Table 3.

Water and power costs in SC and SSC

Cultivation strategy	Submerged cultivationa	Static solid cultivation
Power for aeration (RMB)	2712.6	0
Power for stirrer (RMB)	1995.8	0
Cooling water (RMB)	1814.4	0
Power for heater (RMB)	N/A	0
Equipment depreciation	N/A	N/A
Total cost (RMB)	6522.8	0
Biodiesel value (RMB)	6120b	6120

N/A, not available

^aA 10-ton liquid fermenter is taken as an example. The power parameters for the air compressor (30 kW/h) and stirrer (22 kW/h) and the flow rate of cooling water (4.5 tons/h) were provided by the Fermentation Factory of Tuoxin Group, Xinxiang, China. The water and electricity expenses for industrial use were 2.80 RMB/ton and 0.63 RMB/kWh, respectively

^b Lipid production was calculated based on a lipid productivity of 0.995 g/L/h. Approximately 1.43 tons of lipids and 1.36 tons of biodiesel were produced after 6 days’ fermentation under a 95% biodiesel catalysis efficiency. The biodiesel value was evaluated based on a price of 4500 RMB (The renminbi, the official currency of the People’s Republic of China)/ton