Date Palm Byproducts for Green Fuels and Bioenergy Production

Abstract

The annual products of pruning of date palms are predominantly treated as waste: either open-field burnt or sent to landfills. The date palm leaves representing ~ 54.6% by weight of products of pruning have been successfully used for production of bioethanol with a 60% yield using the simulatanous treatment by 3 enzymes: laccase for lignin degradation, xylanase for hemicellulose hydrolysis and cellulase for cellulose hydrolysis. In anthor study the organoslov process has been successfully used to extract lignin and digestible cellulose pulp from date plam leaves for the production of bioethanol. The maxiumam practical yield of bioethanol was 9.92 g ethanol/100 g raw material representing 90.95% of the theoretical value. Aceton, butanol and ethanol are common solvents used in many important industries and thus can replace energy derived from petrochemicals. A study has been conducted on the use of low-quality surplus date palm fruits as a substrate for fermentation in the production of acetone, butanol and bioethanol using the original Egyptian clostridium strains, isolated from agriculatural soil, cultivated with different plants in Assiut Governorte, Egypt. A research has been conducted on the biodesiel production from date palm seeds. The date seed represents 10–15% of the date fruit weight. The date seed is composed of 3.1–7.1% moisture, 2.3–6.4% protein, 5.0–13.2% fat, 0.9–1.8% ash and 22.5–80.2% dietary fiber. According to FAO statistic 2010 the date production in South-Western Asia and North Africa can be estimated at 7.85 million tons including seeds of 785,000 to 1.18 million tons. Biodiesel is generally considered as the most acceptable biofuel for diesel engines, because of its technical, environmental and strategic advantages compared with fossil-based diesel fuels, such as cleaner engine emissions, biodegradability, renewability and superior lubricating properties. In this research the biodiesel has been produced by transesterification with a yield of 98% and the fatty acid esters were analysed by GC/MS. The research results show that the fatty acid composition of biodiesel was similar to biodiesel fuels produced from other vegetable oils. The date seed biodiesel had a considerable amount of low-chain fatty acids, which gives special features to biodiesel, high cetane number (60.3), low viscosity (3.84mm2/s), flash point (140 °C) and low iodine value (46). The only weak point is its high pouring point (−1 °C), which limits its use in cold weather as compared with other vegetable biodiesel fuels. A study has been devoted to the investigation of production factors to optimize the extraction of date palm seeds oil, production of biodiesel and testing of biodiesel blends in a compression ignition diesel engine. The date palm seeds were sourced from Sharjah date facility in Sharjah (UAE). The date palm seed oil has been extracted using the Soxhlet extraction method, because it represents the most practical option for analytical scale, where parameters can be appropriately monitored and controlled. The resulting biodiesel was characterized and assessed based on widely used international standards (ASTMD6751 and EN14214). Four biodiesel blends were prepared (B5, B10, B15 and B20) and tested in a compression ignition engine at engine speeds from 1600 to 3600 rpm (200 rpm increments) and three engine loads (50, 75 and 100%). A date seed oil biodiesel yield of 92% has been achieved at the following transesterification conditions: 55 °C, 9:1 AOMR, 1wt% CMF and 90 min. Thus the research results lead to the conclusion of fundamental suitability of date palm seeds as a biodiesel feedstock. An important study has been devoted to the production of ethanol from date palm residues. The fermented ethanol can be produced from three groups of feedstocks: sugary, starchy and ligno-cellulosic compounds. In the first generation (1G) processing, sugary and starchy feedstock is converted to bioethanol. However (1G) processing is in contradiction with needs of hummans and animals. Therefore, it is expected that (2G) production of ethanol will prevail in the near future. Bioethanol production from ligno-cellulosic biomass (G2) process is economical only if the sugar concentration exceeds 40 gL−1 and yield is increased. The aim of the present study is to find the optimum ways to convert the date wastes and products of pruning to ethanol and to encourage investors to invest in bioethanol production. Egypt, Iran and Saudi Arabia produce almost ½ the world’s dates production with shares of world production ~ 20%, 14%, 14% respectively. The weight of date seeds varies between 0.5 and 4 g (6–30% of fresh fruit weight). Assuming an average of 13% of total fruit weight belongs to the seed, a weight of 120 kg dried seed per ton of date wastes can be estimated. Thus 13 kg of seed oil (10.85% by weight) can be used for biodiesel fuel production (density 0.871 kg/L). The finding of this study show that there is a great potential to produce ethanol from date wastes and date palm products of pruning in the Middle East countries due to their high availability potential. Besides, these date wastes and lignocellulosic residues are dominantly treated as waste and thus representing a source of environmental pollution. Egypt, Iran and Saudi Arabia can produce annually 173.5, 401 and 438 million liters of bioethanol respectively from date wastes and annual products of pruning. Other date producing countries have the potentiality to produce 1248 million liters of bioethanol. Thus 3260 million liters of bioethanol can be globally produced. The global cost of bioethanol production from date waste is 0.68$ per liter of which feedstock accounts for 85.3% of the total cost of production. The corresponding value for date palm products of pruning is 0.34$ per liter due to high availability potential. An important research has been conducted on the use of date pits for the synthesis of green diesel and jet fuel fractions. Date pits were sourced from a local supplier in Muscat, Oman. A mechanical grinder was used to convert the samples to a powder. After sieving, the oil was extracted using hexane as a solvent in a Soxhlet apparatus following the AOCS official method Am 2–3. After extraction of oil a 100 g sample of date pits was dried at 100 °C for 8 h and then carbonized in a furnace at 500 °C for 5 h with a heating rate of 3 °C/min under N2 gas at a flow rate of 50 ml/min. Active catalysts were thus produced by carbonization and impregnation with Pt and Pd metals. The synthesized catalysts Pt/c and Pd/c were characterized by XRD, SEM, TEM, EDC, BET and XPS. The activity of the catalyst’s performance was evaluated by hydrodeoxygenation of date pits oil. Based on the elemental analysis, the degree of deoxygenation (DOD) of product oil was 97.5% and 89.4% for Pd/c and Pt/c catalysts respectively. The high DOD was also confirmed by the product analysis that mainly consists of paraffinic hydrocarbons. The results also show that between the two catalysts, Pd/c showed a higher activity towards hydrodeoxygenation. Based on the type of components in the produced oil, the maximum fraction of hydrocarbons formed lay within the range of 72.03% and 72.78% green diesel and 30.39 and 28.25% jet fuel using Pd/c and Pt/c catalysts respectively. Thus it can be concluded that waste date pits can be a promising springboard for the production of catalysts and biofuels (green diesel and jet fuel fractions). A research has been conducted to evaluate the potentiality of use of date palm midribs as an alternative source for energy production. Three healthy 10–15 year-old date palms of cultivars Barhi, Khalas, Khodry, Sukkaria and Sullaj, grown at the experimental station for Research and Agriculture of King Saud University were chosen for the conduction of this research. Three date palm midribs were randomly selected from the pruning residues. Each midrib was divided into three zones (base, middle and top). The content of ash was calculated as a percentage of the residues based on the oven-dried midrib meal weight. The higher heating value (HHV) was determined using a calorimeter based on the oven-dry weight. The statistical ANOVA analysis has shown that the chemical constituents of the date palm midribs differed significantly between the researched 5 date palm cultivars. The date palm midrib contents of cellulose, hemicellulose and lignin ranging from 42 to 46%, 25 to 30% and 26 to 31% respectively were found similar to those found in wood species. The lignin content was found to increase moving along the midrib from the base to the top ranging from 24 to 30%. The inverse trend was recorded for the ash content decreasing from 7.6% at the midrib base to 3.4% at the top. Thus it can be concluded that the date palm midribs include higher total extractives (19.34–21.68%) and ash content (3.31–5,85%) as compared with soft and hard woods. The relatively high heating values found for the date palm midribs (17.3–17.9 MJ/kg) prove that they are promising as an energy source. However, the high ash content of all the parts of the date palm midribs, especially the basal part represents a hinderance in their use as a source of fuel. Besides, the date palm midribs exhibited the lowest fuel value index values (97 to 336) as compared with the corresponding values published in the literature for different wood species. A research has been conducted to characterize the date palm midrib as a potential solid fuel for jet and power generation through various thermal conversion processes. To conduct this study date palm midribs were sourced from Medina (Rothanah & Ajwah varieties) and Jeddah (Jeddah & Sukkaria varieties) in Saudi Arabia and from Atbara (Mishria variety), North Sudan. These samples were individually prepared to evaluate their fuel properties: ultimate analysis, proximate analysis and calorific value analysis. All the midrib samples gave calorific values ranging from 16.2 to 16.9 MJ/kg and thus falling within the range of biomass materials from 15 to 20 MJ/kg and close to that of low rank coal such as peat and lignite. Thus it can be confirmed that the date palm midribs enjoy the potentiality of use as a solid fuel for home and industrial applications. As far as the ultimate analysis results are concerned the range of carbon, hydrogen and oxygen in the date palm midribs is comparable with that for typical biomass materials. But the nitrogen and sulfur contents in all samples were found higher than those in most biomasses. The proximate analysis results indicated a significantly high content of volatile matter in the date palm midribs implying their suitability for pyrolysis and gasification processes. Meanwhile, the ash content in the date palm midribs was found comparable with those values in the featured biomasses and lower than in peat, lignite and bitominous coals making the date palm midribs a highly appropriate fuel for continuous thermal processes, where ash removal and handling is a common technical barrier. The thermal decomposition stages were identified based on TGA trends and DTGA peaks. The high reactivity of midrib samples at low temperatures releasing high amounts of volatiles revealed their potentials for pyrolysis and low temperature gasification puroposes. Thus, it can be concluded that the date palm midribs satisfy the typical requirements as a solid fuel for thermal conversion processes in heat and power generation sector. The date palm midribs enjoy the advantages of high availability, low cost and ease of moisture removal in arid and semi-arid regions and thus have high potentials to be used as a solid fuel for thermal applications in the Arab Peninsula and North African countries. Another research was devoted to the study of date palm midribs as an effective feedstock for energy production. To conduct this research date palm midribs of Sukariah, Ajwah and Jeddah varieties were sourced from Madinah Al Munawarah and Jeddah cities in Saudi Arabia. The moisture content, volatile matter, ash and fixed carbon were determined by proximate analysis using Thermogravimetric Analyser (Pyris 1 TGA). Jeddah had the highest value of volatile matter amounting to 83%, whereas Ajwah had the lowest value of 78.2%. The petiole had the lowest value of volatile matter of 55.3% among the date palm biomass. According to published literature, the date palm midribs values of volatile matter content are comparable with other resources, such as sugar cane bagasse, oil palm midribs and western hemlock. Regarding the heating value Sukariah midribs showed the highest value of 16.8 kJ/kg, whereas Jeddah sample revealed the lowest value of 16.4 kJ/kg compared with the seed value of 18.97 kJ/kg and bituminous coal of 34 kJ/kg. Therefore it can be concluded that the date palm midribs can be used as an alternative feedstock for different energy conversion processes, such as gasification, pyrolysis and torrefaction. The presence of metallic elements can cause problems in the thermo-chemical processing systems and therefore require proper handling and treatment during process. A study has been devoted to the characterization of three date palm residues: leaves, empty fruit bunches and petioles and their fast pyrolysis in a bubbling fluidized bed reactor at 525 °C. The date palm residues were sourced from the American University in Sharjah campus (Sharjah, UAE). The fast pyrolysis experiment was conducted at the European Bioenergy Research Institute in Aston University, Birmingham, UK. The comparison of the proximate and ultimate analysis of the leaves, petioles and empty fruit bunches have shown great similarity, but with the leaves much higher ash was noticed. In comparison with other types of biomass and energy crops, the date palm residues can be classified as of high ash, high oxygen, low volatiles and average heat value. The fast pyrolysis product was found to consist of 38.65% bio-oil (including 10.39% reaction water), 37.23% biochar and 24.02% non-condensable gas. The GC–MS analysis revealed for the first time the detailed composition of the date palm pyrolysis oil consisting of at least 140 detectable compounds with the major ones being D-Allose (monosaccharide), phenols, catechol and apocynin. The latter two compounds are of particular interest due to their antioxidation characteristics. The bio-oil heating value was 20.88 MJ/kg, which falls within the low-intermediate range for most fast pyrolysis bio-oils. However the oxygen content was high, and this may have a negative impact on the oil stability and corrosivity. Future work will be directed to the application side of the pyrolysis products including the potentiality of use of bio-oil as a blend with biodiesel for combustion engines, as well as the long-term aging and stability of the bio-oil and potentiality of use of the biochar for soil amendment, especially in desert conditions. An important study has been devoted to the investigation of the thermal behavior of the date palm residues including: leaflets, midribs, trunk, spadix stems and date seeds. These residues have been obtained from a date palm oasis in Tozeur, Tunisia. The ultimate analysis corresponding to the elemental composition of the samples was performed by Service Central d’Analyses (Vernaison, France). The proximate analysis was carried out using a thermogravitmetric analyzer (CAHN121 thermobalance) with gas following upward through the furance at 12NL/h. The thermal behavior of the biomass has been studied under inert and oxidation conditions using a CAHN 121 thermo-balance. The obtained results show that the tested samples have high content of volatiles, carbon, hydrogen and oxygen, whereas the contents of nitrogen and sulfur were relatively low. The researched materials were found to have typical composition as compared with biomass. The heating values (LHV) were found in the range from 15.2 to 19.0 MJ/kg, which are in the same order of magnitude as those for sawdust, olive solid waste, oil palm fruit bunches, Miscanthus, wood pellets and wood chips. It is interesting to note that among the date palm residues the date palm stones having the highest percentage of volatiles and fixed carbon and the lowest ash content enjoy the highest calorific values in terms of low heating value. The bulk density of date seeds was very high (656 kg/m3), higher than that of wood chips (550 kg/m3). The energy density of the date seeds (11.4 GJ/m3) was found much higher than other date palm residues and approaching that of wood pellets (12 GJ/m3). It can be thus concluded that the date palm seeds are the most attractive residue for energy production due to its high energy density and thus low cost of transportation. But the heating values of other date palm residues are high enough to overcome the problems associated with low energy density. Thus, the obtained results can be useful for the design of processing systems for the production of energy from date palm leaflets, midribs, trunks, date stones and spadix stems. There are strong expectations that the fossil fuels such as oil, coal and natural gas will be depleted within the next 40–50 years. Therefore, there is a growing interest among researchers to study the potentiality of use of biomass for energy production as a more sustainable substitute for fossil fuels, as well as for the rescue of the environment from CO2 emissions. Therefore, a study has been conducted for the evaluation of date palm residues combustion in a fixed bed laboratory reactor as compared with sawdust behavior. Samples of Deglet Nour date palm residues were sourced from Djerid region in Tunisia including the leaflets (DPL), rachises (PDR), trunks (DPT), spadix stems (FD) and date stones (DS). The ultimate analyses corresponding to the elemental composition of the date palm residues samples were carried out by Service Central d’Analyses (Vernaison, France) according to the relevant XP CEN/TS15014 standard method. Proximate analysis was conducted using a thermogravimetric analyser (CAHN 121 thermobalance). The high heating values (HHV) were measured following XPCEN/T515103 standard methods using an adiabatic oxygen bomb calorimeter (1KA). The energetic potential for different residues was estimated basing on the calculation of the low heating values, bulk density, energetic density that is the potential of energy per unit of biomass volume. Referring to the results of ultimate and proximate analyses, the weight fractions of the different date palm residues were found of the same order as several biomasses. The comparison between the date palm residues and conventional biomasses has shown higher chlorine content for DPR. FP and DPT samples with values above 1%. Thus future controls of this element in gas and particles in fumes are needed in order to reduce both corrosion impacts and emission factors of persistent organic pollutants as dioxins and furans. The low heating values (LHV) were found within the range from 15.2 to 19.0 MJ/kg, i.e. in the same order of magnitude as for olive solid waste, Miscanthus, wood pellets and wood chips. The date stones (DS) were found to have the highest percentage of volatiles (VM) and fixed carbon (FC) and lowest ash content similar to sawdust. The bulk density is an important characteristic of the biomass materials in relation to transport and storage cost. It was found that the bulk density value for DS is very hight (656 kg/m3) higher than that for wood chips (550 kg/m3). In addition the energy density (ED) of DS was found 11.4 near to that for wood pellets (12 GJ/kg). Thus it can be concluded that date seeds (DS) is the most attractive material for energy production because of its high energetic density and therefore low cost of transportation. The date seeds is one of the best biofuels enjoying the advantages of highest bulk density, calorific value and volatile matter content and the lowest ash content close to 1.2%. Its energy density (11.4 GJ/m3) is much higher than other date palm residues. Although the highest value of LHV was obtained for date palm leaflets, their high ash content (15.2%) represents a hinderance for their development as a biofuel since it may lead to corrosion problems in the combustion chambers. As biofuels the date palm rachis (DPR), date palm trunk (DPT) and spadix stem (FD) have very close energtic density chemical composition. The high amount of chlorine in DPR and DPT may introduce potential risks of corrosion in exchange boiler tubes and the formation of persistent organic pollutants as dioxin during combustion in district or domestic applications. A study has been devoted to the chemical analysis of date palm residues for energy production using ultimate, proximate and thermos-gravimetric techniques: the Sukkari cultivar has been chosen as an important variety cultivated in most areas of Saudi Arabia. The date palm residues were chosen to include palm trunk (PT), palm frond base (petiole)(PFB), palm leaflets (PL), fruit stalk (FS), fruit empty bunch (FEB), date palm stones (DPS) and leaf sheaths fibers (LSF) taking Acacia tortils wood (AT) as a reference. These residues were found to have medium to high cellulose content (33–48%) and lignin (26–40%) and low to medium hemicellulose content (13–31%). The total extractives were (8–33%) and the ash content (1–15%) ( lignin and higher extractive content contribute to a high heating value, whereas ash is considered an undesirable material). The volatile matter content ranged from 74.3% for PL to 87.5% for FEB; fixed carbon ranged from 10.5 for PL to 17.6% for PT and the ash content ranged from 1.4% (DPS) to 15.2 for PL. The heat values of the residues varied from 15.47 MJ/kg for PFB to 19.93 MJ/kg for LSF. However, the heat values based on ash-free dry weight had a wide range from 16.5 MJ/kg for FEB to 22.6 MJ for PL due to the large variation in the ash content (1.3%-11.6%). The fuel value index of DPS was higher (2078) than the value for A.tortilis wood (1170) and other date palm residues. Concerning the ranking of the date palm residues, the date stones (DPS) showed the best value (1.9), followed by leaf sheaths fibers (LSF) (2.5), while the palm frond base (PFB) showed the poorest rating (6.3). Thus it can be concluded that the date palm seeds and leaf sheaths fibers are the most suitable among the date palm residues for energy production. A research has been devoted to the ultrasound assisted oil extraction from date palm kernels for biodiesel production. Three solvent types were used: hexane, isopropyl alcohol and ethanol for oil extraction from date palm kernels and ultrasound was applied for 5 min to 25 min at 5 levels using transesterification of oils with methanol and potassium hydroxide. It was found that the ultrasonic-assisted hexane oil extraction provided the highest yield by extracting 85% of the total available oil present in the date palm kernels. The biodiesel samples produced from oils extracted with and without ultrasonification had similar physical and chemical properties. Thus it can be concluded that ultrasonification has a potential to enchance the industrial processes by reducing the oil extraction time and energy. A research has been devoted to the hydrothermal pretreatment of date palm leaflets and midribs to evaluated their potential for bioethanol production. To conduct this research date palm leaves were sourced from Abu Dhabi in 2013. Leaflets were separated from the midribs, dried and stored before use. The dried material was milled using a knife mill to pass through a 1 mm screen, sequential Soxhlet extractions with water and ethanol were performed based on National Renewable Energy Laboratory (NREL) protocol. The hydrothermal pretreatment was performed at 10% w/w dry matter at 4 temperature levels (180, 190, 200 and 210 °C). Processing time was at 10 min. The research results showed that high glucan (> 90% for both leaflets and midribs) and high xylan (>75% for leaflets and > 79% for midribs) recovery were achieved. Under the optimal conditions of hydrothermal pretreatment (210 °C for 10 min) highly digestible (glucan convertibility 100% to leaflets, 78% to midribs) and fermentable (ethanol yield 96% to leaflets, 80% to midribs) solid fractions were obtained. The fermentability test of liquid fractions proved that no considerable inhibators to saccharomyces cerevisisae were produced in hydrothermal pretreatment. Proceeding from the high sugar recovery, enzymatic digestibility, and ethanol yield it can be concluded that the production of bioethanol by hydrothermal pretreatment from date palm residues is feasible. A research has been conducted on the characterization of pyrolytic products of date palm residues. The pyrolysis process is a thermal cracking of the biomass in an inert atmosphere at temperatures ranging from 300 to 700 °C to produce useful liquid biofuel (bio-oil), solid biocombustible fuel (biochar) and renewable syngas. Therefore, the objective of this study was the investigation of the main characteristics of the obtained products from the pyrolysis of the date pam residues to evaluate their potential as a feedstock for renewable energy and chemical industries. To conduct this study, four date palm residues samples were obtained from the National Institute of Arid Zone (IRA-Kebili, Tunisia): midribs, leaflets, empty fruit bunches and spathes. The samples were finely crushed to small pieces with sizes from 2 to 4 mm and air-dried. The pyrolysis experiments were conducted on a laboratory scale pyrolysis plant under the operational conditions: 500 °C as final temperature, 15 °C/min and 300 g mass initial of the used sample. The elemental composition (CHN-O) of date palm residues, bio-oil and biochar were determined using an elemental analyser (LECOCHNSTRu Spec); the O content was determined by difference. The proximate and ultimate analyses have shown that the date palm spathes had the least ash content of 2.4%, whereas the leaflets had the highest ash content (11.58%). But in general the date palm researched residues had high volatile matter content and ash fairly compared with those found in the literature for lignocellulosic materials converted into biofuels using pyrolysis. The calculated high heat values ranged from 17.88 to 19.09 MJ/kg for all studied residues. These values are low for a commercial fuel. The bio-oil yield ranged from 17.03 wt% for leaflets to 25.99 wt% for empty fruit bunches. Concerning the biochar, the highest yield 36.66 wt% was obtained for leaflets, whereas the lowest one (31.66 wt%) was obtained for the spathes, while the syngas production varied from 39.1 wt% for midribs to 46.31 wt% for leaflets. As a conclusion of this study, the bio-oil which represents moderate amounts of carbon and hydrogen compared to petroleum-based fuels, could be used as a biofuel after grading. The biochar could be used as biocoke in industrial applications. The presence of CH4 and H2 in significant proportions in the gaseous mixture gives the obtained syngas good combustion properties. A study has been conducted to evaluate the technical feasibility of using seawater instead of freshwater in the pretreatment of date palm leaflets for bioethanol production. The lignocellulosic biorefineries are one of the most promising alternatives for fossil oil. But one of the obstacles of proliferation is the excessive utilization of freshwater (1.9–5.9 m3 water per m3 of biofuel), which may be in shortage in arid and semi-arid regions, where the date palms are usually grown. In this study artificial seawater has been used to replace fully the freshwater in the hydrothermal pretreatment of date palm leaflets to produce bioethanol. The results of this study confirm the feasibility of replacing freshwater with seawater in the hydrothermal pretreatment of date palm leaflets to produce bioethanol. However a lower crystallinity of cellulose has been observed after treatment with seawater rather than freshwater. Pretreatment by using seawater produced slightly lower digestibility of solids (glucan-to-glucose conversion) in enzymatic hydrolysis than pretreatment by using freshwater. But there was no significant difference in the bioethanol yield. Moreover, the fermentability test showed no significant difference in the bioethanol yield between liquids from pretreatment by freshwater and seawater. Thus it can be concluded that seawater could be a promising alternative to freshwater in biorefineries processing lignocellulosic materials. Within the expected increase of demand on energy for homes, industries and transportation the expected contribution of biofuels will grow from 50 EJ/year in 2012 to more than 160 EJ/year in 2050. The bioethanol is seen as the main biofuel for the future. Within this framework a study has been devoted for the realization of an experimental solar fermenter for the production of bioethanol from date palm waste (DPW). To conduct this study DPW of Hchef, Kacien and other varieties of date’s scraps of the cattle food were sourced from Algerian Sahara. A batch fermenter was designed and installed to operate effectively by using a solar water heater in order to reduce the cost of the bioethanol generation process. The fermenter was realized within the South Society of Metallic Construction (ECOMES), located in Adrar. Experimentation was performed during the cold season of the year, the 1st week of January 2015. The results of this study indicate that DPW constitute a favorable medium for S.cerevisiae growth, due to its sugar content and is thus considered as attractive feedstock. It is thus technically feasible to produce bioethanol using the solar batch fermenter at relatively moderate cost. The DPW distilled juice produced the highest bioethanol concentraction of about 90° with an acceptable productivity of 3.47 ml/kg/h assessing a scale efficiency 33%. These results represent a strong support to continue R&D in the renewable energy field. It is thus necessary to start to build semi-pilot and pilot fermenters and investigate new methods, microorganisms and other byproducts to improve the quantity of bioethanol produced and to reduce the energy consumption during the bioethanol process transformation to improve the economics of bioethanol production. A study has been conducted to explore the anaerobic digestive technology for processing of date palm residues being the most available and sustainable feedstocks for renewable energy. These residues, annually available with huge quantities are most dominantly treated as waste: being open-field burnt or sent to landfills. Therefore the exploitation of these residues for the production of methane gas should be seriously considered. A carbon to nitrogen (C/N) ratio between 20 and 30 is regarded optimum for anaerobic digestion process. To conduct this study midribs, fruit empty bunches and rotten dates were sourced from the southern oases of Libia. In this research two-liters batch digester was used. The results of the study have shown that production of biogas from fresh waste nitrogen source (NH4CI) gives best biogas production compared to dry waste with nitrogen source (NH4CI) and fresh waste without nitrogen source (NH4CI). The bio-gas production of dry waste nitrogen source (NH4CI) was better than biogas production from fresh waste without nitrogen source (NH4CI). Thus it can be concluded that the heat treatment of date palm residues is very useful to improve the production of biogas. The percentage of methane gas in the produced biogas reached 48% for fresh waste with addition of nitrogen source. The maintenance of pH in the digester at range 6.5–8 is more efficient to produce biogas. The retention time for fresh waste inside the digester is less than that for dry waste. The palm tree wastes contain a high ratio of carbon compared to nitrogen specially the dry one and addition of nitrogen source is required. A study has been devoted to investigate the usage of date palm biomass for biogas production. The Zahdi date cultivar has been chosen because of its abundance in Iraq representing 60% of the country production. The Waste Management Lab/Corneal University (USA) methodology for anaerobic digestion was used in this research. The results of the study indicate that the volatile solids of substrate and inoculums was 39.82, 2.37% respectively with a ratio 16.8:1. The nitrogen content of the substrate was found 2.35 indicating the demand for extra amount of nutrients to provide nitrogen for bacteria growth in the fermentation batch. A total gas pressure with 67% Methane was produced from date pulp waste fermentation with a yield of 0.57 Lit for each gram volatile solid of the substrate. The addition of 1% yeast extract solution as a nutrient increased Methane yield in liters by 5.9%. The high volatile solids content in the date palm biomass compared to inoculums indicates a high potential of biogas production from a small amount of biomass. Given the great abundance of date palms in the Middle East and North Africa there are great future potentials for production of biogas and biofuel in a commertial scale. An important study investigated the production of biogas from date palm fruit wastes by measuring the gas volumetric flow rate directly. Samples of Digal date fruit wastes in their final stage of maturity (with hard texture) were sourced from stores of Diyala province in Iraq. A lab-scale digestion system was used in this research. After the samples were pitted, weighted, mixed with a proper amount of water and placed in the digester, eight mixtures of substrates were divided into two groups. Each group contained 4 samples of substrate having ratios of 0.5, 0.2, 0.15 and 0.1 (w/w). They were subjected to anaerobic digestion at 37 °C for mesophilic and 55 °C for thermophilic conditions. The dischange process of biogas was carried out every 3–5 days and the data was saved on a laptop. Concerning the effect of solid mixing ratio the results of the study showed that under mesophilic temperature of 37 °C, the highest biogas yield was achieved in the case of 0.15 w/w (182 L/kg volatile solid mass), whereas the lowest biogas yield was in the case of 0.5 w/w (84 L/kg volatile solids mass). As far as the effect of recycled digestate is concerned, the research results showed that the use of recycled digestate has improved the production of biogas by 12%. Thus it can be concluded that the date palm fruit wastes are a suitable source for biogas production and that a mesophilic system is the best option for producting biogas from date wastes. A maximum biogas production of 203L/kg volatile solids was achieved for a solid concentration of 0.15 (w/w), when the substrate was mixed with recycled digestate at 25% of the substrate content. A study has been conducted to evaluate the potential impact of date seeds on biogas production. To conduct this study seeds of Khalas and Khudri cultivars were selected. Oil was extracted from the date seeds using an automatic Soxhlet extractor. The oil-spent date seeds were recovered from the extractor, dried and then used for biogas production. The primary waste water treatment sludge was sourced from a nearby domestic wastewater treatment plant. The total solids of the primary sludge was adjusted to approximately 2% and stored in a freezer in small containers until use. The volatile solids after total solids adjustment reached 1.64%. The preparation of the date seeds/sludge mixtures was conducted by thawing the frozen sludge from containers, mixing and adding the predetermined date seed quantity and then adjusting the pH if necessary to approximately 7.3. After 14 weeks of incubation the biogas production expressed in terms of the date seed/sludge ratios, were in the following order: 10% > 7.5%≃5%≃2.5%≃0% > 20% > 40%. The size of the date seed particles did not significantly affect biogas production. The specific gas production was in the range of 370–390 mlg−1 volatile solids for the 0–10% seed/sludge ratios, 245 mlg−1 at 20% and 120 mlg−1 for volatile solids at 40%. The relatively low biogas production from the 20 and 40% seed/sludge mixtures indicated inhibation, which was also, shown by the low pH in the mixtures following digestion. Oil extraction from the date seeds reduced, but did not fully overcome, inhibition of biogas production from the 20% and 40% mixtures.