Flexibility Options of Thermal Waste Treatment Plants due to grid-dependent CO2-Utilization
New Paths of Added Value for Operators by Methanol
From a total of more than 392 million tonnes of waste are app. 11 % (46 million tonnes) being supplied to thermal waste treatment plants (EU-28). Plant operators are currently facing the challenge of volatile electricity prices, which has led to lower revenues. At the same time, the requirements of power grid operators for flexible power feed-in are clearly increasing, in contradiction to the continuity-oriented combustion process of waste treatment plants. The targeted industry-wide increase in the recycling rate will further aggravate this contrasting effect between flexibility and continuity. The reduction of waste quantities puts additional pressure on operators. Market-driven implementation of the requirements requires new alternative value creation paths, which are accompanied by stabilization of revenues.
This challenge has been taken up by bse Engineering Leipzig GmbH (BSE) who has developed a holistic solution together with specialized partners.
Figure: Simplified illustration of a plant system flexible thermal waste treatment plant; © BSE
If one looks at the individual material flows generated, it becomes clear that in addition to electricity and heat, carbon dioxide also forms in the flue gas. In recent years, carbon dioxide has become more and more from a climate polluter to an important raw material, which can be tied up in new material cycles. The use of this raw material in a bulk chemical, which is recycled, increases the carbon recycling rate of the entire waste management system.
Since 1923, the catalytic production of methanol as a bulk chemical is known and is successfully operated worldwide based on a copper-zinc-aluminium catalyst. In the synthesis of methanol, three chemical reactions take place simultaneously:
CO2 + 3H2 ↔ CH3OH + H2O
CO2 + H2 ↔ CO + H2O
CO + 2H2 ↔ CH3OH
The synthesis gas which is not converted to methanol (input H2 and CO2) is directed back to the reactor via a cycle gas compressor after condensation of the methanol. This establishes a stoichiometric balance of carbon monoxide, carbon dioxide and hydrogen that is identical to all methanol plants worldwide.
The circulation of the gas ensures complete conversion of the carbon dioxide after several cycles. This reaction can be reliably operated even with a fluctuating supply of hydrogen. The hydrogen necessary for the reaction is provided by electrolysis. When electricity from the generator of the thermal waste treatment plant is demanded by the power grid, the electrolysis is throttled and the added value of the electricity is regenerated in the electricity market.
The required carbon dioxide is supplied from flue gas of the thermal waste treatment by amine wash on demand for the methanol synthesis which reduces CO2 emissions by up to 15%. This also means an increase in the carbon recycling rate of up to 15%, since the generated methanol is returned in the product cycle as bulk chemical (e.g. for the production of solvents, cleaning agents and diluents or sustainable plastics).
In addition to the value chain as bulk chemical, the versatile methanol also has a new premium market. Because the methanol produced at the thermal waste treatment plants is now recognized as an advanced fuel in the transport fuel sector.
For the operator, in addition to significant economic advantages, as mentioned above, there are also positive technical effects and solutions for future-proof operation:
- Own production of fuel for auxiliary co-firing
- High purity oxygen as the end product of electrolysis (e.g. use in combustion to increase the waste throughput)
- Participation in the balancing market through provision of flexible power capacities
- Creation of synergies at the site, for example by heat recovery (exothermic reaction of the process synthesis and low temperature of the electrolysis for pre-heating of waste or distric heating)
A market-led operation of the methanol plant leads to a significant increase in technical and economic flexibility of thermal waste treatment plants. With the help of flexible methanol production, operators of thermal waste treatment plants can cover their costs for a long term. By using efficient technologies takes a sustainable greenhouse gas reduction place. The carbon recycling rate is increased by up to 15%. The generated methanol represents an important component in the decarbonization. By providing short-term reserve capacities, it is possible to avoid forced shutdowns by the grid operator as well as of unfavourable power price compensation by feed-in to the grid. The requirements of the industry are met by the consortium, which is led by the BSE. It specializes in the implementation of power market-led methanol plants and makes use of already available technically solutions.
bse Engineering Leipzig GmbH
Mr. Christian Schweitzer
Phone: +49 (0) 341 60912-0
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