Gasification of olive mill solid wastes for cogeneration applications in Tizi Ouzou region: thermo-economic assessment

Figures & data

Figure 1. Repartition of olive oil production in Mediterranean countries in 2017.

Figure 2. Location of Biomass and CHP sites (Google map 2020).

Table 1. Olive pomace generated in selected olive mills and their distance from the plant.

Olive mill	After drying (t year^−1) 15% humidity	Average distance from the plant (km)
Ait bouyahia	84.6	Plant location
Tala khelil	93.06	6
Ait bouali	94.752	4
Ait Mesbah	253.8	2
Ouadhia 1	84.6	4.5
Ouadhia 2	338.4	5
Total	949.2	-

Table 2. Proximate and ultimate analysis of the biomass used (Fortunato et al. 2017; Vera et al. 2018a).

Biomass/element (% db)	C	H	O	N	S	Ash	LHV(MJ/kg)	Moisture (% wb)	Fixed carbon	Volatile matter
Olive Pomace	51.31	6.4	35.01	2	0.26	5	16,836	15	17.60	77.38
Olive tree pruning	47.1	6.18	41.66	0.55	0.1	4.41	16,730	5	16.31	74.73

Figure 3. Schematic of the power plant.

Figure 4. Calculations procedure developed by Cycle-Tempo^®.

Figure 5. Schematic of the CHP system in Cycle-Tempo^®.

Table 3. Performance parameters of the EFGT system.

Parameter	value	Unit
Combustion chamber pressure	1.013	bar
Compressor pressure ratio	4.5	-
Combustion efficiency	95	%
HTHE thermal efficiency	90	%
HTHE pressure drop	2	%
Flue gas temperature	950	°C
Hot side temperature difference HTHE	100–110	°C
TiT (Pipe 18, Figure 5)	850	°C
Mass flow air(working fluid)	0.7833	kg s^−1
Compressor isentropic efficiency	0.768	-
Isentropic efficiency of other compressors, blowers and pumps	0.75
Turbine isentropic efficiency	0.826	-
Electric generator efficiency	0.97	-
Mechanical efficiency for turbine and compressor	0.95	-
Exhaust gas temperature (Pipe 2, Figure 5)	555	°C

Table 4. Environment definition used in exergy calculations.

Component	Fraction (Mole %)
Ar	0.91
CO2	0.03
H2O	1.68
N2	76.78
O2	20.60
Environmental conditions
Temperature (°C)	25
Pressure (bar)	1.01325

Table 5. OPEX and CAPEX economic values.

Parameter		Value	Unit
CAPEX
Gasifier + EFGT+HTHE		150	k$
Civil work		10	k$
Engineering+ develop+ grid connection		20	k$
OPEX
Biomass cost	Olive pomace	8.5	$/t
	Olive leave and pruning	6.3	$/t
O&M cost (year)	Maintenance cost	0.0075	$/kwh
	Manpower requirement	1.34	$/hour

Table 6. Composition of the producer gas.

Gas composition (% mole)	Olive pomace	Olive tree pruning	Experimental results (Vera et al. 2014)		Theoretical results
			Olive tree pruning	Olive Pits	Olive pomace (Fortunato et al. 2017)	Olive tree pruning(Vera et al. 2018a)
H2	14.94	14.87	16.96	16	17.19	14.8
CO	18.32	20.69	19.90	22.83	19.23	19.5
CO2	8.32	8.42	11.18	5.11	11.10	9.3
N2	44.97	43.73	47.95	51.27	48.7	41.5
CH4	1.43	1.49	2.73	3.43	3.15	2.3
H2O	11.44	10.25	1.29	1.36	-	11.9
LHV(MJ/kg)	4.12	4.39	4.76	5.45	4.86	4.53
Xof(kgair/kgfuel)	2.09	1.92	-	-	1.88	1.7

Figure 6. Composition of producer gas in function of air/fuel ratio. Olive pomace (a); olive tree pruning (b).

Figure 7. Effects of the OMSW moisture content on the syngas composition. Olive pomace (a); olive tree pruning (b).

Figure 8. Effect of gasification temperature on low heating value.

Figure 9. Effect of the gasification temperature over gasification efficiency.

Figure 10. Electrical efficiency in function of pressure ratio.

Figure 11. Effect of temperatures difference hot side on electrical efficiency.

Figure 12. SANKEY diagram of the CHP plant.

Figure 13. Energy losses in the main components of the plant.

Table 7. CHP plant performances with optimum operating parameters.

Performances	Olive pomace	Olive tree pruning	25 % tree pruning 75 % pomace	50 % tree pruning 50 % pomace	75 % tree pruning 25 % pomace
Energy input kW	414.22	408.19	412.5	410.9	409.6
Electrical power (kW)	75.78	75.78	75.78	75.78	75.47
Thermal power (kW)	170.226	170.226	170.226	170.226	170.226
Electrical efficiency(-)	18.24	18.56	18.37	18.44	18.5
Plant efficiency(-)	59.2	60.26	59.64	59.87	60.05
Biomass consumption(kg/h)	88.92	87.84	88.06	87.8	87.73
Air fuel ratio (-)	2.09	1.92	2.06	2.02	1.97

Figure 14. Exergy distribution in the CHP plant.

Table 8. Comparison between the biomass consumption of the plant and available feedstock.

Biomass	Available feedstock (t/year)	Plant consumption (t/year)
Olive pomace	949.2	666.9
Olive tree pruning	757	658.8

Figure 15. NPV as function of biomass cost (K$).

Figure 16 . IRR as function of biomass cost (%).

Table 9. Financial appraisal of the project.

Biomass used	NPV($)	Pi	IRR (%)	Payback period(Years)
Olive Pomace	295,704	2.59	20	5.7
Olive tree pruning	314,031	2.69	21	5.4

Table 10. Potential of olive oil industry in the region of Tizi ouzou.

Year	Olive oil (t year^−1)	Olive (t year^−1)	Olive tree number	Olive pomace (t year^−1)	Olive tree Pruning (t year^−1)	Harvested area (ha)
2015	6979,304	38,245,7	2,885,328	15,298,28	60,104	28,621
2016	9449,228	53,464,2	3,048,702	21,385,68	63,619	30,295
2017	7516,4	42,920,7	3,048,702	17,168,28	65,058	30,980
2018	12,337,2	76,050	3,117,200	30,420	66,801	31,810
2019	9482,808	50,420,8	3,358,878	20,168,32	70,375	33,512
Average	9153	52,220	-	20,888	65,191	-

Table 11. Potential of electricity generated from olive solid wastes in the region of Tizi ouzou.

Raw material	Quantity generated (t year^−1)	Equivalence in electricity (MWh year^−1)
Olive pomace	20,888	17,801.3
Olive tree pruning	65,191	56,240.6
Total	86,079	74,041.9

Google map. 2020. “Localisation Google_map region de Beni douala.” Accessed 15 March 2020. https://www.google.com/maps/d/edit?hl=fr&hl=fr&mid=138m8iLZdPeZCyDsK0jkfNKxE_f2sCC-q&ll=36.61410834628218%2C4.005867957606256&z=12.

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