An integrated pinch analysis framework for the development of a low carbon dioxide emissions industrial site planning which includes a fuel cell configuration

Abstract

The proliferation of anthropogenic greenhouse gases, of which carbon dioxide is a major constituent, has been the major driver of climate change. South Africa is one of the highest greenhouse gas emitting countries mainly caused by increased industrialisation. Industrial sites in South Africa have been clustered in industrial zones to keep toxic emissions away from residential sites. This zonal planning inadvertently created zones of high carbon dioxide concentration. The South African government has committed to sustaining the national greenhouse gas emissions at a reasonably moderate value of below the 398-440 million tonnes of CO2 equivalent by 2030 as its contribution to lowering the global carbon dioxide emissions. To control the emissions emanating from industrial zones, industrial planners make use of an evaluation framework that accounts for the carbon footprint associated with a particular industrial zone. The existing framework focuses on greenfield sites (new planning sites), and is thus ill-adapted to brownfield sites (existing sites). This study proposes a four-stage carbon dioxide lowering framework that industrial site managers of brown-field sites could use to lower the carbon dioxide footprint of industrial sites. This work extends the current systematic framework for low carbon dioxide industrial site planning framework for a greenfield site, by proposing an alternative carbon dioxidelowering sequential framework for a brownfield site. The framework includes: 1. A baseline study to analyse the current carbon dioxide footprint of an industrial site. 2. A carbon capture and utilisation step to collate the carbon dioxide captured for chemical mineralisation for in-situ utilisation. The inclusion of the direct methanol fuel cell configuration is important to the site because it generates clean carbonneutral power for the hybrid power system while utilising methanol, a carbon dioxide mineralised product. 3. The Total Sites Heat Integration technique to integrate the energy produced in the site could be integrated to reduce external utilities required. 4. The Power Pinch Analysis technique to optimise power distribution from the hybrid power system hub. The study also proposes the option of introducing a subsidiary industry that includes carbon dioxide mineralisation plants to chemically store the captured carbon dioxide. This is because, in water-stressed South Africa, the viability of the geological storage of carbon dioxide has not been considered because of the high probability of contamination of the large water basin that is used to supplement the surface water resource. The challenge can be overcome by increasing the value of carbon dioxide emissions by creating subsidiary industries that can utilise carbon dioxide as raw material and producing other value-added products that can be utilised within the industrial site. This study used an illustrative example to extend the current systematic framework for low carbon dioxide industrial site planning framework used for greenfield site, by introducing an alternative four-stage carbon dioxide-lowering sequential framework for a brownfield site. it was determined that there are three possible opportunities to capture carbon dioxide from stationary. The baseline study included scoping for thermal data, which included the target temperature, supply temperature and specific heat capacity of the streams. The data scoped by the site planner also include the power required and possible power that could be generated within the site. The study conducted a techno-economic investigation of the feasibility of including subsidiary plants producing methanol, calcium carbonate and baking soda from the carbon dioxide captured from the flue gas in the industrial site. This study included the cost of capturing carbon dioxide from selected plants within the industrial site and determined the operating and capital cost required using a bottom-up approach from mass balances. It was determined that a potential 105 ton/day of carbon dioxide could be captured from the flue gas from industries on the site. The cost of producing methanol and calcium carbonate would only be sustainable if the price of raw materials such as hydrogen and wollastonite could be brought down by producing hydrogen through solar-chemical water splitting and the wollastonite from steelmaking slag. Baking production was determined to be the most sustainable subsidiary industry in the carbon capture and utilisation framework with an annual rate of return on investment of 12%. The Total Site Heat Integration was applied for the evaluation, generation, optimisation and usage of energy within the industrial site. it was determined that heat utility saving of 79.95% for the participating industries could be achieved for the industrial site. However, the rate of return is for the Total site Heat integration (TSHI) was a low return of 8.98%. But, since the main aim of the project is to reduce the carbon footprint and this rate of return could be improved by the carbon tax rebate incentives for the carbon dioxide reduction project It was determined that solar and biomass energy were the two viable renewable sources of power that could be used for the illustrative example. The inclusion of a direct methanol fuel cell configuration to the renewable energy mix was important to the site because it generated clean carbon-neutral power for the hybrid power system while utilising methanol produced by the subsidiary industry. Power Pinch Analysis was applied for the distribution of the Hybrid Power System to the existing plant, and to the new subsidiary industry. It was also determined that the renewable sources of power which incorporated the fuel cell configuration would be sufficient to provide carbon-neutral power to the industrial site. The rate of return on the investment of the hybrid power system was found to be 20.68 %. The carbon dioxide-lowering framework for existing industrial sites could provide a sustainable, impactful guide for site planners to assist the country’s commitment to limit greenhouse gas emissions.