(67d) Evaluating Methane Pyrolysis As a Component for CO2 Emission Negative Renewable Energy

The majority of countries agreed that world wide net CO₂ emission must be zero in 2050. Based on the current emission trajectories, most climate researchers agree that CO₂ must also be actively removed from the atmosphere. Therefore, the future requires both a completely regenerative energy sector and measures to remove CO₂ from the atmosphere.

For the latter, several methods have been suggested and some of them are being evaluated in pilot scale. However, most methods have substantial obstacles, are of experimental nature and often have a substantial energy demand. As a consequence, investment and operation costs are high. Especially demanding and energy consuming is the irreversible storage of CO₂, e.g. by transferring highly compressed gas into deep earth layers.

In this study biologically removed CO₂ from the atmosphere is the starting point. Biomass is transformed into the easily storable and transportable energy carrier methane, which in turn could be pyrolysed into depositable carbon and hydrogen retaining parts of the energy. In principle, this could be achieved by a process encompassing de-centralized biogas production, followed by feeding of pre-treated methane into the existing gas grid. Methane pyrolysis can be performed using a newly developed energy efficient moving bed reactors and translation into electric energy in gas power plants. Ideally, biogas is produced continuously, whereas gas power plants are operated in periods, namely winter, where less renewable energy is available and off-heat can be utilized optimally. For electricity production, existing coal power plants might be re-constructed and the coal infrastructure might be employed for depositing the produced carbon.

The process is analysed for ecological (net CO₂ removal), energetical (net energy production) and economical (viable investment and operating costs compared to other methods) performance and the results are presented.