
Management of the thermoelectric plant
B2G Sicily’s (formerly ERG Power) thermoelectric plant is located in the Priolo-Melilli (SR) multi-company site, and consists of a Combined Cycle Gas Turbine (CCGT),
a low-impact, high-efficiency cogeneration system powered by natural gas.
It has a total installed capacity of 480 MW and is composed of:
- Two twin modules, each of which comprises two gas turbines and respective heat recovery steam generators, which fuel a steam turbine;
- Auxiliary systems necessary for operation of the plant;
- A GIS (Gas Insulated Switchgear) substation with two voltage levels (380 kV and 150 kV) that permits connection to the National Transmission Grid and to the Internal Electricity Network of the multi-company site at Priolo.
- The plant’s gas turbines are fuelled exclusively by methane and their exhaust fumes (still hot - around 600°C) are channelled into heat recovery steam generators.
This steam is used to:
- Produce electricity using a steam turbine
- Distribute steam throughout the site network thanks to flow distribution flues at various pressure levels.
Furthermore, thanks to the technology used by the burners (low NOx), it is possible to minimize emissions and reach high levels of efficiency.
Thanks to this system, we are able to:
- Channel all steam produced by the CCGT into the multi-company site network;
- Sell any electricity produced and not consumed on site to the National Transmission Grid.
Maintenance and efficiency of the CCGT
The CCGT at Priolo is the only plant of the B2G Sicily Group’s electricity generation infrastructure not to use renewable resources.
Despite this, thanks to the comprehensive redevelopment carried out in 2010, we have access to a completely new, modern and efficient plant, which holds TEE energy efficiency certificates, and thanks to latest generation burners, produces very low emissions of CO2 and NOx.
Energy efficiency is part of the core business of a thermal plant and as such we are committed to constantly increasing the performance of
our plant: for this reason, over the years we have implemented a “continuous improvement” process, involving all technical personnel to help identify the “changes” that could increase the plant’s productivity.
In this context, we have developed several valuable technical projects:
Thanks to the project aimed at reheating methane and air entered into the turbine, we have improved overall efficiency;
We have revised the steam network and reduced system losses;
Following activities to increase the efficiency of the internal electricity distribution network, we have optimised our systems and the reliability of the site system.
The general shut-down of module 2 of the CCGT in November 2019 was a significant step in the process to improve plant efficiency, enabling us to work on all the hot parts of the module’s gas turbines and carry out extraordinary maintenance on the plants.
In particular:
We replaced the high-pressure rotor of the steam turbine with a new model and new technology (including new metalwork), which will enable greater operating flexibility of the machine and improve system reliability;
We continued with the cryogenic cleaning of the boilers, increasing the heat recovery capacity of the exchangers.
These activities enabled us to increase the general efficiency of the system and, in particular, reduce the plant’s specific consumption.
This trend can also be seen in data for emissions per kWh produced, which have fallen constantly over the years with a reduction of 4.5% since 2015.
Thanks to these activities we are also aiming to improve the flexibility and reliability of our plants, while the positive benefits have also reverberated on economic performance.
This continuity and flexibility of operations and the ability to adapt the plant has enabled us to efficiently follow the trends of energy market demands and to participate in the dispatching services market.
Milestone 1Battery Energy Storage Systems (BESS)
A 10MW battery energy storage systems BESS project can help to optimise the intraday sale of electricity on a base load CCGT by storing excess electricity when demand is low and selling it back to the grid when demand is high. This can be achieved by using the BESS to arbitrage electricity prices, which can increase the profitability of the CCGT. The BESS can also provide frequency regulation services to the grid, which can help to maintain the stability of the electrical grid.
Milestone 2Carbon Capture Plant
A carbon capture plant project is proposed to capture 1 million tons of CO2 emissions per year from 4 turbo gas turbines of a CCGT power plant. The specific technology used will be determined by FEED studies, but the project is likely to use a post-combustion capture process.
In a post-combustion capture process, the flue gas from the turbo gas turbines is passed through a series of columns where a capture agent absorbs the CO2. The CO2-rich capture agent is then passed through a stripper column where the CO2 is released and the capture agent is recycled back to the absorber columns. The captured CO2 is then compressed and transported to a storage site.