The world’s largest internal combustion engine combined cycle plant, the Wärtsilä Flexicycle plants at the Quisqueya I and II power plant complex have a total combined output of 430 MW.

Fuel flexible power plants from Wärtsilä

Fuel flexibility is one of the three cornerstones of Wärtsilä’s Smart Power Generation, the other two being operational flexibility and energy efficiency. Whereas the main global energy trend today is toward the use of natural gas, Wärtsilä’s fuel flexible engine portfolio is well prepared to go beyond the conventional liquid and gas fuels and use various alternative liquid and gas fuels. The company emphasizes the option of using dual- and tri-fuel technologies allows plant owners to hedge for the future. In many cases, liquid fuels are used during the first years of operation until gas becomes available at the site, and thereafter liquid fuel is used as backup in case of interrupted gas supply. In this article, we explore the range of fuel flexibility offered by Wärtsilä.

Text: Andrej Borgmästars Photo: Wärtsilä
 

A brief history

The first engines designed by Wärtsilä in the 1960s were diesel engines used primarily for ships. The diesel engine platform was soon developed to accommodate a wide range of liquid fuels, from light diesel fuel to heavy fuel oil (HFO), crude oil, refinery bottom oils and, more recently, liquid biofuels. During the same time, the engines were increasingly used in land-based power plants, and by the 1980s, it became clear that there was great business potential in gas engines. Wärtsilä already had a solid diesel engine platform, which was used as a base for the development of three gas engine technologies in the 1980s and 1990s. Today, the gas-diesel (GD) engine, spark-ignited gas (SG) engine, and dual-fuel (DF) engine all have long track records, with more than 3500 units in the reference lists. The technologies are continuously being refined for higher efficiency, lower emissions, better reliability and even greater fuel flexibility.

 
Fuel flexibility is one of the three cornerstones of Smart Power Generation
Fuel flexibility is one of the three cornerstones of Smart Power Generation.
 
Wärtsilä has generating sets with a unit power up to 19 MWe. The Wärtsilä 18V50DF shown in the photo is the ultimate ‘fuel flexibility’ engine and can be run on natural gas, light fuel oil (LFO) or heavy fuel oil (HFO).
Wärtsilä has generating sets with a unit power up to 19 MWe. The Wärtsilä 18V50DF shown in the photo (above) is the ultimate ‘fuel flexibility’ engine and can be run on natural gas, light fuel oil (LFO) or heavy fuel oil (HFO). The dual-fuel technology allows the plant operator to change from liquid to gas fuel and back at the flick of a switch. The Wärtsilä 18V50DF engines are used in the IPP4, IPP3 and Quisqueya plants referred to in this article.
 

Alternative fuels for power generation

Many clean fuels besides natural gas are being burned in Wärtsilä’s fuel-flexible installations across the world. These include LPG (propane), ethane and methanol, to name a few. Central America, where Wärtsilä’s first LPG-powered plant went into operation in early 2016, provides an interesting example of the use of one of these fuels. In spring 2016, the company contracted another 28 MW, LPG-fuelled plant in Honduras. Such plants are well-suited for regions where LPG is available and has long been used for heating and cooking in homes but, so far, rarely has been put to use in larger-scale power generation. An important feature of the Wärtsilä LPG plants is that they can be modified easily to use natural gas as fuel, in case gas becomes available in the future.

 Important development of alternative fuels is also happening in the shipping industry, where Wärtsilä’s Marine Solutions business uses the same flexible-fuel engine products. For example, the US shale gas boom and the possibilities to export ethane from the US triggered an order of a series of liquefied ethane gas (LEG) carriers. Now, the natural choice of fuel for these carriers is ethane, and since early 2016, the first Wärtsilä engines burning ethane are in service propelling the ships.

In addition, a major ship owner operating in an environmentally-sensitive area with limitations on fuel sulphur content (SECA) requested Wärtsilä to develop a technology for burning methanol. As a result, Wärtsilä developed a retrofit for existing engines to use methanol and retrofitted the first engine in spring 2015. The fourth and last engine will be retrofitted in 2016.

Wärtsilä has generating sets with a unit power up to 19 MWe. The Wärtsilä 18V50DF shown in the photo (above) is the ultimate ‘fuel flexibility’ engine and can be run on natural gas, light fuel oil (LFO) or heavy fuel oil (HFO). The dual-fuel technology allows the plant operator to change from liquid to gas fuel and back at the flick of a switch. The Wärtsilä 18V50DF engines are used in the IPP4, IPP3 and Quisqueya plants referred to in this article.
 
Wärtsilä’s first propane-fired power plant is in operation in Central America.
Wärtsilä’s first propane-fired power plant is in operation in Central America.
 
The Wärtsilä 34SG is the first large medium-speed engine capable of running on LPG (propane).
The Wärtsilä 34SG is the first large medium-speed engine capable of running on LPG (propane).
 
The JS INEOS INTREPID, one of four new 27,000 cubic-metre, Evergas Dragon series, multi-gas carriers. The Dragon series of vessels are powered by Wärtsilä engines and are the first to use ethane as a fuel. All rights reserved.
The JS INEOS INTREPID, one of four new 27,000 cubic-metre, Evergas Dragon series, multi-gas carriers. The Dragon series of vessels are powered by Wärtsilä engines and are the first to use ethane as a fuel. © INEOS 2016, reproduced with permission. All rights reserved.

Wärtsilä’s role in the shift toward gas

Environmental concerns, particularly emissions output, play a key role in the trend toward gas. But significant savings can also be achieved using gas, which is cheaper than liquid fuels. The development of major gas fields and large-scale LNG shipping during the last 15 years has brought gas to locations lacking their own gas fields. Wärtsilä’s LNG solutions make an important contribution to the small- and medium-scale LNG terminal business by making gas available for power plants and other consumers in areas without a gas pipeline connection.

An example of this is the Tornio Manga LNG terminal. Located in the port of Tornio, Finland, hundreds of kilometres from the nearest gas pipeline, the LNG terminal will make gas and LNG available for power generation and industry in northern Finland and Sweden. Wärtsilä is building the terminal under an Engineering, Procurement and Construction (EPC) contract that includes unloading, a 50,000 cubic meter storage tank and regasification equipment. Wärtsilä seeks to replicate the Tornio model in other remote locations without their own fuel resources.

Putting Wärtsilä technologies to use in the Oil & Gas business

With excellent technologies for burning natural gas, associated gas and crude oil, Wärtsilä has been active in the Oil & Gas business for years. Wärtsilä is focusing especially on efficient utilisation of associated gas, due to the great potential for reducing flaring and the industry’s overall carbon footprint. Today, gas turbine technology is often used for field power, which means that the electrical efficiency, in worst cases, can be well below 30%. This results in a very high carbon footprint. By contrast, Wärtsilä engines can achieve up to 45% electrical efficiency, reducing the carbon footprint by one-third compared to standard gas turbines. Depending on the operating regime, the reductions could reach 50%.

The many years of committed gas engine research and development at Wärtsilä have paid off in other ways, as the company has made major progress tuning gas engines to burn low methane number associated gas and/or gases with low lower heating value (LHV). A fascinating example of this is the 25 MW KivuWatt power plant at Lake Kivu in Rwanda, the only known lake in the world that sits atop a pool of trapped methane gas. One of the reasons why Wärtsilä technology was chosen for the project is that the company’s engines can handle gases with low LHV. Powered by three Wärtsilä 34SG engines, KivuWatt has now been in operation since early 2016, providing low-cost electricity and increased energy security to Rwanda, which has traditionally relied on expensive imported diesel and HFO.

For the Eklutna Generating Station in Alaska Wärtsilä supplied Wärtsilä 50DF dual-fuel generating sets that will be operated primarily on natural gas with light fuel oil (LFO) as back-up.
For the Eklutna Generating Station in Alaska Wärtsilä supplied Wärtsilä 50DF dual-fuel generating sets that will be operated primarily on natural gas with light fuel oil (LFO) as back-up. The flexibility of the equipment in its ability to maintain high efficiency output during wide daily and seasonal swings in load, was another key consideration in the customer’s decision to choose the Wärtsilä engines. With loads swinging from 145 MW peaks in the winter, to as low as 50 MW during hot summer nights, the Wärtsilä multiple-unit plant configuration maintains high efficiency by matching the number of operating engines to the actual load demand. Another important factor in the award of this contract was that the Wärtsilä generating sets meet the strict environmental requirements specific to the project.
 

Looking ahead to a cleaner, cheaper energy future

A relatively new area with great potential for innovation is engine-solar hybrid plants, which pose a novel way to both reduce emissions and save fuel during sunny hours. This is the case in Jordan, where, in 2016, Wärtsilä contracted a 46 MW solar extension of the existing 250 MW, IPP4 tri-fuel plant, making it the world’s largest engine-solar hybrid plant. The flexibility of the IPP4 plant’s Wärtsilä 18V50DF units allows the engines to be started and stopped depending on the output of the solar plant. It complements the country’s IPP3 plant, a 575 MW Wärtsilä 50DF tri-fuel plant – also the largest of its kind worldwide in 2014 – which was originally built to run on HFO until Jordan’s gas infrastructure was completed.

In the case of both the IPP3 and IPP4, if the flow of gas ever stops, the plants can immediately be switched over to run on diesel or HFO as backup until the gas supply is restored. Also, the operational flexibility of the IPP3 and IPP4 plants will facilitate a future, larger-scale development of renewables in Jordan.

Both plants demonstrate the practical value of Wärtsilä’s fuel and operational flexibility in helping make Jordan’s grid sustainable and cost effective in the long term. They are perfect examples of why the future of Wärtsilä’s fuel flexibility initiatives remains so bright. Read more about Wärtsilä’s engine-solar PV hybrid solutions on the article “Bright future for PV solar power”.

The KivuWatt plant with three Wärtsilä 34SG engines. The tuning possibilities offered by the advanced control system of the Wärtsilä 34SG engines allows for use of pipeline gas and associated gas with a wide range of gas compositions.
The KivuWatt plant with three Wärtsilä 34SG engines. The tuning possibilities offered by the advanced control system of the Wärtsilä 34SG engines allows for use of pipeline gas and associated gas with a wide range of gas compositions. 
Wärtsilä delivered IPP4, the 250 MW multi-fuel plant to AES Jordan on a fast-track, turnkey basis in 2014.
Wärtsilä delivered IPP4, the 250 MW multi-fuel plant to AES Jordan on a fast-track, turnkey basis in 2014. The 46 MW solar PV extension scheduled to be delivered in 2017 will be connected to the existing power plant and makes the IPP4 plant the world’s largest engine-solar PV hybrid plant.
 

Conclusion

As regional fuel availability often is an important factor in many power plant projects, Wärtsilä continues to encourage its customers to engage in dialogue about the use of alternative fuels and multi-fuel technologies. Throughout its history, the company has been at the forefront of innovation and fuel flexibility, and it intends to maintain that position.

Both plants demonstrate the practical value of Wärtsilä’s fuel and operational flexibility in helping make Jordan’s grid sustainable and cost effective in the long term. They are perfect examples of why the future of Wärtsilä’s fuel flexibility initiatives remains so bright. Read more about Wärtsilä’s engine-solar PV hybrid solutions on the article “Bright future for PV solar power”.

Leave a comment

Load more comments