Methane Hydrates: The Granddaddy of Fossil Fuels

For those of us who follow energy issues closely, a long-standing, persistent question has been: Are methane hydrates for real? Are they a realistically large potential energy resource? The answer seems to be yes.

Thirty years ago the information available to answer these questions was not available. Today the literature on methane hydrates (also known as methane clathrates, methane ice, fire ice) is extensive and growing. This blog post attempts to capture the main points I came away with in a detailed review of the subject. To this energy wonk it was both fascinating and disturbing – fascinating in nailing down a lot of details about a potentially new and very large energy resource, and disturbing in that it again raises serious concerns for me about our lack of a national energy policy. I will explain further.

First a word about clathrates and hydrates: clathrate is a general term that describes solids in which gases are trapped within any kind of chemical cage, while hydrate is the specific term used when that cage is made of water molecules. In methane hydrates the trapped gas is methane, the principal constituent of natural gas and the simplest known hydrocarbon (CH4). CO2 and other gas hydrates are also possible and are speculated to exist on Mars, other planets and their moons. On our home planet most of the hydrates are filled with methane, and there is lots of it.

Methane hydrates form as a solid similar to ice under the right conditions of methane and water availability, temperature (low) and pressure (high).

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They are fragile, easily destabilized (i.e., returning to separated water and no-longer-trapped CH4) by pressure and/or temperature changes, and are found most often within, and occasionally on top of, sediments on the ocean floors. They are called ‘fire ice’ because they can be lit by a match:

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The most common type of methane hydrate (>99%) has a density of 0.9gm/cc or just slightly less than that of water, so it can float. One liter of the fully saturated solid would yield 120 grams of methane or 169 liters of gas at standard temperature and pressure. It forms in the presence of water and methane under conditions found in the oceans, deep lakes, and under ice caps that fall within a gas hydrate stability zone defined by the following phase diagram:

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The seafloor of most of the world’s oceans fall within the hydrate stability zone. Methane hydrates are also found in Arctic permafrost and continental deposits in sandstone and limestone in Alaska and Siberia. These deposits may cover even larger reservoirs of methane gas beneath.

There are two sources for this methane: thermogenic methane that is formed deep in the earth by the same thermal/high pressure processes that convert organic matter to coal, oil and gas and which leaks upward toward the ocean floor where it forms hydrates when it comes in contact with highly pressurized cold (0-2C) water; and methane generated by microbes degrading organic matter (plankton) in low oxygen environments in sediments. This latter process is the dominant source of CH4 for methane hydrates.

Why are methane hydrates important? The DOE’s Energy Information Administration estimates that such hydrates contain more carbon (and therefore more potential fuel) than all other fossil fuels combined. It also reports that these hydrates could hold as much as 10,000-100,000 trillion cubic feet (Tcf) of natural gas. To put these numbers into perspective, total global consumption of natural gas is currently 120 Tcf. We are talking about a LARGE potential energy resource.

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It is also widely distributed as shown in the following map and has the potential to be an indigenous resource for many countries:

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It is also straightforward to separate the methane from its hydrate cage by heating it up or reducing its pressure. Both techniques have been demonstrated and are currently being explored actively in public and private research programs in many countries. The production problems arise when one tries to convert this resource into a marketable commodity at a reasonable cost. There are also serious environmental questions about methane hydrates because methane is a powerful greenhouse gas in its own right and releases CO2, another greenhouse gas, when it is burned. Both issues are discussed below.

The presence of most of the hydrates on the deep sea floor and in sediments just beneath it means that extraction must be carried out under extreme conditions of depth, pressure and temperature. The methane concentrations are also spread out, increasing the harvesting costs, undersea infrastructure costs, and transmission costs of bringing the gas to the surface. The fragility of the hydrates also requires that they be handled carefully, avoiding a sudden release of gas and resultant overpressurization.

The environmental problems reflect concern about methane’s strong greenhouse gas properties (20 times more effective at trapping heat than CO2) and, when oxidized (either by combustion or aerobic conversion), that it releases CO2, another, although less powerful, greenhouse gas. A saving grace is that in its pure CH4 form in the atmosphere methane’s half life is 7.5 years. CO2 on the other hand has an atmospheric half life of hundreds of years. Leakage of methane from pipelines and other infrastructure is also a concern, as it is for other sources of natural gas.

Another problem for methane production from hydrates is the fact that shale gas via fracking is just coming into its own as a major source of competitive natural gas, thus reducing the commercial incentive to develop the hydrates. Unless the cost of producing methane from hydrates can be reduced significantly this will remain an important barrier as long as shale gas is available in quantity.

The U.S. is one of several countries with an active methane hydrate R&D program. Others include Russia, India, S. Korea and Japan. Japan has been a leader in this research for many years, given its lack of indigenous energy resources and its heavy dependence on imports. Japan’s recent problems with its nuclear power plants has further increased its dependence on imported LNG and its associated costs, which are very high in the Asian market (roughly 3-4 times higher than in the U.S. market).

The U.S. program was jump-started by the passage of The National Methane Hydrates R&D Act of 2000, which requires “the development of a national methane hydrate R&D program that utilizes the talents of federal, private, and academic organizations.” The result is a joint public-private effort supported collaboratively by quite a few U.S. government departments and agencies: USGS, BLM, DOE, DOI, BOEMRE, NOAA, NRL, and NSF. Several National Laboratories (NETL, ORNL,..) are also heavily engaged.

Major arguments in favor of developing methane hydrates are the fact that it is an indigenous resource, thus enhancing national security and potentially reducing energy import costs, and the fact that natural gas can be substituted for coal in electric power plants, thus reducing carbon emissions per unit of energy produced. These are strong arguments, but raise the concern that investments in natural gas will reduce U.S. investments in energy efficiency and renewable energy. This is a serious concern in a country without an articulated energy policy that points us clearly toward a renewable energy future, and without a price on carbon emissions. This lack of a policy structure can only allow a delay in the inevitable transition to an energy economy that is increasingly dependent on renewable energy. It will also allow more carbon into the atmosphere – methane still releases carbon when burned.

In sum, the world is rich in methane, much richer than in other fossil fuels in terms of energy potential, but getting that methane to market at an affordable price is not now, and perhaps not for a long time, easily achieved. Unconventional natural gas production (shale, methane hydrates) and use also present serious greenhouse gas concerns which will require careful regulation and enforcement. It also presents important policy concerns that the U.S. Congress has so far shown a reluctance to address. We need to do better!

A Note to My Readers

I’ve been offline for several weeks, longer than I expected, due to time spent on preparing a book for publication, co-authoring a detailed review of fracking, and getting an old, ‘jittery’ computer to settle down. Now working on my next blog post, which I hope to publish shortly – on methane hydrates, another large potential source of natural gas.

Request to readers: please help me choose a title for an ebook of my blog posts

Dear readers,

At the suggestion of several friends I am gathering many (47) of my first year blog posts (May 2013-March 2014) for publication as an ebook. The title is proving to be an issue. Would like your help in settling on a name – hope to publish soon.

Some possibilities that have been suggested:

Energy, Water and Environment (too boring?)

Energy, Water and Environment: Beyond the BS (too ‘risqué?)

Energy, Water and Environment: Penetrating the Fog

Others – open to all suggestions

Thank you.

Human Wastes: Another Energy Resource Waiting to Be Tapped

Recently I posted a blog entitled ‘Animal Wastes: An Energy Resource That Is Win-Win’. The Washington Post article reproduced below may be considered a follow-up to that blog but focused on using human wastes to generate energy. It usefully points out the several beneficial uses to which human wastes can be put and the economic benefits of doing so. It is worth reading!

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WASTE, NOT WASTED
By Ashley Halsey III
Washington Post (April 6, 2014)

This is a topic that one must approach delicately so as not to offend the reader’s sensibilities, but since it is a matter of importance for which you may receive a bill for some portion of $470 million, we start out with an analogy.

You need energy, so you eat. Through the miracle of digestion, your body sorts what you have eaten, say, a pastrami on rye with a glob of coleslaw and a dill pickle, and plucks out the nutrients — proteins, carbohydrates and sugars it needs to generate power. Then it jettisons the rest.

What your body jettisons disappears forever, carried along in a huge network of sewers to a plant in the southeastern corner of Washington.

Just like you, that plant needs energy. Through a miracle called thermal hydrolysis, it soon will be able to sort through what you have jettisoned and use it to generate electricity.

Yes, from poop will come power — 13 megawatts of it. Enough electricity to light about 10,500 homes.

Ben Franklin never dreamed of this one.

While Ben may have denounced the scheme as impossible sorcery, he also noted that a penny saved is a penny earned, so he might have been at least intrigued by this notion.

More than a few pennies may be saved for the citizens of the District and for some Virginians and Marylanders. Those people — 2.2 million of them — get a monthly bill for the privilege of sending their thoroughly digested nutritional intake to the plant in Southeast Washington operated by D.C. Water.

A chunk of that monthly bill is passed on to another local utility — Pepco. D.C. Water is the electricity company’s No. 1 customer. By converting poop to power, the water company will cut its Pepco bill by about one third and reduce by half the cost of trucking treated waste elsewhere.

But enough about poop, a subject that makes many a reader a bit squeamish. Because we’d rather not drive you away from the description of a wholly remarkable plan that is very likely to affect your pocketbook, henceforth we will refer to the matter that flows through the sewage plant as “the product.”

In fact, you soon will learn, it is going to be turned into a genuine product. One with a price tag. One that you may buy back.

Think about it.

The product has shed the label “wastewater” to morph into something called “enriched water,” a term laden with many more intriguing possibilities.

“It could be a game changer for energy,” said George Hawkins, an environmentalist who became general manager of D.C. Water. “If we could turn every enriched-water facility in the United States into a power plant, it would become one of the largest sectors of clean energy that, at the moment, is relatively untapped.”

What’s nearing completion outside Hawkins’s office window, however, is something never built on this scale anywhere in the world. A decade of study came first, and to see whether the system would work here, D.C. Water paid smaller European utilities that use the same process to modify their product so it more closely matched that which Washington produces.

“We’re confident that this model will work,” Hawkins said.

Something called the Cambi, for the Norwegian company that builds it, sits at the heart of it.

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When the product flows into the more than 150-acre plant known as Blue Plains, it goes through a couple of mesh filters to shed the debris swept up in the sewer system. Then it goes through a treatment process that turns it into what the Environmental Protection Agency categorizes as class B waste, enough to fill 60 big dump trucks with 1,600 tons of product every day.

And out the gate it goes, at a cost of $16 million a year.

That will change in May and June, as D.C. Water begins a phase-in intended to get the new system into full service by January.

Here’s how it works:

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A centrifuge drains off the liquid, and then the screened product will flow into four pulpers, tall stainless steel vats that look like Gulliver’s soda cans. Steam recycled from farther down the process is used to preheat it, and then it flows into one of the two dozen Cambis. They sit like a row of gleaming, blunt-nosed rockets, but they serve as pressure cookers.

The product is heated to more than 320 degrees under as much as 138 pounds of pressure for 22 minutes. Then it moves to a flash tank, where the temperature and pressure drop dramatically and a critical change takes place.

“Because of that pressure difference, the cells burst,” said Chris Peot, director of resource recovery at D.C. Water.

When the cells burst, the methanogens can have their way with them.

That happens in the digesters. They are four huge concrete vats, 80 feet tall and 100 feet in diameter. Right now, their interiors are like vast cathedrals, with domed ceilings and a shaft of light glancing through a hole in the top.

When the whole operation gets rolling, inside them is not a place you would want to be. The product will flow in from the four flash tanks, mixing with the methanogen microorganisms. Methanogens create marsh gases. In the digestive tracts of animals and humans, they also create gas, to the particular delight and fascination of middle-school boys.

That’s what this is all about — creating methane to generate electric power.

The temperature inside the digesters is kept at about that of the human body: 98.6 degrees Fahrenheit. Each digester chamber has five vertical blue tubes, as big around as manhole covers, that suck the product from the bottom and recycle it to near the top. After the product stews there for about two weeks, the methane produced by the process will vent out a 12-inch diameter pipe in the crown.

After a bit more purification, the methane will be used to fire three jet turbine engines that create electricity. A byproduct of that process: steam, which is funneled back to the pulper.

The power portion of the plant will be operated under contract by Pepco. The deal doesn’t allow D.C. Water to sell the power it generates, a moot point since the process of creating it eats up 3 megawatts and the remaining 10 megawatts will be sucked up by operations at Blue Plains.

Once the digester’s work is done, the remaining product will be drained out into dump trucks, but their total load will be cut in half to about 600 tons a day.

Remember that we told you earlier that what you jettison disappears forever? Let’s reconsider that, because there’s actually a chance you’ll see it again. In a strikingly different form. Right back where you saw it first: on your dinner table.

The product that has been trucked from Blue Plains is rated class B. But the product that comes out of the digester will be rated class A.

The difference?

Class B still has some bad stuff in it. Most of it is shipped to farmers, some in Maryland but most of them in Virginia. They get it free, but unless they let it sit for at least a month, and sometimes up to 18 months, the only things they can use it to fertilize are trees and sod used by landscapers.

Class A product can be used right away on anything, including fields that grow the fruits and vegetables you buy at the grocery store and serve for dinner.

That’s because, Peot says, in the Cambi, “All the pathogens are completely obliterated.”

“Our product has these super-elevated levels of these naturally occurring, extremely important plant hormones,” Peot said.

It is a more environmentally sound choice than the chemical fertilizer alternatives. In the raw, the class A product is so potent it needs to be cut with other materials before it is used to fertilize crops.

“We can blend this with sawdust and sand and make a topsoil substitute for use in green infrastructure projects,” Peot said. “We’re still going to go to farms while we try to build the market for this product.”

Hawkins, D.C. Water’s general manager, chimed in: “It’s clean, organic fertilizer. Conceivably, we could sell this product at Home Depot. ”

Unlike most innovations in waste treatment locally and nationwide, this project was not mandated by a federal court order. D.C. Water’s board decided it was a worthwhile investment of ratepayers’ money.

“This was one of the easier $500 million decisions that we’ll ever ask the board to make,” Hawkins said, ticking off the value: a savings in electrical costs of about $10 million a year; lowering the cost of hauling away treated waste; the potential to generate a profit by selling the product; a reduction by one third in the plant’s carbon footprint; and one more critical virtue.

For about three days a month ago, residents of part of Northwest Washington were told to boil their drinking water for fear it might be contaminated. That scare was caused by a power problem that shut down a pumping station.

“It wasn’t Pepco’s problem. It was internal to us,” Hawkins said. “We have great fears here about what would happen if there was a catastrophic power failure and Blue Plains stopped.”

Generating power internally will provide enough juice to keep the basics running, were that to happen, he said.

“This is the rare combination of both environmentally and economically positive,” Peot said.

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A Cambi installation in the UK

Zero Energy Buildings: They May Be Coming Sooner Than You Think

Buildings account for approximately 40 percent of the energy (electrical, thermal) used in the U.S. and Europe, and an increasing share of energy used in other parts of the world. Most of this energy today is fossil-fuel based. As a result, this energy use also accounts for a significant share of global emissions of carbon dioxide.

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Source: U.S. Department of Energy, Buildings Energy Data Book

These simple facts make it imperative that buildings, along with transportation fleets and power generation, be primary targets of reduced global energy and fossil fuel demand. This blog post discusses one approach in buildings that is gaining increasing visibility and viability, the introduction of net zero energy buildings and the retrofit of existing buildings to approach net zero energy operation. A net zero energy building (NZEB or ZEB) is most often defined as a building that, over the course of a year, uses as much energy as is produced by renewable energy sources on the building site. This is the definition I will focus on. Other ZEB definitions take into account source energy losses in generation and transmission, emissions (aka zero carbon buildings), total cost (cost of purchased energy is offset by income from sales of electricity generated on-site to the grid), and off-site ZEB’s where the offsetting renewable energy is delivered to the building from off-site generating facilities. Details on these other definitions can be found in the 2006 NREL report CP-550-39833 entitled “Zero Energy Buildings: A Critical Look at the Definition”.

The keys to achieving net zero energy buildings are straight forward in principle: first focus on reducing the building’s energy demand through energy efficiency, and then focus on meeting this energy demand, on an annual basis, with onsite renewable energy – e.g., use of localized solar and wind energy generation. This allows for a wide range of approaches due to the many options now available for improved energy efficiency in buildings and the rapidly growing use of solar photovoltaics on building roofs, covered parking areas, and nearby open areas. Most ZEB’s use the electrical grid for energy storage, but some are grid-independent and use on-site battery or other storage (e.g., heat and coolth).

A primary example of what can be done to achieve ZEB status is NREL’s operational RSF (Research Support Facility) at its campus in Golden, Colorado, shown below.

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It incorporates demand reduction features that are widely applicable to many other new buildings, and some that make sense for residential buildings and retrofits as well (cost issues are discussed below). These include:
– optimal building orientation and office layout, to maximize heat capture from the sun in winter, solar PV generation throughout the year, and use of natural daylight when available
– high performance electrical lighting
– continuous insulation precast wall panels with thermal mass
– windows that can be opened for natural ventilation
– radiant heating and cooling
– outdoor air preheating, using waste heat recovery, transpired solar collectors, and crawl space thermal storage
– aggressive control of plug loads from appliances and other building equipment
– advanced data center efficiency measures
– roof top and parking lot PV arrays

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U.S. ZEB research is supported by DOE’s Building America Program, a joint effort with NREL, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, and several industry-based consortia – e.g., the National Institute of Building Sciences and the American Institute of Architects. Many other countries are exploring ZEB’s as well, including jointly through the International Energy Agency’s “Towards Net Zero Energy Solar Buildings” Implementing Agreement (Solar Heating and Cooling Program/Task 40). This IEA program has now documented and analyzed more than 300 net zero energy and energy-plus buildings worldwide (an energy-plus building generates more energy than it consumes).

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An interesting example of ZEB technology applied to a residential home is NREL’s Habitat for Humanity zero energy home (ZEH), a 1,280 square foot, 3-bedroom Denver area home built for low income occupants. NREL report TP-550-431888 details the design of the home and includes performance data from its first two years of operation (“The NREL/Habitat for Humanity Zero Energy Home: a Cold Climate Case Study for Affordable Zero Energy Homes”). The home exceeded its goal of zero net source energy and was a net energy producer for these two years (24% more in year one and 12% more in year two). The report concluded that “Efficient, affordable ZEH’s can be built with standard construction techniques and off-the-shelf equipment.”

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The legislative environment for ZEB’s is interesting as well. To quote from the Whole Building Design Guide of the National Institute of Building Sciences:
“Federal Net Zero Energy Building Goals
Executive Order 13514, signed in October 2009, requires all new Federal buildings that are entering the planning process in 2020 or thereafter be “designed to achieve zero-net-energy by 2030”. “In addition, the Executive Order requires at least 15% of existing buildings (over 5,000 gross square feet) meet the Guiding Principles for Federal Leadership in High Performance and Sustainable Buildings by 2015, with annual progress towards 100% conformance”.
Two milestones for NZEB have also been defined by the Department of Energy (DOE) for residential and commercial buildings. The priority is to create systems integration solutions that will enable:
Marketable Net Zero Energy Homes by the year 2020
Commercial Net Zero Energy Buildings at low incremental cost by the year 2025.
These objectives align with the Energy Independence and Security Act of 2007 (EISA), which calls for a 100% reduction in fossil-fuel energy use (relative to 2003 levels) for new Federal buildings and major renovations by 2030.”

A word about cost: ZEB’s cost more today to build than traditional office buildings and homes, but not much more (perhaps 20% for new construction). Of course, part of this extra cost is recovered via reduced energy bills. In the future, the zero energy building goal will become more practical as the costs of renewable energy technologies decrease (e.g., PV panel costs have decreased significantly in recent years) and the costs of traditional fossil fuels increase. The recent surge in availability of relatively low cost shale gas from fracking wells will slow this evolution but it will eventually occur. Additional research on cost-effective efficiency options is also required.

To sum up, the net zero energy building concept is receiving increasing global attention and should be a realistic, affordable option within a few decades, and perhaps sooner. ZEB’s offer many advantages, as listed by Wikipedia:
“- isolation for building owners from future energy price increases
– increased comfort due to more-uniform interior temperatures
– reduced total net monthly cost of living
– improved reliability – photovoltaic systems have 25-year warranties – seldom fail during weather problems
– extra cost is minimized for new construction compared to an afterthought retrofit
– higher resale value as potential owners demand more ZEBs than available supply
– the value of a ZEB building relative to similar conventional building should increase every time energy costs increase
– future legislative restrictions, and carbon emission taxes/penalties may force expensive retrofits to inefficient buildings”

ZEB’s also have their risk factors and disadvantages:

“- initial costs can be higher – effort required to understand, apply, and qualify for ZEB subsidies
– very few designers or builders today have the necessary skills or experience to build ZEBs
– possible declines in future utility company renewable energy costs may lessen the value of capital invested in energy efficiency
– new photovoltaic solar cells equipment technology price has been falling at roughly 17% per year – It will lessen the value of capital invested in a solar electric generating system. Current subsidies will be phased out as photovoltaic mass production lowers future price
– challenge to recover higher initial costs on resale of building – appraisers are uninformed – their models do not consider energy
– while the individual house may use an average of net zero energy over a year, it may demand energy at the time when peak demand for the grid occurs. In such a case, the capacity of the grid must still provide electricity to all loads. Therefore, a ZEB may not reduce the required power plant capacity.
– without an optimised thermal envelope the embodied energy, heating and cooling energy and resource usage is higher than needed. ZEB by definition do not mandate a minimum heating and cooling performance level thus allowing oversized renewable energy systems to fill the energy gap.
– solar energy capture using the house envelope only works in locations unobstructed from the South. The solar energy capture cannot be optimized in South (for northern hemisphere, or North for southern Hemisphere) facing shade or wooded surroundings.”

Finally, it is important to note that the energy consumption in an office building or home is not strictly a function of technology – it also reflects the behavior of the occupants. In one example two families on Martha’s Vineyard in Massachusetts lived in identical zero-energy-designed homes and one family used half as much electricity in a year as the other. In the latter case electricity for lighting and plug loads accounted for about half of total energy use. As energy consultant Andy Shapiro noted: “There are no zero-energy houses, only zero-energy families.”