Vineyards pruning valorisation for energy purposes as local strategy to promote circular economy


Title: Vineyards pruning valorisation for energy purposes as local strategy to promote circular economy

Country/Region: Vilafranca Municipality, Catalonia (Spain)

Stakeholders involved: The involved actors of the biomass value chain include the town council of Vilafranca as the coordinator, COVIDES cooperative in charge of the biomass supply, NOU VERD in charge of the biomass management, and INNOVI addressing biomass consumer engagement and promotion. As the project progressed, new actors were involved to further develop the value chains. More precisely, the value chain currently involves the Celler Cooperativa La Granada, and EM-AVSA, although the municipality is still contributing to further promote the innovative practice.

Description:

Vilafranca Municipality coordinated a project from 2014 to 2016 called Vineyards for heat co-funded by the European Commission’s LIFE Programme, which intended to demonstrate the performance of the biomass circle with pilot tests in two wineries (Codorniu and Vilarnau) and in one area of public facilities in Vilafranca. 

The objective of the project was to apply and implement a vineyards virtuous circle (VVC) as a local strategy to mitigate climate change contributing to meet the goals to reduce greenhouse gas emissions (GHG) according to the sustainable energy action plan (SEAP) derived from the political commitment and engagement to the Covenant of Mayors. The VVC intends to make profit of vineyards pruning to generate heat and cold for institutional guarantor, in this case, the municipality of Vilafranca. By these actions, the region of Penedes could advance to an efficient low carbon economy area and to contribute to the objective of reducing agricultural emissions by 42 % (roadmap 2050). 

After the project has ended, the value chain has evolved to incorporate new actors and improve the value chain design to increase its efficiency.

Vilafranca del Penedès Town Council is located in one of the most important winemaking regions in Catalonia (Spain). Winegrowing in the Penedès region produces 30,000 tonnes of vine pruning waste annually (vine shoots) (Figure 1). This material is usually burned in the vineyards, which does not allow for energy harnessing and causes pollution. Vine pruning waste can easily be transformed into a source of biofuel that has high energy potential.

Figure 1. Location of Vilafranca del Penedès.

The new value chain involves all actors of the biomass value chain, which is key to successfully develop it. The project consortium included the town council of Vilafranca as the coordinator of the project, COVIDES cooperative in charge of the biomass supply, NOU VERD in charge of the biomass management, and INNOVI addressing biomass consumer engagement and promotion. After the project has ended, new actors were involved to further develop the value chain. More precisely, the value chain actors currently involve the Celler Cooperativa La Granada and EM-AVSA, although the municipality is still contributing to further promote the innovative practice.

The main steps of the value chain include:

-        Biomass collection and transport to the storage site

-        Biomass management: pre-treatment, storage and supply

-        Energy production (combustion and ash management)

The technology and equipment currently used along the whole value chain is already commercial (TRL 9).

Biomass collection: The cooperative La Granada annually prunes vine shoots between November and March after grape harvesting. In a project spanning 2014 - 2017, 778 hectares were harvested, yielding 469 tonnes of biomass. 349 tonnes were used in a boiler for district heating. Currently, the cooperative collects vine shoots from 200 hectares. Yield varies from 0.7 to 1.2 tonnes per hectare. Challenges in collection equipment led to the design of a pre-pruning machine, but it was not successful. Instead, they adopted the Peruzzo Cobra Collina, a modified picking and shredding machine, as an effective alternative.

Figure 2. Prototype developed to collect vineyard pruning.

Then, an alternative solution was found by using a different machine that already existed on the market: Peruzzo Cobra Colina, a picking and shredding machine (collector with catcher) that was adapted to collect pruning waste.

Nevertheless, the homogeneity of the material was not optimal and clogging occurrence in the boiler feeding system led to change the collection system. The La Granada cooperative is currently using a regular tractor equipped with an implement which allows the farmer to rake pruning from the rows to the field side (Figure 3and Figure 4).

Figure 3.  Equipment used to rake vineyard pruning.

Figure 4. Vineyard pruning collection.

Once the prunings from a field have been piled, they are placed right next to the road in order to optimize the collection process. A boom truck picks the biomass and transports the biomass to the storage site (Figure 5).

Figure 5. Loading to transport the biomass to the storage site

Although social environmental benefits were identified during the implementation of the project, ensuring the economic benefits is essential to ensure the sustainability and durability, and this consideration was assessed when implementing changes in the value chain. La Granda cooperative provides two services to associates: the first involves complete vine shoot collection, piling, loading, and transport at approximately 60 euros per hectare. The second allows farmers to handle collection and piling, with the cooperative managing loading and transport at around 40 euros per hectare. To improve economic viability, service prices were adjusted from 50 to 60 euros and from 25 to 40 euros per hectare, respectively. Efficient planning across winegrowers' plots is crucial due to their dispersed locations, contributing to maximizing overall efficiency in the biomass collection process.

Biomass management: A key role to achieve good quality of the biofuels involves the storage and pre-treatment.

The storage facility covers an area of 5,000 square metres and is located at a strategic position that facilitates the supply to the district heating in Vilafranca’s La Girada assuring cost competitiveness is achieved by reducing transport costs.  The storage site is divided into two differentiated areas. In one part the vine shoots are unloaded and stored in uncovered piles to dry. In the second area the material is chipped and stored under cover in a shed (Figure 6 and Figure 7).

Figure 6. Vineyard pruning storage.

Figure 7. Chipped material storage under shed.

The chipping is scheduled periodically once a certain minimum amount has been collected. In order to perform the chipping, a high-power equipment is used, and chipping is conducted at the storage site (Figure 8).

Figure 8. Chipping.

During the project, the chipping took place at the field, but the machinery used did not reach a sufficient quality of the product.  The material produced did not reach the required homogeneity and therefore an additional second chipping or a sieving was necessary. The chipper currently used is able to process around 20 to 30 tonnes during a 4 hour period and a better quality material is obtained, particularly regarding the homogeneity (Figure 8 and Figure 9).

Figure 9. Chipped material.

Energy production: La Girada has transitioned to a centralized heating system powered by biomass, replacing natural gas and electricity for heating and domestic hot water. The Heizomat RHK-AK 500 boiler, installed as part of the LIFE Project, initially served four buildings and later expanded to include the Ricard Fortuny Sociosanitary Centre. EMAVSA, a service company, manages the boiler's operation and maintenance, collaborating with the La Granada cooperative for biomass supply. Improvements, including a cutting system to enhance material homogeneity and an upgraded ash removal system, were implemented. The district heating network reduced energy consumption by approximately 153,000 kWh of natural gas and 12,653 kWh of electricity annually, leading to a decrease of about 241 t CO2 in greenhouse gas emissions.

Results/lessons learnt: When installing the biomass boiler, it is important to analyse, which biomass is going to be used because there are certain technical considerations that must be considered. In this case, the agricultural biomass is not very dense and becomes easily entangled as content is high. Therefore, these particularities should be taken into consideration in order to avoid operational problems and inefficiencies. 

On the other hand, agricultural biomass can provide a good thermal performance, although, based on the results achieved, the installation of these boilers is recommended when using a centralized (district heating) boiler and when long-term use is envisaged. This will ensure optimum yields and maximum returns on investment. 

Based on the experience acquired during the development, there are some recommendations: 

  • Use commercial (tried and tasted) machinery for the collection of vine shots.
  • In order to minimize the costs, the collection and management of biomass should be near to the end-users. Firstly, the collection must be planned to be highly efficient, and the further drying and storage of vine biomass must be strategically located near the consumers. These actions will help to keep the selling price competitive.
  • Large facilities with sustained demand are preferable.
  • Technical improvements to boilers and selection of the most appropriate equipment according to the biofuel specific characteristics: boilers should have a chain conveyor system in the combustion chamber to counter the fuel’s lack of fluidity and with continuous cleaning to avoid unnecessary stops and re-starts.
  • Set up of a municipal services company is a key element as it ensures the stability of the project by contributing to ensure energy supply and customer confidence.

Additionally, another relevant aspect concerned the necessity of private and public sector to work together in order to promote and implement the initiative as well as to align all actors involved in the value chain. Based on the municipality experience it is time consuming and sometimes difficult to mobilize agents. Local authorities willing to promote this type of value chain need to clearly define the type of initiative or value chain besides the corresponding business model they intend to develop, taking the region’s specific characteristics into consideration. When designing the project, it is essential to set realistic objectives, both in the short and midterm. It is also relevant to involve professionals with the needed expertise to correctly dimension the value chain and assess its suitability and profitability.

Link to the website: https://intercambiom.org/practicas-innovadoras/