Geothermal energy knowledge

The vegetation that covers our planet is a natural storage of solar energy. The organic matter composing it is called biomass.

Biomass is produced through the photosynthesis process, when carbon dioxide from the atmosphere combines with underground water to produce sugars, starch, cellulose, lignin, protein substances, fats, etc. The same solar energy that activated the photosynthesis is contained in the chemical bonds of these substances. In this way 2 x 1011 tons of carbon are fixed each year, with a corresponding energy content of 70 x 103 megatons of oil.

By burning biomass, atmospheric oxygen combines with the carbon contained in the biomass, freeing carbon dioxide and water, and producing heat. Carbon dioxide goes back into the atmosphere and is ready to be re-used in the photosynthesis process to produce new biomass. Therefore, biomass is a renewable resource.

The term biomass indicates several types of products: agricultural and forest residues, waste of wood processing industry (wood shavings, sawdust, etc.), waste of the zoo-technical industry, agricultural and food residues (residues of crops for the production of human and animal food (straw), “energy cultures” aimed at the production of fuel, and organic biomass from other sources, such as the green fraction of solid urban waste and other types of heterogeneous industrial waste.

What is for?

In The main applications of biomass are: energy production (biopower), fuel synthesis (biofuel) and product synthesis (bioproduct). In the energy field, wood and cellulose biomass (wood and by-products of grass, tree and forest cultivation) is mainly used as multi-purpose fuel: household heating, to produce electric energy and industrial uses.

Where is it?

Biomass is one of the most abundant renewable energy sources on our planet. Its use, however, is not evenly spread. Bioenergy plays a role in all three main energy-use sectors: heat (and cooling), electricity and transport.

A bit of history

Fire, unquestionably the most important discovery in the history of mankind, was discovered thanks to the accidental combustion of wood. Fire has illuminated, heated, protected and fed mankind for thousands of years. Briefly, fired fostered the birth of civilisation.

Biochemical processes

Biochemical processes work thanks to the action of fungi and bacteria that grow in the biomass in specific conditions of temperature and humidity. These micro-organisms digest organic matter freeing molecules that are waste (for them) but precious for us.

Thermochemical processes

It is well known that to light and feed a fire you need materials that burn and these, in technical terms, are known as fuel. Fuel alone is not enough for a fire to burn, another element is required: the combustive agent.

The word biofuel may refer to the fuels used for the production of electric energy, but in general it refers to liquid fuels used for means of transport.

The most common fuels are undoubtedly bioethanol synthetized from carbohydrates and biodiesel (ester) obtained from fats and oils. Although ethanol obtained from starch and sugars, it offers a good contribution from the energy and environment point of view. Later we will examine ethanol produced from cellulose biomass like herbaceous and wooden plants, agricultural and forest residues and large quantities of urban and industrial waste.

In fact, while starch and sugars represent a modest quantity of plant material, cellulose and hemicellulose, which are polymers of sugar molecules, represent most of the biomass. The benefits connected to biofuels derive from the fact that they have a more limited environmental impact than oil derivatives and use waste materials that are usually not employed. Finally, other two biofuels will be analysed, that is methanol and corrected petrol compounds.

Bioethanol

Ethanol has always been used for internal combustion engines, as demonstrated by the history of cars. But, although the initial large availability and the low cost of hydrocarbons had not allowed to use them as fuels, after the oil shock of 1973 many other products were studied to replace car fuel (petrol and gas oil).

Biodiesel

Recycled vegetal oils, animal fats and kitchen fats can be transformed into biodiesel by using a series of technologies in order to activate those chemical reactions, at low temperatures, that lead to the formation of compounds called esters.

Bioproduct

Any compound that can be synthesised from fossil fuels can be similarly produced from biomass. These bioproducts (bioproducts) are therefore produced from renewable energy sources and usually their production needs less energy than their oil-based counterparts.

Methanol

Also known as wood alcohol, methanol is usually produced from natural gas, but it can also be synthesised from biomass.

The biomass dilemma

Today there is a growing interest in the use of biomass for producing biofuels, which can be used together with fossil fuels or can even replace them.