Introduction: Biogas.

Biogas is the product of the anaerobic digestion of biomass. It is composed of methane and carbon dioxide and is traditionally burned to generate green power. With its nearly 2,000 operating plants, Italy is one of the world's leading countries for biogas production.
Biogas was conceived and patented in Italy in the second half of the 1960s.
About 25 years later, more or less in correspondence with the patent expirations, it became public domain and use and Germany supported its use in exchange for significant incentives on the product. It was the beginning of a rapid expansion, first in Germany and, subsequently, in European and non-European countries, not only in the agricultural sector, but also in the treatment of waste, sludge and other applications..

BIOGAS PLANTS
The vast majority of biogas plants in Italy are benefiting from an incentive tariff on the energy produced that usually lasts 15 years and when the incentive ends farmers essentially have two alternatives:
1. Transform the plant from biogas production to biomethane production
2. Shut down and dismantle immediately
Many farmers, without biogas, would inevitably be forced to scale down their agricultural-productive activities. The first option remains, that is, the conversion of the plant from biogas production and, therefore, burning it, green electricity, to biomethane production and its injection into the national grid. In years where methane gas is heavily sanctioned, biomethane production seems to provide a dual solution: decarbonize the current consumption of fossil methane and replace the natural gas that we currently import from abroad.
There are two obvious limits to this solution. The first limit concerns the incentive itself. Switching from producing electricity by burning biogas to producing biomethane to compress and feed into the grid, the net profit for each individual plant decreases drastically and then the incentive must inexorably grow to fill the economic gap and to guarantee a return to the production sector. The second limit, however, is infrastructural. However widespread and distributed Snam's network may be, it does not touch the surroundings of all biogas plants, indeed, a good percentage of them are currently installed a few kilometers away. It is not conceptually or even useful to operate network expansions to connect plants far from it. Since biomethane is not (easily) liquefiable and therefore not even transportable, it turns out that many plants have no interest in making use of the conversion from biogas to biomethane and must, by force and against their will and against our will, abandon their production activities.

ALTERNATIVE SYSTEMS
OTHER OPTIONS.
Since 2018, Fattoria Autonoma Tabacchi S.C. and Politecnico di Milano have entered into a technical-scientific collaboration in the field of process engineering and circular economy to produce methanol from biogas or, better, biomethanol since the origin of carbon is biogenic when starting from biogas.
Methanol is the simplest of the alcohols and is considered one of the key compounds in these decades of transition for its qualities as a carrier for hydrogen, but it is also an advanced and high-octane fuel that generates reduced particulate matter and NOx and is also the basic chemical compound for a significant number of applications and products such as chipboard, polymers, acetates, etc.
Italy is among the world's leading users of methanol and does not have any production plants on its territory, ergo, it depends for over 1 million tons per year on imports from countries that rarely respect European environmental dictates. The imported methanol is, moreover, totally fossil, produced from natural gas or even coal.
But how to produce it in Italy? The idea is precisely to offer a new alternative to those biogas plants that would otherwise be inexorably shut down. There are about a thousand of them. The technology to produce biomethanol from biogas is called BIoGaS to liQUID (BIGSQUID) and was conceived by the Polytechnic University of Milan and in particular by the Centre for Sustainable Process Engineering Research (SuPER) directed by Professor Flavio Manenti, Full Professor of Chemical Plants of the Giulio Natta Department, and patented by the Technology Transfer Office (TTO) directed by Dr. Ivan Ciceri of the Polytechnic University of Milan. The BIGSQUID technology was proposed for engineering and industrialization to Fattoria Autonoma Tabacchi S.C., chaired by Dr. Fabio Rossi, who commissioned the design and control of the process to SMEA Engeenering srl (ing. L. Ceccaroni).
Fattoria Autonoma Tabacchi, through other companies of the group, has been present in the Umbrian territory for over a century and deals with the production of tobacco, cereals, oilseeds, vegetables, hazelnuts, electricity through two biogas plants and several photovoltaic plants.
Pandemics, conflicts and consequent lockdowns, surges in the prices of raw materials and process units have put the development and industrialization activities to the test, but in the end the result has arrived.
The BIGSQUID PILOT plant to produce biomethanol from biogas, the first in Europe and probably in the world, is currently installed at the Giove Locality of Città di Castello (PG) in the biogas plant of Fattoria Autonoma Tabacchi Sca, with satisfaction and pride for Prof. Manenti and the Board of Directors of Fattoria Tabacchi and thanks to the effort of a team of 15 people.
A BIGSQUID plant of 1 MWhe equivalent has a production forecast of 4,000 tons / year of biomethanol at market specification with a value of fossil methanol that varies between 450 and 550 € / ton. In essence, with biomethanol sold at the price of fossil methanol, each biogas plant would be in profit for the first time since its invention without particular incentives. Furthermore, biomethanol has an undoubtedly higher value than its fossil counterpart due to its environmental aspects, but this surplus is not yet defined as there is no large-scale global production already underway. In Italy there are approximately 2,000 biogas production plants, which place our country in second place in Europe and fourth in the world. The technologies present concern plants of variable size, but mainly 1MWh. If a third of the existing plants could not connect to the Snam network to inject biomethane, in Italy up to 3 million tons per year of biomethanol could be produced to specification, completely decarbonizing one of the main industrial sectors and with a surplus of 2 million tons per year produced, which could be exported or, even better, could replace that percentage of fossil methanol that is already used as an additive in gasoline, with further significant environmental benefits. In Europe, the use of methanol other than fuels stands at 10 million tons per year.
An excess production of biomethanol does not impact the overall global demand, which stands at around several tens of millions of tons per year, but there is another significant aspect. Methanol has significant uses and derivatives. A strategically important methanol derivative is dimethyl ether or DME. It is currently a diesel additive, but it is increasingly being considered as its replacement, moreover, in a rather short time since leading car manufacturers have launched entire lines for automotive use. The same agricultural tractors, with slight modifications, can adopt DME as the only fuel. From this perspective, a further use of several million tons per year would open up in Italy alone for the overall replacement of fossil fuels and a total ban on PM10, PM2.5 and NOx from internal combustion engines, while waiting for the transition to complete its path and for hydrogen and electricity to finally find their deserved use in safety and with respect for our planet.
Recalling Natta's famous phrase and saying it in Politecnico style: biomethanol made!

 Figure 1. Construction phase of the first BIGSQUID plant at Città di Castello (PG), Fattoria Autonoma Tabacchi

NEW INDUSTRIAL SCALE BIOMETHANOL PLANT.
Given the market conditions, Fattoria Autonoma Tabacchi has decided to build a dedicated plant capable of absorbing the entire production of its plant equal to 550 m3/h of biogas.
In this case, the production of methanol would become equal to 4,000 tons/year at 75% alcohol, after anhydrous distillation it would be 3,000 t/year.
The SB 01 block diagram explains the various production phases
- Pretreatment
- First compression
- CO2 removal washing column
- Biomethane production membranes
- Steam reforming
- Second compression
- Methanol synthesis
- Condensation
- Distillation
- storage
The attached IM01 plan shows the various machines in plan

COSTS AND CONSUMPTION
The estimate of costs and consumption was made by extrapolating the costs, the experiences, sustained in the small experimental plant currently in operation at FAT.
In fact, there are no similar plants on the market (not even experimental) in particular for this size of methanol production with a feed of 550 m3/h of biogas. This production size of about 500 m3/h of biogas is currently the most widespread in Italy, in anaerobic digestion plants with combined production of electrical energy, equal to 1 Mw. The costs of equipment were therefore evaluated, together with service plants, used in other industrial sectors, appropriately adapted to this innovative and unique experimental process.

The following table provides an estimate of costs and consumption
A budget estimate for costs, including installation and commissioning