Background
Green initiatives have sprouted around the globe with each country doing its part to create a more environmentally friendly world. In Canada, a government agency hopes to lower the country’s carbon footprint with new programs designed to reduce emissions through a variety of methods. That agency, Energy Efficiency Alberta, offers programs and services to help Albertan residents and companies lower their environmental impact.
One of those programs is the Greenhouse Gas Reduction Initiative. Eligible participants include industrial, institutional and commercial customers with facilities operating within the province of Alberta, including natural gas and oil field production facilities, processing plants, pipelines and other related operations. Energy Efficiency Alberta has invested US$170 million into energy efficiency and renewable energy in its first 18 months, using revenue from Alberta’s carbon tax to fund rebates and program incentives. (Calgary Herald, 2019, April 18)
The greenhouse gas reduction program comes at a critical time for Alberta’s gas compression industry as the region seeks to improve reliability and production on existing assets. Canadian producers suffered from takeaway capacity and storage issues in 2018, depressing natural gas prices to more than US$2 below U.S. benchmarks in May of this year. As natural gas companies look for a silver lining in upcoming projects, improving existing plants will be key to keeping Alberta in the center of the supply chain for Canadian natural gas. As the region is facing an effort to dismantle Energy Efficiency Alberta, many compression companies are investing to take advantage of the program’s benefits.
To provide some background, the main contributors to greenhouse gas emissions from a natural gas engine are carbon dioxide (CO2) and unburned hydrocarbons (UHC), including Methane (CH4). Greenhouse gases are measured in units of equivalent CO2 (CO2e) using the Global Warming Potential (GWP) of specified gases. Alberta uses the 2007 GWP as published by the International Panel on Climate Change (IPCC).
CO2e = CO2 + (CH4 x 25) + others
There are two different types of natural gas engines when comparing their operating air-fuel ratio; rich-burn and lean-burn. While lean-burn gas engines typically achieve a higher efficiency, rich-burn gas engines can run with a three-way catalyst (TWC) to achieve significantly lower emissions. Rich-burn engines operate at a very precise air-fuel ratio, slightly rich of the stoichiometric ratio. This produces exhaust gases at high temperatures, which have the ideal composition for a TWC to greatly reduce emission levels. Some of the lowest emissions in the world for natural gas engines are achieved reliably, and cost-effectively, using rich-burn engines with TWCs. For example, TWCs remove 20% to 50% of CH4 from the exhaust and much higher conversions on other non-GHG emissions.
Lean-burn engines operate with excess air in the combustion chamber, which helps them reduce fuel consumption and in-cylinder temperatures. When emissions levels are modestly low, lean-burn engines can achieve low emissions without any aftertreatment. As emissions levels continue to decrease, manufacturers have created lean-burn products to run at lower NOx levels, but other emissions such as UHC often increase.
While emissions regulations such as the National Emissions Standards for Hazardous Air Pollutants (NESHAP) now mandate the use of an oxidation catalyst on lean-burn engines in the United States, such aftertreatment technologies are challenged to handle lower exhaust temperatures and the non-methane/non-ethane hydrocarbon content in higher BTU fuels. Historically, emissions levels were equated directly to fuel consumption, which led to non-OEM aftermarket retrofit kit installations on rich-burn engines that leaned out the air-fuel ratio to decrease fuel consumption. However, those retrofit kits often reduced the completeness of combustion and increased UHC, resulting in a greater negative net impact to the environment.
INNIO’s Waukesha gas engines’ latest rich-burn development can lower fuel consumption and emissions. The solution to simultaneously solve both conditions was not to lean out the engine, but rather to utilize the rich-burn combustion cycle more effectively.
Waukesha’s VHP Series Five gas engine utilizes Miller Cycle combustion, generating more boost pressure with larger turbochargers, then closing the intake valve earlier in the intake stroke. This allows the in-cylinder air-fuel mixture to expand before reaching bottom dead center, which lowers the charge temperature. This lower temperature is maintained throughout the compression, power and exhaust strokes. It allows the engine to be designed with a higher geometric compression ratio, which increases the efficiency of the engine. By moving some of the compression effort from the piston to the turbocharger, the engine operates with a higher fuel efficiency and achieves very low emissions with a TWC.
“Waukesha VHP Series Five gas engine has taken low emissions to the next level,” said Rob Stoppek, CEO, INNIO Waukesha. “While our rich burn +three-way catalyst combination has always produced low NOx, VOCs, and CO emissions, our fuel efficiency improvements have helped improve the value proposition of upgrading legacy engines to the latest … standard.”
A number of upgrades to utilize rich-burn technology are available for Waukesha gas engines in Canada. Several of these gas engines are installed in Alberta, Canada. Some are even being upgraded locally by Ironline Compression, a program ally for Custom Energy Solutions. The company can help operators understand the benefits to upgrading their engines with the latest rich-burn technology and can assist in facilitating the submission and approval process.
The financial incentives are significant – facilities emitting 10,000 tons or more of greenhouse gases annually are eligible for up to CAD$1 million, but there is no minimum tonnage required to participate in the program. Parent facilities partaking in projects at multiple facilities can receive up to CAD$2 million per year.
Through the incentive program, gas compression companies can significantly reduce emissions and, if eligible, receive up to half of their total investment as a rebate. For many of Waukesha’s customers, the incentive plan recovers up to US$300,000 with the reduction of 2000 tons of CO2e emissions.
“We provide a unique solution to Waukesha gas engines operators in Alberta. These are real solutions that reduce greenhouse gases, lower annual maintenance costs and exceed NOx emissions requirements,” said Tim Kelley, CEO, Ironline Compression. “With the support of Alberta’s incentive program and the effectiveness of the upgrades, our customers are making a positive impact for the environment.”