Seeing Our Way To The Future
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BLOG, The Science Debates

By Yasha Husain, posted December 31, 2009

Debate #3: Elusive Water Vapor: High
Altitude Hydrogen Jets, and the Delicate
Stratosphere

Water Vapor 1 Day (Terra/MODIS)

Imagery courtesty of NASA's Earth Observatory,
by Reto Stockli, using data provided by the
MODIS Atmosphere Science Team, NASA
Goddard Space Flight Center.

Moderator Question:

What do we know about manmade water vapor emissions in the lower stratosphere and the implications of risks involved in their release?

Background:

Water vapor remains among the most elusive of greenhouse gases. Perhaps in part because of its innocuous sounding name, its story has seldom been told.  

A 1996 study, however, titled, “Molecular Hydrogen and Water Vapour Emissions in a Global Hydrogen Energy Economy,” by Zittel and Altmann, assumed that about 20 percent of planes at the time flew in the upper troposphere / lower stratosphere. The report, presented at the 11th World Hydrogen Energy Conference, declared a hydrogen fleet of planes emitting water vapor emissions would need to fly well within the troposphere to keep from disrupting the delicate, dry balance in the stratosphere. Starting in 1996, the year the study was published, NASA's modified U2 spy plane, the ER-2, began collecting samples of stratospheric air from which to draw such conclusions. Since then, scientists have continued to elaborate on Zittel and Altmann's findings as well as apply unique methods of analysis in their attempts to understand the potential for stratospheric ozone destruction from commercial hydrogen fleets.

Water vapor in the troposphere, the level of earth's atmosphere that reaches from the ground to between five and seven miles upwards into the sky, is beneficial because it traps heat that keeps the planet warm, and causes clouds to form leading to rain. But in the lower stratosphere, the level of atmosphere just above the troposphere, scientists believe moist water vapor can disturb a much drier region, causing further ozone destuction at the level of the upper stratosphere, where ozone mainly rests and blocks ultraviolet rays.

Following is the third science debate of 2009 on elusive water vapor, high-flying hydrogen planes and the delicate composition of the stratosphere. Perhaps it points to, if nothing else, the notion that flights to and through and approaching the stratosphere ought to be organized under some sort of regulatory plan with water vapor emissions being a strong enough factor.

(The Science Debates are split into two sections. The first section, 'What Is Known', lays out important facts related to what we currently know about the science being debated, and the second section, 'The Unknowns', lists a number of the unknowns related to the proposed science. Inside of each section are 'the basics' and 'the specifics'. The basics offer broad explanations pertinent to the general science, and the specifics describe the applied science in more detail. Feel free to skip between sections and subsections using the hyperlinks below to find the information that is most relevant to you. Please also leave comments at the end that you think will contribute to a healthy debate. They will be posted in the next couple of days.)


SECTION ONE: WHAT IS KNOWN


THE BASICS (KNOWN):

Water vapor is an abundant
greenhouse gas

The lower stratosphere's
environment is a delicate, dry one


Stratospheric ozone protects
the planet from ultra-violet rays


Chloroflourocarbons (CFCs) damaged
ozone in the stratosphere, depleting it


The Montreal Protocol was an instrumental, diplomatic tool for removing CFCs from the environment

Ozone is due to return to normal levels
over Antarctica by 2055,
be it not for unmitigated global warming

Emissions from hydrogen planes


THE SPECIFICS (KNOWN):

Scientists warn about an accumulation
of water vapor in the lower stratosphere
from high flying jets and fleets of planes

Dr. Kristie Boering, of Berkeley, and team of scientists, balance the planetary
hydrogen budget, delivering know-how
for predicting the climatic future

Dr. Drew Shindell at Goddard Institute for Space Studies says moisture has been accumulating in the upper stratosphere

In early 2008, the Hydrogen Hyper-jet, proposed by Reaction Engine of the UK,
was held up as beacon of future aircraft

In October 2007, Boeing successfully tested a hydrogen propulsion system on the unmanned high altitude long endurance (HALE) aircraft

In August 2006, a major conference to discuss effects of aviation on climate change where hydrogen oxides (HOx) from aircraft
water vapor emissions were discussed

In February 2007, the Department of Energy put out a call for bids believing
an additional study of hydrogen emissions
from transportation and stationary power
was needed

Water vapor emissions are only one group
of emissions of greenhouse gasses that can upset the stratosphere's natural balance


SECTION TWO: THE UNKNOWNS

THE BASICS (UNKNOWNS):

The water vapor atmospheric feedback
loops are not yet fully understood

Ozone, as it returns to normal levels over Antarctica may produce a warming
effect in the polar region

How much moisture the stratosphere can tolerate before it reaches a tipping point


THE SPECIFICS (UNKNOWNS):

Future direction of, and possible constraints
on, commercial aircraft industry

Future direction of defense

Future direction of private space flight and space flight in general

Future direction of geoengineering

Potential to conserve and recycle on global scale

Potential and practicality of delivering
space-based energy from solar arrays,
or Helium-3 fusion power from the moon,
to earth

Potential demands of mining activities
on earth, and perhaps in the future,
in space (for example,
extraction of useful ores from asteroids)

Financial viability of large-scale hydrogen production for use in road, air and space transportation
______________________________________

SECTION ONE: WHAT IS KNOWN

THE BASICS (KNOWN):

Water vapor is an abundant greenhouse gas
Water vapor is the most abundant greenhouse gas in the atmosphere and understanding its feedback loop is critical to our ability to predict future climate change scenarios. Scientists around the globe are conducting studies to improve our knowledge about the water vapor feedback loop. Unfortunately, according to the National Climatic Data Center's web site, that feedback loop is as of yet "still fairly poorly measured and understood."

(On 01/29/10, weeks after this post was made, Discovery News published, "Water Vapor: A Warming Wildcard") (Top)

The lower stratosphere's environment is a delicate, dry one
The stratosphere lies directly above the troposhere and stretches upwards to 31 miles high. Its environment is drier and less dense than the troposphere, particularly the lower stratosphere, and is sensitive to moisture in the form of water vapor emissions that may rise from below gradually or else are released directly into it. "Ice from convective plumes" may also be released into the lower stratosphere. Together, the troposphere and stratosphere contain 99.9 percent of "air" in general.

According to Dr. Drew Shindell's Goddard Science Brief from May 2001, "Reaction of Ozone and Climate to Increasing Stratospheric Water Vapor," "the abundance of water vapor in the stratosphere affects ozone, surface climate, and stratospheric temperatures." Increases in stratospheric moisture that have been witnessed for decades, he wrote, may have important consequences.

In the brief, Shindell noted how water vapor breaks down in the stratosphere. It releases reactive hydrogen oxide molecules that in turn destroy ozone. The molecules react with gases that contain chlorine, and cause them to convert to forms that destroy ozone. "So a wetter stratosphere will have less ozone," Shindell wrote.(Top)

Stratospheric ozone protects the planet from ultra-violet rays
The stratospheric ozone layer absorbs and scatters dangerous ultraviolet radiation from the sun. Most of the vital ozone layer is located in the stratosphere, however it is not distributed evenly.(Top)

Chloroflourocarbons (CFCs) damaged ozone in the stratosphere, depleting it
It was first reported in the journal Nature in 1974, by chemists Mario Molina and Frank Sherwood Rowland, that chloroflourocarbons (CFCs), "freons" used in spray bottles, refrigeration and plastic foams, were depleting the ozone. Molina and Rowland proposed that CFC molecules were stable enough to remain in the atmosphere until they reached up into the middle stratosphere. There they would be broken down by ultraviolet radiation, releasing chlorine atoms that in turn breakdown large amounts of ozone. Connections between ozone depletion, CFCs and other ozone depleting substances (ODSs) were later found, leading to adjustments in the Montreal Protocol.
Scientists have simulated what a future world might have looked like without the regulation and elimination of ODSs. By the year 2065, 67 percent of the globally-averaged ozone column would be destroyed compared with 1980 levels.

CFCs were once thought environmentally-benign because in the troposphere they're considered "non-toxic, non-flammable, and non-reactive with other chemical compounds." However, upon the discovery that chlorine- and bromine-containing compounds breakdown ozone in the stratosphere, a search for healthy substitutes began.

Today, hydrochloroflourocarbons (HCFCs) are used as a replacement for CFCs. The hydrogen attached to the CFC makes HCFCs reactive in the troposphere, triggering their breakdown before they can reach the stratosphere.(Top)

The Montreal Protocol was an instrumental, diplomatic tool for removing CFCs from the environment
The Montreal Protocol was initially adopted in 1987 and has been amended five times. 191 parties have ratified the protocol and each party is responsible for essentially eliminating all production and imports of close to 100 ozone depleting chemicals, including CFCs, by agreed upon timelines. The protocol contains a provision allowing for further amendments in the case of evolving science or a need to move targets.(Top)

Ozone is due to return to normal levels over Antarctica by 2055, be it not for unmitigated global warming
In Dr. Drew Shindell's Goddard Science Brief from May 2001, "Reaction of Ozone and Climate to Increasing Stratospheric Water Vapor," he writes that by the year 2055 the amount of ozone-depleting chemicals from CFCs is expected to reach 1980 levels, 1980 being held as the benchmark year for normal ozone, and ozone, consequently, may return to its earlier levels by that year if not for other atmospheric changes.(Top)

Emissions from hydrogen planes
DOE's Energy Efficiency & Renewable Energy page on Alternative and Advanced fuels states water vapor emissions and small amounts of hydrogen alone are emitted from fuel cells. Albeit, whether the hydrogen used for fuels cells is produced using fossil fuels or renewables also determines just how environmentally-friendly the fuels cells are in the end. And for the stratosphere, water vapor emissions from fuels cells, for example, in high altitude flight, may pose a risk.

The way fuel cells work, essentially, is that hydrogen is fed into the fuel cells and "is chemically combined with oxygen from the air." This generates power that's used to run an electrical motor that turns the propeller.

In the article, "Boeing hydrogen plane set to lift off," from Times Online, August 27, 2006, Dr. Jon Moore, Director of Communications at Intelligent Energy, is quoted as saying, "The secret lies in making a fuel cell powerful enough to get an aircraft off the ground and to keep it climbing. That takes a huge amount of energy and it is a big obstacle."

Liquid hydrogen already used in a number of high flying planes can emit water vapor and some nitrous oxide.

In hybrid fuel cell systems, however, the amount of nitrous oxide can be comparitively less than seen in emissions from conventionally-powered craft, according to the NASA Glenn Research Center.(Top)

THE SPECIFICS (KNOWN):

Scientists warn about an accumulation
of water vapor in the lower stratosphere
from high flying jets and fleets of planes
To date, scientists have warned about an accumulation of water vapor in the lower stratosphere from high flying jets. The jets, it's been said, could upset the balance of gases there and further damage the ozone. 

An early study from 1996, titled, “Molecular Hydrogen and Water Vapour Emissions in a Global Hydrogen Energy Economy,” assumed that about 20 percent of planes at the time flew in the lower stratosphere. The report, presented at the 11th World Hydrogen Energy Conference, declared a hydrogen fleet of planes would need to fly well within the troposphere to keep from disrupting the delicate balance in the stratosphere. Starting in 1996, the year the study was published, NASA's modified U2 spy plane, the ER-2, began collecting samples of stratospheric air from which to draw such conclusions. Since then, scientists have continued to elaborate on Zittel and Altmann's findings as well as apply unique methods of analysis in their attempts to understand the potential for stratospheric ozone destruction from commercial hydrogen fleets.(Top)

Dr. Kristie Boering, of Berkeley, and team of scientists, balance the planetary hydrogen budget, delivering know-how for predicting the climatic future
Kristie Boering, professor of chemistry and of earth and planetary science at UC Berkeley, together with a team of scientists from the University of California, Berkeley, the California Institute of Technology, the National Center for Atmospheric Research in Boulder, CO, and UC Irvine, were the first to balance the planetary hydrogen budget using groundbreaking studies of stratospheric air that employ a technique developed by Caltech geochemist John Eiler. The technique, as described by Boering in a ScienceDaily article from September 3, 2003, involves measuring "isotope ratios using as little as 50-100 milliliters of air -- less than half a cup -- instead of the 4,000 liters needed previously -- the approximate volume of a large home propane tank. Obtaining stratospheric air in such large quantities would be difficult."

With a balanced budget, Boering told ScienceDaily, it will be more possible for scientists to predict what will happen if vast amounts of hydrogen for fuel cells are leaked into the atmosphere. Further studies were to follow.

One possible conclusion for a future scenario came from the Stanford Global Climate & Energy Project: Hydrogen Effects on Climate, Stratospheric Ozone, and Air Pollution, which was begun in 2004 and completed in 2007, and led by Mark Z. Jacobson of the Civil and Environmental Engineering department, and David M. Golden, of the Mechanical Engineering department. While the project had numerous papers published, one concluded that wind-powered hydrogen fuel cell vehicles (in the troposphere) might have a positive effect on stratospheric ozone.(Top)

Dr. Drew Shindell at Goddard Institute for Space Studies says moisture has been accumulating in the upper stratosphere
In Dr. Drew Shindell's Goddard Science Brief from May 2001, "Reaction of Ozone and Climate to Increasing Stratospheric Water Vapor," it states that "the abundance of water vapor in the stratosphere affects ozone, surface climate, and stratospheric temperatures." Increases in stratospheric moisture that have been witnessed for decades, he added, may have important consequences.

Shindell found that higher up in the stratosphere, between 30 and 50 km above ground, there is evidence of "increasing water vapor and a very large, global cooling trend of 3° to 6°C (5° to 11°F) over recent decades."

Of the different reasons for increased water vapor emissions being transported to the upper atmosphere Shindell wrote, "Though not fully understood, the increased transport of water vapor to the stratosphere seems to have been caused at least partially by human activities. Because rising greenhouse gas emissions account for all or part of the water vapor increase, it is likely to continue for many decades."(Top)

In early 2008, the Hydrogen Hyper-jet, proposed by Reaction Engine of the UK, was held up as beacon of future aircraft
In early 2008, the Hydrogen Hyper-Jet LAPCAT, proposed by Reaction Engine of the UK, with partial funding from the European Union's Long-term advanced propulsion concepts and technologies, made front page news. Held up as a beacon of the future of aircraft, the high-flying jet would use four Scimitar engines and turbo as well as ramjet propulsion. This reincarnation of the supersonic jet would be several grades above the Concorde, which was cancelled in 2003 after it had flown supersonic transatlantic flights for more than twenty years with a fleet of 20 planes.

But what about the LAPCAT's potential risk to the balance of atmospheric gases in the stratosphere?

The history of "supersonic flight" is a long one. The Royal Swedish Academy of Sciences page attributed to the awardees of the 1995 Nobel Prize in Chemistry, Paul Crutzen, Mario Molina and Frank Sherwood Rowland, describes supersonic history as:

The first threat noted:
supersonic aircraft

The power of nitrogen oxides to decompose ozone was also noted early by the American researcher Harold Johnston, who carried out extensive laboratory studies of the chemistry of nitrogen compounds. In 1971 he pointed out the possible threat to the ozone layer that the planned fleet of supersonic aircraft and supersonic travel (SST) might represent. These aircraft would be capable of releasing nitrogen oxides right in the middle of the ozone layer at altitudes of 20 km. Crutzen's and Johnston's work gave rise to a very intensive debate among researchers as well as among technologists and decision-makers. This was also the start of intensive research into the chemistry of the atmosphere which has made great progress during the past several years. (The subsequent cancellation of plans for a large SST fleet had other reasons than the environmental risks they involved.)

A modern supersonic jet utilizing liquid hydrogen would presumably emit less or zero nitrous oxide, but water vapor emissions have now entered the picture, and according to numerous scientific reports, pose a serious threat to the balance of the stratosphere.

Still, there's considerable interest in building these SST planes for military as well as civilian use in the future.(Top)

In October 2007, Boeing successfully tested a hydrogen propulsion system on the unmanned high altitude long endurance (HALE) aircraft
In October 2007, Boeing successfully tested a hydrogen propulsion system on the unmanned craft High Altitude High Endurance (HALE), at 65,000 feet. Built for the Air Force, the craft's strength is its ability to 'maintain continuous presence over a specific ground location from stratospheric altitudes.' For Boeing, it's the first UAV of its kind that they've built since Condor flew in the 1980s, and first to be funded internally.

An August 2009 press release from Boeing describes HALE this way:

HALE is a hydrogen-powered high altitude long endurance unmanned aerial vehicle system for persistent intelligence, surveillance, reconnaissance (ISR) and communications.

The aircraft will be a propeller-driven lightweight structure with a high aspect ratio wing. Its advanced propulsion system, coupled with HALE’s use of winds to stay on station, enables HALE to provide persistent monitoring over large areas for up to 10 days.

General Characteristics:

Wingspan: 250 ft (76 m)
Takeoff gross weight: 14,125 lbs (5,272 kg)
Cruise speed: 150 kts
Maximum speed: 200 kts
Altitude: 65,000 ft
Endurance: 10 days at 65,000 ft

HALE is only one of several high altitude UAV hydrogen crafts developed in recent years. Aurora Flight Sciences, under contract with the U.S. Army and Missile Defense Command, and in partnership with Boeing since 2006, is developing Orion HALL (High Altitude, Long Loiter), an unmanned aerial vehicle. The Aurora Flight Sciences page states:

Because Orion HALL is powered by commercially developed and proven technologies, it is more capable, lower risk and more affordable than competing hydrogen powered aircraft concepts. This affordability will make it practical for large research centers, universities and civilian agencies such as NOAA to own and operate small fleets of near space unmanned assets that can maintain true persistence over an area of interest.

The Aurora Flight Sciences page goes on to highlight the many brilliant uses for the new Orion HALL UAV, including "long-dwell, high resolution meteorological observations," forecasting hurricane developments and coordinating rescue efforts. But again, the topic of manmade water vapor emissions as a whole, is deferred.

treehugger also reported on October 16, 2009, about the Ion Tiger, a small, merely 37 pound, unmanned, hydrogen fuel cell-powered plane developed by the Naval Research Laboratory, in an article by Brian Merchant, "New Record: Hydrogen Fuel Cell Plane Flies 23 Hours With Zero Emissions." A day earlier, Science Daily reported small UAVs "are growing in importance for naval missions, as they provide capabilities ranging from surveillance collection to communication links."(Top)

In August 2006, a major conference to discuss effects of aviation on climate change where hydrogen oxides (HOx) from aircraft
water vapor emissions were discussed
In August 2006, the Next Generation Air Transportation System/Joint Planning and Development Office and the Partnership for AiR Transportation and Noise Reduction, supported by the FAA and NASA, held a major conference to discuss the effects of aviation on climate change. Hydrogen oxides (HOx) from aircraft water vapor emissions in the stratosphere were among the topics discussed. (I'm awaiting a response from the FAA regarding water vapor emissions from flight and their potential or real effects on the stratosphere and will post any new information to the debate when it is received.)(Top)

In February 2007, the Department of Energy put out a call for bids believing an additional study of hydrogen emissions from transportation and stationary power was needed
In February 2007, the Department of Energy, believing an additional study of the effects of hydrogen emissions 'from the expanded use of hydrogen in transportation and stationary power markets' was needed, put a call out for bids. The DOE reaching out for more conclusions related to the science of fuel cells and the use of hydrogen as an energy carrier may have been a direct result of President Bush's call in 2005 for a "hydrogen economy." But it is a clear sign that more needed to be understood, even at that time, regarding the possible side effects of increases in manmade water vapor emissions in the troposphere.

At present, the National Climatic Data Center web site claims the water vapor feedback loop is still poorly understood.

Yet, at the US Energy Information Administration's FAQs page about Environment & Emissions it states in response to the question, "Does EIA report water vapor emissions?":

"No. Water vapor is the most abundant greenhouse gas, but it is the consensus of the international community that human activity has a very small effect on its concentration in the atmosphere, and therefore EIA does not estimate emissions of water vapor."

The EIA FAQs page was last reviewed on July 6, 2009.

The human activity that creates manmade water vapor is tiny in comparison to the natural causes of water vapor's circulation in the atmosphere, but it could nonetheless be playing a larger role in warming trends than currently thought.(Top)


Water vapor emissions from hydrogen craft are only one group of greenhouse gas emissions that can upset the stratosphere's natural balance
In 2000, Katta G. Murty, Professor of industrial and operations engineering at The University of Michigan, Ann Arbor, wrote, "Green House Gas Pollution in the Stratosphere Due to Increasing Airplane Traffic, Effects on the Environment." In response to the incredible growth in plane travel of the recent decades, he highlighted how modern jet planes fly in the lower stratosphere spewing large amounts of the greenhouse gases carbon dioxide and nitrous oxide, helping to tip the scale of the balance of the atmosphere by affecting one of its more delicate regions. Murty noted as well that with planes traveling around the clock there is a permanent increase in greenhouse gases in the stratosphere and those emissions may be responsible for warming of atmospheric and oceanic temperatures.

According to the NASA Glenn Research Center, there are also "copious" water vapor emissions from conventional planes. Changing to a 50 percent hydrogen economy at ground level, for example, would not yet raise the percentage of manmade water vapor emissions to a significantly higher level than what we have already seen. (Top)

SECTION TWO: THE UNKNOWNS

THE BASICS (UNKNOWNS):

The water vapor atmospheric feedback loops are not yet fully understood
Scientists around the globe are conducting studies to improve our knowledge about the water vapor feedback loop. Unfortunately, according to the National Climatic Data Center's web site, that feedback loop is as of yet "still fairly poorly measured and understood."

(On 01/29/10, weeks after this post was made, Discovery News published, "Water Vapor: A Warming Wildcard") (Top)

Ozone, as it returns to normal levels over Antarctica may produce a warming effect in the polar region
Goddard's Drew Shindell and Gavin Schmidt's report from 2004, Southern Hemisphere climate response to ozone changes and greenhouse gas increases, suggests there may be climate change, or warming, seen in the south polar region in the coming decades as a result of the normalization of ozone levels and greenhouse gases. The implications of the study have led to teams of researchers banding together to further investigate numerous climate models that exist to understand the Southern Annular Mode (SAM).

Shindell and Schmidt's study "found higher ozone levels might have a reverse impact on the SAM, promoting a warming, negative phase. In this way, the effects of ozone and greenhouse gases on the SAM may cancel each other out in the future. This could nullify the SAM's affects and cause Antarctica to warm."(Top)

How much moisture the stratosphere can tolerate before it reaches a tipping point
While numerous studies indicate a wetter stratosphere will result in further destruction of ozone, it is unknown what level of water vapor emissions the stratosphere can absorb before reaching some sort of tipping point.(Top)


THE SPECIFICS (UNKNOWNS):

Future direction of, and possible constraints on, commercial aircraft industry
The 26-month Cryoplane research project completed in May 2002 and led by Airbus, Europe's largest aircraft manufacturer, brought together 35 partners from academic institutions, research centers and industry, across 11 European Union countries, and the EU Commission's Joint Research Centre, to survey the potential of future aircraft powered by liquid hydrogen. The goal of the collaborative was to design the futuristic Cryoplane. The research project concluded:

Liquid hydrogen...can be produced by water electrolysis using power from renewable sources; its primary combustion product is water so that it offers extremely low emissions and it would eliminate dependency on fossil fuels.

That was 2002. Many findings resulted from the work. Albeit, today the EU's movement toward alternative flight schemes to address global warming and projected fuel shortages is symbolized by the EU's Joint Technology Initiative, Clean Sky, one of the largest European research projects ever. It produces feasibility studies that look at improving all of the possible angles of aircraft design and operations. Clean sky focuses on six technology domains:

1. Green Regional Aircraft
2. Smart Fixed-wing Aircraft
3. Green Rotorcraft
4. Sustainable and Green Engines
5. Systems for Green Operation
6. Eco-Design

In general, globally, there have been shifts in the aviation industry toward developing small-sized hydrogen planes equipped with fuel cells. There's also been a tremendous focus on making aircraft low weight, electically-powered, increasingly aerodynamic, and quieter. Some planes have so far run on biodiesel. But there are still many answers sought. The future direction is at best unfolding along with the science.

Direction of commercial craft one would hazard to guess would unfold along with high altitude and military craft and vice versa. The different types of crafts together make up a considerable percentage of greenhouse gases every year.(Top)

Future direction of defense
Waging a war against nonstate actors, as in a war on terrorism, or else becoming engaged in other security-focused conflicts, may be cause for increased surveillance or reconnaissance flights. Anticipated natural resource shortages coupled with increasing demands for aid resulting from climate change, whenever it causes human displacement, health crises and oppressive poverty, may also be a reason for greater capacity in high altitude reconnaissance and telecommunications.

A press release from August 2009 from the Boeing company states that the potential customers for the high altitude long endurance (HALE) unmanned aerial vehicle are Department of Defense, Department of Homeland Security and various telecommunications operations. The HALE UAV is built for "persistent surveillance, reconnaissance (ISR) and communications, and it is a hydrogen craft that flies at 65,000 feet.

To what degree military hydrogen planes will be flying at high altitudes as well as influencing the direction of civilian aircraft into the future will be important in consideration of what is a safe amount of manmade water vapor emissions entering the stratosphere.

Perhaps in the future high altitude planes may operate on solar power. Aurora Flight Systems, along with BAE Systems, C.S. Draper Laboratory and the Sierra Nevada Corporation, under a program called "Vulture" were recently awarded a contract by the Defense Advanced Research Projects Agency (DARPA). The purpose of the Vulture program is to "develop and demonstrate a radical new unmanned aircraft that can stay aloft for five years." Aurora is developing the Odysseus Solar-Powered Aircraft.

Additionally, Aurora has created the SunLight Eagle Program, which aims to develop a second generation solar-powered aircraft to fly at altitudes of 25,000 ft. According to Aurora's SLE page, "the program began in 2008 when Aurora engineers converted a world record-holding human-powered aircraft into an electrically-driven solar-powered aircraft." Today, it is serving as a high altitude test platform for small payloads and sub-systems, and is seeking to spin off technologies for lower altitude and commericial uses.(Top)

Future direction of private space flight and space flight in general
Commercial space flight, in combination with public, or governmental, space missions, has seen growth in recent decades and space missions are now a global phenomenon, with more and more nations, from China to Chile, developing competitive space agencies. To add to that, there's a budding movement in private space flight. Many of the space planes being designed and built will, or are likely to, use some amount of liquid hydrogen. A goal for space innovators and military leaders may also be to build on the scramjet that circulates liquid hydrogen and obtains supersonic flight. The future of space flight therefore requires attention when it comes to determining what is a safe amount of manmade water vapor emissions in the stratosphere. Space science has provided humankind a unique view of the world and yet its missions are likely to be increasingly prioritized in light of potential risk of global warming and advanced atmospheric changes.(Top)

Future direction of geoengineering
There's been a lot of talk about geoengineering in the past couple of years. Models or simulations have been run to indicate it just might work, but with a caveat. Scientists who support the notion of playing with nature as a last ditch effort have watched for years as government hasn't acted, despite the noble warnings of scientists. And so, geoengineering becomes a final option, almost. Paul Crutzen, who won the Noble Prize in 1995, along with Molina and Rowland, wrote an essay in 2006 called Climatic Change that was referenced in WIRED's "Can a Million Tons of Sulfur Dioxide Combat Climate Change", by Chris Mooney, June, 23, 2008. Mooney pulled from Crutzen's essay: "the very best would be if emissions of the greenhouse gases could be reduced so much that the stratospheric sulfur release experiment would not take place. Currently, this looks like a pious wish." Whatever direction geoengineering takes in the future, the possibility of it should be considered alongside emissions and attempts to regulate them.(Top)

Potential to conserve and recycle on global scale
What amount of conservation and recycling can become central to the lifestyles of people across the globe in developed and developing nations? While a very large question, the answer will be crucial to understanding the amount of emissions we will be emitting in the troposphere to the stratosphere and in the stratosphere to the stratosphere in the years to come. From basic bicycles and walk paths, to regional solar and wind power, to the use of LEDs for lighting, to green and earth building, to doing more with less in general, and, logically-speaking, constraining travel requirements for business and pleasure, what does the future along with its new set of priorities look like for high altitude flight?(Top)

Potential and practicality of delivering
space-based energy from solar arrays,
or Helium-3 fusion power from the moon,
to earth
In the 1970s, Gerard O'Neill began writing about space-based solar arrays, or solar power satellites, that would deliver solar energy in the form of low-density radio waves to fenced-off areas on earth, where the waves would be converted back to electricity with an efficiency rate of higher than 90 percent. He proposed using the silicon and other metals in the soil of the moon to make silicon cells and build the arrays. For a group of people who follow advancements in space science and appreciate out-of-the-box solutions this dream is kept alive and has been lobbied for in recent years.

In December 2009, in the private sector, the green light was recently given to Pacific Gas & Electric and Solaren Space to develop a $2 billion space-based solar power collection system. The Southern California start-up, Solaren, is still developing the technology it hopes will deliver 200 megawatts to California.

Others vying to build space-based solar power systems for earth include the Japan Aerospace Exploration Agency with a consortium of Japanese firms. In September 2009, the Japanese released plans to:

build a 1-gigawatt solar power collector in space. That project, "which would beam down enough power to supply hundreds of thousands of homes, will cost well north of $20 billion. They hope to start sending parts of the system skyward in 2015, with their eyes on a completion date in 2030. (click to link to source)

An article in Popular Mechanics from October 2004, by Apollo 17 astronaut Harrison H. Schmitt, discusses another possibility for obtaining energy "independence," here again the plans include traveling to the moon. The idea in this case is to extract Helium 3 from the moon, which is also in the soil there, and return it to earth to be used as a fuel for nuclear fusion.

If the projects move forward the number of flights and emissions, and types of emissions, that would be required, have most likely not yet been tallied or figured with exactitude. But the futuristic flights may be consequential in determining humankind's projected contributions to climate change patterns. Purportedly, if the missions were to become a reality, one would need to weigh in their benefits versus their costs in terms of their emissions, as well as in terms of any potential health effects from the concentration of radio waves beamed to earth. If they're shown to be feasible and affordable projects, one could argue these flights would take priority amongst space missions.(Top)

Potential demands of mining activities on earth, and perhaps in the future, in space (for example, extraction of useful ores from asteroids)
Natural resource shortages may occur in the future in light of population growth expected to continue at least until around 2050, reaching over 9 billion people worldwide, and a possible growing need for rare and unrare metals for renewable and sustainable technologies. Ethical considerations and feasibility studies, one would presume, will need to be explored and reviewed before sending robots or astronauts to space to mine minerals and metals. But the potential of such mining, one could argue, shouldn't be overlooked at this stage. In terms of space flight, and interstate and international travel that would be needed to distribute materials here on earth upon return, what amount of emissions would be created affecting the stratosphere? It's fair to begin projecting what will be viable flight patterns in light of the need to protect both ozone and natural resources.(Top)

Financial viability of large-scale hydrogen production for use in road, air and space transportation
The Obama Administration cut funding for hydrogen transportation research by approximately 60 percent in the first year in office, in part because funding hydrogen research and producing and handling fuel cells is extremely costly while significant, practical results in the field of energy-dense hydrogen storage have yet to develop. So, in addition to what could be hiccups in the science relative to water vapor emissions and the stratosphere, it may be that a future high flying hydrogen fleet is cost-prohibitive in the long-term.(Top)

This post was updated on January 31, 2010

References (not linked to above):         

Belfiore, Micheal. "The Top 9 Airplane Tech Advances of the Last 10 Years." Popular Mechanics. 28 Dec. 2009. 30. Dec. 2009. <http://www.popularmechanics.com/science/
air_space/4340775.html?do=print>.

Committee on Breakthrough Technology for Commercial Supersonic Aircraft, National Research Council. Commercial Supersonic Technology: The Way Ahead. Washington, D.C.: National Academy Press, 2001. <http://www.nap.edu/openbook.php?record_
id=10283&page=28>.

"Liquid hydrogen." Wikipedia, The Free Encyclopedia. 28 Oct 2009, 18:57 UTC. 31 Dec 2009 <http://en.wikipedia.org/w/index.php?title=
Liquid_hydrogen&oldid=322583971>.

"Montreal Protocol." Wikipedia, The Free Encyclopedia. 26 Dec 2009, 23:46 UTC. 30 Dec 2009 <http://en.wikipedia.org/w/index.php?title=
Montreal_Protocol&oldid=334167758>.

"Rocket propellant." Wikipedia, The Free Encyclopedia. 23 Dec 2009, 03:05 UTC. 31 Dec 2009 <http://en.wikipedia.org/w/index.php?title=
Rocket_propellant&oldid=333441600>.

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Debate #3: Comments

Received January 11, 2010 6:02 p.m.

Good to know you are working this issue. 

Yes, it is my understanding also that water vapor is the most important green house component.

Water vapor also plays an essential role in moderating climate and weather around the globe.

I did not see Willie Soon etal., in the rundown...

To see comments for Debate #3, please link to the page, Debate #3: Comments. 

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