Diesel Generators on Green Substations?

Author: Alice Lawrenson, Senior Process Engineer

Offshore wind turbines draw on wind-based generation to operate but sources of back-up power for the substation are essential in the event of an outage of the main power supply (e.g., low wind) and shore connection. Often to supply this reliable back-up power, diesel-fueled generators are used.

Diesel-fueled generators are internal combustion engines that produce emissions of carbon dioxide, nitrogen oxide and particulate matter. Substations have lifespans exceeding 30 years, consequentially meaning that any generators installed now on substations will likely be operating past the UK Government’s 2035 target to ‘fully decarbonise [the UK’s] power system’.

This fact raises a challenge: should diesel generators be installed now on substations and be removed later, or is it worth transitioning to a new technology early? Substitute back-up power solutions include:

• Connection to other platforms’ power supply: avoids reliance on diesel generators but requires the offshore substations to be within close proximity of one another. Local extreme weather conditions would affect the performance of wind turbines for both assets.
• Fuel cell: fuel cells convert energy sources (such as hydrogen) into electricity by a chemical reaction. This produces zero emissions but is expensive; however, as demand increases, prices for fuel cells may drop.
• Batteries: batteries store chemical energy and convert it into electrical energy. They require minimal maintenance and produce zero emissions. However, the significant space and weight required to meet the back-up power needs makes them impractical for a substation.
• Alternative Fuel: Such as Hydrotreated Vegetable Oil (HVO), this is a direct drop-in alternative for regular diesel and amendments to existing diesel infrastructure would not be expected.

Should diesel generators be installed:

• YES
• NO – which do you think would be the best alternative?