Biogas agrees with everyone

This renewable gas obtained from organic waste from the agricultural sector or cities is used to produce electricity or biomethane, a substitute for natural gas that can also be used as fuel for vehicles in pursuit of moving towards decarbonized mobility.

The formula of biogas is irreproachable, a renewable fuel that is obtained from organic waste and is used to produce electricity, heat or biomethane. The authorities are already involved. The Ministry for the Ecological Transition and Demographic Challenge (Miteco) has drawn up a roadmap so that production can multiply by four between now and 2030. There are 146 biogas plants in Spain, a small number but with enormous growth capacity.

Martín Ramírez, who is part of the Department of Chemical Engineering and Food Technology at the University of Cádiz, highlights one of the advantages of this renewable gas: “It is produced 24 hours a day, 365 days a year.” And he points out the potential of an energy that is currently more developed in Italy, France, Germany or the United Kingdom: “Spain is the second largest producer of agricultural waste in the community countries.” These wastes in the form of vineyard prunings, cereal straw or crops not suitable for consumption, together with the organic waste that citizens deposit in the brown bin, are quality raw material to obtain biogas.

Vicente Bernal, scientist at Repsol Tech Lab, continues the line of argument drawn by Ramírez: “The greatest potential is in the field. There are studies that quantify it and place Spain at the head of Europe among the European countries with the greatest potential for biogas production. There could be 2,000 plants, when less than a tenth exist.” The technology for the production of this gas is very mature, now it is the turn of investments.

Víctor Marcos, director of Renewable Energy and Electricity Market at the Institute for Energy Diversification and Saving (IDAE), points to the investment aid plan worth 150 million euros that Miteco has launched. “The aid is aimed at public entities and the private sector.” As an example of the former, there are the Town Councils that manage municipal waste (orange peel or the leaves that cover a cauliflower are excellent raw materials for obtaining biogas). “Many landfills convert organic waste into compost instead of using it to obtain biogas,” explains Ramírez to remind us of the potential that these wastes have beyond the well-known conversion into compost. With respect to private entities, Bernal points to rural cooperatives as a way in which ranchers, farmers, waste managers, etc. can benefit.

The plan consists of agricultural and livestock producers joining together to install a plant near their facilities in which field waste, manure, chicken manure (excrement from poultry farms) or slurry from livestock farms are converted into biogas in a totemic example of circular economy. The renewable gas obtained can be used to power a boiler to heat the stables or to produce electricity to keep cold storage rooms for fruit and vegetables on.

A balanced waste diet

The plants accept various wastes and that is another advantage to improve the performance of biogas plants, which requires a good mix of ingredients; a “balanced diet,” in Bernal’s words. Slurry contains a lot of nitrogen, a lot of water and little organic matter, so it is advisable to add cereal straw or selectively collected organic waste (the brown bucket) to obtain greater performance. Once again, there is the convenience of establishing agreements between different sectors and public and private entities, that is, garbage management concessionaire companies, wastewater treatment plants, farms, farmers and energy companies.

“Biogas creates employment and establishes population in rural areas,” says Marcos, from IDAE. Direct work in the form of installation and maintenance of the plants (of the 146 existing plants in Spain, 129 were operational in 2020, the last year for which Miteco has records). It also guarantees the viability of companies in the agricultural sector, which can better manage their waste and even convert it into electricity or heating, thereby reducing their costs.

Convert biogas into biomethane
If the CO₂ is removed from biogas, which is mostly composed of methane and carbon dioxide, it becomes biomethane, a substitute for natural gas that can be injected into the grid and therefore reduce dependence on this fuel. fossil. One of the main advantages of biomethane is that it allows it to reach applications far from biogas production sites, such as industries and homes. It can also be used as automotive fuel in autogas vehicles. The Government has set the goal that 1% of the gas distributed in Spain will be biomethane by 2030.

To support this objective, a royal decree has just been approved that will make it easier for the biomethane obtained to have certification and can be sold and bought. Bernal, from Repsol, illustrates with an example the benefit of having a guarantee of origin for biomethane. “A plant in Castilla-La Mancha injects biomethane that it has produced from biogas into the natural gas network. An industry in the Basque Country buys that injected amount of renewable gas, which will contribute to achieving its goals for reducing net CO₂ emissions that it has set.”

How to make production profitable
All experts point out that the challenge of biogas is its production cost and therefore its sales price. In the context of price distortion caused by the war in Ukraine, natural gas is more expensive than biomethane. “We will see when we return to the previous situation. Subsidies and incentives from the administration will be necessary if we want to boost the production and consumption of biomethane,” says Bernal. Some of the costs associated with the production of renewable gas come from logistics, transportation and waste management. That is why Marcos points out that it is essential that agricultural and livestock producers, treatment plants, and landfills work together to reduce costs in pursuit of viability.

Citizens can also contribute to the promotion of this energy. It is imperative that the Administrations install the brown bin, the one for the organic fraction, in all municipalities so that it is recycled effectively. Once implemented throughout the country, Bernal aims for its good use. “Segregation in homes is still not as good as it could be,” he says. If the appropriate waste is poured into the brown bucket, the pretreatment process is simplified to separate the so-called improper waste (glass, plastic, etc.), which is expensive and necessary so that the mixture that goes to the digester is of quality. A good mix of organic waste results in cheaper and better biogas, which can compete in price with fossil fuels, because it is always necessary for the industry to be profitable.

Fuente: El País