Global warming from greenhouse gases had caused environmental impact especially from the use of fossil fuel in heating and the electricity sector. Using of biogas was an alternative energy that reduced the amount of greenhouse gases.
Napier grass is an attractive feedstock for biogas & bioethanol production. Napier grass is a perennial species so helps in soil conservation and it has become a priority source of biomass for alternative energy production in Thailand, as the National Energy Policy Council has raised the target of power production from Napier Grass to 3,000 MW under the 10-year alternative energy development plan (2012-2021) for Thailand.
Hybrid Napier can be harvested up to 5 to 6 times per year. In addition to use as animal feed. It is the energy crop of the future because the grass is photo-emissions from the extraction of organic fuels such as alcohols, methane and pyrolytic oils. Napier grass is specifically stored for the production of biofuels and bio-based products, primarily due to its high cellulose content (34.2–40%), high yields per unit area, drought tolerance and forms a complete crop due to a good water use efficiency.
Biogas is an economical alternative source of energy that will reduce the share of fossil fuels used in the transportation sector and productive industry, reducing environmental concerns caused by widespread use of these resources (eg, climate change and global warming) and the energy source will increase, besides the safety, and power supply will also be improved. Nowadays, biomass is responsible for 10% of primary energy consumption worldwide and can be used as a promising feedstock for biofuel production.
Feasibility of Biogas Production from Napier Grass
Napier grass contains 30.9% total carbohydrates, 27% protein, lipid 14.8%, total ash 18.2%, fiber 9.1% (dry weight). Its organic compositions are an ideal feedstock for biogas production. The fresh grass was harvested after 5-week plantation, grounded in 0.5 to 1 mm diameter size before fermentation in mesophilic batch reactors, with varying solid concentrations of 5 - 15%. The optimum condition for the biogas production was found at 5% solid concentration. Methane content, yield and production rate were 53%, 122.4 mL CH4/g TVS remove, 4.8 mL/hr at the optimum condition. Economic analysis of biogas obtained from the experiment with liquid petroleum gas (LPG) with benefit/cost ratio (B/C ratio) greater than 1 suggested that the Napier grass is considered as a potential energy crop.
Napier Grass is considered to be the fresh energy crop to be used in power production, with great potential. The specific species that suits best as energy crop is Pakchong 1 (Super Napier) , harvestable 5-6 times a year and yield as much as 70-80 tons/year/rai, almost seven times more than other grasses. Its nutrition structure fits for microbe to grow and generate methane gas. Napier grass can generate bio gas generation at 6,860-7,840 cubic meters/rai/year that can produce Compressed Bio Gas with heating value of 14-18 MJ/kg, replacing usage of NGV by 3,118-3,563 Kg./year.
There are many high yielding Bajra Napier hybrids viz., APBN-1, Super Napier, CO3, CO5, BNH3, BNH10, IGFRI-5, IGFRI-10, IGFRI-16, NB-21 and PNB-233, are recommended to the dairy farmers in India.
At present scenario, the Super Napier showed promising and remained at the top for high forage production per unit area and time. It produced the highest green forage yield of 300 to 400 tons/ha in 6 to 7 cuttings in one year and thereafter 2- and 3-year, green forage yield is 250 to 300 tons/ha/year. The first cutting will be taken after 50-60 days of planting and the subsequent cuttings at 45-50 days interval.
After reaping and fermenting the age of 60-day old fresh Napier grass, the anaerobic digestion process will result in bio gas. Napier grass can generate bio gas generation at 6,860-7,840 cubic meters/rai/year that can produce Compressed Bio Gas with heating value of 14-18 MJ/kg, replacing usage of NGV by 3,118-3,563 Kg. /Year. One metric ton of Napier Grass can generate 90 cubic meters of bio gas, convertible in to 170 KW/day electricity.
Study of Napier Grass Harvesting Age Influencing on Biogas Production
Biogas production of Napier grass is influenced due to variety/hybrids of Napier grass, soil type and climatic conditions, nutrient management, cutting interval and harvesting age. Here, we will discuss on harvesting age.
Harvesting age of grass is a key consideration factor in biogas plant operation form grass bio methanation.
Study of methane (CH4) production from Napier grass at various cutting intervals.
Napier grass at the cutting interval of 60 days gave the highest CH4 yield of all various cutting intervals. For further information on forage production technology on Napier Grass or other forage crops or on nutrient management on any field crops, please contact to me. Dr.P.C. Patel, patelpc12@gmail.com or Mob No. +91-9909022116

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