The Hydrogen Economy, Hydrogen Sources, and the Science Behind These

The hydrogen-filled Hindenburg in 1936 or 1937. Photo from DeGolyer Library at Southern Methodist University.


The hydrogen economy is a hypothetical future in which energy can be bought, sold, stored, and transported in a currency of hydrogen, much like today’s energy is often exchanged in electricity. Because hydrogen doesn’t need to be attached to the electricity grid, it can be used in forms of transportation like buses and cars.

The end-user of the hydrogen, for example an automobile driver, doesn’t experience significant pollution beyond the formation of water from burning the hydrogen.

For more details about the hydrogen economy see here.

Hydrogen, a gas, isn’t a fuel like gasoline or coal; hydrogen is a way to store and transport energy made from other fuels, like a battery or electricity. Unlike fossil fuels, pure hydrogen isn’t stable, so forming hydrogen in the first place requires energy and produces carbon dioxide, and storing hydrogen involves special considerations because this light gas is very flammable and also quickens rust and oxidation in pipelines and storage containers.


Allowing hydrogen (a gas) to burn in the presence of oxygen releases that stored energy in the form of heat. Hydrogen can also be reacted in a fuel cell to produce electricity. In either case, electricity or heat can then be used to power cars or any number of other devices. Gasoline, biofuels, wood, and other carbon-based fuels all produce carbon dioxide when they are burned, and rising carbon dioxide levels are widely implicated in climate change. Burning hydrogen produces energy, water and a few trace compounds, but it doesn’t produce carbon dioxide.

2 H2 (hydrogen gas) + O2 (oxygen gas) = 2 H2O (water vapor) + energy

It’s unclear what widespread emission of water vapor could do. According to recent published estimates, atmospheric water vapor is responsible for 75 percent of the greenhouse effect. However, water vapor can condense, and it’s naturally-occurring in the atmosphere. It is much easier to trap and transform to liquid than the carbon dioxide normally emitted by burning gasoline. Carbon dioxide won’t form a liquid at atmospheric temperatures and will solidify into dry ice only below -108.4 Fahrenheit, so proponents say it can be easier to trap the vapor in hydrogen-powered machines.

If the energy used to generate and purify and store and ship hydrogen doesn’t require emitting greenhouse gases or toxics, proponents argue that hydrogen is a clean alternative.


Hydrogen, not carbon, is the most prevalent atom in the human body. There are two hydrogen atoms in every water molecule, and as many as hundreds of hydrogen atoms on the basic building blocks of life, from DNA to plant fibers. Nonetheless, harvesting the hydrogen atoms out of any of these structures to make hydrogen fuel isn’t easy because hydrogen likes to be bonded to carbon or oxygen; it doesn’t like to be elemental gas.

To produce pure hydrogen today, industries use primary fuel source like petroleum, natural gas, coal, or biomass. Through chemical processing, the hydrogen atoms are stripped from the fuel by way of an input of energy from electricity (more than 80 percent of which comes from fossil fuels in the United States). Furthermore, the leftover material from the stripping is carbon dioxide, the same carbon dioxide that would have been produced if the fuel was burned in an engine.

The reactions for various fuel to hydrogen conversions can be found on the U.S. Department of Energy website here.

Hydrogen can also be produced, at great energy loss, through the electrolysis of water: using electricity, water is divided into its constituents, hydrogen and oxygen. However, water electrolysis is the least carbon-neutral hydrogen production method, and it is very expensive ($3 to $6 per kilogram instead of a little more than $1 in the case of using coal for hydrogen), according to the U.S. Energy Information Administration. All hydrogen production methods result in a net energy loss.



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What Is A Nuclear Reaction?


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Photovoltaic Cells, Solar Power, and LEDs

Most of the world’s energy can go back to our sun. Every day we are heated by its electromagnetic rays, and plants use the sun’s energy to make sugars and ultimately proteins and other good things to eat. Fossil fuels were also once made from these plant and other organisms that relied on the sun’s energy millions of years ago. Today, humans can convert the sun’s energy directly into electricity, through solar thermal and solar photovoltaic systems.


Solar panels, also called solar thermal, convert sunlight to heat and then heat to electricity. Photovoltaic cells, or solar cells, convert sunlight directly into electric current by way of carefully-engineered semiconductor materials.

Though solar photovoltaics are more efficient converters of sunlight, they are also more expensive.

As of May 2011, the world’s largest solar power plant is a concentrating solar thermal power plant in the Mohave desert in California. Solar Energy Generating Systems has a capacity of 310 megawatts and uses parabola-shaped reflective troughs to concentrate electromagnetic radiation.

The world’s largest solar photovoltaic plant is probably the Sarnia Solar Project in Ontario, Canada. It has a capacity of roughly 80 megawatts.


Sunlight heats a design element (water, air, chemical fluids), and that thermal energy is transmitted for other applications, such as heating water, heating space, or generating electricity. In solar thermal power plants, sunlight heats a specialized fluid, which in turn heats water into steam, which can run turbines and produce electricity.

Solar thermal power plants use concentrators that bounce the sunlight off elliptical mirrors to a central tube, in which the specialized fluid lies.


Photovoltaic cells are made of specialized diodes. Electrons (natural components of atoms) in the photovoltaic cells absorb light, which excites them to a state where they can be conducted as electrical current. This difference in energy, between the valence band (the state of a normal electron staying around its home atom) to the conduction band (electron free to move between atoms) is called the band gap.

Solar photovoltaic farm in Indonesia. Photo by Chandra Marsono.

Well-engineered photovoltaics have a band gap that coincides with the energies of as broad a spectrum of light as possible, to convert the maximum amount of the sunlight into electricity.

As sunlight energy pops electrons into the conduction band and away from their home atoms, an electric field is produced. The negatively-charged electrons separate from the positively-charged “holes” they leave behind, so that when electrons are freed into the conduction band, they move as electric current in the electric field, electricity.


An ever-expanding variety of semiconductor materials can be used to make solar cells; universities and companies worldwide are researching these options, from special bio-plastics to semiconductor nanocrystals. Nonetheless, the photovoltaic cells available today require precise manufacturing conditions and are therefore far more expensive to produce than solar panels.

Silicon has to be processed under clean room conditions — carefully regulated atmospheres — to remove impurities and prevent introducing contaminants, both of which can change the band gap. Thin film-based photovoltaics require special production methods, like chemical vapor deposition. Semiconductor processing also uses strong acids and often dangerous chemicals for etching.

Today, commercially-sold cells are made from purified silicon or other crystalline semiconductors like cadmium telluride or copper indium gallium selenide.


Silicon is plentiful in the Earth’s crust. Cadmium is a readily available but highly toxic heavy metal, as is arsenic, another chemical used in some cells. As tellurium demand is only recently rising in response to solar demand, it’s unknown what the global supply is for this unusual element but it may be quite abundant. Photovoltaics are a lively area of research, and the future production and environmental costs of starter materials, production, and pollution are difficult to predict.

California, Massachusetts, Ohio, and Michigan produced the most photovoltaics in 2009. However, that year, 58 percent of photovoltaics were imports, primarily from Asian countries like China, Japan, and the Philippines.


Photovoltaic cells work in the opposite direction of light-emitting diodes, or LEDs. LEDs are used interchangeably with other lighting, like light bulbs. However, LED’s work in a completely different manner, far closer to the way photovoltaics work.

Click here see a bar chart comparing how much energy is used by various light sources.

LEDs absorb energy in the form of electricity, exciting electrons into the conduction band. When the electrons in the semiconductor material drop back into the valence band from the conduction band, they emit energy in the form of photons, or electromagnetic radiation.

It’s a highly efficient process because energy isn’t wasted on producing heat, which happens with standard tungsten filament bulbs. LEDs also last a much longer time as they do not have filaments to burn out, and because they are very small and several units are used to replace one large traditional lamp, they do not all burn out at once. That makes LEDs a good choice for stoplights or other safety critical applications.


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The Global Energy Mix and Policies

 On this page, you can find energy information about the world’s most populated countries: China, India, the United States, Indonesia, Brazil, Pakistan, Bangladesh, Nigeria, Russia, and Japan. For fossil fuel information about any country, see online tables here.

A nation’s sources of energy hinge on so many factors, from what’s naturally available to geography, political history, and relative wealth.

Even though energy demand is increasing rapidly across the globe, the International Energy Agency estimates a fifth of the world population lacks access to electricity, and a whopping 40 percent of people still use traditional biomass – like wood chips – for cooking. People who live without the energy infrastructure of electricity depend on portable petroleum fuels, manure and methane gas produced from manure, wood, grass, and agricultural wastes. Because these sources of energy are informal, it’s difficult to track and include them in statistics.

World electricity and energy demands are escalating. Countries are expanding energy investment to non-fossil sources like biofuels, wind, solar, and geothermal. At the same time, they are competing to secure access to coal, natural gas, and petroleum both at home and abroad.


Nowhere has rapid energy growth been more conspicuous than in the world’s most populated country, China. While most countries saw moderate energy growth in the same period, this Asian nation doubled energy use in less than a decade – see graph – and surpassed the United States in total energy use in 2009, according to International Energy Agency estimates. Until 2009, the United States lead the world in total energy consumption, though not per person consumption, for decades. For a list of the top 30 countries by total energy consumption see here.

Meanwhile, less than 42 percent of people in Africa had electricity at home in 2009. South Asians seemed better off than Africans that year, at 62 percent, but the real story is much more diverse. Nearly 100 percent of Chinese had access to electricity, while in Burma, only 13 percent had access. Worldwide almost 78 percent of people had access to electricity in 2009, according to the International Energy Agency.




CHINA (Pop. 1.3 billion)

Between 2008 and 2035, China may triple its electricity demand, adding power plant capacity equal to the current U.S. total, the International Energy Agency projects in one scenario of the 2010 World Energy Outlook.

China is the world’s most populated country and also the world’s largest energy consumer. China gets most of its energy from coal, 71 percent in 2008. China is also the world’s biggest coal producer but only third, behind the United States and Russia, in coal reserves.

In 2008, China generated another 19 percent of its energy from oil, which it imported from all over the world, more than half came collectively from Saudi Arabia, Angola, Iran, Oman, Russia, and Sudan. China used to export its oil, but by 2009 automobile investment was expanded by so much, the country became the second largest oil importer (United States is first).

China is in hot pursuit of securing as much oil as possible, as the nation’s reliance on imported oil is growing far more rapidly than its oil production. Several powerful, national oil companies provide the domestic oil, both from on and off-shore sources. Furthermore, China has purchased oil assets in the Middle East, Canada, and Latin America, and it also conducts oil-for-loan exchanges with other countries, $90 billion worth since 2009, according to the U.S. Energy Information Administration.

Only a small proportion of China’s energy comes natural gas, produced domestically and imported in liquified form, but that may change as prices lower and liquified natural gas terminals are constructed.

China is the world’s biggest user of hydroelectric power, which made up 6 percent of energy and 16 percent of electricity in 2009. The country’s Three Gorges Dam, the world’s largest hydroelectric project, is expected to begin operating in 2012. Nuclear power accounts for only 1 percent of total consumption. However, China’s government predicts it will have seven times its current nuclear capacity by 2020.

A homemade oven. West Bengal, India, 2009.

Detailed data on energy in China can be found here.







INDIA (1.2 billion)

India is the world’s largest democracy. Though India’s population is close to that of China’s, it is only the world’s fifth largest energy user, behind the United States, China, Russia, and Japan.

Like China, India’s electricity comes mostly from coal. However, India doesn’t have enough electricity for everyone, and only 65 percent of the population has access to electricity.

Instead, many Indian use fuels at home for lighting and cooking. A 2004-2005 survey by the government found more than 40 percent of rural Indians used kerosene instead of electricity for home lighting. The same survey showed that for cooking, 74 percent of Indians used firewood and wood chips, 8.6 percent used liquified petroleum gas, 9 percent used dung cakes, and 1.3 percent used kerosene.

India produces oil domestically, but like China, the rate of India’s increasing oil consumption far outstrips its production. India therefore has to import oil; in 2009 its most significant sources were Saudi Arabia, Iran, Kuwait, Iraq, the United Arab Emirates, Nigeria, Angola, and Venezuela, in descending order.

India doesn’t have the electricity capacity to serve its population but aims to add many thousands of megawatts in the near future.

Like China, India has nuclear power, with 14 nuclear plants in operation and another 10 in planning, the reactors purchased from France and Russia.


UNITED STATES (300 million)

Until China recently outpaced it, the United States was the biggest energy consumer in the world, though per capita use isn’t the highest but in the same range as several developed countries worldwide and less than the per capita use in Canada. The United States relies on petroleum, coal, and natural gas, as well as a small part nuclear, hydroelectric, and various non-fossil sources. The Unites States has significant oil, coal, and natural gas reserves, as well as the potential for significant investment in solar, off and on-shore wind, and biofuels.

The mix of fuels that provide electricity varies widely from region to region. Find a map of fuel mix by U.S. region from the Edison Electric Insitute here.

For more U.S. information:

-Fossil fuel use in the United States, go here.
-U.S. greenhouse gas emissions and energy here.
-U.S. sources of energy, see here.


INDONESIA (250 million)

Indonesia is an archipelago of more than 17,000 islands — 6,000 are inhabited — and it is home to 76 active volcanoes and a significant undeveloped geothermal capacity, estimated at 28 gigawatts, about as much total electricity capacity as Indonesia had in 2008.

Indonesia’s energy demand is growing rapidly, split between coal, natural gas, and petroleum sources. Traditional sources of energy like wood and agricultural waste continue to be used, particularly in rural areas and remote islands, and the International Energy Administration estimates these fuels provide about a quarter of the country’s energy.

Indonesia exports coal and natural gas. In the past, the country also exported more oil than it used, but as of 2004 that balance changed. By 2009, the country suspended its membership in the Organization of Petroleum Exporting Countries (OPEC) because it was using so much of its own oil.


BRAZIL (200 million)

Tropical Brazil is the largest country in South America both in area and population, and it is the third largest user of energy in the Americas, after the United States and Canada.

Made from sugar cane, Brazil’s ethanol production is the world’s second largest, after the United States, which makes ethanol from corn.

Brazil produces almost as much petroleum as Venezuela and produces slightly more fuel than it consumes.

While Brazil depends on oil for other energy applications like transportation, the country gets an astounding 84 percent of electricity from hydroelectric dams. Brazil also has two nuclear power plants.

PAKISTAN (190 million)

Pakistan has limited access to electricity and energy sources, and its rural population still relies on gathered fuels like wood for heating and cooking.

In 2009 around 60 percent of the population had access to electricity, far better than its neighbor Afghanistan, at just 15 percent. Nonetheless, even with access, most of the population can’t rely on electricity unless they are wealthy enough to own generators. Pakistan suffers from lengthy blackouts, even in its cities, in part because of poor transmission infrastructure and widespread electricity theft. The situation is also aggravated by lack of capacity planning, insufficient fuel, and irregularities in water supply for hydroelectric.

In 2010, angry citizens protested violently after lengthy blackouts — as long as 18 hours according to Reuters — plagued the country. That summer, Pakistan has nowhere near enough electricity for its peak needs, which were roughly 25 percent more than its total production capacity. The widespread blackouts crippled the country’s textile industry, its biggest source of exports, and some reports suggest that hundreds of factories were shuttered as a result of sporadic power.

Meanwhile, several proposals for gas pipelines through Pakistan have yet to get solidified, including one from Iran to Afghanistan (which is opposed by the United States).


BANGLADESH (160 million)

Like nearby Pakistan and India, with which it shares cultural and political histories, Bangladesh also suffers from electricity shortages. Only 41 percent of Bangladeshis had access to electricity in 2009, according to the International Energy Administration.

Most of the electricity in this delta nation is generated from natural gas, with smaller amounts each from oil, coal, and hydroelectric sources. More than 30 percent of the country’s energy comes from biomass, agricultural wastes, and other combustible, renewable materials.

In 2011, Bangladesh signed a contract with oil company ConocoPhillips, allowing off-shore drilling for natural gas, despite internal protests that insisted Bangladesh should keep more of the gas for its own. The agreement gives 20 percent to Bangladesh.


NIGERIA (160 million)

Nigeria is Africa’s most populous country, and it is world famous for its oil, most of which is exported for sale by huge foreign oil companies like Royal Dutch Shell, ExxonMobil, Chevron, ConocoPhillips, Petrobras, and Statoil. Roughly 65 percent of government revenue comes from the oil sector, and around 40 percent its oil exports are sent to the United States. Nigeria also holds the largest natural gas reserves in Africa.

Extensive oil development has wreaked havoc on Nigeria’s ecology. Oil spills have polluted Nigeria’s water, affecting both fishing and agriculture. Much of Nigeria’s natural gas is flared rather than being collected and sold for fuel. Flaring involves burning off naturally-occurring gases during petroleum drilling and refining, resulting in  environmental degradation, greenhouse gas emissions and loss of revenue.

Even though Nigeria is fossil fuel-rich, only 47 percent of the population have access to electricity, and less than a fifth of energy in that country came from petroleum and natural gas in 2007, reflecting the widespread use of more traditional fuels like wood. Nigeria only used 13 percent of petroleum it produced in 2009.


RUSSIA (140 million)

Russia has significant wealth in fossil fuels, including the largest natural gas reserves and the second largest coal reserves, after the United States. In 2009, Russia produced more oil even than Saudi Arabia, mostly from Western Siberia. In 2009, Russia exported far more oil than it used, and 81 percent of its exports went to Europe, notably the Netherlands and Germany.

Russia is also the third largest consumer of energy in the world.

The country has a well-developed pipeline system to transport oil from remote regions, a system which is almost entirely controlled by a single state-run company, Transneft.

Like Nigeria, Russia flares gas in the process of drilling and refining oil, and in 2008 Russia flared more gas than any other country in the world, 1,432 Bcf of natural gas, more than double Nigeria’s output and equivalent to the annual greenhouse gas emissions for 1.4 million passenger cars, according the calculator on the U.S. Environmental Protection Agency website and data from the U.S. Energy Information Administration.

Russia operates 31 nuclear reactors, half of which employ a similar design to the ill-fated Chernobyl plant in the Ukraine.


JAPAN (130 million)

Japan doesn’t have significant fossil fuel resources, one reason that much of its electricity industry relies on nuclear power. It is the world’s third largest user of nuclear power.

Japan is the world’s third larger oil consumer, and it does produce some oil domestically. However, it also imports a lot of oil and natural gas, the later in the form of liquified natural gas, or LNG. Almost half of its energy came from imported oil in 2009, and just 16 percent of Japanese energy came from a domestic source.

Japan also invests heavily in foreign oil, including in the United Arab Emirates, the Congo, Algeria, Russia, Australia, Papua New Guinea, Brazil, Canada, the United Kingdom, Vietnam, and Indonesia, to name a few.

As of June 2011, Japan is still recovering from a massive earthquake and tsunami that devastated its northeast coast on March 11, 2011, forcing the shutdown of several nuclear reactors as well as damaging refineries, oil and gas generators, and electricity transmission infrastructure.

Japan imports most of its oil from the Middle East: Saudi Arabia, Iran, Kuwait, the United Arab Emirates, and Qatar together supplied 77 percent of imports in 2009.

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Major sources of energy/their advantages and disadvantages

There is no easy answer to what is the best source of energy or electricity. Is the priority reliability, affordability, the economy, international human rights, limiting greenhouse gas emissions, preserving environmental resources, or human health?


It’s undeniable that today — whether we like it or not — humans worldwide are overwhelmingly dependent on fossil fuels: coal, oil, and natural gas. Everything eaten, worn, lived in, and bought is tied to availability of fossil fuels. Even if 100 percent of politicians were determined to stop using them today, society has neither the electricity grid nor the vehicular and industrial technology to sustain the current American lifestyle on non-fossil sources of energy. Yet.

When comparing sources of energy, it’s easy to forget how universal fossil fuels are. These sources continue to dominate for reasons that are difficult to measure, like political influence, advertising clout, and control over energy infrastructure. Other sources have disadvantages purely because they don’t fit in as well.

Volume brings another difficulty in comparing sources of energy. There is so much more fossil energy, and it’s been used for a long time, so we know a lot more about its hazards and benefits. More modern technologies are harder to quantify. Some are renewable but still pollute (biofuels), some are very clean except in accidents or waste disposal (nuclear). Most electricity sources (renewable or not) use steam turbines, and all the water to make steam has to come from somewhere, but how important should that factor be?

Clicking the graphic above will give an abbreviated chart comparing sources line by line, but that doesn’t provide anywhere close to the whole story.

Each of the following topics compares the major sources of energy  through a different lens. Though environmental and local issues may seem the most important to those of us who don’t own power plants or utility companies, the cost of energy drives which sources are actually in place today and which sources will see investment tomorrow.












Source: U.S. Energy Information Administration

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The Connection Between Greenhouse Gases, Climate Change & Global Warming



Climate change is the shift in long-term, global weather patterns due to human action; it’s not exclusive to warming or cooling.

Climate change includes any change resulting from different factors, like deforestation or an increase in greenhouse gases. Global warming is one type of climate change, and it refers to the increasing temperature of the surface of Earth. According to NASA, the term global warming gained popular use after geochemist Wallace Broecker published a 1975 paper titled Climatic Change: Are We on the Brink of a Pronounced Global Warming?

Since 1880, the average surface temperature of the Earth has increased by roughly 0.9 degrees Fahrenheit, but the rate it’s increasing is faster than that, depending on which region you live in. If you’re closer to the equator, temperatures are increasing more slowly. The fastest increase in temperatures in the United States is in Alaska, where average temperatures have been increases by more than 3 degrees Fahrenheit per century. For a graph of average global temperatures by year, see the NASA website here.



Greenhouse gases are those thought to contribute to the greenhouse effect, an overall warming of the Earth as atmospheric gases trap electromagnetic radiation from the sun that would otherwise have been reflected back out into space.

Noteworthy greenhouse gases are methane, nitrous oxide, carbon dioxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are thought to affect the climate directly and indirectly, even though they constitute only a small fraction of the blanket of gases that make up the atmosphere.

Currently, the composition of the atmosphere is mostly nitrogen and oxygen, with just 0.033 percent carbon dioxide and all other gases accounting for even less.



According to 2010 models cited by NASA, 20 percent of the greenhouse effect is attributed directly to carbon dioxide and 5 percent to all other greenhouse gases. The remaining 75 percent of the greenhouse effect is thought to be due to water vapor and clouds, which are naturally-occurring. However, even though carbon dioxide and the other greenhouse gases are such a small percentage of the total gas in the atmosphere, they affect when, where and how clouds form, so greenhouse gases have some relevance when it comes to 100 percent of the greenhouse effect. Carbon dioxide is thought to modulate the overall climate, like a atmospheric thermostat.

Some greenhouse gases are produced in natural processes, like forest fires, animal manure and respiration, or volcanic eruptions. However, the majority of new greenhouse gases are produced from industrial processes and energy production.

The four largest human sources of U.S. greenhouse gases in 2009 were energy, non-fuel use of fossil fuels, natural gas production, and cement manufacture, in descending order. Non-fuel, greenhouse gas-producing applications of fuels include industrial production like asphalt, lubricants, waxes and other . Emissions related to cement manufacture happen when limestone (calcium carbonate) is reacted with silica to make clinker, the lumps ground to make cement. ( Emissions of Greenhouse Gases in the United States 2009: Independent Statistics & Analysis.)

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Ocean Energy

You don’t have to talk about hurricanes and tsunamis to know that the oceans are powerful. People have dreamed about harnessing their energies for centuries, and today there are many projects worldwide experimenting with just how to plug into the oceans.

However, ocean energy projects are expensive because of the nature of their energy source. The salty seas can be corrosive, unpredictable, and destructive.

Several aspects of the ocean’s energy can be exploited to generate power;  we’re not limited to the crashing waves. The three most well-developed ideas are tidal power, wave power, and ocean thermal energy conversion.

There are many different projects in various stages of development in coastal states today. However, as yet, ocean energy isn’t a significant source of energy nationally.

Ocean energy is renewable, and it’s clean because of its lack of emissions. However, using ocean energy along coastlines can cause conflict with other coastal uses – transportation and scenic oceanfront – and ocean energy can as affect marine life and environmental conditions.



Wave energy capitalizes on the power of waves as they roll through the ocean. There are small wave systems generating small amounts of electricity today, though the development costs are high and it is difficult to design equipment that can withstand the salt water, weather and water pressures.

Systems have to be designed for average waves but must also withstand the much stronger waves that occur in seasonal storms and the extreme waves that appear only rarely. Waves shift direction, so systems are designed to move to optimize direction.

Prototype plants currently operating have capacities of fractions of a megawatt, which is the tiniest drop in the bucket compared to average-sized power plants in the hundreds of megawatts.

There are over 100 wave energy technologies in various states of planning and testing or in operation as prototypes. However only one type is operating commercially, the Pelamis Wave Power, according to the World Energy Council.

In the United States there are other projects in planning or testing in Hawaii, New Jersey, Oregon, Texas, and California.



Using the potential energy of rising and falling ocean tides is called tidal energy.

One way of harnessing the tides is to trap the high tide behind dams.When the ocean rises to its highest tide, the dam is closed and high water is held in a reservoir by the dam. After the water recedes in low tide, the trapped water can be released through turbines like in hydroelectric plants.

Tidal energy plants of this type demand a large height difference between high and low tides, a condition that applies to only select global locations. However, research is ongoing to bypass this limitation.

The one major tidal power plant in operation is the 240 megawatt plant in La Rance, France, which has been operating since 1966, according to World Energy Council. There is also an 18 MW experimental plant in Annapolis Royal, Nova Scotia and a 0.4 megawatt plant near Murmansk, Russia.

Tidal energy can have the same drawbacks as hydroelectric power, such that dams may interfere with aquatic life.



Thermal energy conversion harnesses the difference in temperature between the warm, surface waters of the ocean and the colder, deep water. The two temperatures of water are matched to a fluid that has a low boiling point, like ammonia. Using the heat of the warmer water in a heat exchanger, the ammonia is evaporated and, once in gas phase, it rotates a turbine. Then, the colder seawater cools the ammonia back to liquid in a second heat exchanger. The rotating turbine generates electricity.

Open-cycle thermal energy conversion is similar but uses low pressure vessels to boil the warm surface water, instead of employing a fluid like ammonia. Water will boil at lower than its boiling point if the pressure is less than atmosphere. The steam runs a turbine, and then the cold seawater cools the steam back into fluid water.

These projects are expensive and difficult to site, since they must have deep enough water to get a substantial enough difference in temperature, yet the site must also be close enough to shore to transmit electricity.

Thermal plants can change the temperature gradient of the ocean around them, having a potential affect on marine life.

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Petroleum, Natural Gas, and Coal

The world depends on fossil fuels for its energy, and the United States is no exception. The vast majority of U.S. energy — more than 80 percent in 2009 — comes from burning fossil fuels. (more…)

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Energy Efficiency, Principles of Consumption, and Conservation

A blower-door test.

Transportation efficiency
Calculating home energy
Lighting efficiency
Heating and Cooling



When trying to lower your energy use, a good place to start is getting a picture of the many ways you use energy now.




An average American uses more than four times as much energy per year than the global average, 308 million British thermal units (Btu) annually, compared to 73 million Btu per person per year globally,according to recent U.S. government estimates. That guess doesn’t account for foreigners’ use of gathered fuels like wood or manure. However, it also doesn’t include the foreign energy used to source, assemble, and ship an endless profusion of products to the United States from other countries, like China.

The most straightforward uses that you can measure and control are probably in the home and through transportation. Every year, the average car in the United States is driven 12,300 miles and consumes about 67.8 million Btu worth of fuel. On average, Americans use more energy in homes than for transport.  The average household uses less (around 41 million Btu worth of electricity). However, to use electricity at home, we have to generate an additional 90 million Btu of primary energy at the power plant, according to the U.S. Energy Information Administration. What is a Btu?



Untangling the individual’s footprint comes with unrelenting complexities. Perhaps you live in an apartment in a big city and commute to work on the train, plug in your phone and computer at work, eat out every day, shower at a gym, and only come home to sleep. Maybe you travel for work, and your employer pays the expenses. You may pay almost nothing for energy directly. Yet, you are participating in energy use through your work, transportation, food, clothes, water, air travel, and electronic devices.

It’s also difficult to calculate how much energy is used up in buying new things. If you replace your car every two years, or you have a large home that you’re constantly remodeling, chances are your true energy footprint is much larger than you will be able to calculate.

The good news is you can calculate some aspects of your energy use and reduce it. And even if you plug in at work, it’s quite possible to make a decent ballpark estimate of how much energy that takes, too.



As a driving culture with access to cheap fuels — relative to our incomes — Americans use a lot of energy getting around. Transportation of goods and people accounted for almost a third of greenhouse gas emissions in 2009, according to the U.S. Energy Information Administration.

Reducing energy use in transportation is guaranteed by replacing car, truck, or motorcycle trips with biking or walking. For a normal healthy adult, walking a mile or two daily should be well within reach. Biking is a faster option, but it’s often considered a child’s transportation method in the United States. In countries like the Netherlands, it’s ordinary to see anyone on a bike, from babies in handlebar seats to well-groomed professionals.

Nonetheless, social customs, transportation infrastructure, suburban development, weather, and promotion of driving over other forms of transportation make it inconvenient and sometimes impossible to change Americans’ driving habits, at least without changing jobs or moving to a new city. A 2005 ABC News/Time magazine/Washington Post poll found that only 4 percent of 1,203 Americans used public transportation to get to work.

Even if driving is a must, driving efficiency can be improved. More efficient vehicles are available, like hybrids and some electric vehicles. Fuel economy can be improved by better car design and better driving. There’s also car-sharing and carpooling.

Analyzing, grouping, and prioritizing destinations can cut down on unnecessary trips. Yes, getting to work is mandatory perhaps, but a whopping 85 percent of car trips are for shopping, errands, and social or recreational reasons, according to a 2001-2002 government survey.

Other alternatives include public transit, ridesharing, and smaller transportation modes like skateboards, scooters, Segways and even electric bikes.

In China, the low-speed electric bicycle is extremely popular and far more efficient than driving or even taking the bus. It’s a regular pedal bike with a rechargeable battery that boosts the pedaler’s power but doesn’t travel faster than about 12.4 miles per hour. Somewhat heavier than standard bikes, electric bikes can still be pedaled without power on the flat or downhill, and the battery can help the rider stay sweat-free and comfortable on the uphill climb.



Estimating home energy use is getting easier now that utilities have installed smart meters that display electricity demand moment-to-moment. Depending on the utility that supplies your power, if you have a smart meter, you may already be able to log in online and track your hour-by-hour power use on any particular day, compare weekdays to weekends, or see if the house-sitter blasted the air conditioning. You can see how much electricity your home draws right now, and you can turn on and off appliances to see how each one contributes.

If you don’t have a smart meter, to calculate the energy that individual items in your home use, you need to look up how many watts each device — televisions, refrigerators, computers, routers, lights, electric air and water heaters — uses. That nameplate wattage is usually printed on the device.

Some sample nameplate wattages (watts):

Clock radio: 10
Coffeemaker: 10
Dishwasher: 1200-2400
Ceiling fan: 65-175
Space heater: 750-1500
Computer: 200-300 (awake), 20-60 asleep
Laptop: 50
Refrigerator: 725

Weekly energy per device = wattage x hours it’s “ON” per week

For devices that cycle on and off, like refrigerators and air conditioners, you’ll divide the resulting number by three.

You’ll also want to examine how much natural gas, propane, or other fuels you use for heating and cooling space, heating water, and cooking. While electric devices tend to be more efficient than gas-powered devices in your home, electric devices actually tend to use more energy overall because of loss of efficiency when the electricity was generated and transmitted to your home.

If you’re in the market for replacing you refrigerator or other appliance, and want to find out more about efficient options, a good resource for information is the Energy Star program.

Another detailed resource for tracking your energy-related emissions of greenhouse gas is the Home Energy Saver, built by the U.S. Department of Energy and Lawrence Berkeley Laboratory.

Know that devices don’t precisely use what their nameplate wattage says. Various factors affect how much energy something uses. For example, using the maximum brightness setting on a laptop computer will require more energy. Air conditioners will require much more energy to operate in very hot weather not only because it’s hotter outside but because the refrigerant becomes less efficient as it gets warmer, particularly if the refrigerant gets into the high nineties Fahrenheit. See below for more about heating and cooling.



You can improve your efficiency by replacing appliances and redoing construction, but you can also conserve energy by using less demanding settings, adjusting the thermostat, and turning items like computers and televisions off when they’re unused.



Unlike the days of candles and whale oil lamps, today we have many electrical lighting options. Our most popular, the standard 100 watt bulb, is being phased out, in part due to Clean Energy Act signed into law by President George W. Bush in 2007.  The maximum wattage incandescent bulb allowed will be 29 watts by 2014, down 70 percent from pre-2011 levels.

Instead, that type of bulb will be replaced by lower wattage incandescent bulbs, as well as compact fluorescent bulbs and even light-emitting diodes.

We can save lighting energy by

1. Turning off unused lights

2. Changing the type of light bulbs we use (see chart)

3. Changing the lighting plan, including adding natural light in the form of windows and skylights and solar tubes.

For more information about design, see the Energy Savers website.

Light can be measured in lumens. A 100 watt incandescent light bulb gives off around 1750 lumens.

The standard light bulb has a tungsten filament that exhibits incandescence when electric current travels through it. The filament burns out over time. The bulb keeps the filament in a special gas atmosphere like argon, instead of being exposed to regular air. Tungsten halogen bulbs operate somewhat similarly, with an incandescent filament, but the bulb contains halogen gas, which helps keep the filament from burning out as quickly.

Compact fluorescent bulbs, the sometimes spiral-looking bulbs, fluoresce instead of incandesce. Electric current travels through argon gas and a small amount of mercury vapor, which emit ultraviolet light. That light, in turn, excites a phosphor (fluorescent) coating on the inside of the bulb, which then emits visible light. So called CFLs are far more efficient and have much longer lifetimes. They do, however, contain a small amount of toxic mercury vapor and shouldn’t be thrown into the trash.

LEDs are also much more efficient than incandescent bulbs and don’t emit mercury if they’re broken. This technology is  sometimes called Solid State — even though the type of physics that the name is based upon has now changed to Condensed Matter. Extremely long-lived and very energy efficient, LED’s use around 20 percent of the energy of an incandescent for the same amount of light. However, they are far more expensive than similar fluorescent or incandescent options. For more about how LEDs work, go here.



Heating and cooling take a lot of energy. Replacing heaters, refrigerators, and single-paned windows costs money. Ripping out walls to add insulation is scary and can become a huge project.

However, today, a wide array of tools and professionals are available to assess the efficiency of heating and cooling and put it into perspective with cost. Home efficiency experts can use infrared detectors to track where heat is lost, and they can use blower door tests to check how quickly air is being exchanged with the outdoors through holes and leaky ducts.

Blower door tests change the air pressure inside a building relative to the outside to measure how quickly the air pressure returns to normal. If you walks through a pressurized house during the test, you can also track where air is leaking.

Even without a professional, you can reassess your home energy use. For tips on do-it-yourself home energy assessment, try the U.S. Department of Energy’s Energy Savers website.



1. Repairing leaky ducts, an often neglected source of heat loss! Ducts are much easier to access than replacing insulation, and they often have holes and cracks, making them a major  source of cold air infiltration, and also indoor air pollution.  Leaks suck in cold, dirty crawl space air including asbestos, dirt, and volatile chemicals (paint thinners, pesticides) that we stow or spray under the house. For more about indoor air quality see the Environmental Protection Agency’s website here.

2. Improve insulation and weather stripping, and seal up cracks. Use curtains or blinds to trap heat in during the winter and block sun out during the summer.

3. Replace air conditioners and heaters with more efficient models.

4. If you live in a dry climate, open windows to vent your home in the evenings, keep windows closed and A/C on during the morning before its the hottest hour of the day. Resist cranking the A/C up during the hottest hours of the day when the coolant fluid is the least efficient.

5. Replace windows and doors with better rated ones. For more about how windows are rated see the National Fenestration Rating Council.



The invention of new electricity-dependent devices outstrips the speed that we are making our homes more efficient. Today, heating, refrigerators, and air conditioners are using less energy, but televisions, computers, and an ever-expanding selection of other electronics are demanding more. For more about electricity in the home see the Basics of Electricity and how energy moves through the home.



A British thermal unit – almost always written Btu or BTU – is a measurement of thermal energy.  The scientific community usually uses the more manageable unit of the joule, which is a metric measurement of energy.  (A Btu is roughly 1,000 joules) A Btu is the English unit.

Fuels are often measured in Btu to show how much potential they have to heat water into steam or provide energy in other ways, like to engines. Steam turbines produce most of the electricity in the United States.


For more about the Smart Grid go to the Power Grid Technology section.

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“Cap-and-Trade” and Carbon Tax Proposals


Phosphorus factory smokestack in Muscle Shoals, Alabama.Source: U.S. Library of Congress.

The idea of “cap-and-trade” first emerged in the United States in the 1960s as a device to get the free economy to control pollution, folding in the cost of pollution instead of telling industry how to stop polluting. Often called emission trading, in a working cap-and-trade system, industries that release undesirable compounds into the air, water, or soil have limits of how much they can emit based upon pollution permits. Depending on the system, polluters either are given or have to buy their permits. The government establishes how much total pollution that the permits will grant, an umbrella cap on the economy. If an industry participant wants to release more than the permit allows, they buy the right from another industry player, if available, or perhaps face penalties, depending on the details.

Cap-and-trade can be used to regulate any pollutant, not only carbon dioxide or other greenhouse gases. The U.S. Environmental Protection Agency has three cap-and-trade programs, none of which apply to greenhouse gases. They aim to combat acid rain by reducing sulfur dioxide and nitrous oxide compounds, mostly an issue with coal power.

There is no U.S. cap-and-trade for carbon dioxide, though proposals have been raised regularly, and the U.S. House of Representatives passed an emissions trading program  in an energy bill in 2009, but the bill hasn’t been approved by the U.S. Senate, as of June 2011.

Australia has been considering a cap-and-trade program for carbon dioxide, but that too hasn’t been implemented as of June 2011. The European Union has had a carbon emissions trading program since 2005.

For more about greenhouse gases, climate change, and their relationship to energy go here.



In the United States, the Acid Rain Program‘s cap-and-trade system has successfully reduced pollution and cost industry far less than expected, at $3 billion per year instead of the feared $25 billion per year, according to a study [that I haven’t found yet] in the Journal of Environmental Management. Savings from cleaner air and water and avoided death and illness are estimated in the range of $100 billion per year, according to the EPA.

However, acid rain chemicals are easier to tame than carbon dioxide. The goal for the subjects of U.S. regulations today – nitrous oxide and sulfur dioxide – is as little as possible. Everyone agrees that these pollutants are bad for the environment and people, and there was a commercially-available solution for nitrous oxides and sulfur dioxide emissions when the cap-and-trade system began in 1990: scrubbers on the smokestacks. Even though the U.S. Congress could have ordered industry to buy the scrubbers, it was easier to pass cap-and-trade politically, and only a certain sector of energy production emits a significant volume of these chemicals. Today, there isn’t consensus about the effects of carbon dioxide gas, which isn’t toxic to humans. There isn’t consensus about how much carbon emissions is acceptable, and there is no viable carbon capture technology. And more than 80 percent (by volume) of energy production methods still produce carbon dioxide, whether that’s from biofuels or coal.

A dynamic map of U.S. carbon dioxide emissions.



In 2005, the European Union passed its own cap-and-trade program to limit carbon dioxide emissions, applied to more than 12,000 factories and power plants in 29 countries. The program includes some limits to nitrous oxide, and airlines will be obliged to participate by 2012. The carbon “cap” on total emissions decreases 1.74% per year.

Some regulators have already claimed success, as the carbon dioxide emissions were reduced in 2009; they increased again a little in 2010. However, the EU admits it gave out too many permits and that future permits will need to be tighter. Furthermore, the recession has acted as a major factor in lowered emissions, and European industries haven’t needed to make any technological changes because of lower demand.

“Power companies were given free carbon permits, but they raised electricity fees anyway — as if they had paid the market price for their permits — and pocketed the markup. Many companies were allocated too many allowances, often the result of powerful industries lobbying the governments that give the permits,”  Arthur Max of The Associated Press wrote from Belgium in a 2011 story about the Europeans’ progress.

If the EU’s carbon dioxide emissions will be reduced in coming years has yet to be determined since the real effects of the cap haven’t truly set in.

For more information about the EU’s program see the EU FAQ here.



Ten states in the Northeast have applied a cap-and-trade system to carbon dioxide as of 2008, in the Regional Greenhouse Gas Initiative, with the goal of reducing greenhouse gas 10 percent by 2018.

California is planning its own cap-and-trade program, slated to begin December 2011. Ten Canadian provinces and Western U.S. states and have joined California in the Western Climate Initiative, with the hope that there will be a regional cap-and-trade program too.



Carbon taxes are another way to integrate emissions reductions into the economy. The taxes makes a beeline for fossil fuels, which are far and away the main source of carbon dioxide emissions, whether they’re burned in vehicles or for electricity. A carbon tax on fuels raises the overall price, in theory reducing our ability to buy too much.  That means that industries or individuals can still produce as much carbon dioxide as they please, but they’ll have to pay for it.

Some economists prefer carbon taxes, as they are simpler to enforce, particularly internationally, and there’s likely to be less dramatic shifts in pricing. Others prefer cap-and-trade because there’s a finite ceiling to emissions. Many other arguments support either measure.

From a carbon tax perspective, diesel fuel and natural gas have an advantage over gasoline and coal, respectively, since they produce less carbon dioxide for the energy they generate. Of course, solar and wind produce none, but biofuels are more complex. Many carbon taxes in effect exclude biofuels like wood waste, even though they produce carbon dioxide.

Several European countries and individual U.S. states have various carbon taxes, applied from anywhere in the range of cents to close to $100 per ton, about as much carbon dioxide as would be emitted from using roughly 103 gallons of gasoline. These taxes are still low enough that they aren’t halting emissions. (For more details about calculating carbon emissions, see The Intergovernmental Panel on Climate Change.)

In the United States, carbon taxes in individual states are currently insignificant compared to other market pressures on the price of fuels, particularly in the case of petroleum.


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