The Future of Sustainable Hydrogen
A Study of Energy, The Environment and a Hydrogen Based Infrastructure, by Caleb Beaudin, May 2nd, 2008
Abstract: Based on increasing global energy needs, a limited supply of fossil fuels, foreign dependence, economic welfare and excessive CO2 emissions, this study summarizes the complex notion of a hydrogen economy. Ongoing research has identified several promising methods for extracting hydrogen from natural gas, biomass, water, and coal, all in which it is naturally found. These cutting edge techniques do, however, require input energy to chemically separate out the hydrogen in these compounds. Thus, hydrogen in itself is not a direct source of energy, but rather an energy carrier and a storage device. A hydrogen economy is comprehensively the production, storage, distribution, and use of hydrogen as an energy carrier. Due to deteriorating environmental conditions and a limited supply of fossil fuels, this study focuses on the latest technology using clean, abundant, reliable and/or renewable energies to perform the hydrogen production process. Once extracted and purified, hydrogen gas is then stored for use in fuel cells where it is an ideal on-demand energy source. Additionally, compressed hydrogen can be burned in appliances, boilers, car engines or any gadget that would otherwise burn natural gas. The other major advantage is that hydrogen burning does not release harmful byproducts; only water and heat. Based on projected energy consumption rates and carbon emissions, there are drastic implications to the notion of renewable hydrogen overtaking current energy production. This paper summarizes the current US energy system and the possibilities of hydrogen production as a viable replacement system. Additionally it weighs the costs, requirements, paybacks and limitations of the most promising hydrochemical systems and addresses the macroscopic economic, political and environmental implications of a national turn toward sustainable hydrogen.
“I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable.”
~Jules Verne, The Mysterious Island (1874)
Introduction, History and Overview
The idea of a hydrogen economy is by no means a new concept. As early as the 16th Century, Francis Bacon first hypothesized using hydrogen for energy storage. In 1874, recognizing the possibilities of hydrogen, science-fiction writer Jules Verne called water the “coal of the future." Similarly in the 1930’s, Rudolf Erren was looking to reduce automotive emissions and oil imports from England and suggested using hydrogen produced from water electrolysis as a transportation fuel. A hydrogen economy is comprehensively the production, storage, distribution, and use of hydrogen as an energy carrier and production source. The bulk of today’s energy is produced through processes involving fossil fuels (coal, natural gas and petroleum). Since more than half of US petroleum is imported, we are continually dependent on foreign governments to sustain our society’s energy needs. As a result, there are significant political and economic implications. Based on increasing global energy needs, a limited supply of fossil fuels, foreign dependence, economic welfare and excessive CO2 emissions, this study takes an in-depth look at the complex notion of a hydrogen economy.
We start with an overview of today’s energy climate, and then break down the distributed sources of this energy. Furthermore, today’s energy production and consumption is a leading contributor to smog, atmospheric pollution and global warming. Upon reviewing the results of this analysis, it becomes apparent that our society is on the verge of a dynamic shift toward a new system of energy. In order to avoid the same pitfalls that have led to our current dilemmas, an ideal replacement system should be environmentally friendly, reliable and economically plausible. Energy should be easily produced, stored and distributed. Additionally, the source must be abundant, sustainable and provide for a facilitated transition. With continued research and development, hydrogen systems promise all of these benefits. Most importantly, the versatility of renewable-source, hybrid hydrogen systems allows us to start with current day energy producers and gradually transition toward more sustainable producers. Hands down, hydrogen has the most potential to play the leading role in the future of global energy reformation.
Production, Consumption, Reserves and Environmental Impact
The US population has recently surpassed the 300 million mark and continues to grow at an average annual rate of 1.1%.i Additionally, 68% of our residents are classified as urban dwellers. The total US energy consumption for 2006 was 99.873 quadrillion Btu, and had increased at an average rate of 1% since 1980.ii The 2006 breakdown by type was 85% fossil fuel, 8 % nuclear and 7% renewable. Similarly, the breakdown for 1996 was 85%, 7.4% and 7.6% respectively. For 1986, it was 86%, 5.7% and 8.1%, thus showing no significant changes over the past 20 years. A further breakdown of energy consumption by type, which has also been relatively consistent over the past 2 decades, is 22.5% coal, 22.5% natural gas, 40% petroleum, 8% nuclear, 3% hydroelectric, 3% biomass and 2% from other renewable sources. As in the US, 86% of global energy is produced from fossil fuels.iii The Energy Information Administration’s (EIA) latest estimate of average energy expenditure per person was $2961 for 2004. US Production numbers by type vary from the consumption breakdown and for 2006 were 33.5% coal, 30% natural gas, 15.3% crude oil, 11.5% nuclear, 4.1% hydroelectric, 4.5% biomass and less than 1% from other renewable sources. In 2006, fossil fuels accounted for 79% of overall national energy production compared to renewables, which came in at 9.5%. In total the US produced 71.034 quadrillion Btu, only 71% of the 99.87 quadrillion Btu used during the year. A shocking extrapolation noted from these statistics is the fact that the US produced only 10.8 quadrillion Btu crude oil in country, but consumed 40 quadrillion Btu in petroleum products. This means that nearly three-fourths of our consumed oil was imported, thus indicating extreme dependence on foreign governments to suffice our transportation needs. According to the Federal Reserve Bank of San Francisco, the US trade deficit went from $360 Billion in 2002 to $816 Billion in 2006. Similarly, the trade deficit due to petroleum products went from $72 Billion in 2002 to $312 Billion in 2006. Based on these stats alone, it’s easy to see why the US dollar has recently been plummeting in global markets. Energy, namely imported petroleum, currently accounts for nearly 40% of the overall US trade deficit.
Click image to to view larger diagram of energy flow.
Fossil fuel consumption and flaring in the US produced 7,075.6 million metric tons carbon dioxide equivalent (MMTCO2e) in 2006; as much as all of Europe and the Middle East Combined.iv On a global scale, the US contributed roughly 21% of all consumer emissions. Of the total, petroleum accounted for 43.5%, coal for 36.0%, natural gas for 19.6% and renewables for 0.2%. Per Btu, petroleum contributes 36.3 times as much CO2 as renewable energy. Similarly, coal and natural gas respectively contribute 54.3 and 29 times as much renewable energy sources. In general, we could say that per Btu, fossil fuels contribute roughly 40 times more pollution renewable energy sources.
Green house gasses are formed when CO2 combines with methane CH4. From 2005 to 2006, the total US green house gas emissions dropped by 1.5% and green house gas intensity of the U.S. economy fell by 4.2 percent, the largest annual decrease since the 1990 base year. Unfortunately, emission intensity, measured in (MMTCO2e)/GDP (Gross Domestic Product), has resulted mainly from reductions in energy use per unit of GDP (energy/GDP) rather than increased use of low-carbon fuels. There is little need for further environmental analysis at this time, as the adverse effects of producing and burning fossil fuels are common knowledge among most everyone.
With the growing dependence on fossil fuels and the depletion thereof, it is important to note their limited availability. Based on today’s consumption rates, coal reserves would last for 164 years, while natural gas and oil would last for 67 and 41 years respectively.v John Turner, a principal scientist at the National Renewable Energy Lab, is working on identifying and developing nanomaterials for photoelectrochemically creating hydrogen. He states, “It's important to turn up the heat on hydrogen research now. In 2030 we're not going to have enough oil, natural gas and coal to meet our energy needs ... and hydrogen is the best carrier for an alternative fuel.” vi To put fossil fuel reserves in perspective, Turner states that for the year 2000, global consumption accounted for 0.5% of coal reserves. Natural gas consumption burned up 1.6% of reserves, oil reserves dropped almost 3%, and nuclear electricity generation consumed the equivalent of 2% of uranium reserves.
Yet another major issue arising from the logistics of any useful form of energy is the efficiency of transporting or transmitting that energy. Transportation efficiency must be considered in terms of both dollars and environmental impact. For high voltage lines, as an example, which deliver a power, P, at a particular voltage, V, the current flowing through the cables is given by I=P/V. Thus, the primary source (roughly 60%) of power loss in the lines, Ploss = R*I 2 = R*P2/V2. The other 40% loss is due to transformers.vii Increasing the voltage by a factor of 10 reduces losses by a factor of 100. Long distance transmission is typically done with overhead lines at voltages of 115 to 1,200 kV. However, at extremely high voltages, more than 2,000 kV between conductor and ground, coronal discharge losses are so large that they can offset the lower resistance loss in the line conductors. Average power loss is 7.2% depending on the distance traveled and the number of transformers encountered.viii Petroleum transportation losses on imports are between 5 and 10%, which does not include the domestic mark up for in-country distribution.ix
Based on the preceding data, there is certainly a need for reforming global energy production, transportation and usage. Since our current energy system revolves around limited-reserve fossil fuels and since all of these major problems result from a fossil fuel society, the reformation will be drastic, costly and inconvenient. An ideal candidate will produce, store and distribute clean, efficient energy. The new system should incorporate an abundant source and the production should be as sustainable as possible. It should account for where our current energy system is at today, facilitating the awkward transition period and utilizing our existing infrastructure to the greatest possible degree. Now we take a brief look at today’s energy producers, and then move on to an overview of the hydrogen system. We will find that hydrogen, as a carrier used in conjunction with today’s energy producers, promises all of these benefits and more. More specifically, hydrogen, when used in conjunction with renewable energy sources, creates this ideal energy system – that is with continued research, technological advancements and once initial costs have been absorbed.
Energy Sources
Fossil Fuels According to the Department of Energy (DoE) fossil fuels (coal, oil and natural gas) currently provide more than 85% of all the energy consumed in the United States, nearly two-thirds of our electricity, and virtually all of our transportation fuels. Moreover, it is likely that the nation’s reliance on fossil fuels to power our expanding economy will actually increase over at least the next two decades even with aggressive development and deployment of new renewable and nuclear technologies.
Petroleum products are the lifeblood of America. We all use them daily and without them we’d all be lost. Petroleum is the basis for motor vehicle transportation and has become the convenient fuel of our time. Unfortunately, the US relies heavily on foreign imports to sustain our required petroleum needs. This dependence and the industry itself has lined the pockets of a few oil tycoons, but overall has greatly contributed to the US trade deficit and plummeting US dollar. Additionally, petrol engine emissions contribute significantly to urban smog and atmospheric pollution. It could be argued that the petroleum industry is critical to the US job market and our economy. However, any replacement energy source would likely replace the lost jobs and act as an economic stimulus.
Natural gas, known for its blue flame, is domestically produced and readily available through the existing utility infrastructure. Serving alternative fuel vehicles, natural gas is clean burning and produces significantly fewer harmful emissions than reformulated gasoline. The US DoE claims that 900 of the next 1000 US power plants will be natural gas, but reserves are not expected to last much longer than petroleum. Depending on future consumption rates and potential implementation of a replacement fuel, natural gas reserves may last as little as a few more decades. In September 2006, the Energy Information Administration (EIA) proclaimed a maximum working gas storage capacity of 3,703 billion cubic feet at standard pressure, which was slightly higher than previously anticipated. Natural gas is the backbone of the Clean Cities program, which strives to advance the nation’s economic, environmental, and energy security by supporting the reduction of petroleum consumption by promoting alternative fuels, advanced vehicles, fuel blends, fuel economy, hybrid vehicles, and idle reduction.
Coal has become the backbone of our nation’s energy production, with one-quarter of the world’s coal supply buried under US soil. The US supply alone will produce more energy than the entire world oil reserve.x Coal burning plants supply more than half of the US electricity each year. This readily available resource does come at a hefty environmental price. In 2006, coal-fired power plants produced approximately 36 percent of the total U.S. CO2 emissions.x In recent years the US government has invested thoroughly in carbon capture technologies and water management innovation. Studies have found that over 40 percent of existing U.S. coal-generating capacity is located directly above potential geologic sequestration sites.xi This includes 150 existing electric power plants, or nearly one-sixth of total U.S. CO2 emissions. The goal of the Carbon Capture program is to eventually contain 90% of CO2 emissions from coal production without increasing the price of the electricity by more than 20%. Coal will likely play a critical role in a hydrogen economy, but further research and development are crucial to cleaning it up. Since coal is so abundant in the US, clean coal is arguably one of our best energy sources for the next few decades.
Nuclear reactors are either pressurized or boiling. In either case thermal energy from a controlled chain of nuclear reactions is used to heat water, which in turn powers a turbine generator. As of 2005, the US had 104 nuclear power plants and had not established a new plant since 1996. Combined, these plants net just under 100,000 megawatts per anum. The world's present measured resources of uranium, economically recoverable at a price of $130/kg, are enough to last for approximately 80 years at current consumption rates.xii Nuclear generation does not directly produce sulfur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels. The primary environmental impacts of nuclear power include Uranium mining, radioactive effluent emissions, direct and indirect greenhouse gas emissions (water vapor, CO2, NO2) and waste heat. Nuclear power is a viable energy producer. In addition to the environmental impacts, the other associated concerns are safety and disposal of spent fuel. Large nuclear reactors produce 3 cubic metres of spent fuel each year, which is primarily composed of unconverted uranium as well as significant quantities of transuranic actinides (plutonium and curium, mostly).xiii In addition, about 3% of the waste is made of fission products. The actinides (uranium, plutonium, and curium) are responsible for most of the long term radioactivity, whereas the fission products are responsible for the bulk of the short term radioactivity.
Renewable Energy is energy that can be reproduced either directly or indirectly by the sun. Renewables include hydroelectric, wind, solar and biomass. Geothermal energy is usually classified with renewables due to its clean and ongoing nature.
Hydroelectric production for the US is around 80,000 megawatts of power per year. Hydropower is a fueled by water, so it is a clean, natural source of energy. Hydropower relies on the water cycle, which is driven by the sun, and so it is a renewable and sustainable power source that is produced domestically. Hydroelectric dams create reservoirs, which allow for power on-demand. On the flip side, dams disrupt the natural flow of water and the spawning patterns of native fish populations. Additionally, stagnant water will create low levels of dissolved oxygen, damaging riparian (riverbank) habitats. The DoE’s hydroelectric resource assessment is very limiting, identifying the potential for only another 30 megawatts within our borders. Although hydroelectric power is relatively clean and beneficial, it can never supply a significant portion of our energy requirements.
Wind. The mechanical concept behind a wind turbine generator is quite simple. As the wind blows, aerodynamic rotors turn the low-speed shaft, which then transfers mechanical energy to the generator shaft by means of a gearbox interface. Wind is currently the fastest growing energy source in the US, going from an 1800 MW capacity in 1996 to more than 11,600 MW in 2006. The average unit installed in 2006 was nearly as tall as the Statue of Liberty with a rotor span larger than a football field. These turbines are rated at 1.5 MW and can produce enough energy for 500 homes. Plans for 2015 include a 5 MW turbine that will stand over 700 feet tall. During 2006, wind energy accounted only for 0.7% of US consumption,xiv but the recent Advanced Energy Initiative launched by President George W. Bush, is looking to take that number up to 20%. Incorporating this amount of wind-generated electricity would avoid 3,500 million metric tons of carbon equivalent through 2050.xv Additionally, it would lead to roughly $332 billion in economic investment and nearly 4 million full-time equivalency job years for construction and plant operation. Furthermore, these jobs would be focused in rural areas, where jobs are most difficult to find. Wind is a clean, abundant, sustainable, domestic, non-polluting energy source. It is currently one of the most economical energy source, pricing out around $.05/kWh. Once the initial costs of the wind farm construction are absorbed, the energy is nearly free. Wind farms can be built on existing farms and ranches allowing these operations to continue as they otherwise would. The initial costs of wind farms are much greater than those of fossil fuel plants, but the major objective to overcome is the intermittence of the power supply. Utility companies that purchase wind energy must either have enormous banks of batteries or they must purchase expensive energy on the spot market. Also they must reserve more open space on transmission lines. Even with these hidden costs, the price of wind to a Montana homeowner, for example, is around $.04/Kwh.xvi Other drawbacks to wind include noise, aesthetic displeasure and the occasional encounter of birds.
Solar. There are three primary types of solar energy gains. Thermolysis, or concentrated solar consists of an array of parabolic or dish mirrors that focus solar radiation on a lateral tube. A series of these heated tubes then power a steam boiler to generate electricity. Concentrating solar power is relatively inexpensive and provides opportunity to deliver power during periods of peak demand, when it is most needed. This means that it can be a major contributor to the nation's future needs for distributed sources of energy. Thermal solar is similar, but the collectors are either flat panel or evacuated tube. These systems are primarily used to heat domestic hot water. Similar to concentrated solar, these arrays are not on the scale of power plants. Rather they are better suited to homeowners and building owners, who can conserve energy and save money on their utility bills. Additionally, a well designed structure can take advantage of passive and active solar heating. By properly orienting windows and areas of thermal mass, a homeowner can take advantage of the natural, free heat offered by the sun. Photovoltaic solar arrays consist of two parallel plates made of differing semi-conducting materials. The n-layer material consists of a semi-conductor material with extra electrons while atoms in the p-layer have extra electron holes. As solar photons encounter a thin microcrystalline silicon alloy film, the photoelectric effect causes electrons to release from their rest shells and flow across the plates inducing a current.
An efficient solar cell will maximize absorption, minimize reflection and recombination, thus maximizing conduction. A study by the National Renewable Energy Laboratory, determined that PV modules require only one to four years to produce the total energy consumed in their manufacture, depending on the type of module. Comparing this to an expected 20 to 30-year module life suggests that PV module production is a healthy net energy generator. Fundamental to current PV research are the physical mechanisms of charge carrier transport, band structure, junction formation, impurity diffusion, defect states, and other physical properties of PV and photo-electrochemical materials. PV solar only contributed .07% to 2006 US energy consumption, due to the relatively high initial costs. Like wind, PV solar arrays are a clean, renewable source; and once the initial costs are absorbed, will provide virtually free energy for the duration of the panels. PV arrays are a viable option for homeowners as well as a supplement to the grid during peak demand.
Geothermal energy makes use of the heat from the Earth. It is clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found several miles beneath the Earth's surface. Around 8,000 megawatts (MW) of geothermal electricity are produced around the world each year, including 2800 MW of capacity in the US, which provides 0.35% of our energy consumption. Today’s technology produces electricity from hydrothermal (hot water/steam) resources. In the future, we may be able to use the heat of the deep, hot, dry rock formations of Earth's crust, and possibly the even deeper, almost unlimited energy in Earth’s magma. The geothermal industry is currently a $1.3 billion/year business.xvii The US DoE’s Geothermal Technologies Program is trying to expand geothermal production to 40,000 MW and reduce the cost to less than $.05/kWh.
Biomass is plant matter such as trees, grasses, agricultural crops or other biological material. It can be used as a solid fuel, or converted into liquid or gaseous forms, for the production of electric power, heat, chemicals, or fuels. Due to combustion of materials such as timber scrap or municipal solid waste to generate electricity, biomass production surpassed hydroelectric as the largest US source of renewable energy. In 2006, biomass accounted for 3.3% of US energy consumption. The six core technology platforms are Sugar-Legnin, Syngas, Bio-Oil, Biogas, Carbon Rich Chains and Plant Products. Biofineries, or plants where all biomass is converted to energy, are highly complex and expensive. Oil refineries, corn wet-mills, pulp plants and paper plants are basically the biofineries of today. Taking maximum advantage of intermediate products and balancing high-value/low volume products with high volume/low-value fuels are the important concepts in today’s ongoing research. High-value bioproducts may meet special needs and generate market excitement, but high-volume fuels are what America needs from this industry to reduce its dependence on foreign oil and to improve the environment.
Hydrogen Overview
Hydrogen is simplest and most common element. It is all around us, but always as a compound with other elements. To make it usable in fuel cells or otherwise provide energy, we must expend energy or modify another energy source to extract it from the fossil fuel, biomass, water, or other compound in which it is found. Nearly all hydrogen production today is by steam reformation of natural gas. This, however, releases fossil carbon dioxide in the process and trades one relatively clean fuel for another, with associated energy loss, and therefore does little to meet national energy needs. Hydrogen is an ideal energy carrier and once separated, it is also a very viable energy producer. For high purity needs, a small amount of hydrogen is produced by electrolysis, but this again is only as good as the energy source used to produce the electricity used. Additionally, there are great efficiency losses during these processes. There are, however, many possible ways to produce hydrogen with renewable energy and abundant resources, which will be the primary focus of the remainder of this paper.
Hydrogen solves many of the problems we face in today’s energy markets, including many distribution and storage dilemmas. Localized production and storage from onsite generation is one of the keys to distributed energy. But hydrogen could easily be piped to homes through the existing natural gas infrastructure we have in place today. Once hydrogen is in the home, the possibilities are endless. A homeowner could fill his hydrogen car at home filling service stations all together. Hydrogen safely compresses up to around 1500 PSI, allowing us to store large volumes in smaller cylinders. Compressed hydrogen is highly explosive and one goal of a hydrogen economy would be to minimize on-road transportation. The heavy cost of a full build-out of a hydrogen infrastructure is due primarily to production, storage and distribution facilities in addition to an underground pipeline.
Purified hydrogen can be used in fuel cells to directly produce DC electricity. It can be used in catalytic burners for heating and cooking without poisoning or damaging the noble metal catalyst materials. In this regard, hydrogen could easily replace natural gas and propane. Hydrogen and oxygen gases can be used for welding and cutting. Hydrogen is also a good motor vehicle fuel and with further efficiency and safety development, may eventually replace petroleum products. The creators of a compound known as Brown’s Gas or HHO, claim that through battery/alternator electrolysis, it can provide hydrogen on-demand to work in conjunction with gasoline in modern vehicle engines. They claim that it raises fuel mileage efficiency by an average of 40%, however the validity of this claim is controversial and skeptical at best. Hydrogen combustion does not contribute to global warming, acid rain, or air pollution. It is clean energy and the only byproduct is water.
Hydrogen can be produced in a variety of ways, which is discussed in the following section. In the cases of clean hydrogen production, as with typical renewable energy generation, the initial costs are high, but the ongoing costs are nearly non-existent. Hydrogen provides for a reliable, on-demand, versatile, sustainable energy supply. Current research focuses on efficiency in hydrogen systems, including production techniques and fuel cells. A hydrogen economy could easily tie in with our current grid system. The versatility of hydrogen allows for local production, which in turn contributes to the notion of distributed energy. Distributed energy is the implementation of sporadic grid tie systems that can produce and contribute during peak hours when system producers are drained. Today, it is not uncommon for areas such as Las Vegas and Los Angeles to experience power loss and system failure due to overloads on the grid. Distributed energy looks to overcome these obstacles. Hydrogen makes for the ultimate hybrid system. The possibility of configurations and hybrids is only limited by the imagination.
One major drawback to hydrogen is the expensive nature of employing a new infrastructure and enduring the transitional period. Even a slow, adaptive conversion will be initially costly and inconvenient. Furthermore, when it comes to hydrogen vehicles, there is an overall sense of fear. Researchers have gone to extreme lengths to make hydrogen cars as safe as possible. For example, one team has been successful dropping cars 80 feet with direct contact between tank and asphalt, or the equivalent of a 50-mile per hour collision, without producing an explosion.
Hydrogen is very high energy for its weigh, but very low energy for its volume, so new technology is needed to store and transport it with greater efficiency. Also fuel cell technology is still in early development, needing improvements in efficiency and durability. If hydrogen is really to solve our energy problems, then it must be produced cleanly, efficiently and affordably from abundant, domestically available renewable resources.
Methods of Hydrogen Production
Today, 95% of hydrogen produced in the US, or roughly 9 million tons per year, uses a natural gas thermal process called steam methane reformation (SMR). SMR is a 2-step process that ultimately produces H2 and CO2. When higher purity hydrogen is needed, an electrochemical process called electrolysis is used. During this process, electricity is passed through a metal catalyst submerged in an electrolyte-water solution in an ionic transfer device, or electrolyzer. Hydrogen and oxygen are chemically separated by the charge and then extracted for storage. Renewable technologies, such as wind turbines or PV arrays, can generate electricity to produce hydrogen from electrolysis with zero greenhouse gas emissions. Unfortunate to electrolysis are the expensive materials required in the electrolyzer apparatus, such as platinum and palladium. Solar or wind powered electrolyzers, in combination with fuel cells, may be one of the most exciting up and coming in-home energy systems of the future. Nuclear high-temperature electrolysis is another technique for producing hydrogen. Heat from a nuclear reactor can be used to improve the efficiency of water electrolysis by increasing the temperature of the water, thus requiring less electricity to split the water. This process reduces the total energy required and boosts the net gain. High-temperature thermochemical water splitting applies similar principles. The process utilizes either a nuclear reactor or solar concentrators to drive a series of chemical reactions that split the water. In this semi-perpetual process, all of the chemicals are recycled. Other potential renewable electric sources for electrolysis are geothermal, hydropower, ocean power, tides, waves, oceanic current, oceanic thermal and concentrated solar.
Hydrogen can also be produced thermochemically from biomass. The use of biomass energy has the potential to greatly reduce greenhouse gas emissions. Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels. However, fossil fuels release carbon dioxide captured by photosynthesis millions of years ago—an essentially "new" greenhouse gas. Biomass, on the other hand, releases carbon dioxide that is largely balanced by the carbon dioxide captured in its own growth (depending how much energy was used to grow, harvest, and process the fuel). The use of biomass can reduce dependence on foreign oil because biofuels are the only renewable liquid transportation fuels available. The two most common types of biofuels are ethanol and biodiesel. Ethanol is an alcohol, the same as in beer or wine, and is made by fermenting any biomass high in carbohydrates through a process similar to beer brewing. Today, ethanol is made from starches and sugars, but researchers are developing technology to allow it to be made from cellulose and hemicellulose, the fibrous material that makes up the bulk of most plant matter. Ethanol is mostly used as a blending agent with gasoline to increase octane and cut down carbon monoxide and other smog-causing emissions. Biodiesel is made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled cooking grease. It can be used as an additive (typically 20%) to reduce vehicle emissions or in its pure form as a renewable alternative fuel for diesel engines. Biomass energy supports US agricultural and forest product industries. The main biomass feedstocks for power are paper mill residue, lumber mill scrap, and municipal waste. For biomass fuels, the feedstocks are corn (for ethanol) and soybeans (for biodiesel), both surplus crops. In the near future agricultural residues such as corn stover (the stalks, leaves, and husks of the plant) and wheat straw will also be used. Long-term plans include using dedicated energy crops, such as fast-growing trees and grasses, that can grow sustainably on land that does not support intensive food crops. With so much potential, biomass will undoubtedly play a large role in the future of hydrogen.
Hydrogen can also be produced by Photobiological and Photoelectrochemical means. When certain microbes, such as green algae and cyanobacteria, consume water in the presence of sunlight, they produce hydrogen as a byproduct of their natural metabolic processes. Similarly, photoelectrochemical systems produce hydrogen from water using special semiconductors and energy from sunlight. As an example, the Hydrogen Solar Company created a tandem cell photoelectrochemical module that utilizes two photo-catalytic cells in series. Tandem cells are 8% efficient to date, a statistic that is comparable to leading electrolyzers. Since metallic materials must continually be immersed in water, they are susceptible to corrosion and are not maintenance free. Researchers are currently testing metal oxides as well as organic compounds to produce higher efficiency films for reacting with incident photons. Hydrogen produced in this manner is 99% pure.xviii
Yet another source of hydrogen is from coal or biomass gasification. Combining coal (or biomass) with oxygen, air or steam at a very high temperature allows for partial oxidation. The temperature must be regulated so that combustion doesn’t occur. The gasification process is much cleaner and more efficient than combustion coal, but only two commercially operated power plants currently use this technique in the US. The gasification technique produces roughly 20% less CO2 emissions than coal burning.xix Carbon capture and sequestration technology also allows for these emissions to become essentially nil.
Analysis and Conclusions
Environmental conditions resulting from today’s energy production/consumption and decreasing supplies of fossil fuels make it imperative that we turn toward cleaner, more sustainable energy sources. Hydrogen clearly opens up the possibilities of finding solutions to major issues we face in this arena. Renewable energy sources greatly reduce emissions providing reliable, clean energy at continually more affordable rates. Billions and billions of dollars have been spent over the past 2 decades on research to develop these technologies. This investment is on the brink of starting to pay itself back. By acting as an energy storage and carrier device, a hydrogen infrastructure would facilitate energy transport and distribution. Stored hydrogen would essentially become a battery pack for the grid, a gaseous source for heating and cooking in addition to providing fuel for transportation. The numerous opportunities to produce hydrogen enable it to be manufactured domestically, which will decrease our dependence on foreign fuels and strengthen our economy. From a social economic perspective, the many possibilities of hydrogen allow for diversified and distributed production, both of which promote smaller corporations and more distributed profits. Hydrogen, a new infrastructure and the use of fuel cell technology are what make all of this possible. There are, however, several remaining concerns that should be identified.
First, the research and infrastructure costs will be significant. The price of energy will certainly continue to increase before a new system pays for itself and prices start to drop. Transitioning to a hydrogen based energy supply will also create temporary inconveniences for individual consumers. There is continued need for research and technological advancement in all areas of hydrogen production, storage, distribution and use. Fuel cell technology promises a bright future, but with efficiencies in the 50% range, there is much room for improvement. After considering all factors, I believe the evidence supports a move toward hydrogen to create a new energy system. Upon accepting this notion, we are at the mercy of the technology and companies that will initiate these inevitable transitions.
So, while a full-fledged hydrogen economy is still down the road a ways, there are many important steps to take in the mean time. For instance, as a society we must reduce, reuse and recycle. These efforts start with individuals and grow to fuller impact as we group together with common goals. Lessening our carbon footprints and overall consumption targets the heart of the problem. Take the time and make the efforts to improve the efficiency of your home and transportation. Change your buying habits. Reduce your consumption and waste. Teach others as you learn. Individually, we can all do our integral parts and together, we can perpetuate the comprehensive solution.
Sources
i US Census Bureau
ii Energy Information Administration (EIA)
iii The International Energy Outlook 2004 - Published by the US Dept. of Energy (US DoE)
iv EIA
v World Coal Institute
vi Science Magazine 2004 305:972
vii Wikipedia
viii US Climate Change Technology Program
ix Dr. Jean-Paul Rodriguez, Dept. of Economics & Geography, Hofstra University
x US DoE website
xii Carbon Sequestration Atlas of the US and Canada
xii Nuclear Energy Agency (NEA) Uranium 2005 – Resource, Production and Demand 2.6.2006
xiii Radioactive Waste Management - Uranium & Nuclear Power Information Centre 2002
xiv EIA
xv US DoE Energy Efficiency and Renewable Energy - Publication May 2007
xvi Gauging the Cost of Wind Power – Missoulian 4.20.08
xvii Heat and Power for the 21st Century – Energy Efficiency and Renewable Energy Publication June 2006
xviii Hydrogensolar.com
xix National Hydrogen Association fact sheet
