Geothermal Energy Tapping the Earth's Heat

Geothermal energy has been used for thousands of years in some countries for cooking and heating. It is simply power derived from the Earth's internal heat.This thermal energy is contained in the rock and fluids beneath Earth's crust. It can be found from shallow ground to several miles below the surface, and even farther down to the extremely hot molten rock called magma.

 

 

 

These underground reservoirs of steam and hot water can be tapped to generate electricity or to heat and cool buildings directly.

 

 

 

A geothermal heat pump system can take advantage of the constant temperature of the upper ten feet (three meters) of the Earth's surface to heat a home in the winter, while extracting heat from the building and transferring it back to the relatively cooler ground in the summer.

This Ggeothermal power plant in Reykjavik, Iceland, is using their underground reservoirs of steam and hot water to generate electricity and to heat and cool buildings directly.

Geothermal water from deeper in the Earth can be used directly for heating homes and offices, or for growing plants in greenhouses. Some U.S. cities pipe geothermal hot water under roads and sidewalks to melt snow.

 

 

 

To produce geothermal-generated electricity, wells, sometimes a mile (1.6 kilometers) deep or more, are drilled into underground reservoirs to tap steam and very hot water that drive turbines linked to electricity generators. The first geothermally generated electricity was produced in Larderello, Italy, in 1904.

 

 

 

There are three types of geothermal power plants:

• dry steam,
• flash, and
•  binary.

1. Dry steam, the oldest geothermal technology, takes steam out of fractures in the ground and uses it to directly drive a turbine.
2.  Flash plants pull deep, high-pressure hot water into cooler, low-pressure water. The steam that results from this process is used to drive the turbine.
3. In binary plants, the hot water is passed by a secondary fluid with a much lower boiling point than water. This causes the secondary fluid to turn to vapor, which then drives a turbine. Most geothermal power plants in the future will be binary plants.

 

 

 

Geothermal energy is generated in over 20 countries. The United States is the world's largest producer, and the largest geothermal development in the world is The Geysers north of San Francisco in California. In Iceland, many of the buildings and even swimming pools are heated with geothermal hot water. Iceland has at least 25 active volcanoes and many hot springs and geysers.

 

 

 

There are many advantages of geothermal energy. It can be extracted without burning a fossil fuel such as coal, gas, or oil. Geothermal fields produce only about one-sixth of the carbon dioxide that a relatively clean natural-gas-fueled power plant produces. Binary plants release essentially no emissions. Unlike solar and wind energy, geothermal energy is always available, 365 days a year. It's also relatively inexpensive; savings from direct use can be as much as 80 percent over fossil fuels.

 Environmental Problems

 

 

But it has some environmental problems. The main concern is the release of hydrogen sulfide, a gas that smells like rotten egg at low concentrations. Another concern is the disposal of some geothermal fluids, which may contain low levels of toxic materials. Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down.

 

Biofuels The Original Car Fuel

Biofuels have been around as long as cars have. At the start of the 20th century, Henry Ford planned to fuel his Model Ts with ethanol, and early diesel engines were shown to run on peanut oil.




But discoveries of huge petroleum deposits kept gasoline and diesel cheap for decades, and biofuels were largely forgotten. However, with the recent rise in oil prices, along with growing concern about global warming caused by carbon dioxide emissions, biofuels have been regaining popularity.

Gasoline and diesel are actually ancient biofuels. But they are known as fossil fuels because they are made from decomposed plants and animals that have been buried in the ground for millions of years. Biofuels are similar, except that they're made from plants grown today.



Much of the gasoline in the United States is blended with a biofuel—ethanol. This is the same stuff as in alcoholic drinks, except that it's made from corn that has been heavily processed. There are various ways of making biofuels, but they generally use chemical reactions, fermentation, and heat to break down the starches, sugars, and other molecules in plants. The leftover products are then refined to produce a fuel that cars can use.



Countries around the world are using various kinds of biofuels. For decades, Brazil has turned sugarcane into ethanol, and some cars there can run on pure ethanol rather than as additive to fossil fuels. And biodiesel—a diesel-like fuel commonly made from palm oil—is generally available in Europe.



On the face of it, biofuels look like a great solution. Cars are a major source of atmospheric carbon dioxide, the main greenhouse gas that causes global warming. But since plants absorb carbon dioxide as they grow, crops grown for biofuels should suck up about as much carbon dioxide as comes out of the tailpipes of cars that burn these fuels. And unlike underground oil reserves, biofuels are a renewable resource since we can always grow more crops to turn into fuel.



Unfortunately, it's not so simple. The process of growing the crops, making fertilizers and pesticides, and processing the plants into fuel consumes a lot of energy. It's so much energy that there is debate about whether ethanol from corn actually provides more energy than is required to grow and process it. Also, because much of the energy used in production comes from coal and natural gas, biofuels don't replace as much oil as they use.



For the future, many think a better way of making biofuels will be from grasses and saplings, which contain more cellulose. Cellulose is the tough material that makes up plants' cell walls, and most of the weight of a plant is cellulose. If cellulose can be turned into biofuel, it could be more efficient than current biofuels, and emit less carbon dioxide.

Hydropower Going With the Flow

Hydropower is electricity generated using the energy of moving water. Rain or melted snow, usually originating in hills and mountains, create streams and rivers that eventually run to the ocean. The energy of that moving water can be substantial, as anyone who has been whitewater rafting knows.




This energy has been exploited for centuries. Farmers since the ancient Greeks have used water wheels to grind wheat into flour. Placed in a river, a water wheel picks up flowing water in buckets located around the wheel. The kinetic energy of the flowing river turns the wheel and is converted into mechanical energy that runs the mill.



In the late 19th century, hydropower became a source for generating electricity. The first hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of Niagara Falls were powered by hydropower. In 1882 the world’s first hydroelectric power plant began operating in the United States in Appleton, Wisconsin.



A typical hydro plant is a system with three parts: an electric plant where the electricity is produced; a dam that can be opened or closed to control water flow; and a reservoir where water can be stored. The water behind the dam flows through an intake and pushes against blades in a turbine, causing them to turn. The turbine spins a generator to produce electricity. The amount of electricity that can be generated depends on how far the water drops and how much water moves through the system. The electricity can be transported over long-distance electric lines to homes, factories, and businesses.



Hydroelectric power provides almost one-fifth of the world's electricity. China, Canada, Brazil, the United States, and Russia were the five largest producers of hydropower in 2004. One of the world's largest hydro plants is at Three Gorges on China's Yangtze River. The reservoir for this facility started filling in 2003, but the plant is not expected to be fully operational until 2009. The dam is 1.4 miles (2.3 kilometers) wide and 607 feet (185 meters) high.



The biggest hydro plant in the United States is located at the Grand Coulee Dam on the Columbia River in northern Washington. More than 70 percent of the electricity made in Washington State is produced by hydroelectric facilities.



Hydropower is the cheapest way to generate electricity today. That's because once a dam has been built and the equipment installed, the energy source—flowing water—is free. It's a clean fuel source that is renewable yearly by snow and rainfall.



Hydropower is also readily available; engineers can control the flow of water through the turbines to produce electricity on demand. In addition, reservoirs may offer recreational opportunities, such as swimming and boating.



But damming rivers may destroy or disrupt wildlife and other natural resources. Some fish, like salmon, may be prevented from swimming upstream to spawn. Technologies like fish ladders help salmon go up over dams and enter upstream spawning areas, but the presence of hydroelectric dams changes their migration patterns and hurts fish populations. Hydropower plants can also cause low dissolved oxygen levels in the water, which is harmful to river habitats.

Fuel Cells Energy Source of the Future

According to many experts, we may soon find ourselves using fuel cells to generate electrical power for all sorts of devices we use every day. A fuel cell is a device that uses a source of fuel, such as hydrogen, and an oxidant to create electricity from an electrochemical process.

 

 

 

Much like the batteries that are found under the hoods of automobiles or in flashlights, a fuel cell converts chemical energy to electrical energy.

 

 

All fuel cells have the same basic configuration; an electrolyte and two electrodes. But there are different types of fuel cells, based mainly on what kind of electrolyte they use.

 

 

 

Many combinations of fuel and oxidant are also possible. The fuel could be diesel or methanol, while air, chlorine, or chlorine dioxide may serve as oxidants. Most fuel cells in use today, however, use hydrogen and oxygen as the chemicals.

 

 

 

Fuel cells have three main applications: transportation, portable uses, and stationary installations.

 

 

 

In the future, fuel cells could power our cars, with hydrogen replacing the petroleum fuel that is used in most vehicles today. Many vehicle manufacturers are actively researching and developing transportation fuel cell technologies.

 

 

 

Stationary fuel cells are the largest, most powerful fuel cells. They are designed to provide a clean, reliable source of on-site power to hospitals, banks, airports, military bases, schools, and homes.

 

 

 

Fuel cells can power almost any portable device or machine that uses batteries. Unlike a typical battery, which eventually goes dead, a fuel cell continues to produce energy as long as fuel and oxidant are supplied. Laptop computers, cellular phones, video recorders, and hearing aids could be powered by portable fuel cells.

 

 

 

Fuel cells have strong benefits over conventional combustion-based technologies currently used in many power plants and cars. They produce much smaller quantities of greenhouse gases and none of the air pollutants that create smog and cause health problems. If pure hydrogen is used as a fuel, fuel cells emit only heat and water as a byproduct. Hydrogen-powered fuel cells are also far more energy efficient than traditional combustion technologies.

 

 

 

The biggest hurdle for fuel cells today is cost. Fuel cells cannot yet compete economically with more traditional energy technologies, though rapid technical advances are being made. Although hydrogen is the most abundant element in the universe, it is difficult to store and distribute. Canisters of pure hydrogen are readily available from hydrogen producers, but as of now, you can't just fill up with hydrogen at a local gas station.

 

 

 

Many people do have access to natural gas or propane tanks at their houses, however, so it is likely that these fuels will be used to power future home fuel cells. Methanol, a liquid fuel, is easily transportable, like gasoline, and could be used in automobile fuel cells. However, also like gasoline, methanol produces polluting carbon dioxide.

 

Words better suited to a high school chemistry class than a high-level policy debate—terms such as praseodymium and dysprosium—have raised alarms around the world about the future of the alternative energy economy.

Seventeen metals on the periodic table of elements have caused the commotion from Tokyo to Washington, D.C. They are known as rare-earth metals, important ingredients in making the motors and batteries of hybrid and electric cars, high-efficiency LED lights, solar panels and wind turbines. The vast majority of the world’s supply of these metals comes from one source—China—raising the issue of whether foreign dependence will bedevil the new energy economy just as it has been a standing feature of the economy powered by fossil fuel.

‘A One-Nation OPEC’

Rare-earth metals, also called rare-earth minerals, include element number 21, scandium; number 39, yttrium; and the 15 lanthanides, numbers 57-71, on the periodic table. However, the name is a misnomer. Rare-earth metals are often found in a cluster, but are not actually rare. Rather, they are valuable because it is difficult to find the minerals concentrated in great enough amounts so that mining the deposit makes economic sense.

The United States, second only to China in energy consumption, is not devoid of rare-earth metals. But the only U.S. mine, near the Mojave National Preserve in Mountain Pass, California (map), became inactive in 2002 after 50 years of production, largely because of economic and environmental issues. The mine, for a time owned by Chevron, was taken over in 2008 by Molycorp Minerals LLC, which has spent more than $400,000 since that time lobbying Congress on rare-earth minerals, according to its Senate disclosure records. On its website, Molycorp says it has plans to modernize and expand the mine and bring it back into full production “with appropriate federal assistance for research, development and capital costs.”

Legislation already has been proposed in the U.S. Congress to extend subsidies and funding to reopen domestic mines, and the focus on the issue intensified after a dispute erupted between Japan and China over rare-earth minerals last week. Japanese industry sources accused China of withholding crucial supplies, an accusation that Beijing denied, but the Japanese government vowed to take action. Foreign Minister Seiji Maehara of Japan said Friday that Tokyo aims to secure more mining development rights overseas to diversify its sources of rare-earth minerals. “Relying on one country is not good,” Maehara said at a news conference.

The discussion this week was much the same in Washington, D.C. Last year, 90 percent of the U.S. imports for rare-earth metals were from China, according to data from the U.S. Geological Survey. But this year, according to USGS, the figure is 97 percent.

“Just as we’ve seen with our reliance on foreign oil, the United States’ total reliance on foreign sources of rare earths puts us in a perilous situation,” said Republican Senator Lisa Murkowski of Alaska, in a prepared statement accompanying legislation she introduced to create a U.S. strategic stockpile of rare-earth minerals and to provide federal loan guarantees to assist the domestic mining industry. “Some have compared China to a one-nation OPEC for rare earths— and China’s recent actions signal that they are well aware of their immense power over the supply of this sought-after commodity.”

E

ven though demand for rare-earth minerals presumably would rise as electric cars and more alternative energy and efficiency applications came to market, consumption of those products has actually decreased dramatically during the economic downtur

n, according to a USGS report. In 2009, the estimated value of these products imported by the United States was $84 million, a 55 percent decrease from $186 million imported in 2008.

Some academics aren’t too concerned that the United States would be held hostage by China over rare-earth minerals.

“The fact is that the more the Chinese and American economics are interrelated, the less likely conflict might be,” said Jerry Taylor, senior fellow at the Cato Institute, a libertarian public policy think tank in Washington, who has written extensively on energy issues. “What would it [China] gain at the end of the day? They would risk a trade war with a country where a huge volume of its liquid capital assets are invested.”

At the hearing Thursday, one of the witnesses, Roderick Eggert, a professor and director of the division of economics and business at the Colorado School of Mines, confirmed that mineral resources were still abundant, and that China’s supply and low prices are currently sufficient to meet the world’s needs.

“Markets provide incentives for investments that reinvigorate supply and reduce supply risk, Eggert said. “The Chinese mineral deposits are quite large and rich . . . and will satisfy [world demand] and have been meeting demand in the last few years.”

Critical to National Defense?

But there’s an important backstory: national defense.

Besides green energy, rare-earth minerals are essential in creating weapons. “Smart bombs” that use neodymium-iron-boron magnets to control the direction when dropped from an aircraft, lasers that employ neodymium, yttrium-aluminum-garnet used to determine the range of enemy targets at distances over 22 miles, and neodymium-iron-boron permanent magnets used for sound system components used in psychological warfare are among the many, according to a 2004 USGS paper.

The U.S. Department of Defense is currently in the early stages of evaluating its dependency on these minerals, as well as the potential national security risks, according to a study by the U.S. Government Accountability Office.

The jury is still out on alternative energy. With the advancement of new technology, certain products, such as high-efficiency solar cells, do not even need rare-earth metals. Other renewable energy products, such as wind turbines, can be created without rare-earth minerals, but their use is highly advantageous and makes for a much more efficient process.

“Are they critical to the [alternative energy] sector? It’s hard to say that they have the choke hold on the industry,” said Mark Brownstein, deputy director of the energy program at the Environmental Defense Fund. “These are valuable materials in that they have facilitated a tremendous innovation in some of the basic building blocks of renewable energy and energy efficiency technologies. The continued access isn’t only important to existing renewable energy, but also for future advances.”

Expect More Floods as Global Water Cycle Speeds Up

There is nearly 20 percent more freshwater flowing into the world's oceans than there was 10 years ago--a sign of climate change and a harbinger of more flooding.
A new indicator has joined the century-long rise in temperature to signal that the planet's climate is changing: the global water cycle is speeding up. Using satellite observations, NASA and university researchers have found that rivers and melting ice sheets delivered 18 percent more water to the oceans in 2006 than in 1994.
The findings, which appear in this week's Proceedings of the National Academy of Sciences, suggest that the volume of water running off the land toward the sea is expanding by the equivalent of roughly one Mississippi River each year.
On the face of it that might sound like a good thing--more water in rivers means more water to tap for agriculture, industry, and growing cities. But most of the increase is occurring in places where extra water isn't needed, like the wet tropics or the remote Arctic, or is being delivered through torrential storms that overwhelm human infrastructure and coping capacities. Though no single weather episode can be pinned to climate change, the massive rains that recently flooded a fifth of Pakistan is the kind of event scientists expect to see more of--and that nations should prepare for.
Why is the water cycle speeding up?
As the atmosphere warms from the addition of carbon dioxide and other greenhouse gases, it can hold more moisture. As a result, more water evaporates from the oceans, leading to thicker clouds that then dump more rainfall over the land. That heavier-than-normal rain can then produce massive flooding as it runs back toward the sea, where the cycle begins all over again.
Scientists have expected global warming to speed up the water cycle in this way, but the use of satellite data allowed the trend to be observed and measured for the first time. The research team, led by Jay Famiglietti of the University of California at Irvine, used satellite records of sea level rise, precipitation, and evaporation to compile a unique 13-year record, the first of its kind.
As the scientific evidence mounts that more severe floods and droughts are on the horizon, getting on with ways of adapting to climatic change becomes just as urgent as slowing the pace of that change.