Global warming refers to the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation. The global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last 100 years. The Intergovernmental Panel on Climate Change (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations" via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. A few individual scientists disagree with some of the main conclusions of the IPCC. Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century. The range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a millennium even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans.

Increasing global temperatures will cause sea level to rise, and is expected to increase the intensity of extreme weather events and to change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, glacier retreat, species extinctions and increases in the ranges of disease vectors.

Remaining scientific uncertainties include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the globe. There is ongoing political and public debate worldwide regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences. Most national governments have signed and ratified the Kyoto Protocol, aimed at reducing greenhouse gas emissions.

The warming of the atmosphere by the trapping of longwave radiation being radiated to space. The gases most responsible for this effect are water vapor and carbon dioxide.

 

Graphic Representation:

 

Carbon dioxide (CO2) is the most important greenhouse gas because its impacts are large and human activities generate so much of it. Each year humans emit more than 6 billion tons of CO2 . Americans are responsible for more than a fifth of these emissions. Carbon dioxide is emitted from the burning of fossil fuels for electricity, to power cars, and from burning wood products. One molecule can warm the atmosphere for up to 120 years.

Fossil fuels are fuels containing carbon – coal, oil and gas – that were formed over millions of years through the decay, burial and compaction of rotting vegetation on land, and of marine organisms on the sea floor. Burning fossil fuels is the major way in which humans add to the greenhouse gases in the atmosphere.

World Fossil fuels consumption between 1965 and 2005

 

Over the last 50 years, while consumption of fossil fuels grew substantially, the world undertook a transition in its usage of fossil fuels, from solids (coal), to liquids (oil) to gases (natural gas). While coal accounted for 62% of all fossil fuel consumption in 1950, this share dropped to 28% in 1998 equivalent to the share of natural gas. The share of oil substantially increased between 1950 and 1980, where it peaked at 45% of fossil fuel use, then declined to 43%.

Hydrogen is the simplest element known to man. Each atom of hydrogen has only one proton. It is also the most plentiful gas in the universe. Stars are made primarily of hydrogen. The sun is basically a giant ball of hydrogen and helium gases. In the sun's core, hydrogen atoms combine to form helium atoms. This process—called fusion—gives off radiant energy. This radiant energy sustains life on earth. It gives us light and makes plants grow. It makes the wind blow and rain fall. It is stored as chemical energy in fossil fuels. Most of the energy we use today came from the sun's radiant energy. Hydrogen gas is lighter than air and, as a result, it rises in the atmosphere. This is why hydrogen as a gas (H2) is not found by itself on earth. It is found only in compound form with other elements.

Hydrogen combined with oxygen, is water (H2O). Hydrogen combined with carbon, forms different compounds such as methane (CH4), coal, and petroleum. Hydrogen is also found in all growing things—biomass. It is also an abundant element in the earth's crust. Hydrogen has the highest energy content of any common fuel by weight(about three times more than gasoline), but the lowest energy content by volume (about four times less than gasoline). It is the lightest element, and it is a gas at normal temperature and pressure.

Hydrogen - An energy carrier

An energy carrier is a substance or system that moves energy in a usable form from one place to another. Electricity is the most well-known energy carrier. We use electricity to move the energy in coal, uranium, and other energy sources from power plants to homes and businesses. We also use electricity to move the energy in flowing water from hydropower dams to consumers. It is much easier to use electricity than the energy sources themselves. Like electricity, hydrogen is an energy carrier and must be produced from another substance. Hydrogen is not widely used today but it has great potential as an energy carrier in the future. Hydrogen can be produced from a variety of resources (water, fossil fuels, biomass) and is a byproduct of other chemical processes. Unlike electricity, large quantities of hydrogen can be easily stored to be used in the future. Hydrogen can also be used in places where it’s hard to use electricity. Hydrogen can store the energy until it’s needed and can be moved to where it’s needed.

How is hydrogen made?

 Since hydrogen doesn't exist on earth as a gas, we must separate it from other elements. We can separate hydrogen atoms from water, biomass, or natural gas molecules. The two most common methods for producing hydrogen are steam reforming and electrolysis (water splitting). Scientists have even discovered that some algae and bacteria give off hydrogen.

Hydrogen can be produced at large central facilities or at small plants for local use. Every region of the country (and the world) has some resource that can be used to make hydrogen. Its flexibility is one of its main advantages.

Uses of hydrogen

About 7.8 million metric tonnes (17.6 billion pounds) of hydrogen are produced in the United States today, enough to power 20-30 million cars or 5-8 million homes. Nearly all of this hydrogen is used by industry in refining, treating metals, and processing foods. Most of this hydrogen is produced in just three states: California, Louisiana, and Texas. The National Aeronautics and Space Administration (NASA) is the primary user of hydrogen as an energy fuel; it has used hydrogen for years in the space program. Liquid hydrogen fuel lifts the space shuttle into orbit. Hydrogen batteries—called fuel cells—power the shuttle’s electrical systems.

 The only by-product is pure water, which the crew uses as drinking water. Hydrogen fuel cells (batteries) make electricity. They are very efficient, but expensive to build. Small fuel cells can power electric cars. Large fuel cells can provide electricity in out of the way places with no power lines. Because of the high cost to build fuel cells, large hydrogen power plants won't be built for a while. However, fuel cells are being used in some places as a source of emergency power to hospitals and to wilderness locations. Portable fuel cells are being sold to provide longer power for laptop computers, cell phones, and military applications.

Hydrogen use in vehicles

There are currently about 200 hydrogen-fueled vehicles in the United States – mostly in California. Most of these vehicles are buses and automobiles powered by electric motors. They store hydrogen gas or liquid on board and convert the hydrogen into electricity for the motor using a fuel cell. Only a few of these vehicles burn the hydrogen directly (producing almost no pollution). Hydrogen vehicles are starting to move from the laboratory to the road. One California family has recently leased a hydrogen car for personal use. The U.S. postal service, a package delivery company, a few Florida Park rangers, and a few private utility companies are also using hydrogen vehicles. It will probably be at least 10 years, though, before you can walk into your local car dealer and drive away in an affordable hydrogen-powered car. Even then, you will need a place to refuel your hydrogen car. Currently, there are about 25 hydrogen refueling stations nationwide. This is the so-called “chicken and egg” problem that hydrogen developers are working hard to solve. Namely: who will buy hydrogen cars if there are no refueling stations? And who will pay to build a refueling station if there are no cars and customers? One possible solution is to eliminate refueling stations entirely. Automobile manufacturers have already designed a refrigerator-sized hydrogen generator for your garage that works off electricity. Consumers would simply refill their cars with hydrogen each night while it is parked.

The future of hydrogen

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