“Natural” Gas: Methane Energy

What Is It, and How Does It Produce Electricity?

Methane has been mentioned in several other sections of this book—bio waste, MSW, bio crops, etc. Methane is the biggest single component of the mixes of gas we call natural gas and synthetic gas (syngas). Like natural gas and hydrogen, methane is an efficient, easy – to-transport, and easy-to-store fuel.

It would seem that methane is a good thing, right? Wrong! Methane is a giant problem. Methane traps heat in the atmosphere far better than does C02. In fact, methane is 23 times more damaging to the environment than is C02. Natural and artificial releases of methane could easily swamp any human efforts to limit global warming by limiting C02.

Methane is a resource we need to use. It naturally seeps to the arctic surface and billows up from livestock facilities to create a dangerous atmospheric pollutant. If we don’t capture it and burn it, it will accelerate global warming.

Where do these releases of methane come from? Methane is naturally produced and released by farm animals, garbage landfills, and the vast stretches of Arctic tundra. One ton of municipal waste in the landfill, for example, can produce 125 cubic meters of methane (the energy equivalent of one barrel of oil).

A new concept is to stop treating these methane-rich dumps as a problem, as environmental ticking time bombs, and look on them as valuable energy resources.

Researchers have recently discovered that more than a trillion tons of methane lie trapped in permafrost and under frozen lakes in the Arctic. As the world (especially the Arctic) warms, and the Arctic tundra thaws, that gas is bubbling out. The U. S. Geological Survey (USGS) estimates that hydrates (methane locked in ice) could contain more organic carbon than all the world’s coal, oil, and nonhydrate natural gas combined! Scientists at the University of Alaska at Fairbanks have spent several years mapping and measuring the hot spots for methane release in rapidly melting regions of Alaska and Siberia.

The problems with capturing and using this immense storehouse of energy (before it escapes and accelerates climate change and global warming) are that these hydrates are fairly evenly spread across hundreds of thousands of square miles of the forbidding Arctic landscapes, and that this energy resource lies very far from any population centers that could use the energy. It has to be collected and then transported (either as methane gas or as electricity) to major urban centers, often thousands of miles away.

Two other ready sources of methane exist. The first is landfills. The garbage in landfills decomposes over time. That decomposition produces gas. Landfill gas is typically 60 percent methane and 40 percent C02. Capturing the landfill gas from all landfills in this country could easily supply 1 to 2 percent of the nation’s electrical energy (while saving the atmosphere from receiving many thousands of tons of greenhouse gases). Utility companies can drill

perforated pipes into and throughout a landfill. Pumps create a partial vacuum that lets gas percolate into the pipe and be sucked to a processing plant, where the methane is burned to produce electricity and the C02 is captured to be pumped deep underground.

The final ready source of methane is livestock operations. A typical dairy cow burps ten cubic feet of methane each day. Cow manure is also rich in methane. It is relatively easy to capture much of this methane and use it to power a farm. No one envisions using these tiny power plants to supply electricity to the national electric grid. But they will supply all of a farm’s on-site electrical needs and, like any conservation measure, eliminate the farm’s need to draw power from the grid. Thus, they will significantly reduce the total demand for electricity.

What’s Happening Now?

In late 2007 Sudbury, Ontario, utilities launched a 1.2 Mw methane plant using methane mined from the local municipal landfill and increased its capacity to 1.6 Mw in 2009. The BMW car assembly plant in Spartanburg, South Carolina, just expanded its methane co­generation plant using methane from a nearby landfill. This 11 Mw plant produces 30 percent of the facility’s electricity and 60 percent of its hot water. As of 2005, the United States had 399 landfill methane recovery plants. The number increased to 519 in 2008. (With 73 such plants, California has the most of any state. Alaska, Nevada, and Wyoming are the only states without any.) Most of these facilities produce methane as a fuel for transportation. However, 61 of them produced electricity as of 2008, and more electric landfill plants are planned and being built.

California has 1,950 dairies and 1.85 million dairy cows. Each cow produces an average of 120 pounds of manure each day. These cows have the potential to provide electricity to 400,000 homes (in addition to milk, cheese, ice cream, and yogurt)! Fourteen dairies have created covered manure ponds where they collect the methane to run electric generators. A typical dairy methane system produces 75 to 100 kw of electricity (with the generator’s waste heat used to warm the manure pond to increase methane production). Two pig farms in San Diego County (each with over 1,000 hogs) have installed similar systems, and each produces 50 kw of electricity.

How Does It Measure Up?

(The Good, the Bad, and the Ugly)

On the plus side for methane:

• Methane is now a free energy resource.

• Burning methane to produce electricity prevents it from getting into the atmosphere, where it would be a dangerous greenhouse gas.

• Methane from landfills and livestock operations is renewable.

• Methane can be directly used in any power plant now using natural gas.

On the negative side for methane:

• Methane is still a hydrocarbon. Burning methane does release some carbon (C02).

What’s the Bottom Line? (How Much Can It Help?)

• Potential: Methane will never be a major contributing fuel source to the national electric grid. It is most unlikely that methane will ever contribute more than 1 percent to the national grid. But it could supply a significant amount of regional electric energy for Alaska, and using it does double good for the environment.

• Key Factors: The Arctic tundra is too far from demand centers. Livestock operations rarely produce enough methane to meet more than their own electrical demand.

• Timeline: Over the next 20 years, look for methane plants at landfills to continue to rapidly increase and for more farming and ranching operations to use their methane to meet on-site electrical needs.

Classroom Activities

Methane is another in the long line of burnable hydrocarbon gases. Let’s start with a quick look at hydrocarbon gases in general.

1. First, what is a gas? Look up the definition and be sure to include how a gas differs from a liquid and a solid. Hydrogen, propane, natural gas, and methane are all gases. Can they also be liquids and solids? Under what conditions does methane become a liquid? A solid? Do we ever liquefy gasses for transport? How and why?

Methane is not only a gas, it is a hydrocarbon gas. What is a hydrocarbon, and why are they called hydrocarbons? We use many of the simple hydrocarbons every day. Look up the names of the simple hydrocarbon chains (those with one-eight carbon atoms in each molecule). How many of these names do you recognize? Which is used in most cigarette lighters? Which is used to measure the quality of gasoline?

Notice that “natural gas” is not on this list. Natural gas is not a single gas. It is a mixture of other simple hydrocarbons, primarily methane, ethane, and propane. Research the heat and burning properties of these simple hydrocarbons. Where does methane fit into this group? Is there any difference between burning pure methane and burning natural gas, propane, or butane?

Now the big questions: Why do we commonly use natural gas and propane as fuels and not the other simple hydrocarbons (including methane)? Who uses methane gas, and for what specific processes? Would it make sense to use methane more if it were readily available? Research these questions at the library and online. Then try to interview local high school or college chemistry teachers to get their answers.

2. Here are three additional methane topics for research, discussion, and debate:

• Is it good or bad to rely on natural gas for electrical production? Increasingly, utility companies are building new natural-gas-fired power plants to replace older coal-fired plants for electric production. They are both fossil fuels. Natural gas, like coal and oil, is a nonrenewable resource. Aren’t they all going to run out? Why should we build power plants that use any nonrenewable fuel?

• The biggest current sources of methane for electrical production are landfills and dairy/cattle operations. Contact and survey local dairy or other livestock farming operators. Do they try to capture the methane their livestock produce? How much methane do they collect? If they use it for electrical generation, how much electricity do they create?

• Arctic hydrates are a worrisome future source of methane. What is methane hydrate? Research methane hydrates. Where are they? How and when was methane trapped in ice crystals locked in the Arctic permafrost? Why are scientists worried about these methane hydrates melting? What will happen to the methane if we can’t collect and use it? How big is this energy resource, and what plans exist to collect and use it?

For Further Reading

DeGunther, Rik. Alternative Energy for Dummies. San Francisco: For Dummies Press, 2009.

Fry, John. Practical Building of Methane Power Plants for Rural Energy Independence. Mechanicsville, PA: Fry Publishing, 1999.

Gibilisco, Stan. Alternative Energy Demystified. New York: McGraw-Hill, 2006.

Johnstone, Hugh. Facts on Future Energy Possibilities. New York: Scholastic Library, 1999.

National Research Council. Charting the Future of Methane Hydrate Research in the United States. Washington, DC: National Academies Press, 2004.

Royston, Angela. Sustainable Energy. London: Arcturus Publishers, 2010.

Sechrist, Darren. Powerful Planet: Can Earth’s Renewable Energy Save Our Future? New York: Gareth Stevens Publishing, 2009.

Web Sites

www. nytimes. com/2008/09/24/…/24farmers. html

A good article on use of animal wastes to generate on-site electricity.

www. anaerobic-digestion. com/…/electridty_from_methane_diges. ph

A description of a process for creating methane and converting it into electricity.

marine. usgs. gov/fact-sheets/gas-hydrates/title. html

Government site assessing the magnitude of and potential problems with Arctic methane hydrates.

www. powerscorecard. org/tech_detail. cfm? resource_id=5

A good assessment of the pros and cons of using methane from landfills for power generation.

www. ornl. gov/reporter/no16/methane. htm

A good site on methane hydrates.

https://www. llnl. gov/str/Durham. htm

Another description of the sources and uses of methane hydrates.

Updated: October 23, 2015 — 12:39 pm