Hera biomethane from waste
From organic waste to biomethane that can directly reach homes after being fed into distribution networks. The project consists in producing methane from renewable sources, specifically by anaerobically biodegrading the organic fraction of separate waste, to be done at the Sant’Agata Bolognese composting plant.
Hera has been producing biogas for years, using biodigesters and landfills, and using it to generate electricity; the next big step is to refine it to make biomethane like the gas that is piped to households. This system is an initial embodiment that will use the organic fraction of separate municipal waste as raw material to produce biomethane and will also become fuel for methane-powered vehicles for local public transport.
The process begins with a semi-dry, continuous flow anaerobic biodigester where the organic waste is anaerobically digested, producing biogas and the digestate. The digestate is then sent to the subsequent composting step that comprises oxidation and final screening, to obtain high quality compost. The biogas is sent to an upgrading section to remove undesired components and obtain methane gas that meets the specifications for being injected into the network. This process is the foundation of a perfect circular economy in which food waste makes natural gas that can be used to cook more food or even be used for heating and for vehicles.
The biodigester will be able to process 100 thousand tonnes per year of organic waste and 35 thousand tonnes of pruning material from separate waste collection, and starting in 2018 it will produce about 7.5 million m3 per year of biomethane and about 20,000 tonnes of compost.
In December 2018, after an initial start-up phase, the biomethane produced began to be injected into SNAM’s network. The biomethane injected into the grid is sold for powering motor vehicles; by doing so Herambiente obtains the incentive through CICs (Certificates of Release for Consumption of renewable fuels). The total amount of this work requires an investment of more than Euro 37 million, of which 33 million already accounted for.
Energy recovery from methane decompression
The project involves the exclusive development, construction and installation of an experimental system, based on a patented technology, to recovery energy from the pressure drop in R&M stations. It is a small to medium sized turbo expander (330 kW electric) installed in the medium sized R&M stations, in combination with a heat pump that uses CO2 as a heat carrier fluid, designed to use part of the electrical energy to preheat the gas used in the process.
A contract was signed in 2017 with BHGE for prototype testing of the system and the design of the prototype and the complementary works necessary for its installation in the “Ducati” R&M station in Bologna were completed.
In 2018, we completed all the authorization activities, the supplier completed construction of the machinery, all the necessary complementary works were carried out and the prototype itself was installed on the site.
As planned, preliminary tests are underway in preparation for the start of the experimental operation phase scheduled for early spring 2019.