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Gestione congiunta di acqua e biomassa
Produzione di energia da biomassa

Punti chiave per frenare i cambiamenti climatici

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The text within this page was first published in French on www.eautarcie.com: in January 2007

The original text has been adapted and translated by André Leguerrier. First published on this page at www.eautarcie.org : 2009-06-15

Last update : 2016-02-21

Produzione di energia da biomassa

Efforts are currently made to seek out « alternative » energy sources to replace fossil fuels. Biomass energy, also known as bioenergy, is an obvious alternative. Yet, a strict set of rules needs to be respected if biomass energy is to truly be renewable.

A Perilous Environmental Wastage

Contrary to generally accepted views, biomass combustion (i.e. when used as a biofuel in whatever form) is absolutely not compatible with the concept of sustainable development.

This is true in all senses, whether the biomass comes from:

• Forestry « energy plantations » (e.g. fast-growing trees for wood fuel such as firewood and wood pellets)
• Agricultural « energy plantations » (e.g. selected crops for production of bioethanol or biomethane),
• Sewage sludge from sanitation plants and industrially-produced pig slurry (fermented to produce biomethane or burned to produce heat)
• By-products/residues from forestry and agriculture as well as industrial/domestic waste, buried in specialized landfills (for biomethane production) or simply burned (for process heat production).

The inherent biological value of biomass is greater than the energy actually recovered from its destruction by combustion. This is especially true in today's context of squanderous energy consumption. Human activity on our planet is destroying its biomass. Maintaining a certain quantity of biomass within the biosphere helps maintain a natural balance, particularly in the matter of temperature stabilization. Below a critical biomass threshold, meteorological instability will doubtless amplify on our planet, with incalculable consequences.

Fifty years of intensive chemical-dependent agriculture has only aggravated the consequences of overgrazing and massive deforestation perpetrated by man for centuries, even millennia. Since the onset of civilization, the fertile regions of each continent haven't stopped shrinking. It isn't exaggerated to say that there is an intimate link between humanity and humus. Most human migrations and bloody wars are ultimately the result of soil degradation due to the disappearance of humus.

In contrast to pre-modern human history, humanity today has no new frontier to conquer or develop – meaning none to destroy. We have come to a point where we absolutely need each kilogram of animal and plant biomass to regenerate our ecosystems. Farmland's humus content and that of forests have dropped to 10% of their value a century ago. Even if no one seems to admit it, that drop is the fundamental cause of our current water problems, including water pollution by nitrates.

Destruction of animal biomass (including human dejecta) for purposes of wastewater treatment/purification (even by means of plant-based phyto-purification!) and destruction of plant biomass for purposes of energy production are setting up grave unbalances in the biosphere, such as floods, droughts and desertification. This will also be amplifying global warming. Massive biomass destruction discharges lots of CO2 in the atmosphere. But it mostly undermines the regenerative capacity of ecosystems as efficient greenhouse gas sinks.

In light of this fact, the use of biofuels (biodiesel, bioethanol, biomethane, wood pellets) is a monumental waste that compromises our future.
A Different Approach to Biomass Energy

Composting versus combustion

It is perilous to thoughtlessly initiate unrestrained combustion of available biomass, without having a full understanding of the process of solar energy storage in plant biomass. This doesn't mean that we must give up biomass as an energy source. At most, we must take a different approach. Plant biomass can provide substantial low temperature energy, for heating.

Even if most scientists ignore this, increasing experimental observations tend to show that plants store more solar energy during photosynthesis than that which can be recovered by simple combustion. This paradox has not found a conclusive scientific explanation. Confirmation of those observations would open up encouraging perspectives for bioenergy development without unbalancing the biosphere.

To use plant biomass to produce energy, the most rational approach appears to me to be the recovery of heat from composting, for example to heat buildings and greenhouses. During combustion, all carbon biomass is transformed into CO2. Composting is different, whereby the end product (i.e. compost) can be used to regenerate farmland and forests, and even help in reclaiming deserts.

This approach would strengthen the role of ecosystems as atmospheric carbon sinks to mitigate the greenhouse effect, while simultaneously reducing CO2 emissions, and still recover as much energy as could have been obtained through biomass combustion, if not more…

The Biological Value of Biomass

This is why for years, I have proclaimed:
« Bioenergy development – at least in the present context – is an immense waste. The inherent biological value of biomass is far greater than the energy we can obtain from its destruction. »

In the biosphere's best interest, it is unadvisable to burn wood pellets, biogas or other biofuels. The composting approach would also provide the means of harnessing animal- and plant-sourced biomass. Toilet effluent and pig slurry for example could be impregnated on plant litter, no doubt constituting the most rational way of eliminating this organic waste. This is the ultimate justification to eliminating flush toilets and generalizing the use of proper dry toilets.

By upgrading forest floors with the compost obtained from dry toilets, forestry production per hectare could be improved, strengthening the woods' role as a carbon sink as a means to counter global warming, as opposed to direct combustion of wood and biofuels, which aggravate global warming.

Also, in regions with cold winter seasons when energy consumption for household heating can be substantial (e.g. 60% of domestic heating needs in Montreal and even Brussels), thermogenic composting could cover substantial space heating needs, while also providing the means of regenerating land.

Food Production versus Biofuels

Governments from many industrialised nations are currently promoting biofuel production. In a relatively near future, it is to be feared that this endeavour will compete directly with world food production. Society will come to a crossroads: feed the population of the poorer countries, or feed the energy squandering of the richer ones.

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