BIOETHANOL PRODUCTION FROM FOOD AND AGRICULTURAL WASTE AND ITS APPLICATIONS  V. Beschkov, K. Semkov, D. Yankov Institute of Chemical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria 7th World Congress on Petrochemistry and Chemical Engineering, Atlanta, November 13-15, 2017

Hundreds of millions years planet history Fossil fuels release in the atmosphere carbon dioxide stored underground for millions of years. For one instance of the planet history man polluted it with waste accumulated for millions of years. The natural vegetation is not capable to assimilate it. -pulse Hundreds of millions years planet history History of humanity THE CARBON CYCLE SHOULD BE CLOSED FOR FUELS PRODUCED NOW!!!

Problem: Greenhouse gas reduction?

Renewable energy sources: Wind energy Solar energy Hydropower Biomass...

Share of renewables, EU statistics, 2015

Biofuels are: Ethanol; Biodiesel; Biogas; n-Butanol.

Benefits of biomass as fuel: Renewable and environmentally sustainable; replace (partially) the fossil fuels Produced locally biofuels lead to energy independence and safety; reduce the dependence of fuel import; Raw materials for organic products instead of oil; Contribute to decrease of greenhouse gas emissions. All they are produced from biomass grown now in amounts that nature can utilize. Drawbacks: Stress on prices of food cereals (ethanol from starch); second generation raw materials (lingo-cellulose); third generation (algae); Menace for biodiversity and environmental balance (plants for ethanol and biodiesel production); Secondary air pollution (for crops cultivation). Problems with waste treatment (e.g. waste glycerol at biodiesel production).

Bioethanol – some applications Ethanol is: easily transportable; safe to handle and store; non-toxic liquid fuel that can be used everywhere. Mishaps do not lead to significant environmental damage as is the case with oil. Ethanol is already a major fuel in Brazil and in the USA and is making its way to Europe. Its current price is significantly lower than that of gasoline on a heating value equivalent while it qualifies for CO2 credits.

Bioethanol – some applications Additive to gasoline and diesel; E5G to E26G (5-26% ethanol, 95-74% gasoline) E85G (85% ethanol, 15% gasoline) E15D (15% ethanol, 85% diesel) Octane booster; Steam reforming to hydrogen: CH3CH2OH + 3H2O → 2CO2 + 6H2 Ethylacetate production: CH3CH2OH + CH3COOH →CH3COO-CH2CH3 Solvent and feedstock for other chemicals and farmaceuticals; Fuel cells.

Ethanol production from lignocellulose materials (2nd generation) Reshamwala et al., Applied Biochemistry and Biotechnology, 1995.

Lignocellulose processing A. Kroumov et al., Int. J. Bioautomation, 2015

Improved methods of producing anhydrous ethanol Azeotropic distillation; Extractive distillation; Pressure swing adsorption (PSA) on molecular sieves; Membrane separation.

Goals: To test other organic waste suitable for ethanol production; To present PSA method for absolute ethanol production; To demonstrate the fuel cell performance of ethanol.

Experimental (1) Raw material: stillage after ethanol distillation; Methods: hydrolysis (alkaline (NaOH), ammonia, acid (1% H2SO4) and enzymes); Enzymes: -amylase and glucoamylase; cellulase. Microbes: Saccharomyces cerevisae; Zymomonas mobilis).

Results and discussion (stillage) Hydrolysis Reducing sugars (mg/ml); alkaline hydrolysis Reducing sugars (mg/ml) by acid hydrolysis compared to alkaline one. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH.

Results and discussion (stillage) Enzyme hydrolysis Reducing sugars after addition of α–amylase and glucoamylase. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH; (4) – 1% NH4OH; (5) – 2% NH4OH; (6) – 6% NH4OH. Reducing sugars after addition of cellulase. (1) - 1% NaOH; (2) – 2% NaOH; (3) – 3%- NaOH; (4) – 1% NH4OH; (5) – 2% NH4OH; (6) – 6% NH4OH.

Results and discussion (stillage) Ethanol and reducing sugars at fermentation after acid hydrolysis. 14 g dm-3 ethanol.

Experimental (2) Substrates: residual grain after ethanol fermentation (ground and not); potatoes cuttings. Hydrolysis: two-step enzyme hydrolysis (thermostable alpha- amylase with consequent saccharification by glucoamylase); Fermentation: industrial strain.

Consecutive acid and enzyme hydrolysis of residual grain 10 g grain + 50 ml 1% H2SO4, 1 bar, 30 min Separation 100 ml phosphate buffer, pH 5.5 α-amylase + glucoamylase, 24 h, 60 oC Separation 100 ml phosphate buffer, pH 4.65 Cellulase, 24 h, 45 oC α-amylase – Fuelzyme - Verenium Corporation, USA glucoamylase – Deltazym GA L-E5, Verenium Corporation, USA cellulase – Onozuca R-10 - Yakult Pharma- Japan

Results (residual grain)

Ultrasonic treatment of residual stillage 10 g grain + 100 ml 1% H2SO4, 15 min ultrasound, 1 bar for 30 min

Results (continued) Ethanol yield (comparison) Substrate Reducing substances, g dm-3 Ethanol concentration, Ethanol yield (96% vol.), ml EtOH/kg substrate   Residual grain (enzyme, our data) 112 62 230 Potatoes cuttings (enzyme, 98 50 212 Stillage (acid, our data) 59 14,6 146 Wheat straw, alkaline peroxide (Saha&Cotta, Biotechnol. Prog., 2006) 41,5 18,9 290 Corn stalks, H2SO4 (Ballat et al., Progress in Energy and Combustion Science, 2008) n.a. 196 Grain, acid (own data) 14,1 140

Anhydrous ethanol - pressure swing adsorption (PSA) based on molecular sieves

Synthesia SA, Gorna Oryahovitza, Bulgaria, 2008 PSA- our achievements Synthesia SA, Gorna Oryahovitza, Bulgaria, 2008 99,96% ethanol; 10000 litres/day

Direct ethanol fuel cell (DEFC) Anode: C2H5OH +3H2O=12H+ +12e-+ 2CO2 Cathode: 3O2+ 12H+ + 12e- = 6H2O Overall reaction: C2H5OH + 3O2 = 2CO2 + 3H2O Energy content of ethanol: 8.0 kWh/kg Energy content of methanol: 6.1 kWh/kg Energy content of hydrogen: 79 kWh/kg Energy content of gasoline: 12,8 kWh/kg

DEFC - results Current density : 70 A/m2 Power density: 16.8 W/m2

Thank you for your attention! Acknowledgement. This work was supported by grant DFNI E02/16 of the Fund of Scientific Research, Republic of Bulgaria.