratio

1.67

1.73

1.81

1.69

1.71

1.57

1.77

1.68

1.79

1.72

1.88

1.83

HRE scenario

 Net diesel demand

1.06

1.24

1.07

1.45

1.08

1.28

1.07

1.50

1.07

1.26

1.06

1.22

GWh

 Net heating demand

1.62

1.56

1.56

1.54

1.66

1.68

1.56

1.61

1.60

1.63

1.61

1.57

GWh

 Net cooling demand

0.24

0.26

0.27

0.26

0.25

0.23

0.26

0.27

0.26

0.26

0.29

0.28

GWh

 Net electricity demand

0.73

0.77

0.79

0.78

0.75

0.72

0.77

0.79

0.78

0.78

0.83

0.82

GWh

 Output–input ratio

2.59

2.66

2.83

2.54

2.63

2.36

2.75

2.50

2.78

2.62

2.94

2.82

Improvement in HRE scenario over base scenario

55.1%

53.6%

56.0%

50.6%

54.2%

51.0%

55.5%

49.2%

55.1%

52.1%

55.9%

54.0%