Heat flux coming from a buried pipeline during onshore transportation can have a significant effect on the surrounding soil, causing the premature fertilisation of plants along the pipeline route. A numerical investigation of Carbon Dioxide (CO2) and natural gas (NG) transmission pipelines under steady state heat transfer is conducted to demonstrate the quantity of heat released from the pipelines. The results demonstrate that there is significant difference in temperature dissipation in NG pipelines compared with CO2 pipelines.
One efficient and identified solution for mitigating CO2 emissions is known as Carbon Capture and Storage (CCS). In CCS schemes, CO2 is captured from large stationary sources and transported (most commonly by pipeline) to appropriate sites for storage or usage, for example the Enhanced Oil Recovery (EOR). Moreover, high pressure pipelines are recognised as the most effective method for transporting large volumes of CO2 (Mohitpour, 2011).
The literature on the effects of heat transferred from onshore pipelines on the growth of crops can be summarised in few published studies. Naeth and Chanasky (1993) highlighted that the heat transferred from a buried pipeline could cause a localised increase in soil temperature. Thus, where the pipeline temperature exceeds that of the surrounding soil, the soil's water may evaporate and create a dry core around the pipe affecting above ground plantations.
A study to assess the effect of heat transferred from the Alliance pipeline in central Alberta, Canada on soil temperature and crop growth (Dunn et al., 2004). The monitoring data gathered indicated that pipeline temperature causes soil heating, within the effective rooting zone for crops as far as 190 km downstream from the compressor stations. However, the availability of soil water required for plant growth revealed that it is not significantly affected by the elevated soil temperature in the vicinity of the pipeline.
Another study carried out for the TransCanada Pipeline (Statoil, 2009), included variations in time to assess the expected changes in the soil temperature profile. Based on a steady-state calculation using a one-dimensional shape factor model for the pipeline and soil interaction, a series of heat fluxes were plotted at varying pipeline depths along the route. The numerical investigation reveals that the greatest difference in increased soil temperature caused by the heat flux from the pipeline, measured between January and April and the greatest margin was measured directly over the pipeline.
Drescher et al. (2013) implemented an experimental study, including numerical investigation, to estimate the cooling rate of pipelines. Which operated by Statoil in 2011, transporting CO2 surrounded by water. A series of 2D simulations were applied from transient to steady state to estimate the overall heat transfer coefficient and temperature distributions around the pipe. The same principles done by Drescher et al. can be applied to estimate the heat released from a pipeline which carries CO2 into the surrounding soil in onshore applications to measure the increased soil temperature with consequences for above plantation prematurity.
