Storing Energy: Fuel Cells and Beyond

Fuel input for hydrogen-fuel-cell-powered vehicle. Photo from Siemens PLM in Cypress California.

Storing energy is important for both long-term and short-term uses: to meet changes in energy supply and demand and to iron out irregularities in energy output, whether that’s in a car engine or on the power grid.

Unfortunately, we can only store a tiny fraction  of the electricity we produce in a single day. Instead, power plants have to send their thousands of megawatts of electricity to the right place, at the right time. For more details about electricity transmission, see Power Grid Technology.

Our current electric grid has various quick storage solutions to help make energy delivey smooth, and we use energy storage in cars, phones, and anything else that needs to be moved around. However, batteries and other storing options leave much to be desired.

Devices like capacitors and flywheels can store energy for extremely short periods.  Few technologies exist to store large amounts of energy over time periods ranging to several days: only pumped (water) storage is widely used to store energy on the scale of a power plant.

As energy sources are expanding to include more renewable and intermittent resources like wind and solar onto the electricity grid as we try to both meet growing energy demand and control greenhouse gas emissions. Likewise, there is increased interest in having reliable energy storage for vehicles, instead of gasoline and diesel fuels.

 

BATTERIES

Depending on the type of battery, these devices can store energy on location, like at home or in the car, in a laptop or cell phone. Note that though batteries and fuel cells can help integrate renewable energy sources, most electricity is still generated from fossil fuels. Both charging batteries and making hydrogen for fuel cells  thus produce greenhouse gas through reliance on the prevailing sources of electricity, and using these devices is less efficient than plugging into the wall because there’s always energy loss to byproducts like heat.

Batteries store chemical energy. Chemical reactions in the battery release that energy as needed. Eventually all the starting materials of the reaction are consumed and the battery is dead, or at least unusable until it’s recharged. There are many kinds of batteries, made of a wide array of chemicals. Polysulfide Bromide (PSB), Vanadium Redox (VRB), Zinc Bromine (ZnBr), Hydrogen Bromine (H-Br), and sodium sulfide batteries are some that the electricity industry has interest in.

Electric utilities use lead-acid batteries, which can be recharged, but there is research into other materials for utility and transportation use. Some of the best batteries used today for cars are nickel metal hydride and lithium ion.

 

HYDROGEN FUEL CELLS

Hydrogen fuel cells aren’t the same as batteries, but they can serve a similar purpose. Fuel cells are lumped with batteries because they both function through stored chemical energy. However, in practice, fuel cells are more like engines. They run off hydrogen “fuel” and produce energy and waste products, mostly  water vapor. As long as hydrogen keeps being added, the cell can run, just like a gasoline engine can keep running as long as more gasoline is added. A battery has a finite amount of energy unless it’s recharged with electricity.

For more about how to make hydrogen for fuel cells, see The hydrogen economy, hydrogen sources, and the science behind these.

For a description of different hydrogen fuel cells in development right now, see here.

 

FLYWHEELS

One way to smooth bumps in electricity delivery is through flywheels, which store energy in the form of rotational kinetic energy. A spinning potter’s wheel stores the energy of a good kick to be used moments later to mold a clay pot, and flywheels operate on a similar principle. In automobile engines, flywheels ease the transition between bumpy firing pistons and the drive shaft.

Flywheels can store energy for limited periods of time, from seconds to a few minutes.

 

PUMPED STORAGE

Pumped storage (of water) is the only widely-used method for storing huge amounts of energy for long periods of time. The United States has a capacity of more than 20,000 megawatts of pumped storage, according to the National Hydropower Association.

During times of excess electricity production, that excess energy is used to pump water to a higher altitude, increasing its gravitational potential energy. When extra energy is needed, the water is allowed to flow back down by way of turbines, turning that potential energy back into electricity.

For a figure of pumped storage see the National Hydropower Association

 

OTHER WAYS TO STORE ENERGY

Other technologies are constantly being investigated for energy storage. Compressed air storage is when air is forced into spaces like mines or caves and held at high pressure, using up energy in the process. When the compressed air is let out again, it can turn turbines to generate electricity.

Thermal energy storage exploits the difference in temperature between a system and the environment. In the late 1800s, Americans used thermal energy storage by cutting blocks of lake ice during the winter and storing them underground packed in insulating wood shavings. When the summer rolled around, they retrieved that stored ice to make food cold, exploiting the difference in temperature to force thermal energy out of the food.

Thermal energy storage can also happen in the other direction. Electricity or other forms of energy can be used to heat various materials, which are stored in insulated containers. Later, when the energy is needed, the hot materials can heat water into steam, and that steam can push turbines, which in turn produce electricity.

Thermal energy storage can also be used through ocean energy.

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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.

 

ENERGY IN THE WORLD’S MOST POPULATED COUNTRIES

 

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?

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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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