In the search for clean alternatives to natural gas and fossil-based hydrogen, one of the oldest processes in the energy industry is being reinvented: gasification. This technique, which converts solid materials such as biomass or organic waste into a hydrogen-rich gas, is becoming a key element in the transition towards a circular, zero-emission economy. It represents the second step in our hydrogen-making process, following the proper selection of the feedstock, and is led by WTE in collaboration with CSIC.
Different ways to provide energy
In a gasification plant, the feedstock must be heated to high temperatures so that it decomposes and releases gases such as hydrogen (H2), carbon monoxide (CO), and methane (CH4).
But where does this heat come from? There are two main ways to supply it:
- Autothermal gasification: the feedstock is partially combusted with oxygen or air, generating the heat required for the process. This method is self-sustaining but leads to carbon losses and the formation of unwanted gases, such as CO2.
- Allothermal gasification: the heat is supplied from an external source, allowing for better temperature control and a more efficient use of the feedstock’s energy without combustion. This approach produces fewer impurities and higher hydrogen yields.
HYIELD aims to combine both strategies to develop a flexible system capable of adapting to different types of waste, while also optimizing energy efficiency.
A staged gasification process
The new design is based on a multi-stage gasification process, in which each stage performs a specific function:
- Feedstock drying: First, the material is dried until it has a moisture content of 15–20%. This step improves process efficiency and enables the treatment of a wide variety of feedstocks, including those with high-water content.
- Low-temperature gasification (650–700 °C): During this stage, the solid feedstock is converted into an intermediate syngas with minimal oxygen.
- Plasma treatment: a plasma reactor operating around 1200 °C breaks down heavier molecules (tars) to improve the overall gas quality. This technology does not require catalysts, and produces a cleaner, hydrogen-rich gas.
- Gas purification: finally, impurities such as ash, water, sulphur, and ammonia are removed to obtain a high-purity hydrogen stream.
Making use of heat that others waste
One of the project’s most innovative elements is the integration of residual heat from other industries—most notably the cement sector, which generates large amounts of heat that usually remains unused.
Instead of letting this energy go to waste, the recovered heat is reused to supply the gasification process, reducing the need for external energy input. Preliminary models indicate that this approach could increase hydrogen yield from 62% to 74%, while simultaneously lowering emissions and operational costs.
More efficiency, less waste
The result is a technology capable of converting organic waste into clean hydrogen, maximizing the use of available heat and minimizing energy losses.
By integrating different energy sources—such as plasma, industrial waste heat, or even concentrated solar power—this new generation of gasifiers aims to transform the concept of “waste” into a valuable source of renewable energy.
If you want to keep learning more about our work at HYIELD, stay tuned. The next stage of the process is coming soon!
The project is Co-founded by Clean Hydrogen Partnership and European Commission.
Writer: Luis Sánchez, Ramón Murillo, Luis La Calle & Oria Pardo
Editorial: Grant Mimms
November, 2025