Biomethane : Biowaste to Biomethane: Italy is stepping up its game

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Italy is currently among the best-performing EU member states in recycling consistent amounts of municipal solid waste (MSW). After a constant improvement of its performance, around 63% of all MSW in 2020 was separately collected and sent to recycling facilities; in the same year, the average MSW production per inhabitant was 488 kg/inhabitant, one of the lowest production rates of this century.

A country diverting food waste to recycling

Biowaste plays a pivotal role in a modern MSW management system that aims to maximise recycling and to reduce the amount of residual waste generated. When biowaste is collected separately and thus diverted from disposal, the fermentability of residual waste is reduced, as is the need for intensive treatments prior to final disposal options; moreover, since biowaste represents a very significant fraction of MSW, lower disposal capacities are needed for residual waste.

Italian municipalities have committed systematically to the separate collection of biowaste by setting up:

  • a scheme for garden and park waste (green waste) relying on bring sites or pay-as-you-throw (PAYT) collections at the doorstep, and
  • a frequent and possibly doorstep collection scheme for food waste that takes advantage of compostable liners to facilitate sorting by households; this allows a large variety of food waste to be collected, including cooked food residues, dairy products, meat and fish.

It is worth noting that, thanks to the particular organisation of food-waste collection, the quantities that remain inside the residual waste fraction are often below 10% (f.m.) and, at present, biowaste accounts for almost 40% of all MSW collected separately in Italy and sent to (material) recycling, which is actually a driver of the overall MSW separate collection.

Updated official data[1] shows that, in 2020, 7.2 million tonnes of biowaste (equivalent to 121 kg per capita) were collected by Italian municipalities, 72% of which was food waste. Food-waste collection has undergone a very significant improvement considering that, between 2010 and 2020 (see Figure 1), separate collection has doubled, while green waste increased by less than 20%.

[1] Source: Italian Environment Agency of the Ministry of Environment (ISPRA)

Figure 1: Separate collection of biowaste

- © CIC

Biogas and compost production in Italy

In the EU, biowaste and other organic waste is recycled through composting and anaerobic digestion, which currently rely on the operation of more than 4,300 plants [ECN, Status Report 2019].

According to CIC’s assessment and based on official Italian Environment Agency (ISPRA) data, Italy was home to 294 composting plants and 65 anaerobic digestion (AD) facilities in 2020. The industrial recycling sector has reached a total organic waste throughput of about 8.1 million tonnes, and is made up of facilities that range from very small to real “jumbo” plants; in fact, the eight largest facilities each exceed 100,000 tonnes per year throughput, and together treated more than 2.1 million tonnes of waste in 2020.

Italian recycling facilities mainly treat food and green waste (more than 81% of the total feedstock), followed by sewage sludge (12%) and other organic waste from the food and beverage industry (7%) (see Figure 2).

The output of the recycling industry consists of around 2.2 million tonnes of compost and 370 million Sm3 of biogas, either exploited for electricity and heat production or, as we will see later, upgraded to biomethane.

Figure 2. Recycling facilities for organic waste in operation in Italy in 2020

- © CIC

Besides a continuous growth of treatment capacity, the facilities have undergone a significant shift over the last 15 years, from plain composting technologies towards an approach based on a pre-digestion step – able to produce biogas from the easily degradable organic matter – followed by a post-composting step of the digestate. There are a number of advantages to this strategy, which combines the production of an energy vector (biogas) with that of a solid organic fertiliser (compost) that is easier to handle, store and market, thus increasing the sustainability of the overall recycling process. Moreover, the presence of the composting phase preserves the possibility to recycle compostable items such as liners and bags[2] that are mandatorily used for the separate collection of food waste.

As anticipated, the number of plants that rely on anaerobic digestion has increased consistently since the early 2000s (see Figure 3), when the Italian Government introduced the first grant schemes for the production of electricity from renewable sources, including biogas production units; since 2018, the main strategic interest has moved to the replacement of fossil fuels with renewable (advanced) fuel, leading to the first biomethane facilities. The result of this step-by-step evolution of regulations and technologies is a pool of 65 facilities in operation, mostly consisting of combined AD and composting plants (there are a few cases of direct digestate application on soil, and others in which digestate is sent to other composting plants), 43 of which exploit the biogas via co-generation, with production of electricity and heat, and 12 plants further upgrading biogas to biomethane sent to the national gas grid with the ultimate goal of replacing conventional fuel for vehicles. Despite the relatively small number of AD facilities, they treat more than 50% of the total organic waste collected and, above all, more than 62% of food waste; on the other hand, green waste is predominantly managed by composting facilities.

[2] There are a number of benefits derived from the use of compostable liners in separate collection of food waste, which are not described in detail in this article.

Figure 3: Evolution of organic waste recycling facilities in Italy. AD and composting includes all the facilities provided with an AD step, either followed by a composting step or differently managing the digestate (see text).

- © CIC

The trend towards biomethane

Given the Government’s strategy of replacing fossil-based fuels, several AD facilities have moved their biogas management towards its upgrading to biomethane; a specific national grant system launched in 2018 favours investments that aim to produce advanced biomethane to be used in the automotive sector. This system – based on the purchase by the Government of the biomethane at a given price and of the Certificates of Release for Consumption of the gas itself – requires either the implementation of dedicated filling stations, or biomethane haulage to existing ones through injection into the Italian pipelines for natural gas (NG), with Italy having one of the most developed networks for NG (almost 41,000 km) reaching households and commercial activities.

Since the promulgation of the regulation promoting the production of biomethane, 12 facilities had gone into operation by 2020, most consisting of plants that were already operating (either composting or AD with biogas exploitation through electricity production), but some being brand-new installations. To date, biomethane production potential is around 130 million Sm3/y, including two additional plants inaugurated between 2021 and 2022 that are still not included in the official statistics provided by ISPRA. In a few (at least two) cases, the CO2 derived from biogas upgrading is exploited as well, and is currently refined and utilised for industrial applications, including in the food sector.

Given the Government’s strategy of replacing fossil-based fuels, several AD facilities have moved their biogas management towards its upgrading to biomethane.
Marco Ricci, CIC

Outlook for Italian biowaste recycling

Whereas the separate collection of biowaste is moving towards 100% coverage of Italian municipalities (7.3 million tonnes collected in 2020, against a potential of 9.1), thus consolidating the annual waste-based available feedstock, the recycling sector is now in a critical phase. On the one hand, the upcoming new EU Fertiliser Regulation (Regulation (EU) 2019/1009) will set new quality standards for compost and digestate, which will require the current recycling industry to step up in order to meet more challenging limits. On the other hand, a national biomethane grant system under revision is creating anxiety amongst operators due to uncertainty about the new rules to come. At the moment, more than 50 projects for new recycling plants, mostly consisting of combined AD and composting facilities that should upgrade biogas to biomethane with an estimated potential of biomethane generation that would double the current one, are in a standby situation, waiting for the new grant system to be clarified. There are high expectations of this, also given the fact that the combination of the biomethane grant scheme and the EU Recovery Fund should move Italian industrial recycling infrastructure to a mature status where all the regions are provided with adequate throughput capacities, and the installations are mostly upgraded to maximise their material and energy recovery.