Skip to main content

Advertisement

Table 5 Total energy input, saccharification yield and energy efficiency of grinding, chemical pretreatment and subsequent milling

From: Gaseous ammonia pretreatment lowers the required energy input for fine milling-enhanced enzymatic saccharification of switchgrass

Sample and pretreatment method Total energy input of initial size reduction + chemical treatment + milling (MJ/kg) Glucose mass yield (kg/kg biomass) Energy efficiency (glucose mass yield/energy input, kg/MJ) Other reducing sugars mass yield (kg/kg biomass) Energy efficiency (other reducing sugar mass yield/energy input, kg/MJ) Energy efficiency (total sugar mass yield/energy input, kg/MJ) [normalized to 65 % carbohydrate equivalent]
Switchgrass, 10 wt% gaseous ammonia + attritor millingi 2.012 (DM = 93 %) 0.309 (total soluble)b 0.154 0.242 (total soluble xylose + arabinose) 0.120 (xylose + arabinose) 0.274 [0.280] (total soluble sugars)
Switchgrass, extrusion and microwave treatmenta,j 900 for microwave alone 0.199c 2.21 × 10−4 0.1744 0.194 × 10−4 4.14 × 10−4
Steam explosion (Spruce)k 1.977f (L/S = 1) 0.346d (monomeric) 0.175 h   [0.260] (monomeric sugars)
Organosolv (Lodgepole pine)l 2.687f (L/S = 7) 1.613f (L/S = 4) 1.254f (L/S = 3) 0.347e (monomeric) 0.129 0.215 0.277 h   [0.187] [0.311] [0.400] (monomeric sugars)
SPORL (Spruce)m (Lodgepole pine)o 1.863f (L/S = 3) L/S = 3 0.372d (monomeric) 0.200 h h   [0.350] (size reduction energy 150 kW-h/ton) (monomeric sugars) [0.270]
Wheat straw without chemical pretreatmentn 2.149 g (L/S = 0.2) 0.118 0.0549 0.058   
Wheat straw with 5 % w/w NaOH dilute pretreatmentn 2.867 g (L/S = 5) 0.332 0.116 0.181   
Wheat straw with 5 % w/w NaOH “dry” pretreatmentn 1.307 g (L/S = 0.2) 0.32 0.245 0.212   
Wheat straw with 5 % w/w NH3 “dry” pretreatmentn 1.620 g (L/S = 0.2) 0.14 0.0864 0.071   
  1. The current process on switchgrass is compared to literature processes for which total energy inputs, saccharification yields and energy efficiencies have been calculated. The total energy input for all processes includes that required for grinding, chemical pretreatment and subsequent milling
  2. aPolysaccharide composition assumed to be the same as in current paper
  3. bEnzymatic hydrolysis at 25 % solids loading
  4. cEnzymatic hydrolysis at 10 % solids loading
  5. dEnzymatic hydrolysis at 2 % solids loading
  6. eEnzymatic hydrolysis at 2 % cellulose loading
  7. fAssumes thermal energy recovery of 50 % for thermal processes
  8. gEnergy calculations are net (power with biomass minus power without biomass) for centrifugal and ball milling
  9. hAssumed to be recoverable from pretreatment stream
  10. iCurrent work
  11. jKarunanithy et al. [54]
  12. kSöderström et al. [48] and Zhu et al. [20]
  13. lPan et al. [49] and Zhu et al. [20]
  14. mZhu et al. [20], SPORL (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose)
  15. nBarakat et al. [22]
  16. oZhu et al. [50]