A revolution rooted in the circular economy: thanks to separate waste collection, organic waste is fed into an anaerobic digestion process to produce biogas.
Biomethane: a clean resource of biological origin
So, what makes this source of methane “bio”? Quite simply, it’s how it is produced: not by drilling into deep underground deposits, but by fermenting organic waste in dedicated facilities. Biomethane can be produced continuously, it is inexhaustible, and production can be increased simply by building more plants. This makes it one of the clearest examples of a circular economy.
In Spilamberto, a biodigester converted into a biomethane plant
An innovative plant for the production of biomethane is in operation in Spilamberto, in the province of Modena. It was developed by the NewCo Biorg, a joint venture between the Hera Group and Inalca (Cremonini Group), through a total investment of around €28 million and the use of the best available technologies.
Starting from separately collected organic waste and agri-food effluents, the plant – the result of converting an old biodigester – produces, at full capacity, 3.7 million cubic metres of biomethane per year, a 100% renewable fuel intended for transport, and around 18,000 tonnes of compost.
A cutting-edge plant for the energy transition and the circular economy
The 100% renewable natural gas is produced through anaerobic digestion of organic waste from separate collection carried out mainly in Modena and the province, along with waste from local agri-food processing and meat production by Inalca. Once refined, it becomes biomethane and can be fed into the gas network.
Significant environmental benefits: around 7,000 tonnes of CO₂ avoided
Thanks to the injection of biomethane into the network and its use in transport, significant environmental benefits are expected. Every year, around 3,000 tonnes of oil equivalent (TOE) in fossil fuels are saved, and approximately 7,000 tonnes of CO₂ emissions are avoided. Absorbing such an amount of CO₂ would require, on average, 280,000 trees.
What happens in our plant in Sant'Agata
Organic waste, collected through separate waste collection, undergoes anaerobic digestion to produce biogas. This is how the process works: the waste is shredded and screened, then remains for about 21 days in four horizontal digesters, where suitable microorganisms carry out the digestion process and produce biogas (composed of methane and carbon dioxide). After this, the biogas undergoes an upgrading, or purification, phase using pressurised water: the carbon dioxide dissolves and separates from the methane. The result is biomethane, a gas with a methane content above 95%, and a completely renewable source of energy. Not only that: at the end of the digestion process, lignocellulosic material is added to the outgoing solid fraction, producing a compact mass that then undergoes composting to create high-quality compost, which can be used as potting soil or agricultural fertiliser.
Biomethane is therefore another revolution rooted in the circular economy, one that we at Hera Group are committed to advancing. We do all this with the goal of creating shared value, as Andrea Ramonda, CEO of Herambiente, emphasises: “The direction we have taken looks towards the industrial sector with an increasing focus to creating shared value and partnerships. We are aware that sustainable waste management, focused on recovery and in full compliance with regulations, is essential in today’s world and generates benefits for the entire community.”
Working together for a circular city
At Hera Group, we have joined forces with Bologna Airport and Tper to launch a circular economy project that contributes to decarbonising urban mobility and improving air quality.
What does this partnership involve? The Airport delivers its organic waste to Hera, which collects it at the Sant'Agata Bolognese plant together with similar waste produced by citizens and transforms it into biomethane that Tper purchases to feed the fuel tanks of a significant part of its bus fleet.
This is an important step forward for our Group and for two major organisations in our area, which, like us, serve hundreds of thousands of people. We share a commitment to improvement and sustainability, in line with the UN 2030 Agenda.
Ferrara, the city of "green" heat
What's Ferrara's green secret? It lies underground, where a geothermal reservoir powers the city’s district heating system. As a result, 95% of the thermal energy distributed in the city is clean and we avoid about 26,000 tonnes of CO2 emissions per year.
A hidden treasure lies beneath the ground in Ferrara. Not a chest full of gold coins or a vault hiding works of art, but a gift that nature has bestowed on the city. Roughly two thousand metres below ground, near the village of Casaglia, there is a geothermal reservoir that supplies water at a temperature of around 100°C. It is one of the most important reservoirs in the world and represents a renewable, completely clean energy source.
This natural treasure is what makes Ferrara’s district heating system one of the most advanced geothermal plants in Europe. The reservoir supplies 55% of thermal energy to a 179-kilometre-long network that serves around 27,000 homes. Thanks to geothermal energy, combined with heat recovered from the waste-to-energy plant in Via Diana, 95% of the heating we provide in Ferrara is green. Hera’s district heating system allows the city of Ferrara to save 26,000 tonnes of CO₂ emissions every year.
This source of clean energy is managed by the Hera Group, in partnership with Enel Green Power through a Temporary Grouping of Companies created specifically to manage the Casaglia geothermal source.
The strategy we have developed over the years has just one goal: to boost district heating in the city and create value for both residential and industrial customers.
District heating: an answer to the problem of air pollution
The district heating service offers an answer to air pollution problems because it allows heat generation to be concentrated in efficient production centres. To produce the heat needed for domestic heating and hot water, it is possible to recover energy from other processes and use renewable sources, resulting in extremely low pollutant emissions compared to conventional domestic or building-level boilers. For example, Ferrara’s system has obtained the Carbon Footprint certification in accordance with ISO 14067/2018 for thermal energy production, and it has a carbon footprint 64% lower than a traditional boiler-based system.
Across all areas served, in 2024 Hera’s district heating system avoided 16,000 tonnes of oil equivalent (TOE), 35,000 tonnes of greenhouse gas emissions, and 48 tonnes of nitrogen oxides.
