Performance, Emissions, and Decarbonization of an Industrial Gas Turbine Operated With Hydrotreated Vegetable Oil

Abstract

Abstract As part of Uniper’s plans for its 22.5 GW of installed power-generating capacity in Europe to be carbon neutral by 2035, a Kraftwerk Union/Siemens V93.0 gas turbine (GT) in Malmö, Sweden was operated with hydrotreated vegetable oil (HVO) as a low-carbon replacement for gas oil in July 2021. An extensive feasibility study was first undertaken to understand the potential impacts of replacing gas oil with HVO in this GT. This included a fuel analysis, flame temperature modelling to predict the impact on NOx emissions, and a detailed hazard identification study for the short-duration trial. During the two-day demonstration, baseline GT performance and accredited emissions were first measured using the existing gas oil. HVO was subsequently used in all operating conditions including start-up, full load, part load, and shut-down. Accredited emissions of NOx, CO, SO2, and dust were measured to allow direct comparison between fuels. When operating with HVO, all required performance targets were achieved, including an onload fuel switch from HVO to gas oil. Direct flame imaging through a silo combustor sight-glass was used to observe the HVO start-up ignition process and to allow for a flame intensity comparison between fuels. NOx emissions were measured for each fuel, and no significant difference was identified across all operating conditions. As a result, no changes to the water injection rate for NOx control were required when switching fuels, which confirmed the predictions of the preliminary flame temperature modelling. Measurable reductions in dust, CO, and SO2 emissions were observed during HVO operation. These emissions reductions are respectively attributed to the low ash and aromatic contents of HVO, the increased hydrogen content of HVO relative to gas oil, and that HVO is essentially sulfur-free. HVO also enables significant lifecycle CO2 emissions reductions of over 90% compared with fossil diesel. In this trial, ∼163 tCO2 emissions were avoided by using HVO. The success of this demonstration provides evidence for future site conversion and has led to successful HVO demonstrations on other liquid fuel and dual-fuel GTs in the Uniper fleet. Long-duration testing and monitoring is required to build the evidence base regarding the impact of HVO operation on fuel storage, fuel delivery, and hot gas path components. To the authors’ knowledge, this field trial is the first successful demonstration of HVO use in an industrial gas turbine in the world.