System design and thermodynamic evaluation of natural gas based combined cycle plants (NGCC) systems with carbon capture and hydrogen storage

 

Background

Natural gas (consisting mostly of methane) is one of the more cleaner energy sources of the fossil fuels currently used for power production. The Netherlands is the largest producer and exporter of gas in the EU. Although the point of peak gas production has passed and the gas reserves are diminishing, the Netherlands can maintain its current position until around 2025. Producing clean power/co-generation from gas thus seems to be a viable and economical option.

Natural gas based combined cycle plants (NGCC) offer sufficient flexibility to include carbon capture and polygeneration units. In order to minimize GHG emissions a carbon capture unit will be used in the system which separates out most of the carbon in the fuel to the gas turbine. A pre-combustion technology will be used wherein a hydrogen rich fuel will be used to generate power in the combined cycle. The essence of separating out CO2 from the fuel is to use methane reforming and water gas shift reactions as shown in Fig 1[1].

In order to minimize load fluctuations in the plant, excess hydrogen produced could be stored with appropriate technologies for future usage during peak loads. There are many options but this work will mainly focus on studying the feasibility for hydrogen storage with metal hydrides (M-H).

 

Chair:

Involved People:

Facilities used:

 

Objectives

The main objective of the assignment is to develop and design system/process models for natural gas based combined cycle plants (NGCC) with carbon capture and study the feasibility for hydrogen storage with metal hydrides.

The models will be used to study and compare between different configurations in terms of efficiency, losses, complexity and feasibility of application.

 

Activities

1.    Literature Review: Getting familiar with the process, unit operations. Different reforming techniques (gas heated, ATR, solid oxide fuel cells, sorption enhanced reforming etc.) will also have to be briefly looked into. Thermodynamic aspects of  hydrogen storage with metal hydrides (P-C isotherms) will have to be studied.

 

2.    Base case model (Case I): As the first step a base case NGCC model without carbon capture and without hydrogen storage will be set up. This will be used to make comparison with future cases. The model will be defined with global boundary conditions given by the ETBF document [2] for consistency with literature[3][4]. (2-3 months)

 

3.     Case II NGCC with carbon capture : Reformer and water gas shift units will have to be added to the base case model. An appropriate choice for the solvent/absorber in the CO2 separation unit will have to be made. (2-3 months)

 

4.    Case III NGCC with carbon capture and H2 storage:  Dissociation of a M-H is endothermic while loading of the M-H is exothermic. Hence a proper heat integration/balance is required to be included in this system. (4-5 months)

 

References

 [1] Nord, L.O, Bolland, O. Plant flexibility of a pre-combustion CO2 capture cycle, 2011, Energy Procedia 4 2556-2563

 [2] Franco. F. et al., 2009. Common Framework Definition Document

 [3] Manzolini, G. et al., 2011, Integration of SEWGS for carbon capture in natural gas combined cycle. Part B: Reference case comparison. International Journal of Greenhouse gas control 5 214-225

 [4] Gazzani, M. et al., 2013, CO2 capture in natural gas combined cycle with SEWGS. Part  A: Thermodynamic performances. International journal of greenhouse gas control 12 502-509