RNG Questions & Answers

What is renewable natural gas?

Renewable natural gas (RNG) is produced from organic materials like wood waste, food and agricultural waste, and even human waste. As these materials decompose, they produce methane. That methane can be captured and then conditioned to natural gas pipeline quality. You can use RNG in any application that uses natural gas: vehicle fuel, space and water heating, cooking and more. No new equipment is required.

Where does RNG come from?

Today, the primary sources of RNG in North America are landfills, wastewater treatment plants, food waste and dairy farms.

Large amounts of biogas (the raw, freshly emitted and untreated gas) can be collected at local landfills, wastewater treatment plants, commercial food waste facilities and agricultural operations, such as dairies.

Once this raw biogas is collected and upgraded (cleaned and conditioned) to meet natural gas pipeline quality specifications, we call it renewable natural gas.

As of mid-2018, 75 RNG projects are up and running in the United States and Canada. Another 20 are under construction (three in Oregon), and another 25-30 in the advanced planning stages.

In Europe, nearly 500 biomethane (RNG) facilities are in operation. Check out this online map of North America projects

What makes it “renewable”?

Organic materials produce methane as they decompose. Natural gas is made of methane. Conventional natural gas is considered a “fossil” fuel because it comes from fossilized deposits trapped in geologic formations, thousands of feet below the Earth’s surface. Renewable natural gas captures “new” methane that would otherwise be released into the atmosphere. When burned, the byproduct of carbon dioxide goes back into the atmosphere and the carbon cycle. 

What are the emissions benefits of RNG?

Renewable natural gas has a significantly lower carbon footprint than conventional natural gas.   

Depending on the source of raw biogas, RNG offers reductions of 40% to 450% in carbon dioxide-equivalent emissions, compared to conventional natural gas. What’s more, RNG’s carbon intensity is about half that of solar-generated electricity when considering the full lifecycle of emissions. And using power-to-gas for storage of excess electricity generated from renewable sources? That’s the lowest carbon intensity methane available. 

Does NW Natural deliver RNG?

Not yet. We plan to begin accepting our first RNG onto our pipeline system in 2019.

Portland Wastewater Treatment Project: We have partnered with the City of Portland on the Columbia Boulevard Wastewater Treatment Plant RNG project to bring renewable natural gas (RNG) onto our system. Fuel will be used at a new CNG station on site. The remaining RNG will be placed on the gas grid and brought to market. 

Policy and Public Outreach: We are working with local stakeholders to explore policy options to deliver RNG to our customers’ homes and businesses – as RNG is interchangeable with conventional natural gas.

We will continue to help our customers reduce and offset their consumption as we support the development of renewable natural gas supply and explore other cutting edge solutions to lower the carbon intensity of our product, such as power to gas. We are talking with other governments and project developers to better understand the opportunities for RNG in Oregon and Washington, and the barriers to greater RNG project development.

How much does RNG cost?

Price depends on a number of factors. In some cases, such as landfills, biogas is already being captured and cleaned, so production of RNG requires less capital investment. In others, such as dairies, there is little existing collection of biogas so more substantial capital investment is required.

Production costs can range from $5 to $30 per MMBtu.* To offset these costs, many RNG projects can earn substantial credits under both the federal Renewable Fuel Standard and the Oregon Clean Fuels Program. In some cases RNG can earn credits within these programs well above the cost of production.

 * Million British Thermal Units, a measure of energy content. 

Is all RNG the same?

As an energy source: Yes. We will condition all RNG to the same rigorous quality standard of natural gas from conventional sources. RNG will also meet our same energy content requirements.

At the same time, different feedstocks used to make RNG require a variety of collection and processing equipment. This can result in different project development costs.

Sources of RNG also have varying “carbon intensity” (CI) values,* a measure used to compare the complete lifecycle emissions of different fuels. Gasoline and diesel have CI values of around 100.

Compressed natural gas (CNG) made from a wastewater treatment plant’s RNG might have a carbon intensity score of 20. Landfill gas may be somewhat higher.

CNG from dairies can have net-negative values of -100 or -200. These negative values reflect the capture and use of methane that would otherwise have been stored in lagoons and released as methane directly into the atmosphere. 

 *CI values are expressed as grams of carbon dioxide-equivalent per megajoule of energy.

Could NW Natural switch to RNG? 

We aren’t there yet. It is technically possible to provide RNG to homes and businesses today, but a few things have to happen before we can start delivering significant amounts of RNG to our NW Natural customers.

Policy support could provide a framework for the purchase and delivery of RNG to customers using natural gas for space and water heating. The RNG projects now being built in Oregon will primarily serve the alternative fuels market in the near term.

Stable and long-term market demand from our natural gas customers will also be important to establish RNG markets. Technology improvements, resulting from additional RNG projects being developed, may help reduce project costs. 

What’s the long-term goal for RNG?

The technical potential for RNG statewide, including forests residues on the ground, could someday approach 100% of our total natural gas sales. Only a portion of this technical potential will make economic or environmental sense to pursue.

We look forward to the final report that will be produced by the Oregon Department of Energy in the fall of 2018 that will summarize the current RNG opportunity in Oregon.

When we established our Low Carbon Pathway in 2016, we assumed that RNG would make up about 10 – 15% of our sales volume by 2035. Now, we’re looking at RNG as a cost-competitive resource, given future expected carbon compliance costs. As a result, we are assessing several RNG projects as potential supply resources within our 2018 Integrated Resource Plan.

What steps is NW Natural taking to advance RNG?

We’re working on a number of fronts to move this forward.

Assess Potential: NW Natural was an original drafter of a proposed bill, which passed as SB 334 in 2017, to identify the technical potential of RNG in Oregon, and to identify the barriers to developing this new energy supply for the state.

Now, we’re working closely with the Oregon Department of Energy, other gas utilities in Oregon and other stakeholders to understand how the political, regulatory, and market barriers facing greater RNG development can be addressed.

Build Awareness: In 2017 we co-hosted Oregon’s first RNG conference, The Power of Waste: Renewable Natural Gas for Oregon. We’ve joined the Coalition for Renewable Natural Gas, and we’re a founding member of the newly formed Northwest Alliance for Clean Transportation, which promotes the use of natural gas and RNG as a transportation fuel in trucks, buses and fleets.

So, why do this now?

RNG is the lowest-carbon fuel option for medium- and heavy-duty vehicles. No other technology on the market today provides that combination of environmental benefits all at once. Additionally, RNG can offer tremendous emissions reductions when used in our system for direct use by our customers in their furnaces, hot water heaters, and other gas appliances.

Medium- and heavy-duty natural gas vehicles equipped with near-zero emission engines produce 90% lower nitrogen oxide emissions than even the cleanest diesel engine. By using RNG, that same truck’s greenhouse gas emissions can drop 80% below diesel.

Through cooperative efforts to develop RNG, NW Natural’s pipeline system can help communities close the loop on waste, which reduces air pollution and carbon emissions, and supports diverse and innovative energy opportunities. We will continue helping our customers reduce and offset their consumption as we support the development of renewable natural gas supply and explore other cutting edge solutions to lower the carbon intensity of our product.

What other benefits come from a locally produced energy source?

Jobs and Local Economy: Regional production of RNG offers a buy-local alternative to most fuels currently in use. In Oregon, practically all natural gas delivered to customers today originates outside the state. Locally produced RNG would effectively displace imported conventional gas, delivering new jobs and income sources alongside environmental benefits. 

Resilient Energy Systems: Locally produced RNG provides an additional energy source that can be stored and distributed via the natural gas pipeline infrastructure. In the event of a significant disruption or natural disaster, local energy sources like RNG can help keep essential services and fleets in operation until networks can be restored.

Where can I learn more about RNG? 

Here are a few resources showcasing projects and studies related to RNG.

Fortis BC has North America’s most established program, delivering RNG to home and commercial customers in British Columbia.

University of California at Davis prepared a report on the carbon intensities and costs of various RNG sources. 

Vermont Gas is developing an RNG project that will supply renewable gas to customers, including Middlebury College.