Greenhouse gas emissions consequences of utilization of excess heat from an oil refinery

Paper in proceeding, 2015

Increasing utilization of industrial excess heat is an important step towards reaching EU targets for increased energy efficiency and decreased greenhouse gas (GHG) emissions. There are many options for harnessing excess heat. However, the corresponding impact on GHG emissions differ significantly depending on the assumed marginal production technology replaced in the surrounding energy system. In order to identify robust solutions and avoid sub-optimization, different possibilities for utilizing excess heat need to be compared and evaluated using a systems perspective with different future energy markets scenarios. The purpose of this paper is to investigate and compare different utilization options in terms of GHG emission reduction potential. The paper presents an illustrative case of a large modern refinery on the West Coast of Sweden with a crude oil capacity of 11.4 Mt crude/y. The potential for producing electricity with an Organic Rankine Cycle (ORC), delivering excess heat to a district heating (DH) network and using it for post combustion carbon capture (CCS) are quantified using pinch analysis tools. Consequences for GHG emissions are evaluated based on different assumptions for future grid marginal electricity production. The results indicate that the GHG emission reduction potential is larger for CCS and DH than for electricity production via ORC. CCS achieves the highest GHG reduction potential per MW of recovered excess heat whereas DH shows the largest total potential for GHG reduction. It is possible to combine CCS and DH, and it is recommended to utilize first the maximum amount of excess heat in CCS and the remaining in DH. This combination results in GHG emission reduction corresponding to up to 40% of the onsite CO2 emissions.