DOCSLIB.ORG

Hydrogen, Nuclear, Ammonia Another (Blue Sky) Way

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hydrogen, Nuclear, Ammonia Another (Blue Sky) Way Department of Department of Mechanical Mechanical Engineering Engineering Powertrain & Vehicle PowertrainLow & Vehicle-Carbon Aviation – How can this be achieved? Research Centre Research Centre Dr James Turner Professor of Engines and Energy Systems University of Bath, UK Niels Bohr “Prediction is very difficult, especially if it's about the future.” Overview of Presentation Downsized engines . The historical link between aviation and automotive Our need to change . The growth in transportation energy The need for high energy density fuel in aviation . Pure hydrocarbons and the problem with everything else Some options for decarbonizing fuel in aviation . Hydrogen, nuclear, ammonia Another (blue sky) way . ZELTA Carbon-neutral liquid fuels . Decarbonizing practical fuels Concluding remarks Downsized, Boosted Engines – the Link Aviation pursued engine boosting to maintain power at altitude and then to increase specific output significantly Many of the engine technologies now employed in road vehicle engines effectively came from aviation via racing . Twin-spark ignition 1923 Halford . Double overhead cams (DOHC) Special Engine . Four valves per cylinder (4vpc) 4vpc, DOHC 6-cylinder The first turbocharged . Supercharging (then turbocharging) car engine . High octane fuels . Direct injection (DI) . Water injection (‘ADI’) Major Frank Halford designed all of de Havilland’s Major Halford was engines and all of the Napier H-engines, as well as being President of the fundamental in the successful development of the gas RAeS in 1951 turbine (with ‘straight-through’ combustion chambers) Automotive Engines are Architecturally-Frozen Aero Engines… It could be argued that the template for the modern automotive engine was actually laid down by Napier in 1916 with the Lion . 4vpc, DOHC, narrow valve angle and a single cam cover . 101 years old Then general automotive engineering followed aero engine technology after a 10-20 year delay… However, in the 1940s/50s the gas turbine comprehensively broke this delayed take-up link . …And the automotive industry never adopted the sleeve valve as a result Consequently the modern automotive engine shares Napier Lion much in common with the Rolls-Royce Merlin, Daimler- Benz 601 and Allison V-1710 . Effectively it’s architecturally frozen at 85 years old Potential Transfer of Automotive Technology Back to Aviation It has been attempted to use an automotive engine in light aviation before – the Porsche Flugmotor PFM 3200 . Development started in 1981 . 212-241 bhp Modern downsized, boosted, DI automotive engines are light, reliable and fuel efficient, and their control systems may well be more reliable than current light aircraft avionics . Due to on-board diagnostics requirements There are now several all-aluminium 2.0 litre DI engines which deliver 200-350 bhp . Is this an option worth persuing? This would be going full circle on engines… UK Transport Energy Consumption by Mode, 1970-2014 Air transport represents a particular problem: How do you fully decarbonize an aircraft? Air Water Road Rail Taken from: Energy Consumption in the UK (2015), DECC Change in UK Transport Energy Consumption, 1970-2014 Long-range aircraft present a significant problem Even hybrid aircraft propulsion systems can only Air reduce CO2 while there is fossil carbon in the fuel % Water Road Air: +320 Air: Rail Taken from: Energy Consumption in the UK (2015), DECC UK Road Transport Energy by Type of Vehicle, 1970-2014 2008: Beginning of Simple: let’s just electrify the private road transportation fleet EU CO2 legislation Consumption of road transport is ‘only’ 40 Mtoe… Cars 1 Mtoe = 41.87 PJ (41.87 x 1015 J)… This is a continuous output of 1.33 GW over a year – more than a good-sized nuclear power station (~ 1 GW) HGVs LGVs Buses Motorcycles Taken from: Energy Consumption in the UK (2015), DECC UK Transport Energy Consumption by Mode, 2014 53 x 1 GW nuclear The total design power of the two power stations Hinkley Point C reactors is 3.2 GW 16.5 Hinkley Point Cs For perspective, in 2014 the average UK electrical power demand was 34.4 GW (or only half the total transport demand) Peak demand in 2015 was 52.7 GW To date, the only practical energy 5.3 Hinkley Point Cs system for transport has been fossil oil 17 x 1 GW nuclear power stations Which, because we have developed fuel supply together with transportation, has developed symbiotically with it By my reckoning, we pump oil at a rate of 7.4% of the flow of Niagara Falls… Taken from: Energy Consumption in the UK (2015), DECC Long-Range Aircraft Battery Sizing Calculation At take-off, a Boeing 787-9 has 50.7 tonnes of fuel on board for a 9000 km flight . This is 605 MWh of energy (2.18 x 106 MJ) To convert to electric propulsion, we should allow an approximate factor of two to allow for increased electric machine efficiency versus thermal engines . Implies energy at take-off for the electric version is 302.5 MWh (1.09 x 106 MJ) • Or 3000 Tesla Model S P100D batteries (which are 700 kg each…) Using 150-250 Wh/kg as a cell energy density, this gives a battery mass of 1210-2017 tonnes (cell level) Calculation courtesy of Current 787-9 fully-laden take-off Dr Richard Pearson, BP weight is 253 tonnes . Battery will be 5-8 times heavier At 1.4 MW it would take 216 hours (9 days) to fully charge it… Plainly, this isn’t going to work! On-Board Energy Density: Batteries v Everything… HTA 30 aviation Diesel/Kerosene really 25 Road Gasoline needs to transport be here Rider: at 20 could E85 automotive happily scale Densities: live here M85 15 Ethanol Liquid (cryogenic) H2 = 70.8 kg/m3 H is hardly 2 Kerosene (jet fuel) = better than Methanol 10 840 kg/m3 batteries Liquid H2 (or 11.8 times greater) 5 700 bar H2 200 bar Methane This makes them really expensive and heavy Net volumetric energy density / [MJ/l] / density energy volumetric Net 0 Compared to liquid fuels batteries don’t really get off the origin… Batteries 0 5 10 15 20 25 30 35 40 Net gravimetric energy density / [MJ/kg] Courtesy Lotus Engineering How do you Decarbonize Aviation? General Electric Ammonia (NH3) and X211 turbojet: Hydrazine (N2H4) have also nuclear core (!) been researched, as has… Hydrogen Uranium Oxide Requirement to carry significant energy makes liquid hydrogen viable here NERVA Nuclear Rocket Engine Carbon-Neutral Ammonia Battlefield Mobile Compact 82% of power to Reactor electrolysis What could possibly go wrong? 32.7% efficient in terms of HHV Allison PD-81 Ammonia Taken from RRHT Allison Branch Research Engine Newsletter, November 2011 Can Hydrogen Work? (1) Liquid hydrogen has historically been investgated by the Lockheed Skunk Works and Pratt & Whitney – Project ‘Suntan’ . Hydrogen was considered attractive because of its high lower heating value and the fact that a lot of energy would have to be carried Suntan performed preliminary design work and P&W built a liquid H2 engine . The 304 . But the idea was dropped because of the problem of difficulties in hydrogen storage The concept was rescoped and became the SR-71 Pratt & Whitney 304 ‘Suntan’ engine Taken from: “Advanced Engine Development at Pratt & Whitney” by Mulready, R.C. Can Hydrogen Work? (2) Recently the EU-funded ‘Cryoplane’ project investigated the use of liquid hydrogen to fuel long-range passenger aircraft . Combustion tests using hydrogen were conducted to establish engine control limits Investigations into global warming potential were conducted . H2 was found to significantly better than kerosene . Water is a greenhouse gas too, but if the hydrogen cycle is closed then this is not an issue – as long as ‘green’ hydrogen from e.g. electrolysis is used Unfortunately the requirement for a Note impact of large particular shape of tank – torospherical – torospherical tanks meant that the concept was not viable There is also the need to derive lift from the fuel energy in heavier-than-air aircraft 6 For the 787-9: 2.18 x 10 MJ = 18 tonnes of H2 Which occupies 254.2 m3 c.f. 60.4 m3 of kerosene – 4.2 times greater Cryoplane ZELTA – Zero Emission Lighter-Than-Air If the requirement for high-speed aerodynamic efficiency and the need to carry the energy to generate lift can be removed, an interesting possibility arises… A preliminary design study has been conducted at the University of Bath . Suggests that a 100-tonne payload, 100 knot airship with sufficient range to fly from Cardington to San Francisco could be built and fuelled using liquid hydrogen Note: helium would be the lifting gas, not hydrogen! . Exhaust ballast recovery and fuel cells to generate electricity and supply potable water would also be incorporated LH2 Tank ZELTA Richardson, A., ‘Study of design factors for rigid airships for long- range, high-payload operation with zero in use carbon emissions’ Returning to the Actual Problem… The real problem with transport is that we operate the vehicles on fossil fuels . Economically-affordable engines do not have to use such fuels: both Diesel and Ford made their engines run on biofuels – we then made them run on fossil fuels instead But there is no shortage of carbon-free energy . We just need to find a means to convert it to a form usable in existing vehicles Solving the Problem… A pragmatic solution would be to use renewable energy to synthesize drop-in alternatives to the fuels we use now These are known as ‘Carbon-Neutral Liquid Fuels’, ‘Electrofuels’ or ‘Synthetic Fuels’ Solving the Problem: the Sustainable Methanol-Based Cycle Feed stocks are water, air Energy in Hydrogen from and renewable energy electrolysis of water: 1 H O H + O 2 2 2 2 The price of these feed stocks is free and a high- value product is made Carbon out Methanol synthesis: Provides the economic Synthetic CO 2 + 3H2 C H3 OH + H2 O hydrocarbons From Lackner, K.,‘Options for and products driver to decarbonize and Capturing Carbon Dioxide CO2 consumption from the Air’, May 2008 a valuable buffer for Fuel use: renewable energy 3 CH OH + O Direct air 3 2 2 capture of CO2 CO 2 + 2H2 O Carbon in CO2 from fossil fuel burning Atmospheric CO 2 power plants Gasoline, diesel and kerosene CO2 emission can also be synthesized from AdaptedAdapted from Olah fromet al., The Olah Methanol et Economy al., these feed stocks – with an ‘The Methanol Economy’ energy penalty (c.
Load more

Recommended publications
  • Solar Thermochemical Hydrogen Production Research (STCH)
    SANDIA REPORT SAND2011-3622 Unlimited Release Printed May 2011 Solar Thermochemical Hydrogen Production Research (STCH) Thermochemical Cycle Selection and Investment Priority Robert Perret Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550 Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Approved for public release; further dissemination unlimited. Issued by Sandia National Laboratories, operated for the United States Department of Energy by Sandia Corporation. NOTICE: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government, nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represent that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof, or any of their contractors or subcontractors. The views and opinions expressed herein do not necessarily state or reflect those of the United States Government, any agency thereof, or any of their contractors. Printed in the United States of America. This report has been reproduced directly from the best available copy.
    [Show full text]
  • A01 the Most Important Industrial Gases – Applications and Properties
    A01 The most important industrial gases – Applications and properties Gas overview (table) Name Property / hazards Delivery form / hazards Liquefied Inert / non- Oxidising/fire Dissolved (in Cryogenically Combustible Gaseous under pres- Solid flammable intensifying solvent) liquefied sure Acetylene X X Argon X X X Helium X X X Carbon dioxide X X X X Oxygen X X X Nitrogen X X X Hydrogen X X X Propane (bu- X X tane) Acetylene (C2H2) Properties / manufacture Acetylene is a colourless, non-toxic fuel gas with a faint odour that is slightly lighter than air (relative density = 0.91). Acetylene is transported and stored in pressurised gas cylinders with a porous filling, dissolved in acetone. The cylinder must therefore be stored upright. It is produced from calcium carbide in acetylene generators or by the petrochemical sector. Main applications Multi-purpose fuel gas (autogenous welding and cutting process), chemical synthe- ses, etc. Safety Under unfavourable conditions, the energy-rich acetylene molecule can decompose without the involvement of oxygen, thereby releasing energy. This self- Shoulder decomposition can be initiated when an acetylene cylinder is exposed to high levels colour “oxide red” of heat or by flashback in the cylinder. The start of decomposition can be detected RAL 3009 by the generation of heat in the cylinder. Acetylene forms explosive mixtures with air. Ignition range in air: 2.3 - 82 % Self-ignition temperature in air: 305 °C A01 The most important industrial gases IGS-TS-A01-17-d Page 1 of 4 Argon (Ar) Properties / manufacture Argon is a colourless, odourless, non-combustible gas, extremely inert noble gas and heavier than air (relative density = 1.78).
    [Show full text]
  • THE HYDROGEN ECONOMY. a Non-Technical Review
    Hydrogen holds out the promise of a truly sustainable global energy future. As a clean energy carrier that can be produced from any primary energy source, hydrogen used in highly efficient fuel cells could prove to be the answer to our growing concerns about energy security, urban pollution and climate change. This prize surely warrants For more information, contact: THE HYDROGEN ECONOMY the attention and resources currently being UNEP DTIE directed at hydrogen – even if the Energy Branch prospects for widespread 39-43 Quai André Citroën commercialisation of hydrogen in the A non-technical review 75739 Paris Cedex 15, France foreseeable future are uncertain. Tel. : +33 1 44 37 14 50 Fax.: +33 1 44 37 14 74 E-mail: [email protected] www.unep.fr/energy/ ROGRAMME P NVIRONMENT E ATIONS N NITED DTI-0762-PA U Copyright © United Nations Environment Programme, 2006 This publication may be reproduced in whole or in part and in any form for educational or non-profit purposes without special permission from the copyright holder, provided acknowledgement of the source is made. UNEP would appreciate receiving a copy of any publication that uses this publication as a source. No use of this publication may be made for resale or for any other commercial purpose whatsoever without prior permission in writing from the United Nations Environment Programme. Disclaimer The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the United Nations Environment Programme concerning the legal status of any country, territory, city or area or of its authorities, or concerning delimitation of its frontiers or boundaries.
    [Show full text]
  • Colonization of Venus
    Conference on Human Space Exploration, Space Technology & Applications International Forum, Albuquerque, NM, Feb. 2-6 2003. Colonization of Venus Geoffrey A. Landis NASA Glenn Research Center mailstop 302-1 21000 Brook Park Road Cleveland, OH 44135 21 6-433-2238 geofrq.landis@grc. nasa.gov ABSTRACT Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system. It is proposed here that in the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and that in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus. INTRODUCTION Since Gerard K. O'Neill [1974, 19761 first did a detailed analysis of the concept of a self-sufficient space colony, the concept of a human colony that is not located on the surface of a planet has been a major topic of discussion in the space community. There are many possible economic justifications for such a space colony, including use as living quarters for a factory producing industrial products (such as solar power satellites) in space, and as a staging point for asteroid mining [Lewis 19971. However, while the concept has focussed on the idea of colonies in free space, there are several disadvantages in colonizing empty space. Space is short on most of the raw materials needed to sustain human life, and most particularly in the elements oxygen, hydrogen, carbon, and nitrogen.
    [Show full text]
  • 2013 News Archive
    Sep 4, 2013 America’s Challenge Teams Prepare for Cross-Country Adventure Eighteenth Race Set for October 5 Launch Experienced and formidable. That describes the field for the Albuquerque International Balloon Fiesta’s 18th America’s Challenge distance race for gas balloons. The ten members of the five teams have a combined 110 years of experience flying in the America’s Challenge, along with dozens of competitive years in the other great distance race, the Coupe Aéronautique Gordon Bennett. Three of the five teams include former America’s Challenge winners. The object of the America’s Challenge is to fly the greatest distance from Albuquerque while competing within the event rules. The balloonists often stay aloft more than two days and must use the winds aloft and weather systems to their best advantage to gain the greatest distance. Flights of more than 1,000 miles are not unusual, and the winners sometimes travel as far as Canada and the U.S. East Coast. This year’s competitors are: • Mark Sullivan and Cheri White, USA: Last year Sullivan, from Albuquerque, and White, from Austin, TX, flew to Beauville, North Carolina to win their second America’s Challenge (their first was in 2008). Their winning 2012 flight of 2,623 km (1,626 miles) ended just short of the East Coast and was the fourth longest in the history of the race. The team has finished as high as third in the Coupe Gordon Bennett (2009). Mark Sullivan, a multiple-award-winning competitor in both hot air and gas balloons and the American delegate to the world ballooning federation, is the founder of the America’s Challenge.
    [Show full text]
  • HYDROGEN for HEATING: ATMOSPHERIC IMPACTS a Literature Review
    HYDROGEN FOR HEATING: ATMOSPHERIC IMPACTS A literature review BEIS Research Paper Number 2018: no. 21 November 2018 7th October 2018 HYDROGEN FOR HEATING: ATMOSPHERIC IMPACTS – A LITERATURE REVIEW R.G. (Dick) Derwent OBE rdscientific, Newbury The preparation of this review and assessment was supported by the Department for Business, Energy and Industrial Strategy under Purchase Order No. 13070002913. BEIS Research Paper No. 21 1 HYDROGEN FOR HEATING: ATMOSPHERIC IMPACTS – A LITERATURE REVIEW Summary Introduction The Department for Business, Energy and Industrial Strategy (BEIS) is undertaking work to strengthen the evidence base on the potential long-term approaches for decarbonising heating. One approach being explored is whether hydrogen could be used in place of natural gas in the gas grid to provide a source of low-carbon heat in the future. BEIS commissioned rdscientific to carry out a literature review to assess the evidence on the potential atmospheric impacts of increased emissions to the atmosphere of hydrogen. Headline Findings This review summarises the present state of our understanding of the potential global atmospheric impacts of any future increased use of hydrogen through release of additional hydrogen into the atmosphere. This review has identified two global atmospheric dis- benefits from a future hydrogen economy: stratospheric ozone depletion through its moistening of the stratosphere, and contribution to climate change through increasing the growth rates of methane and tropospheric ozone. • The consensus from the limited number of studies using current stratospheric ozone models is that the impacts of hydrogen on the stratospheric ozone layer are small. • The best estimate of the carbon dioxide (CO2) equivalence of hydrogen is 4.3 megatonnes of carbon dioxide per 1 megatonne emission of hydrogen over a 100- year time horizon, the plausible range 0 – 9.8 expresses 95% confidence.
    [Show full text]
  • Atmospheric Planetary Probes And
    SPECIAL ISSUE PAPER 1 Atmospheric planetary probes and balloons in the solar system A Coustenis1∗, D Atkinson2, T Balint3, P Beauchamp3, S Atreya4, J-P Lebreton5, J Lunine6, D Matson3,CErd5,KReh3, T R Spilker3, J Elliott3, J Hall3, and N Strange3 1LESIA, Observatoire de Paris-Meudon, Meudon Cedex, France 2Department Electrical & Computer Engineering, University of Idaho, Moscow, ID, USA 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 4University of Michigan, Ann Arbor, MI, USA 5ESA/ESTEC, AG Noordwijk, The Netherlands 6Dipartment di Fisica, University degli Studi di Roma, Rome, Italy The manuscript was received on 28 January 2010 and was accepted after revision for publication on 5 November 2010. DOI: 10.1177/09544100JAERO802 Abstract: A primary motivation for in situ probe and balloon missions in the solar system is to progressively constrain models of its origin and evolution. Specifically, understanding the origin and evolution of multiple planetary atmospheres within our solar system would provide a basis for comparative studies that lead to a better understanding of the origin and evolution of our Q1 own solar system as well as extra-solar planetary systems. Hereafter, the authors discuss in situ exploration science drivers, mission architectures, and technologies associated with probes at Venus, the giant planets and Titan. Q2 Keywords: 1 INTRODUCTION provide significant design challenge, thus translating to high mission complexity, risk, and cost. Since the beginning of the space age in 1957, the This article focuses on the exploration of planetary United States, European countries, and the Soviet bodies with sizable atmospheres, using entry probes Union have sent dozens of spacecraft, including and aerial mobility systems, namely balloons.
    [Show full text]
  • Rest of the Solar System” As We Have Covered It in MMM Through the Years
    As The Moon, Mars, and Asteroids each have their own dedicated theme issues, this one is about the “rest of the Solar System” as we have covered it in MMM through the years. Not yet having ventured beyond the Moon, and not yet having begun to develop and use space resources, these articles are speculative, but we trust, well-grounded and eventually feasible. Included are articles about the inner “terrestrial” planets: Mercury and Venus. As the gas giants Jupiter, Saturn, Uranus, and Neptune are not in general human targets in themselves, most articles about destinations in the outer system deal with major satellites: Jupiter’s Io, Europa, Ganymede, and Callisto. Saturn’s Titan and Iapetus, Neptune’s Triton. We also include past articles on “Space Settlements.” Europa with its ice-covered global ocean has fascinated many - will we one day have a base there? Will some of our descendants one day live in space, not on planetary surfaces? Or, above Venus’ clouds? CHRONOLOGICAL INDEX; MMM THEMES: OUR SOLAR SYSTEM MMM # 11 - Space Oases & Lunar Culture: Space Settlement Quiz Space Oases: Part 1 First Locations; Part 2: Internal Bearings Part 3: the Moon, and Diferent Drums MMM #12 Space Oases Pioneers Quiz; Space Oases Part 4: Static Design Traps Space Oases Part 5: A Biodynamic Masterplan: The Triple Helix MMM #13 Space Oases Artificial Gravity Quiz Space Oases Part 6: Baby Steps with Artificial Gravity MMM #37 Should the Sun have a Name? MMM #56 Naming the Seas of Space MMM #57 Space Colonies: Re-dreaming and Redrafting the Vision: Xities in
    [Show full text]
  • Are Airships Making a Comeback? Nicolas Raymond
    Mike Follows Are airships making a comeback? Nicolas Raymond Hot air balloons over When hot air balloons are propelled through the Quebec, Canada air rather than just being pushed along by the wind they are known as airships or dirigibles. The heyday of airships came to an abrupt end when the Hindenburg crashed dramatically in 1937. But, as Mike Follows explains, modern airships may Key words have a role in the future. density According to Archimedes’ Principle, any object forces immersed in a fluid receives an upthrust equal to the weight of the fluid it displaces. This can be Newton’s laws applied to lighter-than-air balloons: a balloon aircraft will descend if its weight exceeds that of the air displaced and rise if its weight is less. We can also think of this in terms of density. A balloon will rise if its overall density (balloon + air inside) is less than the density of the surrounding air. In hot-air balloons, the volume is constant and the density of air is varied by changing its temperature. Heating the air inside the envelope using the open flame from a burner in the gondola suspended beneath causes the air to expand and escape out through the bottom of the envelope. The top of the balloon usually has a vent of some sort, enabling the pilot to release hot air to slow an ascent. Colder, denser air will enter through the hole at the bottom of the envelope. Burning gas to give a hot air balloon greater lift 16 Catalyst February 2015 www.catalyststudent.org.uk Airships of the past airships.
    [Show full text]
  • To What Extent Does Modern Technology Address the Problems of Past
    To what extent does modern technology address the problems of past airships? Ansel Sterling Barnes Today, we have numerous technologies we take for granted: electricity, easy internet access, wireless communications, vast networks of highways crossing the continents, and flights crisscrossing the globe. Flight, though, is special because it captures man’s imagination. Humankind has dreamed of flight since Paleolithic times, and has achieved it with heavier-than-air craft such as airplanes and helicopters. Both of these are very useful and have many applications, but for certain jobs, these aircraft are not the ideal option because they are loud and waste energy. Luckily, there is an alternative to energy hogs like airplanes or helicopters, a lighter-than-air craft that predates both: airships! Airships do not generate their own lift through sheer power like heavier-than-air craft. They are airborne submarines of a sort that use a different lift source: gas. They don’t need to use the force of moving air to lift them from the ground, so they require very little energy to lift off or to fly. Unfortunately, there were problems with past airships; problems that were the reason for the decline of airships after World War II: cost, pilot skill, vulnerability to weather, complex systems control, materials, size, power source, and lifting gas. This begs the question: To what extent does modern technology address the problems of past airships? With today’s technology, said problems can be managed. Most people know lighter-than-air craft by one name or another: hot air balloons, blimps, dirigibles, zeppelins, etc.
    [Show full text]
  • Biogeochemical Cycle
    Biogeochemical cycle In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical substance moves through biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth. There are biogeochemical cycles for the chemical elements calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, and sulfur; molecular cycles for water and silica; macroscopic cycles such as the rock cycle; as well as human-induced cycles for synthetic compounds such as An illustration of the oceanic whale pump polychlorinated biphenyl (PCB). In some showing how whales cycle nutrients cycles there are reservoirs where a through the water column substance remains for a long period of time. Contents Systems Reservoirs Important cycles See also References Further reading Systems Ecological systems (ecosystems) have many biogeochemical cycles operating as a part of the system, for example the water cycle, the carbon cycle, the nitrogen cycle, etc. All chemical elements occurring in organisms are part of biogeochemical cycles. In addition to being a part of living organisms, these chemical elements also cycle through abiotic factors of ecosystems such as water (hydrosphere), land (lithosphere), and/or the air (atmosphere).[1] The living factors of the planet can be referred to collectively as the biosphere. All the nutrients—such as carbon, nitrogen, oxygen, phosphorus, and sulfur—used in ecosystems by living organisms are a part of a closed system; therefore, these chemicals are recycled instead of being lost and replenished constantly such as in an open system.[1] The flow of energy in an ecosystem is an open system; the sun constantly gives the planet energy in the form of light while it is eventually used and lost in the form of heat throughout the trophic levels of a food web.
    [Show full text]
  • Hydrogen Storage Materials with Focus on Main Group I-II Elements Department: Materials Research Department
    Ris0-PhD-21(EN) Hydrogen Storage Materials with Focus on Main Group l-ll Elements Anders Andreasen Ris0 National Laboratory Roskilde Denmark October 2005 Hydrogen storage materials with focus on main group I II elements Preparation and characterization Ph.D. thesis by Anders Andreasen Rise National Laboratory Roskilde, 2005 Author: Anders Andreasen Riso-PhD-21(EN) 2005 Title: Hydrogen Storage Materials with Focus on Main Group I-II Elements Department: Materials Research Department This thesis is submitted in partial fulfillment of the requirements for the Ph. D. degree at the Department of Chemical Engineering, Technical University of Demnark Abstract (max. 2000 char.): ISBN 87-550-3498-5 A future hydrogen based society, viz. a society in which hydrogen is the primary energy carrier, is viewed by many as a solution to many of the energy related problems of the world { the ultimate problem being the eventual depletion of fossil fuels. Although, for the hydrogen based society to become realizable, several technical difficulties must be dealt with. Especially, the transport sector relies on a cheap, safe and reliable way of storing hydrogen with high storage capacity, fast kinetics and favourable thermodynamics. No potential hydrogen storage candidate has been found yet, which meets all the criteria just summarized. The hydrogen storage solution showing the greatest potential in fulfilling the hydrogen storage criteria with respect to storage capacity, is solid state storage in Contract no.: light metal hydrides e.g. alkali metals and alkali earth metals. The remaining issues to be dealt with mainly concerns the kinetics of hydrogen uptake/release and the thermal stability of the formed hydride.
    [Show full text]