PRESENTATION.
The development of industrial biogas plants is limited by many factors that make difficult the progress of these projects and limit them to those cases where a number of technical and economic requirements are met. Economy of scale plays a decisive role, making the largest projects, which are the most complicated to implement in terms of raw material supply and financing, more profitable.
At the same time, there are many small producers of organic waste in Spain whom the cost of management is very expensive or who cannot even manage it and have to go landfill along with urban waste. Many industries, including those with seasional production, generate small quantities of waste whose logistical cost makes management expensive or imposible, while the total quantity available does not justify an industrial biogas project. Usually, are smalls and isolated companies that find difficult to manage their waste properly and often have to bear more expensive energy, that is the reason why this companies are the ones that can get higher economic benefit with a different biogas project and adjusted to their needs.
In developing countries, the absence of organic waste management often leads to increased health and social problems, so the management of organic waste has more than just an economic or energy component.
At national level, apart form industries producing small quantities of organic waste, the main source of dispersed and untreared organic waste is usually the Organic Fraction of Municipal Solid Waste (OFMSW). In the best cases, its management does not go beyond selective collection and composting, with landfill being the most common solution, which does not represent optimal management.
MANAGEMENT CHAIN. THE CIRCULAR ECONOMY OF ORGANIC WASTE.
The organic waste, and mainly edible food waste that has a high moisture content, can enter into a circular economy process following the next steps in order of hierarchical preference.
- Reduce its production. It is advisable to reduce the amount of waste generated when its possible.
- Prefered food use. If they can be used to feed humans or animals, they must be used for these purposes as a matter of priority.
- Anaerobic process. Biogas/energy production. Those wastes that cannot be used in cased 2 should be used for for biogas production. This process will convert the raw material back into elementary harmless compounds following the natural processes of nature’s closing cycle. In addition, to closing the carbon cycle will generate a fuel such as methane with versatility of use in different applications. The anaerobic process is optimal for waste with moisture, as it converts the solid fraction into gas, removing solid matter and producing a liquid that contains all the moisture form the input material. In this case, the moisture is not losed and is generated as a by-product of the plant that can be put to different uses. In desert areas, the biogas production is a process that also recovers water in a usable form.
- Comporsting. In cases where case 2 or 3 cannot be carried out, it is advisable to use the organic waste for composting. It is a mineralisation process, which transforms organic carbon into inorganic, closing the carbon cycle by producing CO2 and evaporating the moisture present in the material. This process does not allow the energetic use of the material, it generates a mineralised solid and water recovery is lost. It still been the best solution in case a previous treatment is not possible.
- Landfill. This is the last alternative. Only in those cases where no other previous alternative is possible, either for economic, geographical or social reasons, among others.
These wasters are discarded from being used as direct fuel because of their high moisture content. Combustion should be reserved for lignocellulosic or very dry wastes or materials. Biogas production is the best management and energy option for materials with high moisture content.
Therefore, it can be concluded that majority of organic waste is produced in a dispersed manner, so in order to treat it properly, it is necessary to decentralise management, avoiding the environmentally negative landfill, and leaving composting processes to those places where it is not profitable or possible to produce energy from gas.
In order to make possible a wider management of waste with energy recovery, AGF PROCESOS BIOGAS SL is developing a model of Mini Biogas Plant, the MPB.
THE TECHNICAL CHALLENGE.
AGF has wanted to confort the challenge of making a small, cost-effective biogas plant for years. Many European companies have tried, and have achieved diverse products and results in design and configuration, but most of these plants have problems of stable operation, technical designs problems, and costs between 500,00-800,00€ per unit, which makes it very difficult to make this business profitable. Some of them are big companies of the biogas sector from countries where biogas was on the rise, during the late first decade and early second decade of this century. These companies offer a new small-scale product that is a design on the industrial scale plants. There are also, companies dedicated to this sector of small-scale biogas plants, without any previuos relation with the biogas sector, and, therefore, without its indispensable technological knowledge base.
In addition to these companies, and due to the market situation, many research and developments projects have been carried out that have developed their own designs in this sector. In Spain there are different cases of these R+D projects headed by technology centres, companies and universities.
It is possible that all these designs have not produced products that are profitable, as they do not seem to be having a commensurate business run. Therefore, solving this problem is currently a technological challenge due to the dispersion, the low profitability margin, the complexity of maintaining a plant in optimal operation and, especially, the loss of an environmental awareness at a particular level and the different adminsitrations.
INDUSTRIAL DESIGN AND DEVELOPMENT.
Usually, designing industrial technologies at small scale is difficult due to the high weight of scale economy, which makes these designs unprofitable. AGF hopes to achieve a small scale application with a high efficiency technology, such as the one it is developing in industrial facilities, which will be able to increase the number of cases in which this product is profitable and financeable.
A demanding engineering design is to be applied in terms of automation, allowing the plant to operate autonomously and to be able to produce biogas in a controlled manner. This way, it will not be necessary to install a biogas storage facility, reducing the investment cost, the footprint of the plant and the external elments, such as gas storage.
The design of the plant seems to be organised, minimalist and operator friendly, combinig a complicated industrial design but simplified to the maximum, looking for simplicity. It do not have any unnecessary external elements, it seeks to be transportable and capable of leaving all its elements completely collected once it has finished working with it.
The basic design of the plant, Model 01.19, has been made for substrates that do not require any kind of pretreatment, such as industrial organic sludge, by-products or OFMSW. A modified plant design has been considered in order to be able to process animal by-products not intented for human consumption which require prior sanitisation. In addition, this plant can be combined with the Method 1 corpse sterilisarion plant developed by AGF, which is a pioneer in Spain.
The design of the MPB has taken into account the possibility of transporting it by sea to any part of the world, with the international market being the main market of the plant. In this context, negotiations are advanced for projects in the United Kingdom, as well as in African and Latin American countries, so maritime transport will be a fundamental part of the delivery process of the plant.
In order for this plant to meet its production targets, AGF will offer a remote operation service for the plant, so that the promoter only has to take care of the feeding and the general maintenance. This operation will control the process in order to reach optimal levels of biogas production. Small plants need to be monitored in a similar way to an industrial plant, the processes are carried out under similar conditions, although the MPB will require less human activity than in an industrial installation.
Once AGF decided to start the design and investment for the assembly of the MPB 01.19, different possible locations for the pilot plant came up. There was the possibility of installing this plant on the industrial plant site, currently AGF has industrial installations in Burgos, Zaragoza and Tarragona. At these locations, there is enough organic matter to feed the plant on a daily basis, they are located in or near big cities.
However, AGF has its Centre of Applied Research and Development (CIAD) and its Plants Operation Centre (COP) in the village of La Lapa, in Badajoz. It is advisable to locate the MPB plant in this location because of the synergies with CIAD and the R+D capabilities that having a pre-industrial plant brings, as well as the proximity to the COP, which is responsible for the operation of the MPB.
AGF as a company is committed to the development of the area and seeks to be a technology-based company, generating knowledge with high added value, which develops part of its activity in the rural world. With all this, AGF will have made an investment in La Lapa closer to 500,000€ in these five years of the company’s life and is gradually creating stable Jobs between CIAD and the COP.
But locating the plant at La Lapa presented some problems. The main one is the absence of organic waste to feed the MPB. There are no producers of industrial organic waste in the area, and therefore no authorised waste managers. The main source of waste is OFMSW, which is associated with a management problem. In order to feed the plant, it is necessary to rely on OFMSW, the management of which is the responsibility of the administrations. To this purpose, the city councils and the provincial council of Badajoz were contacted. Their response has been positive and they have been proactive in participating in this project.
For this reason, the project has been given a greater social aspect, it needs the involvement of other social sectors, not only companies. Although the construction and design of the MPB is a project that is expected to have national and international repercussions, the demonstration project of organic waste management through circular economy is a pioneering example of sustainable management at a national level. This should position a small village in the province of Badajoz at the top of decentralised municipal waste management in Spain.
The aim is that the local councils facilitate the collection of OFMSW and for the Provincial Council modify the route of a vehicle to collect the selected material and transport it to the plant. AGF has prepared a proposal for a collection line after talking to the main producers of organic waste in the area, although the idea is to expand it to the general public, especially with the general participation of the largest producer of OFMSW: the people. Originally, the participation of big producers such as restaurants, canteens, hospitals and supermarkets has been seek, but local councils must collaborate to try to expand social participation in the project.
This experience is also intented to find out how much OFMSW a rural population actually generates through direct knowledge, in order to be able to study any future investment in this sector. According to some studies from actual practical experience in Spain, the production of organic waste is very low, about 150 grams per inhabitant equivalent per day. Therefore, an MPB plant could serve a population of around 10,000 equivalent inhabitants.
Organic waste is not collected separately because of two main problems: the need of a final treatment point and the logistical cost of separate collection. Separate collection without a final treatment point means that the separated fraction is mixed again with all the other fractions and sent to landfill. Furthermore, in the case of separate collection, it would be necessary to invest in new collection trucks or to assign trucks to collect this fraction, increasing the cost of collection in order to manage the same quantity that was previously mixed.
The solution to the first problem may be to have a decentralised treatment plant, such as an MPB. In cases where this is possible, due to a higher volume of concentrated population, it would be better to undertake a higher investment in an industrial biogas or biomethane plant.
The solution to the second problem is to have a plant close that serves as a final disposal point, at a distance that justifies the separate collection of OFMSW and even reduces the total costs in cases where landfilling is a long distance away.
Therefore, MPB can be a solution for waste collection as well as for small organic waste producers.
CIRCULAR ECONOMY DEMOSTRATION.
The MPB should be a step to a circular economy cycle. One of the most important, as it closes the natural carbon cycle by generating energy.
All of the above does not have much business potential if it does not achieve an economic profitability that in the worst case scenario, sustains the activity and generates sufficient profitability for this type of project to be financed. The last proposal is to evaluate how this new sector can be economically sustainable through a new, clearly circular economic cycle.
To achieve this profitability it is necessary to generate income from the biofuel gas generated as from the management of the waste.
In order to make the plant profitable in developing countries, it may be sufficient to produce electricity or heat. Therefore, the MPB is designed for the production of hot water and electricity for self consumption or export. Its design can be modified to add CHP units and adapt it to the needs of each project, both in the power supply system and in energy production.
But to make this new business profitable in developed countries, it is necessary to enrich the gas to biomethane quality. For this purpose, AGF has developed the Mini Biomethane Plant. By integrating the MPBiogas with the MPBioCH4, we have the MP2B model, which integrates an enrichment plant to the MPB. Gas separation is carried out in a low-pressure biomethane plant, which operates by absorption in water without chemical reaction in a closed water cycle. This plant should bring the gas down to levels suitable for compression and use as a carrier gas or injection into a pipeline.
This new market, is a valid technical solution and a profitable economic balance can be achieved, can give rise to the concept of the biogas plant. Filling points for renewable gas vehicle fuel that has been generated just a few metres from the filling point, without any cost or transport footprint on the fuel; it is a fuel that does not emit long-cycle CO2 and whose production process leads to a reduction of emissions.
The different options available for MPB and MP2B will seek to adapt to a potentially huge and international market, with producers of a waste with high management costs with a particular interest.
