Analysis of Hydrogen Power as an Alternative Energy Resource

In his State of the Union address on January 28, 2003, President George W. Bush officially announced his $1.2 billion federal Hydrogen Initiative. While some hail it as a step forward for renewable energy sources, others declare it a "Trojan horse" plan designed to increase profits for the energy companies that environmentalists are fighting so hard to break free from. Advocates for hydrogen power foresee cars powered by hydrogen fuel cells on the road before 2020 and major impacts on America's energy policy by 2050, but most experts agree that hydrogen will not be the primary supply of energy until the second half of the century. Additionally, critics argue that Bush's initiative increases the use of fossil fuels and is draining the budget for other potential energy sources. Can hydrogen eventually be a viable energy option for the United States in the near future? The answer seems to be yes, but policy changes might be in order and more research definitely needs to be done to improve current technology.

Introduction

With so many benefits of hydrogen power, it is hard to argue against it. It is clean, efficient, can be produced in many ways, could create hundreds of thousands of jobs in a slumping economy, and perhaps most importantly, reduce or even end our reliance on foreign oil. Environmentalists support it because it can reduce pollution; energy companies support it because they stand to be the main suppliers of the energy required to produce hydrogen. But before hydrogen rushes to the rescue of America's energy woes, problems need to be addressed. Improvements in hydrogen production, delivery, storage, and safety have to be made, and many believe the current energy plan needs an overhaul if we are to reduce our dependence on fossil fuels.

The immediate use for hydrogen is in fuel cells. A cell is composed of an electrolyte between a cathode and anode with a bipolar plate on each side; the plates evenly spread the gases and act as current collectors. Hydrogen enters the cell through channels and at the anode is separated into protons and electrons. The protons and electrons both move to the cathode, but the protons pass through the electrolyte while the electrons move through an external circuit; the electron flow creates a current (electricity) used to power whatever the cell is in. The protons and electrons then recombine with oxygen at the cathode to produce water, and since the reaction is exothermic, the fuel cell generates heat which can be used for additional work.

Fuel cells are more efficient than standard combustion engines, operate quietly, have few moving parts, are easily scalable, run on nothing but hydrogen and oxygen, and produce no harmful emissions. A typical combustion power plant generates electricity at an efficiency rate of about thirty-four percent, while a fuel cell can reach up to sixty percent efficiency. A conventional gasoline engine converts the chemical energy in gasoline into power at an efficiency rate of less than twenty percent; a fuel cell could be in the range of forty to sixty percent. Since fuel cells have very few moving parts compared to combustion engines, they are less likely to have mechanical problems and produce minimal noise. Though individual cells do not produce much power, many cells can be combined in series to form a stack; these stacks can range in size and make the fuel cell a versatile power source. The fuel cells just require hydrogen and oxygen (usually supplied by air) to operate and the only emissions are heat and water vapor. With a little more research, fuel cells have the potential to power everything from laptops to entire cities.

Current Status of Hydrogen Power

A common misconception is that hydrogen is a new energy source. Hydrogen is actually an energy carrier and needs to be produced by other forms of energy. However, one of the appeals of hydrogen is that it can be manufactured in numerous ways. Hydrogen can be created via natural gas reformation, renewable electrolysis, gasification, renewable liquid reformation, nuclear high-temperature electrolysis, high-temperature thermochemical water-splitting, or photobiological and photoelectrochemical methods. Natural gas reformation is the most well-developed and widely used process and is a potential short-term solution. Hydrogen is produced from methane in natural gas using high-temperature steam; this method is known as steam methane reformation and is responsible for ninety-five percent of the hydrogen produced in the United States. A similar process-partial oxidation-involves burning methane in air to create hydrogen. Both processes produce "synthesis gas" (a blend of carbon monoxide and hydrogen) that can be reacted with water to produce more hydrogen. "Synthesis gas" reactions often involve organometallic catalysts which are used to promote the reaction; these catalysts are reusable, enhancing the appeal of this method.

Renewable electrolysis uses electric current to split water into hydrogen and oxygen, though the title of "renewable" is a bit misleading. While the electricity can come from renewable sources such as wind and solar, it is most often from coal, natural gas, and other fossil fuels. Jeremy Rifkin, president of the Foundation on Economic Trends, labels hydrogen produced from fossil fuels "black hydrogen" and accuses the Bush administration of deceiving the public. He points out that instead of moving towards renewable, sustainable energy, Bush's plan "represents the interests of the same energy industry that they've been representing from the get-go." Rifkin calls for "green hydrogen" produced from non-fossil energy sources, and Amory Lovins, chief executive of the Rocky Mountain Institute, echoes his call: "Resources like wind are not only widely available in the market but are sufficiently abundant to meet all U.S. electricity, or even total energy needs."

Production of hydrogen via gasification is done by converting coal or biomass to "synthesis gas" through physical and chemical reactions. Obtaining hydrogen directly from coal in this manner is more efficient than using electricity produced by coal to create hydrogen. However, carbon capture and sequestration is needed to make this process clean. Presidents Bush and Obama support research into carbon capture technology, but it is currently not affordable enough to compete with gasoline. Furthermore, Obama's current energy plan, which calls for research into clean coal, has recently been blocked in the Senate. Critics of carbon capture and sequestration are skeptical that it could even work. Experts say it is impossible "to guarantee that the sequestered carbon would not eventually escape into the atmosphere, causing a potentially catastrophic overload of carbon dioxide." If carbon capture and sequestration becomes affordable and efficient, gasification of biomass could yield near-zero net greenhouse gas emissions, since biomass consumes carbon dioxide in the growth process.

Other methods are in the early stages of development and are potential long-term options. Nuclear high-temperature electrolysis uses the heat generated in nuclear reactors to increase the temperature of the water being electrolyzed. In higher temperature water, electrolysis is easier, so less electricity and energy are required. However, Lovins is critical of nuclear power, even as a method to create hydrogen. He states that carbon is very efficient at producing hydrogen from steam and sequestration might even be possible, but he argues that making hydrogen from thermally generated electricity is not cost-effective and also results in hazardous nuclear fuel. Renewable liquid reformation involves processing biomass into renewable liquid fuels such as ethanol and reacting it with steam to produce hydrogen. High-temperature thermochemical water-splitting uses high temperatures produced from solar concentrators or nuclear reactors to drive chemical reactions that split water into hydrogen and oxygen; chemicals involved in the process could all be recycled.

Photobiological methods rely on microbes such as green algae and cyanobacteria to create hydrogen in their metabolic processes. This method is somewhat appealing because the microbes grow all year, compared with biofuels obtained from plants that only grow during the spring and summer. Photoelectrochemical systems can produce hydrogen from water using special semiconductors and sunlight. These processes all hold potential for production of hydrogen in the future. However, more research needs to be done to improve efficiency and lower the costs to compete with fossil fuels; at this point, hydrogen is decades away from being a viable energy source.

Besides production problems, a major issue hydrogen faces is overcoming the lack of infrastructure. Most hydrogen is currently produced at or near where it is used, since no cost-effective and energy efficient system is in place for transport. Building pipelines would be the least expensive way, but the initial costs are relatively high and additional research needs to be done to improve the physical structure of the pipes. Concerns also exist about the durability of the pipes; hydrogen may corrode or make the pipes brittle and leakages would be very likely since hydrogen molecules are extremely small. Construction of the pipelines would take a considerable amount of time as well, as only 1,200 miles of pipelines currently exist (compared with over one million miles of natural gas pipelines). Using highways to transport hydrogen in high-pressure tubes on trailers is rather expensive and would only be effective for distances under 200 miles. In order to move it over long distances, liquefied hydrogen is preferred, but it too is costly and takes large amounts of energy (to liquefy the hydrogen). The costs for transport are so high because hydrogen has a low volumetric energy density; that is, it provides a small amount of energy by volume compared to gasoline or natural gas. To transport a large enough "energy quantity" of hydrogen would require moving an enormous volume, whether in liquid or gaseous form, and would be quite inefficient. Like the production aspect, new technology is needed to lower the cost of the compression and transport of hydrogen if it is to replace fossil fuels.

As if distribution of hydrogen was not complex enough, storing it may be even more economically difficult. Hydrogen is hard to store in bulk without taking up large amounts of space, so new ways are being developed to increase the efficiency. One method is to store the actual hydrogen as a compressed gas or cryogenic liquid. Another pathway being researched is storing hydrogen within the structure or on the surface of other materials in the form of chemical precursors. The other materials would likely be easier and cheaper to store, and a chemical reaction would release the hydrogen when it was needed. As with transport, these can be costly and inefficient without new technology.

Storage issues are especially important when considering the use of hydrogen as a fuel for cars. Though hydrogen has a low energy to volume ratio (about one-fourth that of gasoline), it makes up for this with a high energy to weight ratio (about three times that of gasoline). Present estimates show a car needing five to thirteen kilograms of hydrogen to travel 300 miles, depending on the type of vehicle. With currently available technology, a 300 mile radius requires a fuel tank larger than the trunk of a standard car; a tank this large and heavy would reduce fuel economy. People must also be able to refuel at ambient temperature and at an acceptable rate. If there are only a handful of hydrogen fill stations and it takes drivers twice as long to fill their hydrogen powered cars, they would be less likely to make the switch from gasoline to hydrogen. These issues need to be resolved if hydrogen is to replace gasoline or diesel in automobiles.

A final concern for using hydrogen is safety. Hydrogen is highly flammable and invisible when it burns, possibly making car accidents even more hazardous. It also requires a low energy for combustion, and a low concentration of it has similar energy to other fuels. These two qualities could make hydrogen catastrophically dangerous; a small quantity of leaked hydrogen could possibly create a large explosion from a tiny spark. And like natural gas, it is odorless, colorless, and tasteless, although it differs in one important way. Natural gas has odorants added to it so it can be detected by human senses, but no current odorant is light enough to travel with hydrogen; even if an odorant is created, it could potentially damage the fuel cell. Supporters of hydrogen are quick to dismiss safety concerns, noting that hydrogen is extremely light and so will disperse quickly from a leak, preventing an explosion. Again, more research needs to be done to improve existing technology if hydrogen is to be a viable option.

New Achievements and Forthcoming Plans

Progress has been made in bringing hydrogen-powered cars to the road and more plans exist to support hydrogen research. At the 2005 North American International Auto Show, General Motors unveiled the Sequel, their hybrid crossover SUV concept that uses a hydrogen fuel-cell stack to power the car. The first drivable version appeared in fall of 2006 and is the "first electrically-driven fuel cell vehicle to achieve 300 miles on one tank of hydrogen... while producing zero emissions." The Sequel stores eight kilograms of hydrogen in three carbon composite pressurized fuel tanks mounted beneath the cabin floor and still maintains dimensions comparable to that of other SUVs.

California governor Arnold Schwarzenegger has created a program to construct a "hydrogen highway," with at least 150 fueling stations. The first station opened in Los Angeles on October 22, 2004, and there are currently twenty-seven stations in California. Across the United States and Canada, seventy-one fueling stations are operational and another forty-three are planned. In Europe, nine cities tested hydrogen-powered buses over a two-year period, and six regions were slated to use hydrogen buses under the European Hydrogen Bus Initiative, signed in 2006. Although steps have been taken to introduce hydrogen-fueled cars, switching an entire nation to hydrogen could pose a potential problem. The United States has approximately 167,000 gas stations, and converting them to hydrogen stations could cost billions of dollars. With the current economic situation, the likelihood of this occuring soon is low. A National Academy of Sciences panel has also concluded that hydrogen-fueled cars would not have a major impact on the auto industry until at least 2025; by then, however, technology could drastically improve and hydrogen-powered cars could be a reality.

Though it seems America is well on the way to replacing fossil fuels with hydrogen, there are still many obstacles to overcome. Bush's Hydrogen Initiative, coupled with his FreedomCAR program introduced in 2002, pumped a total of $1.7 billion into hydrogen research over five years, but at what expense? Some renewable energy sources, such as biomass, are receiving less funding due to this push towards hydrogen, despite the belief of many experts that these other sources present a much more viable short-term solution. Bracken Hendricks, executive director of the Apollo Alliance, notes that "hydrogen is a very promising technology... but it's a long-range solution, and there are vast opportunities that can be captured immediately with existing technology." Bush's plan would also increase domestic production of fossil fuels, meaning America would be relying even less on renewable energy sources like wind and geothermal.

With the present state of the economy, the current plan of the Department of Energy shows promise. On April 15, 2009, Energy Secretary Steven Chu announced that $41.9 million from the American Recovery and Reinvestment Act will be used to fund fuel cell technology. "Developing and deploying the next generation of fuel cells will not only create jobs," he says, "it will help our businesses become more energy efficient and productive." The plan calls for immediate distribution of nearly 1,000 fuel cell systems for use as emergency power and in material handling. If the program is widely adopted, the Department projects that hydrogen research will create up to 675,000 jobs across forty-one industries. The cost of fuel cells used in cars has also decreased drastically, from $275/kW in 2002 to $73/kW in 2008, a reduction of nearly seventy-five percent in just six years. With US oil prices peaking at $134.44 per barrel in July 2008, these announcements could not have come at a better time.

Outlook for the Future

It is clear America needs to reduce dependence on fossil fuels, especially those imported from foreign nations, both to combat pollution and to become self-reliant for energy. As Asian economies like India and China grow, the demand for passenger cars will continue to increase, so now more than ever a clean solution must be found. Progress is being made to introduce hydrogen as a viable power option for public and private transportation, as well as for commercial and industrial use. Hydrogen offers a promising future, though an economy powered entirely by hydrogen is decades away. With more research, a power supply of hydrogen produced by renewable sources such as wind, solar, geothermal, and biomass could prove to be a viable solution for energy in the United States.

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