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ETW Energietechnik Reports CHP Units with SCR catalysts Overall Efficiency 85 percent+

ETW Energietechnik

ETW Energietechnik Reports CHP Units with SCR catalysts Overall Efficiency 85 percent+

The Rems-Murr waste management company in Backnang-Neuschöntal in Baden-Württemberg has two new energy-efficient combined heat and power plants in which methane from biogas plants is co-incinerated. From 2023 onwards, they will emit five times less nitrogen oxide than today.

On 23 October 2019, two new combined heat and power (CHP) plants of the municipal waste management company Rems-Murr (AWRM) went into operation in Backnang-Neuschöntal. They were built by the company ETW Energietechnik GmbH from Moers in North Rhine-Westphalia. For the renewal, the two old gas engines of the waste management company were replaced after 65,000 operating hours and more than eight years of operation. This resulted in a leap in efficiency, which is essentially based on the installation of the larger, more powerful gas engines as well as the further developed gas engine technology. In addition, fuel savings are achieved by using the residual methane content in the fermentation residue exhaust air.

ETW Energietechnik took a step-by-step approach to this: First, the used CHP engines with 800 kilowatts (kW) each were dismantled. At the same place, the company installed two new larger gas engines with an electrical output of 1560 and 1200 kilowatts. These are each container CHP units, i.e. the power plants fit into a special container measuring 14 by 3.2 by 3 metres.

First, there is the container CHP “ETW 1560 BG” with a gas genset MWM TCG 2020 V16 (electrical output: 1560 kW, thermal output: 1528 kW, fuel input: 3683 kW). The second is the container CHP “ETW 1200 BG” with a gas aggregate MWM TCG 2020 V12 (electrical output: 1200 kW, thermal output: 1153 kW, fuel input: 2804 kW).

Compared with the old gensets, the changeover increases the electrical efficiency by almost 1.6 percentage points: Whereas the used CHP units had an electrical efficiency of 40.4 percent, this now amounts to 42 percent. The overall efficiency of the plant increases slightly to 85 percent.

The heat utilization concept contributes significantly to this high figure. The waste heat from the block-type thermal power stations is used to heat the fermenters and the operating building. The excess waste heat is then made available to the city of Backnang for drying sewage sludge.

A further leap in efficiency is achieved by a special feature of the plant: fermentation residue exhaust air is added to the combustion air of the gas engines. Although this exhaust air has too low a methane content (less than 1.75 percent) for it to be used directly in a gas engine, the plant is able to use it in a gas engine. However, by mixing it into the combustion air, the low methane content is made usable. This has a further advantage: This methane content in the combustion air does not have to be supplied via the biogas pipe and can, therefore, be saved on the biogas side.

“This was the first time that we have equipped an ETW plant in this way,” reports Alexander Szabo. The engineer is the responsible sales manager at ETW Energietechnik.

The municipal waste management company hopes that this exchange will enable it to make CHP operation more variable in the future due to the higher engine output while maintaining the same gas quantities during the day. In addition, the waste management company is expecting an increase in the amount of electricity fed into the public grid.

For the pilot project, the fermentation residue exhaust air extracted from the liquid fertilizer storage tanks and the sedimentation tank of the biogas plant is cleaned by a gas washer-dryer and then fed into the combustion air supply of the gas engines. To avoid an ignitable mixture in the combustion air, the fermentation residue exhaust air freed from hydrogen sulphide (H2S) is continuously monitored by means of gas analysis.

The system update is sustainable in that two expected changes in legislation in Germany are already being fulfilled:

-One is the use of residual methane in the fermentation residue exhaust air to prevent greenhouse gas from escaping. This system was designed by the planning company Ingenieurgruppe RUK GmbH from Stuttgart.

-It has already been decided that CHP plants from 2023 may not emit more than 100 milligrams of nitrogen oxides (NOx) per cubic meter. Currently, this upper limit is 500 mg/m³. These values apply in each case at a residual oxygen content of five percent. This is stated in the Ordinance on Medium-Sized Combustion, Gas Turbine, and Internal Combustion Engine Installations, the 44th Federal Immission Control Ordinance (44th BImSchV), which was updated in June 2019.

In order to avoid later, costly retrofitting of the exhaust system, both cogeneration plants have therefore already been equipped with modern nitrogen oxide catalytic converters. The catalytic elements are mounted on a ceramic carrier. This SCR technology – SCR stands for “Selected Catalytic Reduction” – is the only technology for reducing the amount of sick oxides (NOx) in the exhaust gas of the gas engine. The nitrogen oxides in the exhaust gas are composed of nitrogen monoxide (NO) and nitrogen dioxide (NO2).

To reduce nitrogen oxides, Adblue must be injected into the exhaust system – this mixture has a urea content of 32.5 percent. The high exhaust gas temperature converts Adblue into ammonia. The ammonia reacts with the nitrogen oxides on the catalytic surface of the catalyst elements with the following reaction formula: 4NO + 4NH3 + O2 4N2 + 6H2O

ETW Energietechnik has already installed some of the SCR catalytic converter elements. These reduce – even without urea injection – formaldehyde in the exhaust gas. Formaldehyde (CH2O) is converted into water and CO2. The complete SCR catalytic converter system including urea injection will not go into operation until 2023. In order to comply with the stricter limits, only minor retrofitting is then required due to the modern exhaust gas cleaning system (see below).

Following the award of the contract for the new CHP plants, ETW Energietechnik GmbH was also awarded the contract for the extension of the waste fermentation plant. This includes the entire process, measurement, and control technology. The scope of supply also includes the gas wash drying plant for the fermentation residue exhaust air.

Retrofitting for NOx reduction
In 2022, ETW Energietechnik will retrofit the two combined heat and power plants so that they can comply with the limit value for nitrogen oxides of 100 mg/m³ from 2023 onwards:

A urea tank, the stainless steel piping between urea tank and injection, a suction line into the gas engine and a urea dosing device are still needed. This requires an air compressor, pressure and temperature sensors, nitrogen oxide and oxygen sensors upstream and downstream of the catalytic converter. For this purpose, the catalyst housing is completely equipped with catalyst elements.

A container CHP in side view with biological
The insulated SCR-catalytic converter
housing with demountable insulation elements to replace the catalytic converter


ETW Energietechnik GmbH has been developing and producing energy plants in Moers, Germany, since 1997. The company‘s core business comprises the construction and maintenance of combined heat and power (CHP) plants in the output range of 400 to 4,600 kWel. as well as highly efficient Biogas Upgrading plants that produce pure Biomethane out of raw Biogas using a high-end PSA technology.

The company is a one-stop provider: From the transfer of biogas to the feed- in of power into the grid and the provision of heat, ETW also takes care of the construction, commissioning, and maintenance of CHP and Biogas Upgrading plants.

The clientele of ETW Energietechnik GmbH includes large energy suppliers, agricultural plants, municipalities, and industrial businesses of various types and sizes, all of which attach importance to eco-friendly, economic energy generation.

One of the strategic highlights is the implementation of economic, sustainable plant concepts that are planned individually and adapted to the respective requirements. A qualified service team ensures operational reliability and maximum availability of the plants.

The medium-sized, family-owned enterprise employs a staff of nearly 100 and is managed by its founder Helmut Weiss and his two sons Marco and Carsten.


Anheuser-Busch Keeps Beer Deliveries “Green”

Emissions-free beer delivery is another eco-friendly accomplishment announced this week through a collaborative effort between Anheuser-Busch, Nikola Motor Company, and BYD. Bud Light brand beer was onboard the zero-emissions fleet which included a Nikola hydrogen-electric vehicle and an electric BYD vehicle from the Anheuser-Busch brewery to the Enterprise Center in St. Louis.

“At Anheuser-Busch, we are continuously searching for innovative ways to improve sustainability across our entire value chain, progressing towards reaching our sustainability goals and driving our industry forward,” said Ingrid De Ryck, Vice President of Procurement and Sustainability at Anheuser-Busch. “No single company can build a more sustainable future alone but this zero-emission delivery has shown what is possible when we bring together the various strengths and assets within our supplier network to work towards a shared objective of a better world.”

Anheuser-Busch is dedicated to its 2025 Sustainability Goals which includes a 25 percent reduction in reducing carbon emissions by 2025. The company continues to maximize emissions-free efforts through partnership projects, including one with BYD that would add 21 BYD electric trucks as well as a 958.5 kW solar array vehicle charging to four of its SoCal distribution facilities.  Additionally, the company ordered 800 hydrogen-electric powered Nikola semi-trucks last year, adding more value to eco-friendly efforts.

“As the first commercial delivery of freight with our hydrogen-electric truck, this is an exciting time for both Nikola and Anheuser-Busch. This milestone will become an example for all other OEM’s to move away from diesel trucks and towards zero-emission vehicles,” said Trevor Milton, Nikola’s chief executive officer. “We look forward to helping the Anheuser-Busch team achieve their sustainability goals by leveraging Nikola’s zero-emissions technology. We are now preparing production vehicles for Anheuser-Busch and plan on delivering the trucks as fast as possible.”

“Partnering with Anheuser-Busch is a great opportunity to showcase BYD’s performance and reliability with an industry leader,” said Stella Li, President of BYD Motors. “Our dedication to innovation pairs nicely with Anheuser-Busch’s sustainability commitment.”

Wando Welch Terminal

SCPA’s Wando Welch Terminal Confirmed for Sustainable Crane Upgrades

RTG cranes at South Carolina Ports Authority’s Wando Welch Terminal will soon operate on sustainable and eco-friendly engines thanks to a $2 million grant from the U.S. Environmental Protection Agency.

“Through a great partnership with DHEC, we have secured EPA funding to upgrade our 12 least efficient RTG cranes with high performing, environmentally friendly battery/genset hybrids,” said Stephen Brisben, Mechanical Technical Specialist for SCPA’s Heavy Lift Maintenance Department. “This aligns with our efforts to upgrade equipment to both improve air quality standards in the Lowcountry and enhance terminal operations.”

The grant was issued as part of the  Diesel Emissions Reduction Act (DERA) program supporting the upgrading of various fleets from school buses, transit airport buses, long and short-haul trucks, marine engines, locomotive replacements, and more for cleaner environments and an overall reduction in harmful emissions.

“For the past 10 years, the DERA program has played an important role in helping to reduce harmful emissions from diesel engines while simultaneously creating opportunities for economic growth and development in South Carolina,” DHEC’s Bureau of Air Quality Chief Rhonda Thompson said. “We are excited about this new opportunity to work alongside the South Carolina Ports Authority — an entity whose work is crucially important in supporting both our state and regional economies.”

SCPA’s Chief Operating Officer Barbara Melvin confirmed the 12 rubber-tired gantry cranes (RTG) upgrades are part of the overall vision to implement sustainable and efficient equipment solutions. Additionally, the upgrades were reported to support reducing fuel consumption while cutting up to 96 percent of particulate matter, air toxins, and nitrogen oxides.