Investing in biogas
AKNO and environmental protection
In fact, we believe that it is everyone’s responsibility to do everything they can to protect the environment, but especially those who build and manage large facilities for civil, commercial or industrial use. They should understand every influence their work has on the health of the planet.
For this reason, among others, we adhere to the LEED programme (The Leadership in Energy and Environmental Design), a system which classifies the energy efficiency and ecological footprint of buildings that, since its inception in 1998 in the USA, has always been characterised by its transparency of evaluation criteria and for the public discussion of these criteria, involving professionals and scientists.
What we like best about the LEED system is the fact that it is open to the contributions that science and technology continuously offer to those working in the construction and plant sectors. We believe, in fact, that only through a continuous process of scientific and technological improvement can we achieve the most challenging objectives in terms of environmental protection.
We must not forget that environmental protection, when implemented intelligently, often also represents an economic saving for those who have to manage the facility and precisely through technical tools such as the one we are talking about today, biogas, it is possible to combine economic efficiency with eco-sustainability.
Where does biogas come from?
As the word itself suggests, biogas is a gaseous fuel obtained from a biological process: that is, from the action of living organisms on organic material. Its composition varies according to the type of material it comes from, but it has an extremely high percentage of methane, which in some cases represents all of the combustible gas produced.
Biogas production is based on the principle of fermentation of organic substances from animals or plants by specific bacteria. During the first phase, which usually occurs in a few hours and needs oxygen, the organic mass loses carbon dioxide and water and increases its mineral content, preparing for the next phase of methane production.
If at the end of this aerobic phase the organic substances are in the complete absence of oxygen, the bacteria can begin the anaerobic phase which starts with the production of acids and then continues with an abundant release of methane combined with carbon dioxide. This second phase, which is the moment of true biogas production, is unfortunately always an incomplete reaction and must be regulated with suitable temperature conditions to maximise the yield.
The organic material that can be used to produce biogas is very varied, but from a practical point of view only some of the theoretically possible solutions are currently used. One of these is to use waste from the agro-food industry, including shredded crops such as corn and sorghum; another is to grow plants specifically for the purpose, such as cane, sugar beets or wheat in addition to the aforementioned corn and sorghum.
A second method of obtaining an organic mass to be digested by the bacteria is to exploit the waste from the livestock industry, such as animal carcasses, manure or other types of excreta. It is also possible to obtain the necessary organic substances from the collection of urban waste, especially if it has been separated.
Waste treatment to obtain biogas
The share of organic material in normal urban waste is between 30% and 40% and can be an interesting source of digestible matter to obtain biogas. The interest in this type of production chain stems from the fact that, in addition to producing energy through the fuel obtained, it contributes to solving the serious problem of waste management. As we know, the volume of waste is often so large that simple and environmentally sustainable solutions for its disposal are not practicable.
It is possible to obtain biogas directly from landfills, where the biological processes described above take place spontaneously, but this although this solution has the advantages of a low cost system and a certain ease of management, the resulting methane-producing reactions are mostly incomplete and therefore produce much less biogas than would be possible to obtain by better control of the process phases.
The solution that AKNO adopts in many of its facilities is to build fermentation plants directly in the vicinity of buildings that use the energy derived from biogas. To supply the constantly digested organic mass in the fermentation facilities, we use organic urban waste from separate waste collections.
This also gives us a very positive balance in terms of our buildings’ carbon footprints, i.e. the quantity of carbon dioxide emitted to run the plants. In fact, biogas producing reactions release less CO2 than would be obtained by treating waste in another way and, even though the combustion of biogas still produces carbon dioxide, the overall balance between this production chain and that of energy production by traditional waste disposal remains positive.
How is biogas used?
Digestion of organic waste takes place in fermenters where the temperature, humidity of the material and the percentage of methane produced are all kept under control. The obtained biogas is stored in special tanks and can be used for two different purposes.
It is possible to burn this fuel directly in the boiler of a central heating system to produce, among other things, the heat necessary to keep the temperature of the fermentation plant under control or to supply an internal combustion engine with biogas produces electricity by means of a generator.
In either case, fossil fuel consumption is reduced as is its extraction and transport, all of which represent a serious source of pollution for the planet and there can also be significant economic savings in plant management for a relatively low initial investment.