9.6
Comparison of Different Biogas Upgrading Technologies
Elevated fuel price and the demand for alternative unlimited renewable fuel source
pave the way for many biogas upgrading technologies. Viable biogas upgrading
technologies are available that overcome the disadvantages in the traditional
techniques. The biogas upgrading technologies (i.e. physical/chemical methods
(pressurised water scrubbing, organic physical scrubbing, chemical scrubbing, pressure swing adsorption method, membrane technology, cryogenic technology, in situ
methane enrichment method and hybrid technology (Sahota et al. 2018)) and
biological methods (chemoautotrophic and photoautotrophic) (Angelidaki et al.
2018)) are compared based on the factors such as economic, technological, environmental (Sahota et al. 2018), operational and social indicators (Toledo-Cervantes
et al. 2017) (Table 9.1a and 9.1b). Based on these factors, the pros and cons of those
biogas upgrading technologies are analysed (Table 9.2).
(a) Economic Indicators
The economic indicators include investment cost, operation cost, maintenance
cost and sales cost (Toledo-Cervantes et al. 2017). Cheap electricity price is one of
the cost factors to be considered while selecting an upgrading technique. Also, the
cost of the upgrading technique depends upon the size of the plant (Petersson and
Wellinger 2009).
Comparing the absorption technologies pressurised water scrubbing, organic
physical scrubbing and amine scrubbing, the investment is about 1,000,000 €/year,
1,000,000 €/year and 2,000,000 €/year, respectively. The operation cost and maintenance cost are 14 ct/100 m
3 h and 15,000 €/year, respectively; for pressurised water
scrubbing, 13.8 ct/100 m
3 h and 39,000 €/year, respectively; and for organic physical
scrubbing and amine scrubbing, 14.4 ct/100 m
3 h and 59,000 €/year, respectively.
While comparing the cost analysis of absorption methods with adsorption methods,
the adsorption method requires high investment cost (1,750,000 €/year), less maintenance cost (12.8 ct/100 m
3 h) and comparatively high maintenance cost (56,000 €/
year). Various technologies such as pressurised water scrubbing and in situ methane
enrichment are economically suitable when compared to the amine scrubbing and
cryogenic method (Bauer et al. 2013a, b).
The fabrication cost is minimum, investment cost is maximum (20,000 €/year),
operation cost is comparatively high (10.8–15.8 ct/100 m
3 h) and maintenance cost is
comparatively less (25,000 €/year) for polymeric membrane technology, and fabrication cost is maximum for inorganic membrane technology among the membrane
separation technologies. The membrane cost is too high for polymeric membrane
technology (Vrboba and Karel 2017).
The plant capacity is high for polymeric membrane technology and pressure
swing, temperature swing and vacuum swing adsorption method. But, low operational cost is pronounced more with the hybrid technologies (Sahota et al. 2018). The
investment cost is 1.6 times more for the biological method than the conventional
physical/chemical method, and so the biological method is economically not
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B. S. Dhanya et al.
Comparison of Different Biogas Upgrading Technologies
Elevated fuel price and the demand for alternative unlimited renewable fuel source
pave the way for many biogas upgrading technologies. Viable biogas upgrading
technologies are available that overcome the disadvantages in the traditional
techniques. The biogas upgrading technologies (i.e. physical/chemical methods
(pressurised water scrubbing, organic physical scrubbing, chemical scrubbing, pressure swing adsorption method, membrane technology, cryogenic technology, in situ
methane enrichment method and hybrid technology (Sahota et al. 2018)) and
biological methods (chemoautotrophic and photoautotrophic) (Angelidaki et al.
2018)) are compared based on the factors such as economic, technological, environmental (Sahota et al. 2018), operational and social indicators (Toledo-Cervantes
et al. 2017) (Table 9.1a and 9.1b). Based on these factors, the pros and cons of those
biogas upgrading technologies are analysed (Table 9.2).
(a) Economic Indicators
The economic indicators include investment cost, operation cost, maintenance
cost and sales cost (Toledo-Cervantes et al. 2017). Cheap electricity price is one of
the cost factors to be considered while selecting an upgrading technique. Also, the
cost of the upgrading technique depends upon the size of the plant (Petersson and
Wellinger 2009).
Comparing the absorption technologies pressurised water scrubbing, organic
physical scrubbing and amine scrubbing, the investment is about 1,000,000 €/year,
1,000,000 €/year and 2,000,000 €/year, respectively. The operation cost and maintenance cost are 14 ct/100 m
3 h and 15,000 €/year, respectively; for pressurised water
scrubbing, 13.8 ct/100 m
3 h and 39,000 €/year, respectively; and for organic physical
scrubbing and amine scrubbing, 14.4 ct/100 m
3 h and 59,000 €/year, respectively.
While comparing the cost analysis of absorption methods with adsorption methods,
the adsorption method requires high investment cost (1,750,000 €/year), less maintenance cost (12.8 ct/100 m
3 h) and comparatively high maintenance cost (56,000 €/
year). Various technologies such as pressurised water scrubbing and in situ methane
enrichment are economically suitable when compared to the amine scrubbing and
cryogenic method (Bauer et al. 2013a, b).
The fabrication cost is minimum, investment cost is maximum (20,000 €/year),
operation cost is comparatively high (10.8–15.8 ct/100 m
3 h) and maintenance cost is
comparatively less (25,000 €/year) for polymeric membrane technology, and fabrication cost is maximum for inorganic membrane technology among the membrane
separation technologies. The membrane cost is too high for polymeric membrane
technology (Vrboba and Karel 2017).
The plant capacity is high for polymeric membrane technology and pressure
swing, temperature swing and vacuum swing adsorption method. But, low operational cost is pronounced more with the hybrid technologies (Sahota et al. 2018). The
investment cost is 1.6 times more for the biological method than the conventional
physical/chemical method, and so the biological method is economically not
262
B. S. Dhanya et al.