Biomass district heating: the best technologies to generate clean energy

The primary goals of the Green Deal, bolstered by the REPowerEU Plan of March 2022, are to achieve climate neutrality and combat energy poverty by diversifying and facilitating access to energy sources. The plan aims to reduce dependence on fossil fuels and accelerate the energy transition. EU Directive 2023/1791 provides an analysis and synthesis of best practices to guide this process, adapting and updating the previous regulatory framework to promote the use of renewables as a primary source.

Within this framework, the same directive recognises that 'efficient district heating and cooling has significant potential for primary energy savings', where energy is produced with high-efficiency cogeneration, biomass and waste heat. In recent years, energy networks are slowly becoming more widespread, making it possible to assume that by 2050 energy networks could cover 50 per cent of the heating needs of users in EU countries, producing overall CO2 savings of around 13 per cent.

The term 'biomass' summarises various items, including wood chips from the forestry sector, agricultural and food waste, residues from mowing and pruning of public green areas. Their transformation involves several critical issues related to the running of a complex supply chain that starts from the practice of recycling and ends with the transformation of waste materials.

Typically, material of varying composition has to be burned in order to produce energy from biomass. This reveals the other side of the coin, namely the emission of particulates and other airborne pollutants generated by this type of process which can contribute to air pollution and potentially endanger respiratory health, if released into the environment.

A CITY HEATED (ALSO) WITH BIOMASS: BAT AND KNOW-HOW FOR INTEGRATED DUST AND NOx ABATEMENT

Heating the main public buildings, some commercial premises and around 4,000 residential units was the aim of the project that, for some years now, has been instrumental in changing the habits and quality of life of the inhabitants of Ivrea (TO).

With the aim of reducing the demand for fossil fuels (natural gas), the decision was made to equip the existing power station with an additional biomass boiler, in this case consisting of virgin wood chips, while keeping atmospheric emission values unchanged.

Extensive knowledge of the Waste-to-Energy and biomass treatment sectors - documented by multiple success stories - led the customer to TAMA AERNOVA as a strategic partner, capable of designing and implementing a biomass boiler filtration system suitable for the infrastructure built to supply the Ivrea energy community.

In managing the project, therefore, immediately leapt to mind the need to provide a solution that could simultaneously manage both the problem of pollutants from the combustion of woody biomass, and the need for a product that could handle and withstand the high temperatures necessary to allow urea to react in the NOx abatement process at the optimum point of 350°C.

TAMA AERNOVA proposed a turnkey solution ranging from the engineering study to on-site installation. The project included the integrated study of several components: the Pulco Air filter with catalytic ceramic candles, the deNOx system to corroborate the process, the fan and the smoke stack for the emission of treated air into the atmosphere.

The filter treats gases resulting from the combustion of biomass, feeding them back into the energy production system to provide water at a temperature of 90°C for the district heating network.

Before entering the filter, hot gases pass through the bypass system, which functions as a protection against the entry of gases at too low a temperature - which could lead to condensation - or too high a temperature - which might damage the filter elements. An aqueous mixture of urea is then injected into the hot gases. With these additives, the gases enter the filter and pass through the catalytic ceramic plugs, which, thanks to the catalyst with which they are impregnated, allow the urea to react, converting NOx into nitrogen and water vapour. This process enables the abatement of up to 99.99% PM and up to >90% NOx.

A single electrical panel, which can also be monitored and controlled remotely, manages the operation and correct functioning of the entire system: filter services; the operation and input of urea based on the amount of NOx emissions; the setting and control of temperature thresholds of the bypass system, managing the shutters that allow or block the entry of air to the filter.

The integrated approach adopted by TAMA AERNOVA to manage this ambitious assignment once again highlights the value of turning to a partner who goes beyond simply offering the best product. Such a partner understands the bigger picture and prioritises not just product quality, but also long-term reliability and solution longevity.