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Bio-energy - Corn 'hotter' than Coal |
The total potential biomass in Serbia is almost 12.5 million tons annually. From that amount 25% could be used for stubble and other preparations such as fertilizer, where it helps produce better harvests, the next quarter could be used for production of livestock feeds, another quarter could be used for making heat energy and the rest could be used for other things such as a raw ingredient in the construction, metal and, food production industries. From the total amount of biomass designated for heating energy, [approx. 3,880,000 metric tons] could be used to save an equivalent amount [1,317,000 metric tons] of extra light heating oil. The same amount of diesel fuel is consumed in the entire agricultural production process.
When we refer to 'biomass' in agricultural, then we are considering mostly crop and plant residues and, the remainders or, 'tailings' from the production of fruits and wines. It's estimated that every year in Serbia 12.5 million tons of biomass are produced which mean that it is a renewable resource. The question concerns whether it is easier and safer to dig and transport coal over long distances or, to gather residues from all over the land for biomass and, use them in the place of coal. Especially because there is such a large amount of biomass available, which renews every year and, especially since it's incorrectly utilized by being burned in the field. It could be the largest resource for energy, when currently it is the least used.
Insignificant sulfur levels
Straw from grains and oilseeds can be use for the production of paper and fiber boards, for soil preparations and heating. The cobs from corn can be used to prepare livestock feeds, for heating, in preparing polishes for metal surfaces and cosmetics. Sunflower seed hulls are also good for livestock feeds, and for producing energy. The heads and stems of sunflowers can be prepared and pressed and also used for producing heat energy as well as, the stems from hops and tobacco. Branches trimmed from fruit trees and grape vines are some of the best-suited for this purpose.
The elementary chemical composition of the biomass in relation to sulfur is minimal. Sometimes the percentage of sulfur can be up to 0.1%. In comparison with the total sulfur of some other conventional fuels [1-3 % S], this is about 10-30 times less. In addition, burning of traditional fuels creates Sulfur oxides [SO] which greatly harm the environment, especially when they come into contact with atmospheric moisture. This is the first step in the process of sulfur oxides becoming sulfuric acid. Biomass is much more efficient in this area, when compared to conventional fuels.
Fuel ingredients constitute more than 50% of the total of biomass. Ash in agricultural waste accounts for about 2-7% [maximum 8%] and 11.6% for corn cobs. Ash content in corn cobs is a bit higher than for sunflower seed hulls, 6% and, for seed hulls about 2%; when they contain flammables [the 'burning' part of fuel] this can be as high as 80%. Sunflower seed hulls, as a bio-fuel as a 'bottom' in the furnace at oil factories in Vrbas, Sombor and, Zrenjanin and, corn cobs are used in most seed houses.
The heating value of wheat and soy straw is about 15.7 – 18 Mega Joules [MJ]/kg and, for corn cobs reaches about 17.4 percent. The highest heating power of oklaska is about 14.7 MJ/kg and the lower limit is about 13.3 MJ/kg, at a moisture content of about 11%. For example, 2.56kg of oklaska, with a moisture content of 7.4% [dry mass], has the same heat power as one kilogram of light heating oil.
Sunflower hulls have a heating value of about 17.55 MJ/kg; one kilogram of hulls could be exchanged with about 0.4 kg of oil and, with a well functioning boiler won't harm the environment. The products of burning, particulate smoke have no harmful ingredients and the ash remaining is minimal. As well, the ashes from burning sunflower shells can be used as a mineral fertilizer. The lower average heating value for sunflower shells is from 15.6 to 16.7 MJ/kg, which is dependent of the moisture content, [about 12-14%]. Thusly, the use of biomass in agriculture will conserves a certain amount of crude oil, giving agriculture freedom from petroleum products; leaving producers dependent only on the residues that they produce and, the use of non-conventional fuels would then not depend on the shortage nor, the high price of conventional fuels.
Bio-Fuels Save Heating Oil
The largest amount of biomass in Serbia comes from corn. It can be used as a livestock feed and, as a soil conditioner. It can also be used as a fuel, and in the furniture industry as pressboard and as a stabilizer.
Reports concerning the burning of corn residues indicate that it can be used as a bio-fuel. The ash content of bio-fuels are greater than that of wood but, still have an ash content less than that of coal [almost 10 times less]. While the ash from conventional fuels is quite harmful to the environment, ash from bio-fuel can be used as a mineral fertilizer. The energy value of corn residues as a bio-fuel are about 16.6 MJ/kg., which means that about 2.7 kg of corn residues can replace one kg of heating oil.
The energy value of corn residues as a bio-fuel, are greater than that for coal. Because of this, it can be used for the production of thermal energy by complete or incomplete burning [gasification]. Gasification of the biomass results in more complete utilization of it because the produced biogas can be used directly for heating. When cleaned and cooled, it could also be used as a fuel for internal combustion engines.
Furnaces for Domestic Use
Corn residues, cobs and, other residues have been used for a long time as heating fuel in rural houses. Wood is only useful for starting the fire and, coal for extending the fire. Slight changes to the classic stove, to convert it to the burning of corn bio-fuel, would burn the residue at a very high temperature, to completely utilize the heat energy and, would solve the problem of trying to heat a large number of homes such as in villages and, small suburban areas. This is not proposed as simply a temporary solution to the problem but, to adapt these furnaces to burn corn residues.
Some of the best known producers of equipment for burning of biomass to produce heat energy [both bunkers and burners] are "Bratstvo" in Subotica, "Inomag" from Backa Topola, "Novkabel," "Nigal" and, "Apic" from Novi Sad, "Termoing" from Kula, "CER" from Cacak and, others. "Terming", Nigal", and "Apic" are still actively selling equipment. During the last 12 years, 1,400 different biomass installations have been completed in the region of Vojvodina, with a total heat energy capacity of almost 140 MW and, an equivalent energy savings of 10,000 tons of fuel oil. These results are extremely modest, as only 1% of the total annual production of biomass is being used in the production of energy.
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Source: Prof. Dr. Miladina Brkica |
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