More than half of state governments in the US have set carbon reduction or net-zero targets for 2050. As part of this effort, many of EN’s clients have established carbon reducing programs to pursue their net-zero goals, and the strategy includes the use of renewable natural gas (RNG) and hydrogen.
According to the National Academies of Science, Engineering, and Medicine, there are four main strategies for achieving the net-zero goal–generating electricity without emissions, using vehicles and equipment powered by electricity instead of fossil fuels, using energy more efficiently, and removing carbon dioxide from the atmosphere.
It isn’t surprising that people focus on electric vehicles, wind turbines, and solar panels since these are well known conventional types of renewable energy. However, when the sun isn’t shining, or the wind isn’t blowing to produce clean energy, there is a need for backup power, and that is where natural gas, and now RNG and hydrogen, come in.
As a natural gas engineering and design firm, EN Engineering knows that RNG and hydrogen are an essential part of the future, supporting renewable energy. EN also has the necessary expertise to help companies utilize these components to meet their 2050 carbon reduction goals.
When EN works with our clients on renewable energy, we look to develop their entire renewable program that will achieve their net-zero goals. The program will consist of the above carbon reduction programs, but will also include projects associated with operational efficiencies, electrification, wind, solar, battery storage, carbon capture sequestration, waste heat recovery, and biomass. Programs can be customized to help clients reduce greenhouse gas emissions and also give an estimate for how many metric tons of carbon dioxide (CO2) will be eliminated from the atmosphere.
Renewable natural gas is associated with biogas production facilities. Biogas could be the biggest and, some might say, the stinkiest, new tool in the net-zero arsenal–at least until it is processed.
Sources of biogas can be animal waste, water treatment plants, landfills, and synthetic natural gas plants. EN often works with many different companies associated with an RNG project. These can include:
As an example, animal waste from a dairy farm is currently transferred into an anaerobic digester, and about four weeks later, biogas can be removed from the digester and used on-site while the solids can be used as a nutrient-rich fertilizer.
This type of project captures the biogas in its raw form, which has about half the energy of pipeline natural gas. The heat content of pipeline natural gas is approximately 1,000 BTU/scf, while biogas ranges between 500-800 BTU/scf due to the large amount of carbon dioxide (CO2) and other impurities contained in the raw biogas.
To convert biogas into renewable energy or RNG, we need to remove the carbon and other impurities from the raw biogas. Therefore, the raw biogas is then sent to a processor and purified, removing H2S, CO2, oxygen, water, and other contaminants—until what remains is clean, pipeline-quality gas that is close to the 1,000 BTU/scf heat content.
A testing system that analyzes the treated biogas must be included in the RNG project design to ensure that all contaminants have been removed and the biogas is clean pipeline-quality RNG before it is introduced to the natural gas pipeline. The testing process is a critical component as any impurities could cause pipeline corrosion or combustion problems. If the analysis finds any impurities, the biogas is recirculated back through the cleaning process and retested before the RNG is blended into the natural gas pipeline.
Another factor to consider when looking at an RNG project is the financial return. Natural gas is currently purchased for $3-6 per million BTU (mmBTU). When carbon credits are factored into pricing RNG, renewable index credits are trading upwards of $20-$40/mmBTU. This is one part of what makes RNG beneficial for suppliers and end-users alike.
EN completes many pipeline interconnects for utilities, interstate pipelines, and midstream companies for blending RNG into the pipelines. The RNG space is a new twist on what EN has been doing for decades. With these projects, we use our expertise to work with owners/operators/developers to process the biogas and design a pipeline interconnect for the clean pipeline-quality RNG. The blended RNG is then sent to homes, businesses, industrial buildings, and power plants for consumption.
While the utility industry is historically conservative when working with new technologies, the net-zero goals and drive toward renewable energy has EN’s clients moving much faster, especially on hydrogen blending projects.
Hydrogen, in fact, has the potential to revolutionize the industry. Interestingly, there is nothing that produces hydrogen. Instead, it is always linked to something, such as water or natural gas.
Countries abroad are much further along than the US in the development of technologies to pull hydrogen away from what it is bound to. If, for instance, we pull hydrogen away from methane (CH3) (the largest component in natural gas), we remove the carbon from the combustion, thus reducing the GHG, and hydrogen alone becomes an energy source. This is an innovative way to create a new energy source, reduce GHG, and helps companies to achieve their net-zero goals.
When the hydrogen is blended in with the natural gas, and to ensure that the blending is accurate, EN recommends an off-system skid that is set to blend a certain percent of hydrogen at a particular rate. At the pipeline interconnect location, the natural gas flowrate of the pipeline is measured. Knowing this volume of natural gas, the correct amount of hydrogen is injected into the center of the pipeline to ensure that you get proper mixing and at the proper blend percentage.
Other considerations when designing a hydrogen blending project include how to size the blending skid. Natural gas pipeline flowrates significantly vary from summer to winter. These flowrates can vary more than 10 times in winter when compared to summer. Therefore, the hydrogen blending skid needs to be able to handle the proper blending percentages as the natural gas demand increases and decreases throughout the year.
Although technology is moving quickly on hydrogen blending, there are many challenges, ranging from combustion issues to fracture from pipeline embrittlement.
This embrittlement problem is caused by hydrogen, the lightest element, diffusing through the pipeline steel which can cause premature cracking and leaking. This is one reason why the US is being conservative and introducing hydrogen to their pipelines at a rate of one to three percent while Europe is already completing hydrogen blending projects up to 20 percent or greater. In fact, most of the recent hydrogen blending projects are being designed on plastic distribution systems to avoid embrittlement and other degradation issues realized on steel pipeline systems, while industry and academic research continues.
EN is at the forefront of the hydrogen revolution with an internal task force that is focused on hydrogen blending and studying how hydrogen impacts our industry. EN is also participating in an industry task group researching the effects hydrogen has on pipeline welding.
Most projects that are being completed in the US are prototype projects. For the most part, it’s either sending the blended hydrogen into an R&D facility or distributing it to a small number of residential homes. This serves to control the new technology so that operators know what equipment is burning the blended gas and they can monitor the blended gas system to ensure the safety of the infrastructure and their customers.
As a pipeline and facility engineering firm, EN is committed to designing safe and reliable interconnects for RNG and hydrogen blending projects. A key part of this is procedure development, best practices, and analysis of potential risks and putting together procedures and designs that mitigate them.
Other components of a successful RNG or hydrogen program include the development of operational procedures, maintenance procedures, and design standards. All of which EN has completed for our clients for many years.
As you can see, there are many factors to consider when developing and designing RNG and hydrogen blending projects. Being recognized as a leader in the industry for over 20 years, EN’s clients rely on our high quality, technical assistance to ensure safe and reliable infrastructure. Renewable energy, including RNG and hydrogen blending, is another area where EN will steer our industry in the pursuit of net-zero goals. For more information on how EN assists our clients with their carbon reduction programs or any type of renewable energy, contact John Wilson at jwilson@enengineering.com.
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