Cartones Ponderosa S.A. de C.V. is a leading producer of coated cardboard in Mexico. In order to enable a switch from heavy fuel oil to cleaner burning and cheaper natural gas, Wärtsilä converted three engines as an Engineering, Procurement and Construction (EPC) project. The conversion has not only reduced the cost of electricity produced by approximately 50%, it has also reduced emissions.
A more efficient energy supply
With the old set up of engines running heavy fuel oil (HFO), the primary method for supplying energy to the paper mill was to buy from the grid, and use the engines as needed. However, the fluctuation in grid prices and the higher price of HFO compared to natural gas were a key driver for the customer to undertake the gas conversion projects. The fact that a natural gas pipeline was constructed near the plant also helped to make the economic case for conversion.
Lower costs and emissions, new opportunities
The conversion was carried out in two phases. The first phase converted two of the plant’s Wärtsilä 18V34 engines from HFO to dual fuel (DF) operation and the second phase is converting the final engine to pure gas operation (SG). Since the conversion, Cartones Ponderosa now runs the engines continually to power the mill, and power is only bought from the grid as needed. Not only is natural gas about 60% cheaper than HFO, it also lowers emissions per kW/hour of power generated.
Mexico’s electricity markets were opened up in 2017, which means Cartones Ponderosa can also explore the possibility to sell surplus electricity to the grid, creating a new source of revenue in the process.
A full EPC project with guaranteed performance
Wärtsilä carried out the gas conversions as a full EPC project, delivered in phases to suit the customer’s needs. Not only did this minimise hassle for the customer, it also meant Wärtsilä could offer guarantees and warranties. The conversion returned the engines to “as new” condition, meaning they started from zero running hours. The standard warranty on an engine after gas conversion is 12 months, with Wärtsilä also guaranteeing engine performance.
As part of the project, Wärtsilä used their feasibility tool for maximum transparency. Together with Cartones Ponderosa, all relevant parameters were entered into the tool – including local fuel prices, the cost of the conversion, and maintenance costs – to come up with a realistic payback time.
Thanks to the excellent results, the cooperation between Wärtsilä and Cartones Ponderosa is continuing with an ongoing gas conversion at another plant, to be completed in 2020. ”We're happy with the cooperation with Wärtsilä on this project. The performance upgrade will help us to reduce costs as well as emissions, and the process has been transparent,” says Francisco Javier González Pruneda, Cogeneration Manager, Cartones Ponderosa, S.A. de C.V.