The biomass , in ecology, refers to the total amount of living matter contained in an individual, a rung of a food chain , a population or an ecosystem, expressed as weight per unit volume.
On the other hand, biomass is also the organic matter that is generated by a biological process , either spontaneous or provoked, and that has the necessary properties to become a source of combustible energy. We could call this last meaning the “ useful biomass ”, since its area of interest is specific to obtaining biofuels (agricultural fuels).
This term has become more relevant since the rise of biofuels, necessary as an alternative to fossil fuels and their fluctuating market. However, the “organic matter” necessary for biomass is often confused with living matter , that is, with which it integrates living beings such as trees (although much of the bark that sustains them may be, indeed, dead).
It is also a mistake to use the term biomass as a synonym for the potential energy that said organic matter contains, more than anything because the relationship between the amount of usable organic matter and the energy that can be obtained from it is variable and depends on many factors.
The “useful” biomass
Biomass is used to obtain energy . This is based on taking advantage of the processes of decomposition of organic matter under controlled environmental conditions, in order to obtain mixtures of hydrocarbons of energy potential, especially when feeding internal combustion engines, such as those of a car.
We can identify three types of useful biomass:
- Natural biomass . The produced without any intervention of man, such as the fall of the leaves in a forest .
- Residual biomass . It is the waste or by-product of other economic activities , such as agriculture, livestock, forestry or the food industry, or even the recycling of oils.
- Energy crops . Whole crops destined to obtain biofuels, focused on some type of plant or fruit tree whose energy power is high.
Advantages and disadvantages of biomass
The use of biomass as fuel presents positive and negative aspects:
- It is less polluting . Compared with oil and oil, or coal, biofuels generate low amounts of CO 2 and less environmental damage, although this does not mean that they really ecological fuels.
- Take advantage of residual matter . Much of the material that is normally going to be given to garbage or decomposes uselessly, has a certain energy value if it is used as a biofuel raw material . That also makes these relatively inexpensive and easy to obtain.
- It is not as effective as other fuels . Compared to fossil fuels, its performance is insufficient to be, for the moment, an effective alternative for global energy demand.
- It involves ethical dilemmas . More than anything regarding the diversion of food (corn, fruits, grains and cereals) from the food industry to the energy industry, which is more important to obtain fuel than to feed the hungry population.
Examples of useful biomass
- Firewood. A classic example of using organic matter is the collection of firewood to burn and thus obtain heat, both to heat a home through fireplaces, and to feed a fire in which food is cooked. This method dates from time immemorial and still persists among human customs.
- Seeds and nutshells . These residues from the intake of food products are commonly discarded in the garbage, but have a negligible fuel value. In many rural homes it is stored and used to feed fires, or even to obtain vegetable oils for lubricant.
- Remains of food . The organic matter left over from our meals has a relative energy potential, not only as food for composting and soil fertilization processes, but also in obtaining biogas through anaerobic digestion processes (without the presence of oxygen). The bacteria that star in this process produce high levels of methane, similar to what happens in our intestines, which makes biogas very flammable.
- Beet, cane, corn . Fruits rich in sugars, such as cane, beets, corn, are usable in obtaining bioethanol, through a fermentation process similar to that of obtaining liquors, since it produces a hydrated alcohol. To said alcohol 5% of water is removed and an energy-efficient fuel, similar to gasoline, is obtained.
- Stems, pruning waste, wood and other greens . Sugars such as cellulose, starches and other carbohydrates from photosynthesis are stored in the body of the plants , which are used as biomass in processes of conversion into fermentable sugars to obtain biofuels. Many of these wastes are collectible without sacrificing food, since many plants must be pruned, reseeded or plucked after bearing fruit and usually this material is discarded.
- Corn, wheat, sorghum, barley and other cereals . Similar to obtaining beer, these cereals and vegetables are extremely rich in starches, which are complex carbohydrates from which bioethanol can be obtained through alcoholic fermentation.
- Sawdust or sawdust . A possible source of biomass is found in the huge amounts of powdered wood discarded by sawmills and the timber industry as such. All this powder has the same potential fuel of wood, in addition to being a source of cellulose to obtain fermentable sugars in bioalcohols.
- Wine must and sulfur wines . Decomposed wines and must residues of their manufacture are sources of biomass, since they provide raw alcohols to which sulfur dioxide (SO 2 ), its methanol load (corrosive to combustion engines) must then be removed and can finally be used to Get bioethanol
- Livestock waste . Livestock is an important source of organic matter that can serve as biomass, such as ruminant droppings (whose exclusive food for plant cellulose is promising) or even the leftover fats from animal use.
- Domestic residual oils . A source of liquid biomass is the oils that we discard after cooking, mostly made from sunflower, canola, even olive, in short, vegetable products. The production of biodiesel from them requires filtering of solid waste, transesterification steps to convert triglycerides into methyl esters, and the addition of methanol. After neutralizing the pH of the result, biodiesel and glycerol are obtained. The latter is removed and is usable for the soap industry, while biodiesel is purified and used as fuel.