Boost to a circular economy project that will convert rice straw into renewable gas

20 October 2021

• Enagás, Genia Bioenergy and Naturgy sign a protocol with the Regional Government of Valencia (Generalitat Valenciana) to promote the production of 87 GWh per year of renewable gas from rice straw and introduce it into the gas infrastructure.

• This initiative will also improve the air quality around the city of Valencia and its metropolitan area, as it helps to solve the environmental problem of pollutant emissions associated with the burning of rice straw, thanks to a process of energy recovery that represents a clear model of circular economy.

• By means of anaerobic digestion technology, waste is recovered by converting it into biogas which, following an enrichment or upgrading process, leads to biomethane, a renewable gas that is injected into the gas network to be used for the same end uses as natural gas, and also as a fertiliser that can be reused in agriculture.

• This management model aims to help improve agricultural practices by bringing sustainability to rice farming in the Albufera and allowing the rice straw to be managed sustainably and with minimum environmental impact.

Enagás, Genia Bioenergy, Naturgy and Nedgia, Naturgy’s gas distributor, have signed a protocol with the Regional Ministry of Agriculture, Rural Development, Climate Emergency and Ecological Transition of the Generalitat Valenciana to promote a circular economy project. Rice straw will be used to produce 87 GWh per year of renewable gas, equivalent to more than 15% of the natural gas consumption of the city of Valencia. This fully decarbonised gas, which will be purified for injection into the gas infrastructure, will prevent 150,000 tonnes of CO2 from being released into the atmosphere.

Representatives of the Generalitat Valenciana, Nedgia, Naturgy, Genia Bioenergy and Enagás at the signing of the protocol.

The event was attended by the Regional Minister for Agriculture, Rural Development, Climate Emergency and Ecological Transition of the Generalitat Valenciana, Mireia Mollà; the Regional Secretary for Climate Emergency and Ecological Transition, Paula Tuzón; the Director General of Environmental Quality and Education, Joan Piquer; the Director of Innovation and Renewable Gases of Enagás, Jesús Gil; the CEO of Genia Bioenergy, Gabriel Butler; the Head of Biomethane Projects of Naturgy, Marta Peiró; and the Head of New Business Development of Nedgia, Francisco Torres.

The launch of this initiative has its origin in a pilot project promoted by Nedgia with the technology developed by the Valencian engineering company Genia Bioenergy, which was subsequently validated on a pre-industrial scale by the AINIA technology centre. This pilot demonstrated the feasibility of producing renewable gas from rice straw using anaerobic digestion technology, despite the high silica and lignocellulose fibre content of this bio-waste, and the solution it could provide to solve, to a large extent, the environmental problem of rice straw management in a protected area of natural interest such as l’Albufera Natural Park.

Contribution to the energy transition

This project offers a solution to environmental problems. Using the anaerobic digestion technique, the waste is turned into renewable gas, which is injected into Nedgia’s distribution network to be used for the same end uses as natural gas, as well as nutrients and fertiliser products that can be applied, once again, in agriculture, creating a circular economy model. In doing so, the project contributes to advancing the decarbonisation goals and the process of achieving the energy transition.

Likewise, the implementation of this initiative will help to solve, to a large extent, the environmental problem of poor air quality generated by the burning of rice straw in the surroundings of Valencia and its metropolitan area, as well as the problems with irrigation ditches and aquifers, and the degradation of water and soil due to anoxia and greenhouse gas emissions when the straw is left to rot in the open air, facilitating more sustainable agricultural uses in an environment with a high ecological value.

This pioneering initiative, which promotes investments for the improvement and sustainability of agricultural practices, can be applied to other large areas of Spain where rice is grown, such as the Ebro Delta, Extremadura or the Guadalquivir marshes, while promoting sustainable economic development of rural areas and territorial cohesion in areas with demographic challenges.

Green energy

Renewable gas (in this case biomethane) is a green energy with zero emissions balance, which is fully interchangeable with natural gas, so it can be distributed through the nearly 90,000 kilometres of existing gas infrastructure and used with the same energy applications in homes, industries, businesses and also for mobility in transport, helping towards decarbonisation.

The development of renewable gas will contribute to meeting some of the European Union’s energy and climate targets, reducing greenhouse gas emissions and increasing the use of renewable energy.


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