The KVOC system.

Red light burning for Statoil VOC system

Norwegian government controlled oil company Statoil is persisting with its inefficient and expensive technology to comply with official requirements that 40 per cent of all loading and storage operations should be VOC (Volatile Organic Compound) free by the end of this year. The system being forced on all owners loading offshore on Norwegian account is now 100 per cent owned by Statoil, since the company took over the licence from Kvaerner-Hitec.
By all accounts the system cannot comply with current requirements, and unpublished reports indicate that it is risky to use, requires too much electric power, is too expensive and is limited in use. Neither can it be used while unloading because of the power requirement.
A more efficient VOC system is available, as we noted in a report in August last year. This system is developed by Knutsen OAS in Haugesund and installed on one of their tankers, the Ragnhild Knutsen.
However, Statoil will not approve a better and less expensive system, because it is competing with their own, expensive development. Knutsen OAS could now be excluded from business with Statoil.
The matters will come to a head this spring, and operators feel that the truth about the Statoil system must be revealed and considered by the department of the environment and its control agency STF. The truth is that Statoil has re-written the laws of physics with un-known consequences for the environment.

Inherent dangers in the system
VOC emissions in the North Sea is a serious environmental problem and it should be solved with the best available technology not be driven by Statoil’s requirements to retrieve a failed investment. So why is the Statoil VOC system inefficient and expensive, and in many ways self-defeating in terms of protecting the environment?
Simplified the Statoil system is built to recover released non-methane VOCs, rather than to prevent their release in the first place. This technology, which involves a high energy demanding process and therefore plenty of electric power, will require the main machinery to run a full power for generation of electric power.
It needs approximately 2.3 megawatts of power, and the unnecessary emission of CO2 and NOX, surely, must come into the equation. Experts also note that dangerous pressure tends to build up in the system. More pressure creates even more VOCs because of the increased boil-off. It is difficult to control excessive vapour pressure, which is created as a result of absorption of a portion of Inert Gas into the crude oil cargo. High pressure is an inherent danger to the ship and her crew.
30 or so offshore loading vessels in the North are required to reduce VOC emissions and they may be forced to use the Statoil system. Operators in other offshore areas in the world will not even touch the Statoil system for the reasons noted above.
However, the most compelling reason to investigate the matter is that a less complex, less expensive, more efficient and environmentally friendly system is available. The system is developed by Knutsen OAS under the name of KVOC (see illustration).
This system prevents the release of VOCs rather recovering the VOCs after they have been released. For this reason there is no treatment and no extra energy is required for restoration of a homogenous liquid cargo once a gas phase has been developed. The system is designed to work during loading and has been shown to significantly restrict the evolution of hazardous gases such as H2S.

Compelling data
The KVOC system could reduce emissions in the North Sea by around 180,000 tonnes per year and with savings of around NOK 9.0 million per vessel. KVOC is also much better at reducing emission – between 80 and 95 per cent is claimed.
There are no comparable figures available for the Statoil system. Investment is KVOC is up to 20 per cent cheaper than comparable systems. There is no operating cost and the building and installation time is short. The system is also independent of loading rate and oil type. Safety is good since there is no oil treatment above deck. Efficiency is also the same whether loading from terminal or offshore installation and the system can be used equally well in production vessels and storage ships.
Surely these advantages should be compelling in their own right, but Statoil’s dominant position in North Sea operations has so far prevented KVOC from competing with the Statoil system. Statoil could do well by being a little more transparent in this matter. If they believe their system does the job, we suggest they come out in the open and prove it. Surely, attitudes will change when all the facts are known at high level.

//Petter Arentz

Back to SSG 10, 16 May