Forest residues such as dead trees, wood, wasted gases, yard clippings, wasted organic matter (including dead plants and animals), etc., constitute biomass. Such materials also include biodegradable waste that can be burnt further to source fuel. Biomass energy (one of the alternative energy sources) implies generating electricity using biomass as fuel.
Cost of Production and Process for Biomass Energy
Biomass energy is converted into sources of fuel through thermal and chemical processes. Even biochemical processes are used for conversion of this energy to tangible fuel sources. Provided below is a quick glance of some biomass energy resources, and the processes for producing biofuel types, along with the costs incurred in utilization of biomass energy.
In thermochemical processes, decaying plant matter is heated, which emits many gases (like methane) leaving behind the residue in a liquid or solid state. These gases can be processed and utilized with useful fuels like alcohol. The methane emitted from plants can also be used by biomass gas turbines to produce electricity. Another alternative is to utilize the biomass energy in fuel cells, which can effectively convert hydrogen-rich fuels into electricity and water with less pollution. Meanwhile, biochemical processes also help in making biomass energy.
Yeasts and enzymes break down carbohydrates through fermentation. This is how biomass liquids are converted to alcohol, which is a combustible fuel. Similarly, grain alcohol (ethanol) can be mixed with gasoline to produce a biomass fuel called gasohol. When biomass decomposes, it emits methane and carbon dioxide, of which methane is again a source of combustible fuel. Many biochemical processes are used today to extract biomass energy, which can be further used for generating electricity. Even soybean oil can be converted to diesel fuel through chemical processes. For instance, cooking oil that is wasted in restaurants, can be used to produce biodiesel through such processes.
Concerning electricity, biomass energy cost per kwh (Kilo watt hour) is about 5 - 10 cents, which approximately amounts to USD 1500 - USD 1800 per Kwp (Kilo watt peak). However, the cost of electricity generated from biomass energy differs, as it is also dependent on certain factors as listed below:
- Kind of the biofuel used
- Method adopted to generate biomass energy from the biofuel
- Size of the plant for generating biomass energy
- System design of the plant
In Pacific Northwest and Oregon, cost of the biomass energy is about 5.2 - 6.7 cents per kwh. This is comparatively more expensive than the electricity generated from natural gas, which is only 2.8 cents per kwh. There is a reason for the costly side of this type of energy. To generate electricity from this source, a massive amount of biomass is required to produce the biofuel. Availability of the required sources is not consistent, as reliance on the forest and agricultural residual sources is quite uncertain.
Costs involved in generating electric power from anaerobic digestion of animal manure is about 3.7 - 5.4 cents per kwh. To serve such options, there are large farm site manure digester machineries. However, the cost of such equipment is factored by various conditions, such as the site location and the number of animals it can house. A plug flow digester equipment can help in processing manure of about 500 cows.
Costs incurred in this investment for production of biomass ranges between USD 230,000 - USD 260,000. The heat generated from digester gases is used in generation of electricity, and the residual liquid and fiber digester residues serve the purpose of fertilization for soil in an effective manner. The cost of biomass energy can be recovered from the energy cost savings. Producing biomass energy from ethanol is quite an extensively used method.
About 85% of ethanol in United States is produced from corn feedstock. The estimated cost for producing ethanol is about USD 1.10 - USD 1.43 per gallon. Ethanol is mixed with gasoline to make a blended biofuel - gasohol (10% ethanol and 90% gasoline). Nowadays, biodiesel is becoming a popular choice for fuel. The only hurdle faced in commercial production of this fuel is the losses incurred in producing the energy source.
Approximately 75% of the expense of producing biodiesel is accountable for procuring vegetable oil seeds, extracting oil from them, storage, and, transportation. For example, the cost of producing biodiesel in Idaho is about USD 2.56 per gallon of rapeseed methyl ester. However, a blended fuel of biodiesel, which contains about 80% of petroleum diesel can considerably reduce production cost to USD 1.10 per gallon. Instead of using vegetable seeds, inexpensive organic oil feedstock (like waste food processing tallow) can also be used. This will aid in bringing down the losses incurred in the production of biodiesel.
Today, biomass fuel constitutes about 11% of electricity generation in United States. On a global level, biomass fuel meets about 14% of world's energy requirements. One of the most important advantages of this energy is the re-usability of fuel resources without polluting the environment. Biomass energy costs are definitely high, but with economical alternatives cropping up, and by proper utilization and use of the right technology, it is bound to become an indispensable source of fuel.