Demonstration of a mobile unit for hybrid energy storage based on CO2 capture and renewable energy sources

PROJECT DESCRIPTION

BACKGROUND

As part of the European Green Deal, the European Commission proposed in September 2020 to raise the 2030 greenhouse gas emission reduction target, including emissions and removals, to at least 55% the level of 1990. Furthermore, the EU aims to be climate-neutral by 2050 – i.e. net zero greenhouse gas emissions. The transition to a climate-neutral society is both an urgent challenge and an opportunity to build a better future for all.

Energy in many forms can be transformed, transmitted, and consumed with high efficiency and flexibility in the form of electricity. However, electricity suffers from one main disadvantage compared to other energy carriers: it cannot be stored economically, which means that electricity must be consumed the same second it is produced in order to keep up a functional transmission system (unlike the transmission of gas for example).

Operators fear that the growth of RES, such as the solar and wind power, could destabilise the grid leading to brownouts or blackouts. Excess or surplus electricity produced from solar or wind plants at peak periods must be consumed, otherwise this energy will be lost or cause grid instability. Although short-term electricity surpluses are often observed in some EU countries (e.g. Denmark and Germany), they are not yet commonplace. On the contrary, remote areas, such as islands that are not connected with the national grid, suffer from a high risk of power failures, especially during peak holiday periods.

With the increasing use of renewables, smart grid approaches must be adopted and effective solutions for storage and utilisation of surplus electricity will need to be further developed. Over the past few years there has been a surge in interest, along with the pre-commercial development, of power-to-gas as a potential means of providing storage for this excess energy.

Currently, only two methods have been shown to have a realistic capability of storing electricity: pumped storage hydroelectric and conversion to hydrogen. An alternative to storing hydrogen is to convert it to methane, which has a higher energy density and can be directly fed into the inter-continental natural gas grids, used as a local heat source, or as a biofuel in the transport sector. The power-to-gas concept has the additional benefit of converting more of the carbon present in biomass and exhaust gases into a fuel product, thus regaining its energy value. Current technologies in this area focus on thermochemical catalytic conversion or on biologically mediated systems using defined microbial cultures, and require relatively pure sources of CO₂ (from ethanol plants etc.) at high concentrations. Nevertheless, ‘pure’ CO₂ is already used for other purposes (e.g. manufacturing of soft drinks) and cannot be considered as a low value by-product.

OBJECTIVES

The overriding objective of the LIFE CO2toCH4 is to expand the currently restricted capacity of the power-to-gas concept, in an economically competitive way. It plans to achieve this aim by developing and demonstrating an innovative, integrated and sustainable industrial process for simultaneous energy storage and CO₂ capture and utilisation (CCU). The end goal is to construct, test and operate, TRL8, a smart mobile unit for hybrid energy storage that can be installed in remote energy systems that commonly have low capacity (e.g. remote areas or islands that are not connected with the central energy grid). The technology is based on the use of RES for water electrolysis, and subsequently the produced H₂ will be biologically converted into methane (as a non-fossil biofuel) together with CO₂ from exhaust gasses.

Specifically, the project aims to:

• Construct a demonstration mobile unit that offers renewable energy storage, biofuel production, CO2 emission savings, and energy autonomy in remote areas;
• Demonstrate an ex-situ freestanding process able to treat exhaust gases;
• Achieve high H₂ gas-liquid mass transfer rates by developing an efficient injection system, which offers improved distribution of the injected gases into the reaction matrix;
• Maximise the efficiency of methanation by developing technically advanced systems and control architectures based on microbial resource management;
• Produce a robust analysis of the energy balance;
• Evaluate the technology by an integrated sustainability assessment using techno-economic, environmental, and social criteria in a full life-cycle assessment (LCA) methodology;
• Operate the demonstration unit to identify any safety, environmental, regulatory, or resource (economic) constraints that may affect its market penetration;
• Assess the viability, cost and benefits of the proposed system;
• Define business requirements and critical success factors to be met;
• Improve the knowledge base of available CO₂ emission sources (e.g. power plants, cement industries) in Greece and to define an optimal supply chain for optimum replication of the CCU system;
• Promote public awareness on climate change mitigation, circular economy concepts and reduction of CO₂ emissions.
• Foster employment growth and increase capacity building in relevant technologies for increased competitiveness; and
• Contribute to the implementation of EU policy and legislation on the promotion of the advanced biofuels, circular economy and sustainable waste management.
  

The project will contribute to the European Green Deal, European climate legislation, the 2030 climate target plan, the Renewable Energy Directive and the EU’s emissions trading system.

RESULTS

Expected results:

• Production capacity of the mobile demonstration system of around 600 litres of biomethane a day, which is equal to a thermal energy of around 21 MJ/day (considering the average heating value of methane);
• CO₂ capture and utilisation efficiency from the mobile system of around 1kg CO₂/day;
• 95-100% reduction of air pollutants, such as NOx, in exhaust gases via a dedicated gas cleaning DeNOx unit;
• Conversion efficiency of CO₂ and H₂ to CH₄ of more than 90%;
• Full exploitation of the thermal energy produced from water electrolysis to cover the energy needs of the methanation unit;
• More than 100% GHG emission savings generated from the mobile demonstration system;
• Construction of a complete mobile demonstration system and demonstration of the concept for the first time in Greece;
• Successful operation of the concept with intermittent H₂ provision offering possibilities of Energy Storage-On-Demand, along with a report on the test operation and optimisation of the hybrid energy storage system;
• Optimised microbial resource management strategies ultimately enhancing the stability and robustness of the gas fermentation system;
• Experimental protocol and laboratory analytical procedure;
• Platform user guide (pdf and DVD);
• Life Cycle Analysis report on the assessment of the project‘s socioeconomic impact;
• Production and installation of notice boards (10), leaflets (four sets), newsletters (six), posters and roll-up banners (two sets), a YouTube video clip for virtual tours to the living lab, and scientific and technical publications;
• Οrganisation of a launching event, 10 demonstration and training events and a scientific conference;
• Economic feasibility study, along with a business plan; and
• Replication and transfer strategy and a policy proposal.