Renewable gases are a key element in solving the climate problem

Renewable gases, understood as those that can be used to generate energy and come from renewable raw materials or sources, play a key role in decarbonization, as well as in better environmental waste management and in rural development and energy self-sufficiency. Spain has great potential in this area, especially with hydrogen.

The director of New Business at Naturgy, Silvia Sanjoaquín, explains the uses that renewable gases can have, which are estimated to be able to reduce 35 million tons of CO2, if Spain develops its full production potential. This is the CO2 emitted by the entire fleet of passenger cars in a year or that absorbed by the entire forest area of the country in 2017. All in all, it would mean saving more than 10% of the greenhouse gas emissions planned for 2030.

Sanjoaquín also addresses the projects that her company is promoting to test this new, more sustainable energy source, in towns such as Vila-sana and Cerdanyola del Vallès.

--- To begin, what types of renewable gases are there?

--- They can be grouped into three types. First, biogas, which is obtained through the anaerobic digestion process of biodegradable organic materials (agro-livestock waste, sewage sludge, organic fraction of municipal solid waste, etc.), from which biomethane is also produced through an upgrading process. Then, there is synthesis gas or syngas, obtained through the thermal gasification process of organic materials. Finally, there is hydrogen, obtained by biological, catalytic or electrochemical methods. At Naturgy, although we have projects related to all types of renewable gas, we have a clear commitment to the development of both biomethane and renewable hydrogen.

--- What is the difference with natural gas?

--- Its origin. Natural gas has a fossil origin, while biomethane, which is nothing more than biogas to which an upgrading process is applied to eliminate CO2, is similar in composition to natural gas, but with a biological origin. On the other hand, hydrogen has very different characteristics from the previous ones, it has excellent energy qualities and is so abundant, considering that it is the main component of water, that it is inexhaustible.

--- What can they be used for?

--- Biomethane is a green energy with a net-zero emissions balance, which is fully interchangeable with natural gas, so it can be distributed through the existing gas infrastructure and used for the same energy applications in homes, industries, businesses, and also for mobility in transport, contributing to decarbonization. Likewise, hydrogen can be consumed both directly and through the gas network. One of the main uses of renewable hydrogen in the short term is as a raw material, replacing gray hydrogen used, for example, in refineries or fertilizer-producing industries.

--- Any other uses?

--- In the medium term, a great potential for utilization is expected in the mobility sector, as an alternative to electric batteries due to autonomy requirements, charging times, or reasons related to tonnage capacity. Also in the production of synthetic fuels, for industry and for heavy mobility, essentially maritime and air, and in industrial heat generation.

--- Why is the transition from natural gas to renewable gases needed?

--- Renewable gases are a key element in solving the climate problem and will play a crucial role in making the change in the energy system, as renewable electricity generation will not be enough to meet all our energy needs.

"In the medium term, a great potential for the use of renewable gases is expected in mobility, as an alternative to electric batteries; and in the production of synthetic fuels for industry"

--- To achieve the decarbonization objectives set by Europe, it is necessary to work with a mix of energy solutions. In addition to accelerating electrification with an increasing development of renewable energies, renewable gases such as hydrogen or biomethane allow decarbonization to be brought to sectors that are difficult to electrify, such as, for example, the industrial heat sector, and some transport applications (heavy, maritime and air transport, for example). In Spain, at least 40% of CO2 emissions do not have an electrifiable alternative, and that is where renewable gases offer the most efficient alternative. Furthermore, the use of renewable gases in the existing gas infrastructure allows their use to be extended to all sectors connected to the infrastructure (building, industrial, mobility, etc.), and therefore it is a quick and effective decarbonization solution applicable to any sector.

--- What benefits do biogas, syngas, and green hydrogen present compared to conventional energy sources?

--- In a few decades, all our energy needs for electricity generation, industry, transport, or buildings must come from carbon-free sources. This will require significant changes in little more than a generation and innovative solutions and policies will be necessary. And, specifically, the benefits of using renewable gases compared to conventional ones are very numerous. For example, they serve to reduce greenhouse gas emissions by avoiding CO2 emissions from the fuel they replace. They also allow for a reduction in energy dependence: renewable gases are produced domestically. It should be remembered that, currently, 70% of the energy consumed in Spain comes from other countries.

--- I understand.

--- Likewise, renewable gases promote the circular economy, as they contribute to the sustainable management of agro-livestock waste. Finally, it can be added that they generate employment and fix population in rural areas, which is where the raw material for biomethane production is generated, mainly from agricultural and livestock waste.

--- In Spain, do large investments have to be made for the production and distribution of natural gases?

--- The use of the existing gas network is the most economical way to transport and distribute significant volumes of renewable gases. Currently, biomethane injection into the network is a reality and is helping our customers reduce their carbon footprint. However, Spain is at the bottom of Europe in terms of the number of operational biomethane plants, so the growth potential is large. In the case of hydrogen, it is necessary to work on the injection limits into the network, since today it is not directly permitted in Spain and limited to a concentration of 5%. Various studies consider that this threshold can be higher, so it is expected that in the future the regulations for hydrogen injection into the network will be revised. On the other hand, significant investments are planned to transport and distribute hydrogen for direct use.

--- In that sense, Naturgy has various projects underway to determine the production costs of renewable gases. Two of them are carried out in Catalonia, in the municipalities of Vila-sana and Cerdanyola del Vallès. What is being observed?

--- The conclusion is that biomethane is a mature and competitive technology. In 2019, through the Life Methamorphosis project financed with European funds, Naturgy already satisfactorily tested biomethane produced at the Vila-sana biogas plant in two compressed natural gas (CNG) vehicles and, a year later, the biomethane generated was taken to Zaragoza for use in the urban transport of that city. Indeed, the use of this renewable gas can remove gasoline vehicles from circulation, although its use must be in vehicles manufactured to be able to use CNG. In the coming months, we will adapt the installed biomethane plant to inject 11.8 GWh/year of biomethane into the gas distribution network, equivalent to the annual consumption of 3,150 homes. In the case of the Cerdanyola del Vallès biomethane plant, biogas is generated in the closed Elena municipal waste landfill, and has represented an investment of 2.2 million euros. The Cerdanyola del Vallès plant produces 12 GWh/year of biomethane, which is equivalent to the annual consumption of 3,200 homes.

"Biomethane is a mature and competitive technology"

--- Currently, we have two plants in operation that are injecting biomethane into the Nedgia network: the Cerdanyola plant mentioned above, and the Bens plant in A Coruña, which utilizes sludge produced in the wastewater treatment plant to produce biomethane. The distribution of biomethane is as safe as that of natural gas, since, in order to inject biomethane, it must meet minimum quality specifications that are interchangeable with the gas circulating through the network. It is worth noting Nedgia's capacity to carry out this type of project thanks to the strength of its distribution network, which is prepared to distribute renewable gases thanks to investments made in recent years.

--- What investment does Naturgy foresee to boost renewable gases in its daily operations?

--- In our strategic plan, we have set the production target of 1 TWh of renewable gases by 2025, betting on both biomethane and renewable hydrogen, with a development model based on multisectoral collaboration and alliances. Regarding the development of biomethane, the plants we already have injecting have involved an investment of close to 5 million euros, which shows Naturgy's commitment to the development of this energy vector. The high potential for biogas production in Spain, as well as the objectives established in the RePower EU Plan, encourage us to continue betting on new, larger biomethane plants that will require more investment, as an immediate solution to reduce energy dependence on fossil fuels.

--- And, in the case of hydrogen?

--- At Naturgy, we are paying special attention to the reconversion of our coal-fired thermal power plants in just transition zones, specifically in the thermal power plants of La Robla (León) and Meirama (Galicia), where we are generating new opportunities in areas that have been affected by the change in the energy model. We are working on creating hubs for green hydrogen production, through electricity produced by nearby wind or photovoltaic farms. With these projects, we aim to develop large-scale renewable hydrogen production, promoting a quantitative leap in terms of electrolyzer size, promoting the transition from the MW range to tens/hundreds of MW, necessary to develop economies of scale that make green hydrogen production viable and therefore optimize costs and performance. These are ambitious projects, which involve the participation of other companies, and which we hope will be supported by the administrations for their development.