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How Much Renewable Natural Gas Can Be Produced?

Germany Invests In Renewable Energy Sources

Renewable natural gas (RNG) is methane produced from biomass that is cleaned to pipeline quality standards and blended with fossil natural gas. RNG, also known as biomethane, is carbon-neutral and chemically identical to fossil natural gas allowing it to be blended without restriction. Renewable natural gas is produced from a variety of (mostly waste) resources including landfills, sewage, farm waste and food waste. Biomass energy crops could be cultivated for RNG production, but currently those resources tend to be used for liquid fuels.

The major benefits of RNG production are that it takes methane already naturally produced from waste and prevents it from going into the atmosphere as a potent greenhouse gas, instead turning it into a valuable carbon-neutral fuel. RNG also helps address energy security because it is a locally-produced fuel available in every community. RNG is also a universal fuel certified for use in existing infrastructure without technical issues and it can be used for heat, power and transportation.

A series of studies from government research agencies and industry in the last few years have found that anywhere from 5% to 20% of today’s natural gas demand could be met with RNG. These studies have attempted to quantify the resource by sector and region that are available for RNG production. The studies covered in this article do not include power to gas, nor synthetic natural gas which is produced from other fossil fuels such as coal.

Assumptions for how resources are calculated vary from model to model, particularly in the use of energy crops, which is the single biggest variable that differs among the studies. Conversion efficiencies and costs also vary by feedstock and by conversion process, but conversion efficiencies typically range from 60% – 70%.

US, NREL (National Renewable Energy Laboratory)

Biogas Potential in the United States (Fact Sheet), 2013:

The methane potential from landfill material, animal manure, wastewater, and industrial, institutional, and commercial organic waste in the United States is estimated at … about 420 billion cubic feet… This amount could displace about 5% of current natural gas consumption in the electric power sector and 56% of natural gas consumption in the transportation sector (EIA 2013).

The methane generation potential is expected to be much higher if lignocellulosic biomass resources are used. Future estimates reach 4.2 trillion cubic feet per year… which could displace about 46% of current natural gas consumption in the electric power sector and the entire natural gas consumption in the transportation sector.

dodge rng1

AGA (American Gas Association)

The AGA is one of the USA’s major natural gas industry trade associations. AGA formally endorses the development of the RNG industry and the blending of biomethane with fossil natural gas in pipelines and for transportation.

AGA argues that RNG helps reduce greenhouse gas emissions, increases domestic energy production, improves waste management, provides new revenues for farmers, and helps creates jobs.

AGF (American Gas Foundation)

The American Gas Foundation is a group related to the AGA that conducted a major study in 2011 on US RNG resources and potential.

The Potential for Renewable Gas: Biogas Derived from Biomass Feedstocks and Upgraded to Pipeline Quality.

This report breaks down the resources by state and includes both anaerobic digestion and thermal gasification pathways.

This analysis presents three potential degrees or scenarios of total biomass utilization or market penetration:

  • Non-aggressive. This scenario assumes roughly 5% -25% (depending on resource) of biomass is processed into biogas. Total RNG production is 0.97 quads per year or 4% of US natural gas demand.
  • Aggressive. This scenario assumes 15%-75% (depending on resource) of biomass is processed into renewable gas. The Aggressive scenario represents a concerted national effort to employ this renewable resource. Total RNG production is 2.48 quads per year, 10% of US natural gas demand.
  • Maximum. This scenario assumes 100% biomass utilization and conventional conversion efficiency. It provides a theoretical upper limit for renewable gas production. Total RNG production is 9.5 quads per year, or 40% of US natural gas demand.

Resources calculated for the study include:

  • Animal waste from dairy cows, beef cattle, hogs and pigs, sheep, broiler chickens, turkeys and horses.
  • Wastewater from 436 wastewater facilities.
  • Landfill gas from 2,402 landfills.
  • Municipal solid waste, thermal gasification of MSW not already used in waste-to-energy projects.
  • Wood residue, from forests, mills and urban wood collection.
  • Energy crops, switch grass, willow, hybrid poplar, but not food crops such as corn or soy.
  • Agricultural residues, from corn, wheat, soybeans, cotton, sorghum, barley, oats, rice, rye canola, beans, peas, peanuts, potatoes, safflower, sunflower, and flaxseed.

dodge rng2National Grid

National Grid is a major power and gas utility based in the UK that also has significant operations in the Northeast US. In 2010 they released a study titled, Renewable Gas – Vision for a Sustainable Gas Network where they presented the business and resource case for RNG in their operating area.

The biggest driver of renewable gas is GHG reduction, but what makes renewable gas more compelling is that it also enhances diversity of supply while providing a solution for using local waste resources to produce renewable energy.

National Grid estimates that over the long term renewable gas has the potential to meet up to 16% of the natural gas demand in the four states they service: Massachusetts, New Hampshire, New York and Rhode Island.

dodge rng3National Grid is a partner with the New York City Department of Environmental Protection on one of the biggest RNG projects in the US. Newtown Creek is the largest of NYC’s 14 wastewater treatment plants and uses 8 digester eggs to process 1.5 million gallons of sewage sludge every day. Food waste is also added separately in a partnership with Waste Management, Inc. who preprocesses food waste collected from local schools into biosludge that is delivered to Newtown Creek for digestion. Methane production numbers were not available as the system is still undergoing commissioning.

dodge rng4

National Grid commissioned a similar study in 2009 to analyze RNG potential in the UK. The report, titled The Potential for Renewable Gas in the UK, came to similar conclusions as reports in the US. The baseline scenario found that 5% of UK natural gas demand could be met by RNG and that the aggressive or ‘stretch’ scenario was 18% of total UK gas demand.

dodge rng6

NPC (National Petroleum Council)

The NPC issued a paper in March 2012, Renewable Natural Gas for Transportation. In the paper NPC finds:

  • Approximately 4.7 trillion cubic feet of RNG is potentially available from domestic resources in the US. 4.7 TCF is about 20% of US natural gas consumption.
  • If used for transportation fuel, this amount of RNG would amount to 40 billion gasoline gallon equivalents per year and would result in 90% reductions in greenhouse gas emissions.

A literature review in the paper reviewing costs for RNG production states:

  • The California Energy Commission estimated the costs of producing pipeline quality RNG from landfill gas to be $1.7 – $2.2/MMBTU.
  • CALSTART estimated current (2010) RNG production costs of $5.9/MMBTU from livestock manure for a medium sized facility and $9/MMBTU for a smaller one. The dominant cost was upgrading the biogas to RNG: $4/MMBTU for a medium sized facility and $7/MMBTU for a small one. Biogas production was typically $2 per 1000 ft3 of biogas, with covered lagoons being the lowest cost and the large, covered lagoon system at Hilarides only $0.38.
  • A 2009 California Energy Commission study did a detailed economic analysis of RNG from dairies injected into the pipeline using current technology and costs. They found that the cost of pipeline injection could be significant, especially for dairies miles from an interconnection to the natural gas grid. For example, the cost of pipeline injected RNG would be $12/MMBTU for the Hilarides Dairy compared to $42/MMBTU for the Castelanelli Dairy which would require 5 miles of Capital costs, including the costs to pipeline interconnect, were the cost drivers.
  • NREL’s case study for biogas from dairy farms resulted in a RNG cost of $11/MMBTU delivered into the This consisted of $6 paid to the farmers, $2.5 for RNG production and $3 for delivery (10 miles) into the pipeline.
  • ECN in the Netherlands estimated costs of RNG production from biomass using the MILENA gasification technology ranging from $13/MMBTU at a large facility to $42/MMBTU at a smaller one, including biomass costs of $3.7 to $7.7/MMBTU of RNG.

dodge rng7 Bioenergy Association of California

The Bioenergy Association of California issued a paper in November, 2014 calling for a Renewable Gas Standard, similar to the Renewable Portfolio Standard and the Renewable Fuels Standard to help promote RNG. According to BAC, RNG could meet over 10% of California’s roughly 2,300 Bcf annual natural gas demand.

World Bioenergy Association

The World Bioenergy Association from Stockholm, Sweden issued a fact sheet titled Biogas – An Important Energy Source, in which they state that 25% of global natural gas demand or 6% of global primary energy use could be met with biogas.

Conclusions

Though estimates vary for how much renewable natural gas can be produced, depending on how aggressively analysts calculate the resource base, and whether energy crops are included, there is a broad consensus that RNG can make a substantive and valuable contribution to global renewable energy production.

RNG offers multiple benefits. First, methane emissions from natural sources that would otherwise be going into the atmosphere as a potent greenhouse gas are converted into a valuable asset.

Second, RNG is a universal fuel that can be used for heat, power and transportation, meaning that it can be directed into sectors in greatest need of greenhouse gas emission reduction.

Third, since RNG is chemically identical to conventional natural gas, it can utilize existing infrastructure without concern for pipeline degradation or interference with end use devices. Alternative biofuels such as ethanol, methanol or biodiesel are greatly challenged in this regard because they are chemically different from the fossil fuels they seek to replace and require expensive upgrades to engines, storage and delivery systems.

Waste feedstocks for RNG production are widely distributed throughout society and every community has an opportunity to contribute to this valuable stream of renewable energy production. Anywhere there is waste, local citizens can be employed to convert this waste into valuable clean fuel creating win-win scenarios or an improved environment and improved energy security.

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Roger DePoy's picture
Roger DePoy on December 22, 2014

If one were to site a digester inside the Beltway, we would have a virtually inexhaustable supply of

bull*#*% to convert to fuel…this is something that we can all get behind!

Seriously, the amount of energy in the waste stream is enormous, and recapturing it  would be a feather in the cap of civil and chemical engineering practitioners.

 Nice article!

Roger DePoy's picture
Roger DePoy on December 22, 2014

If one were to site a digester inside the Beltway, we would have a virtually inexhaustable supply of

bull*#*% to convert to fuel…this is something that we can all get behind!

Seriously, the amount of energy in the waste stream is enormous, and recapturing it  would be a feather in the cap of civil and chemical engineering practitioners.

 Nice article!

Engineer- Poet's picture
Engineer- Poet on December 22, 2014

The cost of pipeline injected RNG would be $12/MMBTU for the Hilarides Dairy compared to $42/MMBTU for the Castelanelli Dairy which would require 5 miles…

By way of comparison, the 2006 and 2008 NG price peaks at the Henry hub were less than $15/mmBTU.  The Henry hub price is currently under $5/mmBTU.  Schemes such as this require massive subsidies and should be considered irresponsible to promote and pursue.

Since purification and pipelines are the costly elements of biomethane use, the obvious thing is to use biogas as-is and where-is.  Burning it in engines to generate grid power (perhaps only for peaking hours, if storage can be arranged) would eliminate the need to transport the gas and only minimal purification would be required.  Engine waste heat could provide necessary services, such as operating absorption chillers to hold milk at dairies.  Delivering services cheaply means doing it efficiently, with minimal waste.  Waste is something we must avoid.

Ed Dodge's picture
Ed Dodge on December 22, 2014

Avoiding waste is precisely the reason we need to subsidize RNG. Today TCF of methane is going to waste as a GHG because fossil natural gas is cheaper.

We need to make investments in infrastructure in order to make it feasible for folks to capture their biomethane. Once the infrastructure is established it can last for generations and pay for itself.

Jeffrey Miller's picture
Jeffrey Miller on December 22, 2014

Some of the carbon offset funds that I have seen (and donated to) invest in biogas projects. These qualify as true offsets because they would not be built without some kind of subsidy. I agree with EP though, that using biogas on site whenever possible makes a lot of sense.

Engineer- Poet's picture
Engineer- Poet on December 22, 2014

Avoiding waste is precisely the reason we need to subsidize RNG.

Non-wasteful uses do not require subsidies.  If you are trying to compensate for carbon emissions, use an implicit carbon tax.  $42/mmBTU for a new pipeline is roughly equal to $2/kg of methane; since 1 kg CH4 yields 2.75 kg CO2, this costs $727 per metric ton of CO2 emissions avoided (ignoring processing energy).

I can think of a heap of things that will eliminate CO2 emissions at a lower cost than $727 per ton, including hauling all the pieces of San Onofre’s reactors back to the site and putting the plant back together!  To put it bluntly, if you think $42/mmBTU is a sensible price to pay for “renewable” NG, you are more than part of the problem, you are getting perilously close to being THE problem.

Rick Engebretson's picture
Rick Engebretson on December 22, 2014

When I did a requested proposal for “livestock septic tanks” in 1987 I didn’t even know about “greenhouse gas climate change.” I was asked if the gas potential was there, and I just added the use of recycled plastic material to improve tank cost/performance. When the review cited comparisons to the “International Harvester” tanks, meaning the blue steel “Harvestore” grain storage version of the “Slurrystore” manure tank by AO Smith, I knew I was dealing with a flaky government group. Never again, forget any government subsidies. But one government guy did inform me of the greenhouse issues, and quit Minnesota State to become a USDA scientist.

The main points of organic waste handling are not the gas recovered, which is substantial. Raw, untreated livestock sewage, in close confinement feedlots should be an obvious problem to anybody who can read this. Nutrient recycling and dispersal are certainly simplified by “digesters.”

Also, piles of rotting garbage are not in the community interest.

If our growing world can’t figure out basic hygene, we have no future anyway.

Hops Gegangen's picture
Hops Gegangen on December 23, 2014

 

I was reading a while back about a company building a product for remote oil wells that captures waste gas and converts it to liquid fuels for transport, avoiding the gas pipeline issue in cases in which accessing a pipeline is not economical.

 

 

Ed Dodge's picture
Ed Dodge on December 23, 2014

Projects need to be priced out on a case by case basis. But there are plenty of investment worthy projects with sufficient quantities of gas to justify the capex. Commercial projects are being developed today even without support. 

All of the resources used for RNG are waste products just sitting there as liabilities creating toxic emissions. It costs us money to not use these resources. It is certainly worth some measure of public policy support to turn these waste liabilities into green commercial assets.

RNG is the lowest carbon fuel we have available, it is non-toxic, and we can use it for heat, power, and transportation.

Nathan Wilson's picture
Nathan Wilson on December 23, 2014

With projected RNG limits of 5-18% percent of national gas demand (and a much smaller percentage of total hydrocarbon use), yes this could be a non-zero contribution to a fossil fuel dominated energy system.  But the most important conclusion we should draw is that methane can’t be a dominant energy carrier in a non-fossil energy system!

In any plausible non-fossil energy system, electricity must be the primary energy carrier.  Synfuels from power-to-fuel plants plus steam/hot-water as carriers for thermal energy from nuclear plants can be major contributors also.  But biofuels and RNG from waste must be small because the resources are small.

We must not let the promise of RNG make us forget that we must phase out use of fossil fuels (and therefore most hydrocarbon fuel).

Hops Gegangen's picture
Hops Gegangen on December 23, 2014

 

There’s this dead zone full of algae that is about the size of New Jersey where the Mississippi dumps fertilizer into the Gulf. 

Could we harvest that? Put nuclear reactors on cargo ships, suck up the algae, and use the nuclear to process the algae?

Jeffrey Miller's picture
Jeffrey Miller on December 23, 2014

EP, one thing to keep in mind is that we need to be capturing methane from farming and waste in addition to eliminating CO2 emissions from the energy sector. These are two independent sources of anthropologically driven emissions, both of which need to be controlled. I agree that as we have limited resources we should prioritize the low hanging fruit first. That said, as we have a very short time to address things, in practice we need to be working simultaneously on many fronts. 

Engineer- Poet's picture
Engineer- Poet on December 23, 2014

we need to be capturing methane from farming and waste

… as I wrote above, “the obvious thing is to use biogas as-is and where-is.”

Engineer- Poet's picture
Engineer- Poet on December 23, 2014

Agreed that biogas is cheap, and sometimes even a waste product.  But if purifying it costs $7/mmBTU and sending it to the pipeline costs multiples of that, it makes no sense to put it in the pipeline.  If you can scrub silane (which burns to SiO2, not something you want in machinery), landfill gas burns fine in engines.  Conversion to CNG (requiring CO2 to be removed) competes with $25/mmBTU diesel fuel instead of $5/mmBTU pipeline gas.  Dumping excess gas to engines, especially operating as peaking generators, is a potentially high value-added application.  Electric generation would displace gas consumption elsewhere without requiring a pipeline.  That is the low-hanging fruit that needs to be picked first.

Engineer- Poet's picture
Engineer- Poet on December 23, 2014

I’ve seen a number of articles recently on both LNG-in-a-box and GTL-in-a-box.

Nathan Wilson's picture
Nathan Wilson on December 24, 2014

Algae-to-fuel is getting research attention now, maybe something will come of it.

But when people say “dead zone” in the ocean, they are trying to emphasize a pollution problem, not trying to invite a major nuclear powered industrial activity.  Algae in the ocean is still a dillute resource; it is hard to imagine a harvesting process which will be sufficiently low impact to gain broad acceptance from environmental groups.

In contrast, production of hydrogen and ammonia from nuclear power have nearly zero environmental footprint, and can be produced close to the point of consumption.

Mark Heslep's picture
Mark Heslep on December 24, 2014

I can think of a heap of things that will eliminate CO2 emissions at a lower cost than $727 per ton, including hauling all the pieces of San Onofre’s reactors back to the site and putting the plant back together!”

That’s my energy quote of the year.  Merry Christmas.


Robert Bernal's picture
Robert Bernal on December 26, 2014

This report says that biofuels could provide between 40 and 1,100 exajouls (and expect 250 to 500)

http://www.europabio.org/sites/default/files/report/biofuels_for_transportation._global_potential_and_implications_for_sustainable_agriculture_and_energy_in_the_21st_century.pdf

From the same link…

<blockquote>”The average person in the United States generates approximately 1.8 kilograms ofmunicipal solid waste (MSW) every day. Of this, typically about 75 percent is predominantly cellulosic organic material, including waste paper, wood wastes, cardboard, and waste food scraps. Thus, a city with 1 million people produces around 1,800 tonnes of MSW in total, or about 1,300 tonnes per day of organic material. Using technology that could convert organic waste to ethanol, roughly 330 liters of ethanol could be produced per tonne of organic waste. Thus, 1,300 tonnes per day of organic waste from a city with 1 million people would be enough feedstock to produce about 430,000 liters of ethanol per day, or approximately 150 million liters per year. This is enough fuel to meet the needs of more than 58,000 people in the United States; 360,000 people in France; ornearly 2.6 million people in China at current rates of per capita fuel use.Source: Jim Easterly, Easterly Consulting, personal communication with Peter Stair, WorldwatchInstitute, March 2006.”</blockquote>

 

The wastes from 1,000,000 people can provide the energy needs for 58,000 people which indicates that you can get 1/17th the energy out from “energy in”. Energy to wastes can not provide more than 1/17th of our energy supplies. Again, every little bit helps, however, we must also consider that it may be much more profitable (in the long run) to simply put back some of it into the ground, for better soils for natural CO2 sequestration, as we are going to have to provide for ourselves, much more than just a fraction of current energy demands from clean sources. Furthermore, it is impossible to get more energy out than what is put in, thus a civilization should rely on its wastes and very much more.

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