Why oil products' volume rises or drops during transportation


A boy hikes a lift on a moving oil tanker along Obote road in Kisumu on November 26, 2020. [Denish Ochieng, Standard]

In the heart of Nairobi, amidst the hustle and bustle, a driver found himself facing an unexpected dilemma. It was a hot afternoon, and the fuel gauge signaled that a stop for a refill was imminent. Remembering a piece of advice from a fellow driver, he decided to wait until evening, anticipating cooler temperatures that could potentially enhance his car’s performance and fuel efficiency.

But do you know that behind this seemingly routine decision lies a web of intricate scientific principles governing the gain and loss of petroleum products during their journey from source to destination?

Let us delve into the complex interplay of factors that contribute to the decrease and increase in petroleum product volume. Indeed, product loss, a common phenomenon in the petroleum industry, occurs at various stages of handling such as storage, transportation, and loading into pipelines or trucks. Evaporation, measurement inaccuracies, and unauthorised activities contribute to this decrease in product volume.

Within the petroleum sector, two types of losses exist—actual and apparent. Actual product loss involves spillages, leakages, theft, and operational losses. On the other hand, apparent loss occurs without a physical escape of the product from the delivery chain.

Factors like equipment inaccuracies, density measurement errors, temperature, density and pressure variations during transportation contribute to apparent losses. For instance, when petroleum products move from the port (low altitude) to say, Nairobi (high altitude) and again to Kisumu (low altitude), evaporation is bound to occur due to the temperature variations, leading to apparent losses in the delivery chain.

Additionally, the effect of temperature fluctuation on a static petroleum product in a storage tank results in variations in the product level and volume over a period of time. This is dependent on the time the tank will be operated, which can result in an apparent loss or gain due to temperature variations.

Further, apparent loss can also be caused by interface sloping (when two different products mix) and the effect of interface sloping is such that the cumulative volume of the two products contracts due to difference in molecular sizes. Other losses which are very rare occur during maintenance of the pipeline.

Despite advancements in technology and industry practices to minimise losses, the inherent nature of petroleum products results in some unavoidable loss during transportation and handling. Governments worldwide set allowable loss margins for pipeline companies, reflecting global best practices.

In Kenya, the Ministry of Energy and Petroleum and the Energy and Petroleum Regulatory Authority (EPRA) have established a minimum allowable product loss and gain margin of 0.25 per cent. In 2023, KPC reported an average product loss of 0.06 per cent, surpassing both internal and EPRA thresholds, showcasing efficiency.

The set threshold is in accordance with global best practices guided by the accuracy of measurement equipment and applicable technologies. To this end, the government is aiming for a target of 0.1 per cent which is applicable in Europe and other countries where fuel is transported through a pipeline.

At KPC, we have been actively working on improving the pipeline systems and infrastructure and our efforts in addressing these challenges and minimising losses can be reflected in the continuous security enhancement measures and monitoring along the pipeline network.

This includes the recent rollout of a Leak Detection System. We have also commissioned Bottom-Loading Facilities (BLF) in our Nakuru, Eldoret and Kisumu depots. The BLF at the Nairobi Terminal is scheduled for completion in the next 10 months.

Bottom loading of products to road tankers is not only environmentally friendly but also critical in minimising considerable losses. Bottom loading not only aligns with environmental conservation goals but also minimises losses from evaporation.

KPC’s commitment to environmental sustainability is further demonstrated through the conversion of storage tanks to dome-shape for diesel and floating roofs for petrol.

Beyond the phenomena that explain the natural losses and gains of petroleum products, the integrity of storage and transportation infrastructure is as important as the product itself and deserves attention.

Leaks, permeation, and improper handling can lead to both gain and loss of petroleum products. KPC is enhancing this through investing in a robust infrastructure and adhering to best practices which ensure a more efficient and sustainable supply chain for our petroleum products.

In conclusion, navigating the complexities of petroleum product transportation requires a deep understanding of the dynamic causes behind product losses and gains.