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Interview: WinGD Discusses New Engine Tech to Help Tackle Methane Slip

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January 8, 2021

With International Maritime Organization targeting a 50% reduction in greenhouse gas emissions from ships by 2050, focus is shifting to which alternative fuels will help the industry achieve the ambitious target. One such fuel, liquefied natural gas (LNG), has emerged as a favored early bridge between your standard marine fuel and future carbon-neutral fuels. Although LNG produces less CO2 than other fossil fuels when burned, a small percentage of methane, a more potent GHG than CO2, can slip through the engine without being combusted. Down the road, this “methane slip” could become the target of international regulations.

With this in mind, Swiss engine developer WinGD has recently unveiled a new technology designed to slash methane emissions and cut fuel consumption in its X-DF dual-fuel engines. The launch of Intelligent Control by Exhaust Recycling (iCER) is the first development to be introduced as part of X-DF2.0, WinGD’s second-generation dual-fuel engine platform.

To understand a little more about this technology, we sent over a few questions to WinGD experts to explain the tech and give us some background on why it’s important now.

Can you provide a little background on the X-DF dual-fuel engine, the X-DF2.0 and how the iCER technology builds on those platforms?

The X-DF dual-fuel engine was developed as a solution to the two-fold challenge of meeting IMO Tier III emissions levels as well as initiating a significant reduction of GHG (greenhouse gases) emissions in the global shipping industry. The opportunity arose in part due to the availability of “free” fuel in the form of natural boil-off when used on LNG carrier ships, addressing another key challenge of reducing fuel consumption. With the growth in the global demand of natural gas for all applications from domestic to industrial, the market for LNG carrier ships has seen strong growth over the past several years. WinGD’s X-DF portfolio of engines has provided the answer to market demand along with solutions to many important technological challenges facing the shipping industry.

Due to the lean-burn Otto combustion process successfully developed and implemented by WinGD on the X-DF engines, the IMO Tier III requirements have been met without the need for exhaust gas after-treatment. Through the low-pressure gas supply system, the X-DF engines have also proven to be a cost-effective solution for the shipowner. The simplicity of the low-pressure equipment (pumps, compressor, evaporator, piping, sensors) contributes to a significantly lower cost compared to that of its high-pressure alternative.

With the extensive experience in low-pressure dual-fuel X-DF engines, WinGD recognized the potential for further optimization through recycling cooled exhaust gas. The new iCER (intelligent control by exhaust recycling) technology is the first to be introduced as part of X-DF2.0 engine portfolio.

What are the environmental benefits of each?

The X-DF engines substantially reduce emissions that have a toxic effect on human health (NOX, SOX, PM) to the lowest level currently available in the industry. Providing the most environmentally sustainable total emission footprint in compliance with IPCC, WHO and IMO. The WinGD offer of the Otto/lean burning combustion, can be adapted for any pre-mixed and injected fuels through the reliable and well known common rail injection system.

The iCER technology fulfills a primary role in the further reduction of CH4 emissions (“methane slip”), as well as a role in combustion control for the reduction of NOx emissions when operating in diesel mode. It also improves energy consumption which has an overall environmental benefit through a reduction in fuel.

Can you explain the importance of combustion control and use of inert gas?

EGR (exhaust gas recirculation) has been used in diesel engines for many decades, and now as a way to control combustion and reduce emissions of pollutants such as NOx. Intelligent control systems progressed significantly since the early days of EGR applications, to the point that today a variable rate, cooled exhaust gas can be considered as an active part of the combustion strategy and a powerful tool for combustion optimization over a wide range of engine speeds and loads.

The introduction of the iCER technology this year from WinGD is based on an EGR concept, delivering enhanced combustion control by cooling and recirculating part of the exhaust gas through a low-pressure path during operation in gas mode. The result is a reduction in methane slip emissions of up to 50% when using LNG and a significant reduction of fuel consumption, of 3% in gas mode and 5g/kWh in diesel mode.

What is methane slip and why is it important?

As in any type of internal combustion engine, the combustion process is never 100% efficient. A small part of the fuel injected into the combustion chamber will always remain unburnt. In conventional petrol or diesel engines, this unburned part is released into the exhaust as unburned hydrocarbons (HC). Over the years, these emissions have been dramatically reduced through the study and optimization of combustion fluid dynamics using sophisticated software modeling and simulation, plus the use of exhaust gas catalysts that capture and break down most of the remaining HC emissions.

Natural gas engines have very low overall emissions; however, the amount of unburned methane gas (CH4) cannot be reduced down to zero through the optimization of combustion alone. The currently available catalysts are not capable of capturing methane gas volume flows of any two-stroke engines, the best way to reduce these emissions is to recirculate part of the exhaust gases. CH4 has a greenhouse effect that is 30 times higher than CO2, hence a global relevance of CH4 emissions in the climate change discussion. It also needs to be underlined, that the CH4 emissions of the shipping industry are extremely small compared to other sources currently uncontrolled or not subject to regulations from other industries. Around 74% of global methane emissions originate from animal farming, agriculture, wastewater, biomass and landfills, with another 25% coming from oil and gas extraction, and coal mining. Only 1% of global methane emissions come from all forms of transportation, making the shipping industry a very small contributor to what is a much larger scale problem. Despite this small global percentage WinGD’s R&D are committed to sustainability and are investing in finding every improvement possible.

What type of vessels do these engines work with? Which are most common, and which would you like to see go dual-fuel?

The low pressure dual-fuel concept is in principle applicable to any kind of low speed engine, and to most types of vessels. However, there are certain economies of scale related to size therefore today WinGD’s low pressure dual fuel engines have been the predominant choice for LNG carriers (which benefit by using natural boil-off from the transported LNG as “free fuel” for propulsion) and on large container ships. The X72DF is the best seller in the WinGD portfolio. WinGD’s 12X92DF, the largest Otto engine in the world, is now powering ultra-large container vessels running on LNG. But there is growing interest for X-DF technology in car carriers, bulk carriers and tankers as well.

What type of carbon-neutral fuels could the X-DF2.0 potentially work with? Are they “ready” or would they need modifications?

WinGD is developing the technological solutions to keep our engines “future fuel ready”. Whether this will require modifications to the engines (injection systems, materials technology, control strategies, etc.) will depend very much on the chemical and thermal characteristics of the carbon-neutral fuels of the future.

Looking at two opposite ends of the spectrum, it is possible that certain synthetic fuels will be designed to match the characteristics of existing fuels more closely, while fundamentally different chemicals such as Ammonia will need to be handled specifically and will require an assessment of the engine, fuel storage and fuel delivery characteristics. Pure hydrogen on the other hand is difficult to handle and very inefficient when used in an internal combustion engine, so it will most likely be used primarily in fuel cells for electric propulsion.

The situation is currently very uncertain, and no one can predict what the “winner” will be in ten years’ time. Regardless, WinGD is working towards making its engine portfolio compatible with the carbon-neutral fuels that will prevail on the market in the coming years. and is committed to working in partnership with external stakeholders in the alternative fuels sector, to explore, validate and test the most promising solutions to be ready when the market requires it.

When do you see the first shipboard trials taking place? What are the next stages of development and when will the product be available?

Test engine program is well underway and iCER hardware is available to be installed on a pilot installation.

WinGD is already working to extend the application field of iCER technology for MGO operation. With this step WinGD wants to offer a CAPEX neutral technology by applying iCER to both gas & liquid mode operation. This would make the expense of an SCR system obsolete, eliminating unnecessary costs. First development steps are already in process and a pilot installation for this application is expected to be ready in Q2/2022

What sort of other project is WinGD working on within the maritime industry?

As part of the ongoing drive to reduce CO2 emissions and increase efficiency, WinGD is actively researching hybrid diesel / electric propulsion systems using batteries to supplement diesel (or LNG) power in specific operating conditions, and to reduce the requirement for on-board internal combustion engines for electric power generation. The studies conducted by WinGD show that such a “smart” hybrid solution will lead to significantly reduced OPEX for the ship owner through reduced overall fuel usage (for both propulsion and on-board electricity generation).

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