More sustainable power solutions for oil and gas

2015-03-15 - Powering offshore installations from shore with renewable energy slashes emissions and costs.

A major part of Norway's carbon dioxide emissions are caused by gas turbines on offshore platforms. They use natural gas from the process to generate power and the heat needed for recovering and producing vast oil and gas resources.

There is only one way to avoid onboard gas turbines, which is to connect the petroleum installation with a cable to shore that utilizes power from the national grid, in Norway's case mostly hydro power.

For the oil and gas producing companies, the most important drivers for power-from-shore (PFS) are:
- Better energy efficiency and reduced greenhouse gas emissions
- Lower operation and maintenance costs, higher uptime and more gas for sale
- Improved safety and a better work environment

In theory it is a long extension cord, but in practice these can be 500 MUSD projects that take years to plan and execute. The most recent project is equipping Statoil's Troll A-platform with its second HVDC Light (high voltage direct current) from ABB, following the successful, similar installation in 2005.

During the European summer of 2014 the Lewek Connector cablelaying vessel deployed 350 kilometers of cable to the seabed between the platform and the onshore plant. The two DC-connections power compressors that are used to increase flow in the pipelines, since reservoir pressure drops as gas is being extracted.

EMAS Lewek Connector

The cable-laying vessel EMAS Lewek Connector deployed the four DC cables and one AC cable (5x70 kms) from the Troll A platform and to shore during European spring of 2014. In the shallow waters near the shore a smaller vessel, EMAS FOB Jr, took over (seen in front of the main vessel).

The new Troll power link will be commissioned in 2015, and it underlines how the Norwegian Continental Shelf has become the global laboratory for groundbreaking power-from-shore projects, with four successfully completed and three more power links being commissioned in the year to come. ABB is a main vendor in all of the projects.

But power-from-shore is no longer an experiment, it is a powerful tool in the hands of the oil companies providing an opportunity to extract natural resources more carefully. Whether the emphasis is on the climate or economy, power-from-shore is an investment in the future.

If the power comes from renewable sources, power-from-shore will almost always be a positive thing from a climate perspective. It will always be favourable with regards to health, safety and environment (HSE). In the longer term it will often be commercially profitable, but this needs to be assessed from case to case.

HVDC module
Impressive size of the “M13” module – the offshore converter station, with a height of almost 20 metres. Here while being constructed and equipped with electrical HVDC components and auxiliary systems at the shipyard in Haugesund, Norway.

Climate and energy efficiency benefits

In the third part of the Fifth Assessment Report on climate, the UN’s Panel on Climate Change states that emissions must be reduced by 40-70 per cent in the period to 2050, before then being reduced to zero towards the end of the century. Power from shore may eliminate major point sources of greenhouse gases thereby permitting gas producing countries to develop new fields, while also meeting their climate obligations.

The main factor that affects the entire greenhouse gas inventory is how much power we get out of each unit of gas produced, along with the option for CO2 capture and storage. The gas not used offshore will be exported and used directly in households or used to generate power in large-scale gas-fired power plants onshore, both usages more energy efficient than the offshore gas fired plant.

Lower life cycle costs

Although power-from-shore results in a higher investment cost, it also results in significantly lower operating costs. This means that the recovery rate could increase as production will be profitable even with lower volume. The field can therefore operate for longer with lower production. However, whether power-from-shore is commercially profitable will vary from field to field.

Power-from-shore is more profitable when applied on new fields than on existing installations, as it is taken into account right from the design and construction phase. A new field will have a longer payback time, i.e. several years over which to divide the investment costs and several years of lower operating costs. Power-from-shore has however been retrofitted successfully on existing installations too.

Improved health, safety and environment performance

From an HSE perspective, power links to platforms will always be beneficial. Gas turbines cause noise and vibration which will be eliminated completely by using power from shore. There is also less risk of explosion and fire as the risk of gas ignition is reduced.

Electrical systems consists of fewer moving parts than offshore gas turbines and hence there is less need for maintenance and repairs. This means that fewer people have to travel offshore, reducing the risk for individuals and the need for noisy, polluting traffic to the platforms.

Summary

Powering oil and gas installations from shore is a positive aspect for the global climate and often favourable on a commercial level, and it will definitely improve working conditions offshore:
- PFS has a beneficial effect on climate due to lower global emissions overall and because you can generate more power out of every unit of gas produced.
- PFS is profitable long term due to lower operating costs and increased recovery rates.
- PFS has an immediate positive effect on the health, environment and safety for everyone working offshore.
Power-from-shore is environmentally friendly and cost-effective, and hence represents a shortcut to a more sustainable and profitable oil and gas industry.

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