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135-451: A single-stage-to-orbit ( SSTO ) vehicle reaches orbit from the surface of a body using only propellants and fluids and without expending tanks, engines, or other major hardware. The term exclusively refers to reusable vehicles . To date, no Earth-launched SSTO launch vehicles have ever been flown; orbital launches from Earth have been performed by either fully or partially expendable multi-stage rockets . The main projected advantage of
270-475: A thrust to weight ratio in excess of 1, enabling them to lift off. Clearly, one of the main issues with nuclear propulsion would be safety, both during a launch for the passengers, but also in case of a failure during launch. As of February 2024, no current program is attempting nuclear propulsion from Earth's surface. Because they can be more energetic than the potential energy that chemical fuel allows for, some laser or microwave powered rocket concepts have
405-404: A body is proportional to the product of the masses of the two attracting bodies and decreases inversely with the square of the distance between them. To this Newtonian approximation, for a system of two-point masses or spherical bodies, only influenced by their mutual gravitation (called a two-body problem ), their trajectories can be exactly calculated. If the heavier body is much more massive than
540-427: A certain time called the period. This motion is described by the empirical laws of Kepler, which can be mathematically derived from Newton's laws. These can be formulated as follows: Note that while bound orbits of a point mass or a spherical body with a Newtonian gravitational field are closed ellipses , which repeat the same path exactly and indefinitely, any non-spherical or non-Newtonian effects (such as caused by
675-621: A clean and renewable fuel . Among disadvantages of ammonia as an energy carrier are its high toxicity, energy efficiency of NH 3 production from N 2 and H 2 , and poisoning of PEM Fuel Cells by traces of non-decomposed NH 3 after NH 3 to N 2 conversion. Numerous industry groups (gas networks, gas boiler manufacturers) across the natural gas supply chain are promoting hydrogen combustion boilers for space and water heating, and hydrogen appliances for cooking, to reduce energy-related CO 2 emissions from residential and commercial buildings. The proposition
810-412: A focal point of the ellipse, as described by Kepler's laws of planetary motion . For most situations, orbital motion is adequately approximated by Newtonian mechanics , which explains gravity as a force obeying an inverse-square law . However, Albert Einstein 's general theory of relativity , which accounts for gravity as due to curvature of spacetime , with orbits following geodesics , provides
945-516: A global carbon tax is placed on gray hydrogen. In terms of cost per unit of energy, blue and gray hydrogen will always cost more than the fossil fuels used in its production, while green hydrogen will always cost more than the renewable electricity used to make it. Subsidies for clean hydrogen production are much higher in the US and EU than in India. The distribution of hydrogen for the purpose of transportation
1080-419: A lesser extent hydrogen-powered aircraft and heavy goods vehicles), and long-term energy storage. Other applications, such as light duty vehicles and heating in buildings, are no longer part of the future hydrogen economy, primarily for economic and environmental reasons. Hydrogen is challenging to store, to transport in pipelines, and to use. It presents safety concerns since it is highly explosive, and it
1215-545: A lot of energy to stay cold in their liquid state . In 2023 the Laura Maersk was the first container ship to run on methanol fuel. Ethanol plants in the midwest are a good place for pure carbon capture to combine with hydrogen to make green methanol, with abundant wind and nuclear energy in Iowa , Minnesota , and Illinois . Mixing methanol with ethanol could make methanol a safer fuel to use because methanol doesn't have
1350-402: A more accurate calculation and understanding of the exact mechanics of orbital motion. Historically, the apparent motions of the planets were described by European and Arabic philosophers using the idea of celestial spheres . This model posited the existence of perfect moving spheres or rings to which the stars and planets were attached. It assumed the heavens were fixed apart from the motion of
1485-559: A network of wind turbines to produce hydrogen and oxygen for long-term energy storage through electrolysis , to help address renewable power's variable output . The term "hydrogen economy" itself was coined by John Bockris during a talk he gave in 1970 at General Motors (GM) Technical Center. Bockris viewed it as an economy in which hydrogen, underpinned by nuclear and solar power, would help address growing concern about fossil fuel depletion and environmental pollution, by serving as energy carrier for end-uses in which electrification
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#17330861201401620-459: A number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen -free form. In addition, liquid hydrogen is a cryogen and presents dangers (such as frostbite ) associated with very cold liquids. Hydrogen dissolves in many metals and in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement , leading to cracks and explosions. Hydrogen
1755-420: A practical sense, both of these trajectory types mean the object is "breaking free" of the planet's gravity, and "going off into space" never to return. In most situations, relativistic effects can be neglected, and Newton's laws give a sufficiently accurate description of motion. The acceleration of a body is equal to the sum of the forces acting on it, divided by its mass, and the gravitational force acting on
1890-557: A proposed SSTO. It is one of only a few prototype SSTO vehicles ever built. Several other prototypes were intended, including the DC-X2 (a half-scale prototype) and the DC-Y, a full-scale vehicle which would be capable of single stage insertion into orbit. Neither of these were built, but the project was taken over by NASA in 1995, and they built the DC-XA, an upgraded one-third scale prototype. This vehicle
2025-490: A proton exchange membrane system and were supplied with raw hydrogen from a BP refinery in Kwinana, south of Perth. The hydrogen was a byproduct of the refinery's industrial process. The buses were refueled at a station in the northern Perth suburb of Malaga. In October 2021, Queensland Premier Annastacia Palaszczuk and Andrew Forrest announced that Queensland will be home to the world's largest hydrogen plant. In Australia,
2160-399: A range of estimates of the levelized costs of gray, blue, and green hydrogen, expressed in terms of US$ per kg of H 2 (where data provided in other currencies or units, the average exchange rate to US dollars in the given year are used, and 1 kg of H 2 is assumed to have a calorific value of 33.3kWh). The range of cost estimates for commercially available hydrogen production methods
2295-526: A relatively large natural gas pipeline system already in place include Belgium , Germany , France , and the Netherlands . In 2020, The EU launched its European Clean Hydrogen Alliance (ECHA). Green hydrogen has become more common in France. A €150 million Green Hydrogen Plan was established in 2019, and it calls for building the infrastructure necessary to create, store, and distribute hydrogen as well as using
2430-481: A relatively small delta-v increase can be helpful, and outside assistance for a vehicle is therefore desirable. Proposed launch assists include: And on-orbit resources such as: Due to weight issues such as shielding, many nuclear propulsion systems are unable to lift their own weight, and hence are unsuitable for launching to orbit. However, some designs such as the Orion project and some nuclear thermal designs do have
2565-547: A reusable vehicle must be able to reenter without damage, and land safely. While single-stage rockets were once thought to be beyond reach, advances in materials technology and construction techniques have shown them to be possible. For example, calculations show that the Titan II first stage, launched on its own, would have a 25-to-1 ratio of fuel to vehicle hardware. It has a sufficiently efficient engine to achieve orbit, but without carrying much payload. Hydrogen fuel might seem
2700-515: A significantly higher degree of regular maintenance. It is considered to be marginally possible to launch a single-stage-to-orbit chemically fueled spacecraft from Earth. The principal complicating factors for SSTO from Earth are: high orbital velocity of over 7,400 metres per second (27,000 km/h; 17,000 mph); the need to overcome Earth's gravity, especially in the early stages of flight; and flight within Earth's atmosphere , which limits speed in
2835-410: A single point called the barycenter. The paths of all the star's satellites are elliptical orbits about that barycenter. Each satellite in that system will have its own elliptical orbit with the barycenter at one focal point of that ellipse. At any point along its orbit, any satellite will have a certain value of kinetic and potential energy with respect to the barycenter, and the sum of those two energies
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#17330861201402970-413: A star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point . Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets and satellites follow elliptic orbits , with the center of mass being orbited at
3105-674: A sufficiently efficient propulsion system and discontinued development. Single-stage-to-orbit is much easier to achieve on extraterrestrial bodies that have weaker gravitational fields and lower atmospheric pressure than Earth, such as the Moon and Mars, and has been achieved from the Moon by the Apollo program 's Lunar Module , by several robotic spacecraft of the Soviet Luna program , and by China's Chang'e 5 and Chang'e 6 lunar sample return missions. Before
3240-487: A technical sense—they are describing a portion of an elliptical path around the center of gravity—but the orbits are interrupted by striking the Earth. If the cannonball is fired with sufficient speed, the ground curves away from the ball at least as much as the ball falls—so the ball never strikes the ground. It is now in what could be called a non-interrupted or circumnavigating, orbit. For any specific combination of height above
3375-479: A vacuum bell in atmosphere would have disastrous consequences for the engine. Engines designed to fire in atmosphere therefore have to shorten the nozzle, only expanding the gasses to atmospheric pressure. The efficiency losses due to the smaller bell are usually mitigated via staging, as upper stage engines such as the Rocketdyne J-2 do not have to fire until atmospheric pressure is negligible, and can therefore use
3510-406: A visible flame in the daylight and doesn't emit smoke, and ethanol has a visible light yellow flame. Green hydrogen production of 70% efficiency and a 70% efficiency of methanol production from that would be a 49% energy conversion efficiency . Hydrogen can be deployed as a fuel in two distinct ways: in fuel cells which produce electricity, and via combustion to generate heat. When hydrogen
3645-505: Is a constant value at every point along its orbit. As a result, as a planet approaches periapsis , the planet will increase in speed as its potential energy decreases; as a planet approaches apoapsis , its velocity will decrease as its potential energy increases. There are a few common ways of understanding orbits: The velocity relationship of two moving objects with mass can thus be considered in four practical classes, with subtypes: Orbital rockets are launched vertically at first to lift
3780-523: Is a convenient approximation to take the center of mass as coinciding with the center of the more massive body. Advances in Newtonian mechanics were then used to explore variations from the simple assumptions behind Kepler orbits, such as the perturbations due to other bodies, or the impact of spheroidal rather than spherical bodies. Joseph-Louis Lagrange developed a new approach to Newtonian mechanics emphasizing energy more than force, and made progress on
3915-407: Is adopted of taking the potential energy as zero at infinite separation, the bound orbits will have negative total energy, the parabolic trajectories zero total energy, and hyperbolic orbits positive total energy. An open orbit will have a parabolic shape if it has the velocity of exactly the escape velocity at that point in its trajectory, and it will have the shape of a hyperbola when its velocity
4050-464: Is also a vector. Because our basis vector r ^ {\displaystyle {\hat {\mathbf {r} }}} moves as the object orbits, we start by differentiating it. From time t {\displaystyle t} to t + δ t {\displaystyle t+\delta t} , the vector r ^ {\displaystyle {\hat {\mathbf {r} }}} keeps its beginning at
4185-972: Is also used as a fuel for spacecraft propulsion . In the International Energy Agency 's 2022 Net Zero Emissions Scenario (NZE), hydrogen is forecast to account for 2% of rail energy demand in 2050, while 90% of rail travel is expected to be electrified by then (up from 45% today). Hydrogen's role in rail would likely be focused on lines that prove difficult or costly to electrify. The NZE foresees hydrogen meeting approximately 30% of heavy truck energy demand in 2050, mainly for long-distance heavy freight (with battery electric power accounting for around 60%). Although hydrogen can be used in adapted internal combustion engines , fuel cells, being electrochemical , have an efficiency advantage over heat engines. Fuel cells are more expensive to produce than common internal combustion engines but also require higher purity hydrogen fuel than internal combustion engines. In
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4320-487: Is an important concept in the engineering of a rocket. However, mass fraction may have little to do with the costs of a rocket, as the costs of fuel are very small when compared to the costs of the engineering program as a whole. As a result, a cheap rocket with a poor mass fraction may be able to deliver more payload to orbit with a given amount of money than a more complicated, more efficient rocket. Many vehicles are only narrowly suborbital, so practically anything that gives
4455-518: Is because of both the low density and the additional insulation required to minimize boiloff (a problem which does not occur with kerosene and many other fuels). The low density of hydrogen further affects the design of the rest of the vehicle: pumps and pipework need to be much larger in order to pump the fuel to the engine. The result is the thrust/weight ratio of hydrogen-fueled engines is 30–50% lower than comparable engines using denser fuels. This inefficiency indirectly affects gravity losses as well;
4590-666: Is being tested around the world, particularly in the US ( California , Massachusetts ), Canada , Japan , the EU ( Portugal , Norway , Denmark, Germany ), and Iceland . An indicator of the presence of large natural gas infrastructures already in place in countries and in use by citizens is the number of natural gas vehicles present in the country. The countries with the largest amount of natural gas vehicles are (in order of magnitude): Iran , China , Pakistan , Argentina , India , Brazil , Italy , Colombia , Thailand , Uzbekistan , Bolivia , Armenia , Bangladesh , Egypt , Peru , Ukraine ,
4725-466: Is broad, As of 2022, gray hydrogen is cheapest to produce without a tax on its CO 2 emissions, followed by blue and green hydrogen. Blue hydrogen production costs are not anticipated to fall substantially by 2050, can be expected to fluctuate with natural gas prices and could face carbon taxes for uncaptured emissions. The cost of electrolysers fell by 60% from 2010 to 2022, before rising slightly due to an increasing cost of capital . Their cost
4860-481: Is consumed in fuel cells, the only emission at the point of use is water vapor. Combustion of hydrogen can lead to the thermal formation of harmful nitrogen oxides emissions. In the context of limiting global warming , low-carbon hydrogen (particularly green hydrogen ) is likely to play an important role in decarbonizing industry. Hydrogen fuel can produce the intense heat required for industrial production of steel, cement, glass, and chemicals, thus contributing to
4995-418: Is flammable when mixed even in small amounts with ordinary air. Ignition can occur at a volumetric ratio of hydrogen to air as low as 4%. Moreover, hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns. A hydrogen infrastructure is the infrastructure of hydrogen pipeline transport, points of hydrogen production and hydrogen stations for distribution as well as
5130-491: Is generally envisaged that the future hydrogen economy replaces gray hydrogen with low-carbon hydrogen. As of 2024 it is unclear when enough low-carbon hydrogen could be produced to phase-out all the gray hydrogen. The future end-uses are likely in heavy industry (e.g. high-temperature processes alongside electricity, feedstock for production of green ammonia and organic chemicals , as alternative to coal-derived coke for steelmaking ), long-haul transport (e.g. shipping, and to
5265-621: Is going to build two combined cycle power plants in the Midwest that can mix 30% hydrogen with the natural gas. Intermountain Power Plant is being retrofitted to a natural gas/hydrogen power plant that can run on 30% hydrogen as well, and is scheduled to run on pure hydrogen by 2045. More widespread use of hydrogen in economies entails the need for investment and costs in its production, storage, distribution and use. Estimates of hydrogen's cost are therefore complex and need to make assumptions about
5400-404: Is greater than the escape velocity. When bodies with escape velocity or greater approach each other, they will briefly curve around each other at the time of their closest approach, and then separate, forever. All closed orbits have the shape of an ellipse . A circular orbit is a special case, wherein the foci of the ellipse coincide. The point where the orbiting body is closest to Earth is called
5535-420: Is inefficient compared to direct use of electricity . Since relatively small amounts of low-carbon hydrogen are available, climate benefits can be maximized by using it in harder-to-decarbonize applications. As of 2023 there are no real alternatives to hydrogen for several chemical processes in which it is currently used, such as ammonia production for fertilizer . The cost of low- and zero-carbon hydrogen
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5670-414: Is likely to influence the degree to which it will be used in chemical feedstocks, long haul aviation and shipping, and long-term energy storage. Production costs of low- and zero-carbon hydrogen are evolving. Future costs may be influenced by carbon taxes , the geography and geopolitics of energy, energy prices, technology choices, and their raw material requirements. It is likely that green hydrogen will see
5805-581: Is located in the plane using vector calculus in polar coordinates both with the standard Euclidean basis and with the polar basis with the origin coinciding with the center of force. Let r {\displaystyle r} be the distance between the object and the center and θ {\displaystyle \theta } be the angle it has rotated. Let x ^ {\displaystyle {\hat {\mathbf {x} }}} and y ^ {\displaystyle {\hat {\mathbf {y} }}} be
5940-482: Is low carbon: steam fossil fuel reforming with carbon capture and storage , green hydrogen produced using electrolysis, and hydrogen produced from biomass . CO 2 emissions from 2021 production, at 915 MtCO 2 , amounted to 2.5% of energy-related CO 2 emissions and 1.8% of global greenhouse gas emissions. Virtually all hydrogen produced for the current market is used in oil refining (40 Mt H 2 in 2021) and industry (54 MtH2). In oil refining, hydrogen
6075-434: Is made using SMR with carbon capture and storage ( blue hydrogen ), or through electrolysis of water using renewable power ( green hydrogen ), accounted for less than 1% of production. Virtually all of the 100 million tonnes of hydrogen produced each year is used in oil refining (43% in 2021) and industry (57%), principally in the manufacture of ammonia for fertilizers, and methanol . To limit global warming , it
6210-507: Is mostly consumed at the site of production, notably for the synthesis of ammonia . For many years hydrogen has been stored as compressed gas or cryogenic liquid, and transported as such in cylinders, tubes, and cryogenic tanks for use in industry or as propellant in space programs. The overarching challenge is the very low boiling point of H 2 : it boils around 20.268 K (−252.882 °C or −423.188 °F). Achieving such low temperatures requires expending significant energy. Xcel Energy
6345-488: Is projected to fall significantly to 2030 and 2050, driving down the cost of green hydrogen alongside the falling cost of renewable power generation. It is cheapest to produce green hydrogen with surplus renewable power that would otherwise be curtailed , which favors electrolyzers capable of responding to low and variable power levels . A 2022 Goldman Sachs analysis anticipates that globally green hydrogen will achieve cost parity with grey hydrogen by 2030, earlier if
6480-469: Is that current end-users of piped natural gas can await the conversion of and supply of hydrogen to existing natural gas grids , and then swap heating and cooking appliances, and that there is no need for consumers to do anything now. A review of 32 studies on the question of hydrogen for heating buildings, independent of commercial interests, found that the economics and climate benefits of hydrogen for heating and cooking generally compare very poorly with
6615-402: Is that it was able to account for the remaining unexplained amount in precession of Mercury's perihelion first noted by Le Verrier. However, Newton's solution is still used for most short term purposes since it is significantly easier to use and sufficiently accurate. Within a planetary system , planets, dwarf planets , asteroids and other minor planets , comets , and space debris orbit
6750-547: Is to reduce emissions where cheaper and more energy-efficient clean solutions are not available. In this context, hydrogen economy encompasses the production of hydrogen and the use of hydrogen in ways that contribute to phasing-out fossil fuels and limiting climate change . Hydrogen can be produced by several means. Most hydrogen produced today is gray hydrogen , made from natural gas through steam methane reforming (SMR). This process accounted for 1.8% of global greenhouse gas emissions in 2021. Low-carbon hydrogen , which
6885-431: Is used to remove a large fraction of these emissions, the product is known as blue hydrogen . Green hydrogen is usually understood to be produced from renewable electricity via electrolysis of water. Less frequently, definitions of green hydrogen include hydrogen produced from other low-emission sources such as biomass . Producing green hydrogen is currently more expensive than producing gray hydrogen, and
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#17330861201407020-412: Is used, in a process known as hydrocracking , to convert heavy petroleum sources into lighter fractions suitable for use as fuels. Industrial uses mainly comprise ammonia production to make fertilizers (34 Mt H 2 in 2021), methanol production (15 Mt H 2 ) and the manufacture of direct reduced iron (5 Mt H 2 ). Hydrogen gas is produced by several industrial methods. Nearly all of
7155-526: The Australian Renewable Energy Agency (ARENA) has invested $ 55 million in 28 hydrogen projects, from early stage research and development to early stage trials and deployments. The agency's stated goal is to produce hydrogen by electrolysis for $ 2 per kilogram, announced by Minister for Energy and Emissions Angus Taylor in a 2021 Low Emissions Technology Statement. Countries in the EU which have
7290-588: The SSME ) + 10 x turboramjets. Around 1985 the NASP project was intended to launch a scramjet vehicle into orbit, but funding was stopped and the project cancelled. At around the same time, the HOTOL tried to use precooled jet engine technology, but failed to show significant advantages over rocket technology. The DC-X, short for Delta Clipper Experimental, was an uncrewed one-third scale vertical takeoff and landing demonstrator for
7425-768: The United States . Natural gas vehicles can also be converted to run on hydrogen . Also, in a few private homes, fuel cell micro-CHP plants can be found, which can operate on hydrogen, or other fuels as natural gas or LPG. Western Australia 's Department of Planning and Infrastructure operated three Daimler Chrysler Citaro fuel cell buses as part of its Sustainable Transport Energy for Perth Fuel Cells Bus Trial in Perth. The buses were operated by Path Transit on regular Transperth public bus routes. The trial began in September 2004 and concluded in September 2007. The buses' fuel cells used
7560-461: The apoapsis is that point at which they are the farthest. (More specific terms are used for specific bodies. For example, perigee and apogee are the lowest and highest parts of an orbit around Earth, while perihelion and aphelion are the closest and farthest points of an orbit around the Sun.) In the case of planets orbiting a star, the mass of the star and all its satellites are calculated to be at
7695-461: The eccentricities of the planetary orbits vary over time. Mercury , the smallest planet in the Solar System, has the most eccentric orbit. At the present epoch , Mars has the next largest eccentricity while the smallest orbital eccentricities are seen with Venus and Neptune . As two objects orbit each other, the periapsis is that point at which the two objects are closest to each other and
7830-453: The perigee , and when orbiting a body other than earth it is called the periapsis (less properly, "perifocus" or "pericentron"). The point where the satellite is farthest from Earth is called the apogee , apoapsis, or sometimes apifocus or apocentron. A line drawn from periapsis to apoapsis is the line-of-apsides . This is the major axis of the ellipse, the line through its longest part. Bodies following closed orbits repeat their paths with
7965-718: The three-body problem , discovering the Lagrangian points . In a dramatic vindication of classical mechanics, in 1846 Urbain Le Verrier was able to predict the position of Neptune based on unexplained perturbations in the orbit of Uranus . Albert Einstein in his 1916 paper The Foundation of the General Theory of Relativity explained that gravity was due to curvature of space-time and removed Newton's assumption that changes in gravity propagate instantaneously. This led astronomers to recognize that Newtonian mechanics did not provide
8100-446: The three-body problem ; however, it converges too slowly to be of much use. Except for special cases like the Lagrangian points , no method is known to solve the equations of motion for a system with four or more bodies. Rather than an exact closed form solution, orbits with many bodies can be approximated with arbitrarily high accuracy. These approximations take two forms: Differential simulations with large numbers of objects perform
8235-462: The variability of renewable energy output. Producing green hydrogen can both reduce the need for renewable power curtailment during periods of high renewables output and be stored long-term to provide for power generation during periods of low output. An alternative to gaseous hydrogen as an energy carrier is to bond it with nitrogen from the air to produce ammonia, which can be easily liquefied, transported, and used (directly or indirectly) as
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#17330861201408370-460: The 1990s) which were never constructed include: Star-raker : In 1979 Rockwell International unveiled a concept for a 100-ton payload heavy-lift multicycle airbreather ramjet/ cryogenic rocket engine , horizontal takeoff/horizontal landing single-stage-to-orbit spaceplane named Star-Raker , designed to launch heavy Space-based solar power satellites into a 300 nautical mile Earth orbit. Star-raker would have had 3 x LOX/LH2 rocket engines (based on
8505-532: The 2010s, notably with the forming of the World Hydrogen Council in 2017. Several manufacturers released hydrogen fuel cell cars commercially, with manufacturers such as Toyota, Hyundai, and industry groups in China having planned to increase numbers of the cars into the hundreds of thousands over the next decade. The global scope for hydrogen's role in cars is shrinking relative to earlier expectations. By
8640-565: The DC-X, often said that he thought the first successful orbital SSTO would more likely be fueled by propane. Some SSTO concepts use the same engine for all altitudes, which is a problem for traditional engines with a bell-shaped nozzle . Depending on the atmospheric pressure, different bell shapes are required. Engines designed to operate in a vacuum have large bells, allowing the exhaust gasses to expand to near vacuum pressures, thereby raising efficiency. Due to an effect known as Flow separation , using
8775-410: The Earth at the point half an orbit beyond, and directly opposite the firing point, below the circular orbit. At a specific horizontal firing speed called escape velocity , dependent on the mass of the planet and the distance of the object from the barycenter, an open orbit (E) is achieved that has a parabolic path . At even greater speeds the object will follow a range of hyperbolic trajectories . In
8910-461: The SSTO concept is elimination of the hardware replacement inherent in expendable launch systems. However, the non-recurring costs associated with design, development, research and engineering (DDR&E) of reusable SSTO systems are much higher than expendable systems due to the substantial technical challenges of SSTO, assuming that those technical issues can in fact be solved. SSTO vehicles may also require
9045-580: The Sun are proportional to the squares of their orbital periods. Jupiter and Venus, for example, are respectively about 5.2 and 0.723 AU distant from the Sun, their orbital periods respectively about 11.86 and 0.615 years. The proportionality is seen by the fact that the ratio for Jupiter, 5.2 /11.86 , is practically equal to that for Venus, 0.723 /0.615 , in accord with the relationship. Idealised orbits meeting these rules are known as Kepler orbits . Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general,
9180-420: The Sun is not located at the center of the orbits, but rather at one focus . Second, he found that the orbital speed of each planet is not constant, as had previously been thought, but rather that the speed depends on the planet's distance from the Sun. Third, Kepler found a universal relationship between the orbital properties of all the planets orbiting the Sun. For the planets, the cubes of their distances from
9315-403: The accelerations in the radial and transverse directions. As said, Newton gives this first due to gravity is − μ / r 2 {\displaystyle -\mu /r^{2}} and the second is zero. Equation (2) can be rearranged using integration by parts. We can multiply through by r {\displaystyle r} because it is not zero unless
9450-421: The atmosphere to reduce the take-off weight of the vehicle. Some of the issues with this approach are: Thus with for example scramjet designs (e.g. X-43 ) the mass budgets do not seem to close for orbital launch. Similar issues occur with single-stage vehicles attempting to carry conventional jet engines to orbit—the weight of the jet engines is not compensated sufficiently by the reduction in propellant. On
9585-693: The atmosphere when it is at low altitude, and then using onboard liquid oxygen after switching to the closed cycle rocket engine at high altitude, the McDonnell Douglas DC-X , the Lockheed Martin X-33 and VentureStar which was intended to replace the Space Shuttle, and the Roton SSTO , which is a helicopter that can get to orbit. However, despite showing some promise, none of them have come close to achieving orbit yet due to problems with finding
9720-468: The atmosphere, and achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit, plus a meaningful payload weight. Air-breathing designs typically fly at supersonic or hypersonic speeds, and usually include a rocket engine for the final burn for orbit. Whether rocket-powered or air-breathing, a reusable vehicle must be rugged enough to survive multiple round trips into space without adding excessive weight or maintenance. In addition
9855-458: The atmosphere, in an act commonly referred to as an aerobraking maneuver. As an illustration of an orbit around a planet, the Newton's cannonball model may prove useful (see image below). This is a ' thought experiment ', in which a cannon on top of a tall mountain is able to fire a cannonball horizontally at any chosen muzzle speed. The effects of air friction on the cannonball are ignored (or perhaps
9990-461: The calculations in a hierarchical pairwise fashion between centers of mass. Using this scheme, galaxies, star clusters and other large assemblages of objects have been simulated. The following derivation applies to such an elliptical orbit. We start only with the Newtonian law of gravitation stating that the gravitational acceleration towards the central body is related to the inverse of the square of
10125-517: The center of gravity and mass of the planet, there is one specific firing speed (unaffected by the mass of the ball, which is assumed to be very small relative to the Earth's mass) that produces a circular orbit , as shown in (C). As the firing speed is increased beyond this, non-interrupted elliptic orbits are produced; one is shown in (D). If the initial firing is above the surface of the Earth as shown, there will also be non-interrupted elliptical orbits at slower firing speed; these will come closest to
10260-635: The cheapest way to move hydrogen over long distances compared to other options. Hydrogen gas piping is routine in large oil-refineries, because hydrogen is used to hydrocrack fuels from crude oil. The IEA recommends existing industrial ports be used for production and existing natural gas pipelines for transport: also international co-operation and shipping. Several methods exist for storing hydrogen . These include mechanical approaches such as using high pressures and low temperatures, or employing chemical compounds that release H 2 upon demand. While large amounts of hydrogen are produced by various industries, it
10395-459: The coordinate system at the center of the mass of the system. Energy is associated with gravitational fields . A stationary body far from another can do external work if it is pulled towards it, and therefore has gravitational potential energy . Since work is required to separate two bodies against the pull of gravity, their gravitational potential energy increases as they are separated, and decreases as they approach one another. For point masses,
10530-408: The cost of energy inputs (typically gas and electricity), production plant and method (e.g. green or blue hydrogen), technologies used (e.g. alkaline or proton exchange membrane electrolysers), storage and distribution methods, and how different cost elements might change over time. These factors are incorporated into calculations of the levelized costs of hydrogen (LCOH). The following table shows
10665-486: The cost of hydrogen for harder-to-decarbonize applications in industry and transport. As of 2019 although technically possible production of syngas from hydrogen and carbon-dioxide from bio-energy with carbon capture and storage (BECCS) via the Sabatier reaction is limited by the amount of sustainable bioenergy available: therefore any bio-SNG made may be reserved for production of aviation biofuel . Hydrogen poses
10800-477: The decarbonization of industry alongside other technologies, such as electric arc furnaces for steelmaking. However, it is likely to play a larger role in providing industrial feedstock for cleaner production of ammonia and organic chemicals. For example, in steelmaking , hydrogen could function as a clean energy carrier and also as a low-carbon catalyst replacing coal-derived coke . The imperative to use low-carbon hydrogen to reduce greenhouse gas emissions has
10935-522: The deployment of district heating networks, electrification of heating (principally through heat pumps ) and cooking, the use of solar thermal , waste heat and the installation of energy efficiency measures to reduce energy demand for heat. Due to inefficiencies in hydrogen production, using blue hydrogen to replace natural gas for heating could require three times as much methane , while using green hydrogen would need two to three times as much electricity as heat pumps. Hybrid heat pumps, which combine
11070-683: The distance r {\displaystyle r} of the orbiting object from the center as a function of its angle θ {\displaystyle \theta } . However, it is easier to introduce the auxiliary variable u = 1 / r {\displaystyle u=1/r} and to express u {\displaystyle u} as a function of θ {\displaystyle \theta } . Derivatives of r {\displaystyle r} with respect to time may be rewritten as derivatives of u {\displaystyle u} with respect to angle. Plugging these into (1) gives So for
11205-434: The distance between them, namely where F 2 is the force acting on the mass m 2 caused by the gravitational attraction mass m 1 has for m 2 , G is the universal gravitational constant, and r is the distance between the two masses centers. From Newton's Second Law, the summation of the forces acting on m 2 related to that body's acceleration: where A 2 is the acceleration of m 2 caused by
11340-516: The early stages of flight due to drag, and influences engine performance. Advances in rocketry in the 21st century have resulted in a substantial fall in the cost to launch a kilogram of payload to either low Earth orbit or the International Space Station , reducing the main projected advantage of the SSTO concept. Notable single stage to orbit concepts include Skylon , which used the hybrid-cycle SABRE engine that can use oxygen from
11475-589: The efficiency of energy conversion is inherently low. Other methods of hydrogen production include biomass gasification , methane pyrolysis , and extraction of underground hydrogen . Green methanol is a liquid fuel that is produced from combining carbon dioxide and hydrogen ( CO 2 + 3 H 2 → CH 3 OH + H 2 O ) under pressure and heat with catalysts . It is a way to reuse carbon capture for recycling . Methanol can store hydrogen economically at standard outdoor temperatures and pressures , compared to liquid hydrogen and ammonia that need to use
11610-405: The end of 2022, 70,200 hydrogen vehicles had been sold worldwide, compared with 26 million plug-in electric vehicles . Early 2020s takes on the hydrogen economy share earlier perspectives' emphasis on the complementarity of electricity and hydrogen, and the use of electrolysis as the mainstay of hydrogen production. They focus on the need to limit global warming to 1.5 °C and prioritize
11745-453: The energy requirement for transportation might be between 20% and 30% fulfilled by hydrogen and synthetic fuels . Hydrogen used to decarbonize transportation is likely to find its largest applications in shipping , aviation and to a lesser extent heavy goods vehicles, through the use of hydrogen-derived synthetic fuels such as ammonia and methanol , and fuel cell technology. Hydrogen has been used in fuel cell buses for many years. It
11880-424: The energy source for electrolysis, and principally on the use of hydrogen in transport, where he regarded aviation and heavy goods transport as the top priorities. A spike in attention for the hydrogen economy concept during the 2000s was repeatedly described as hype by some critics and proponents of alternative technologies, and investors lost money in the bubble . Interest in the energy carrier resurged in
12015-428: The entire analysis can be done separately in these dimensions. This results in the harmonic parabolic equations x = A cos ( t ) {\displaystyle x=A\cos(t)} and y = B sin ( t ) {\displaystyle y=B\sin(t)} of the ellipse. The location of the orbiting object at the current time t {\displaystyle t}
12150-421: The exhaust gases down to near vacuum pressures. As a result, these engine bells are counterproductive due to their excess weight. Some SSTO concepts use very high pressure engines which permit high ratios to be used from ground level. This gives good performance, negating the need for more complex solutions. Some designs for SSTO attempt to use airbreathing jet engines that collect oxidizer and reaction mass from
12285-408: The force of gravitational attraction F 2 of m 1 acting on m 2 . Combining Eq. 1 and 2: Solving for the acceleration, A 2 : where μ {\displaystyle \mu \,} is the standard gravitational parameter , in this case G m 1 {\displaystyle Gm_{1}} . It is understood that the system being described is m 2 , hence
12420-789: The fuel to power local transportation systems like buses and trains. Corridor H2, a similar initiative, will create a network of hydrogen distribution facilities in Occitania along the route between the Mediterranean and the North Sea. The Corridor H2 project will get a €40 million loan from the EIB . German car manufacturer BMW has been working with hydrogen for years. . The German government has announced plans to hold tenders for 5.5 GW of new hydrogen-ready gas-fired power plants and 2 GW of "comprehensive H2-ready modernisations" of existing gas power stations at
12555-417: The gravitational energy decreases to zero as they approach zero separation. It is convenient and conventional to assign the potential energy as having zero value when they are an infinite distance apart, and hence it has a negative value (since it decreases from zero) for smaller finite distances. When only two gravitational bodies interact, their orbits follow a conic section . The orbit can be open (implying
12690-450: The gravitational force – or, more generally, for any inverse square force law – the right hand side of the equation becomes a constant and the equation is seen to be the harmonic equation (up to a shift of origin of the dependent variable). The solution is: Hydrogen fuel The hydrogen economy is an umbrella term for the roles hydrogen can play alongside low-carbon electricity to reduce emissions of greenhouse gases . The aim
12825-435: The greatest reductions in production cost over time. The U.S. Department of Energy's Hydrogen Hotshot Initiative seeks to reduce the cost of green hydrogen drop to $ 1 a kilogram during the 2030s. The concept of a society that uses hydrogen as the primary means of energy storage was theorized by geneticist J. B. S. Haldane in 1923. Anticipating the exhaustion of Britain's coal reserves for power generation, Haldane proposed
12960-490: The highest accuracy in understanding orbits. In relativity theory , orbits follow geodesic trajectories which are usually approximated very well by the Newtonian predictions (except where there are very strong gravity fields and very high speeds) but the differences are measurable. Essentially all the experimental evidence that can distinguish between the theories agrees with relativity theory to within experimental measurement accuracy. The original vindication of general relativity
13095-481: The larger bell. One possible solution would be to use an aerospike engine , which can be effective in a wide range of ambient pressures. In fact, a linear aerospike engine was to be used in the X-33 design. Other solutions involve using multiple engines and other altitude adapting designs such as double-mu bells or extensible bell sections . Still, at very high altitudes, the extremely large engine bells tend to expand
13230-410: The last drop of specific impulse, and shaving off the last pound, costs money and/or reduces reliability. The Tsiolkovsky rocket equation expresses the maximum change in velocity any single rocket stage can achieve: where: Orbit In celestial mechanics , an orbit (also known as orbital revolution ) is the curved trajectory of an object such as the trajectory of a planet around
13365-406: The light road vehicle segment including passenger cars, by the end of 2022, 70,200 fuel cell electric vehicles had been sold worldwide, compared with 26 million plug-in electric vehicles. With the rapid rise of electric vehicles and associated battery technology and infrastructure, hydrogen's role in cars is minuscule. Green hydrogen , from electrolysis of water , has the potential to address
13500-536: The main challenge is achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit , plus a meaningful payload weight. One possibility is to give the rocket an initial speed with a space gun , as planned in the Quicklaunch project. For air-breathing SSTO, the main challenge is system complexity and associated research and development costs, material science , and construction techniques necessary for surviving sustained high-speed flight within
13635-494: The mass ratio to delta-v curve is very steep to reach orbit in a single stage, and this makes a 10% difference to the mass ratio on top of the tankage and pump savings. The overall effect is that there is surprisingly little difference in overall performance between SSTOs that use hydrogen and those that use denser fuels, except that hydrogen vehicles may be rather more expensive to develop and buy. Careful studies have shown that some dense fuels (for example liquid propane ) exceed
13770-504: The mountain is high enough that the cannon is above the Earth's atmosphere, which is the same thing). If the cannon fires its ball with a low initial speed, the trajectory of the ball curves downward and hits the ground (A). As the firing speed is increased, the cannonball hits the ground farther (B) away from the cannon, because while the ball is still falling towards the ground, the ground is increasingly curving away from it (see first point, above). All these motions are actually "orbits" in
13905-410: The object never returns) or closed (returning). Which it is depends on the total energy ( kinetic + potential energy ) of the system. In the case of an open orbit, the speed at any position of the orbit is at least the escape velocity for that position, in the case of a closed orbit, the speed is always less than the escape velocity. Since the kinetic energy is never negative if the common convention
14040-473: The obvious fuel for SSTO vehicles. When burned with oxygen , hydrogen gives the highest specific impulse of any commonly used fuel: around 450 seconds, compared with up to 350 seconds for kerosene . Hydrogen has the following advantages: However, hydrogen also has these disadvantages: These issues can be dealt with, but at extra cost. While kerosene tanks can be 1% of the weight of their contents, hydrogen tanks often must weigh 10% of their contents. This
14175-498: The orbiting object crashes. Then having the derivative be zero gives that the function is a constant. which is actually the theoretical proof of Kepler's second law (A line joining a planet and the Sun sweeps out equal areas during equal intervals of time). The constant of integration, h , is the angular momentum per unit mass . In order to get an equation for the orbit from equation (1), we need to eliminate time. (See also Binet equation .) In polar coordinates, this would express
14310-411: The orbits of bodies subject to gravity were conic sections (this assumes that the force of gravity propagates instantaneously). Newton showed that, for a pair of bodies, the orbits' sizes are in inverse proportion to their masses , and that those bodies orbit their common center of mass . Where one body is much more massive than the other (as is the case of an artificial satellite orbiting a planet), it
14445-421: The origin and rotates from angle θ {\displaystyle \theta } to θ + θ ˙ δ t {\displaystyle \theta +{\dot {\theta }}\ \delta t} which moves its head a distance θ ˙ δ t {\displaystyle {\dot {\theta }}\ \delta t} in
14580-477: The other hand, LACE-like precooled airbreathing designs such as the Skylon spaceplane (and ATREX ) which transition to rocket thrust at rather lower speeds (Mach 5.5) do seem to give, on paper at least, an improved orbital mass fraction over pure rockets (even multistage rockets) sufficiently to hold out the possibility of full reusability with better payload fraction. It is important to note that mass fraction
14715-493: The performance of hydrogen fuel when used in an SSTO launch vehicle by 10% for the same dry weight. In the 1960s Philip Bono investigated single-stage, VTVL tripropellant rockets , and showed that it could improve payload size by around 30%. Operational experience with the DC-X experimental rocket has caused a number of SSTO advocates to reconsider hydrogen as a satisfactory fuel. The late Max Hunter, while employing hydrogen fuel in
14850-627: The perpendicular direction θ ^ {\displaystyle {\hat {\boldsymbol {\theta }}}} giving a derivative of θ ˙ θ ^ {\displaystyle {\dot {\theta }}{\hat {\boldsymbol {\theta }}}} . We can now find the velocity and acceleration of our orbiting object. The coefficients of r ^ {\displaystyle {\hat {\mathbf {r} }}} and θ ^ {\displaystyle {\hat {\boldsymbol {\theta }}}} give
14985-422: The potential to launch vehicles into orbit, single stage. In practice, this area is not possible with current technology. The design space constraints of SSTO vehicles were described by rocket design engineer Robert Truax : Using similar technologies (i.e., the same propellants and structural fraction), a two-stage-to-orbit vehicle will always have a better payload-to-weight ratio than a single stage designed for
15120-481: The potential to reshape the geography of industrial activities, as locations with appropriate hydrogen production potential in different regions will interact in new ways with logistics infrastructure, raw material availability, human and technological capital. Much of the interest in the hydrogen economy concept is focused on hydrogen vehicles , particularly planes . Hydrogen vehicles produce significantly less local air pollution than conventional vehicles. By 2050,
15255-415: The production, transportation and use of green hydrogen for heavy industry (e.g. high-temperature processes alongside electricity, feedstock for production of green ammonia and organic chemicals, as alternative to coal-derived coke for steelmaking ), long-haul transport (e.g. shipping, aviation and to a lesser extent heavy goods vehicles), and long-term energy storage. Hydrogen production globally
15390-548: The radial and transverse polar basis with the first being the unit vector pointing from the central body to the current location of the orbiting object and the second being the orthogonal unit vector pointing in the direction that the orbiting object would travel if orbiting in a counter clockwise circle. Then the vector to the orbiting object is We use r ˙ {\displaystyle {\dot {r}}} and θ ˙ {\displaystyle {\dot {\theta }}} to denote
15525-408: The rocket above the atmosphere (which causes frictional drag), and then slowly pitch over and finish firing the rocket engine parallel to the atmosphere to achieve orbit speed. Once in orbit, their speed keeps them in orbit above the atmosphere. If e.g., an elliptical orbit dips into dense air, the object will lose speed and re-enter (i.e. fall). Occasionally a space craft will intentionally intercept
15660-507: The sale of hydrogen fuel , and thus a crucial prerequisite before a successful commercialization of fuel cell technology. The hydrogen infrastructure would consist mainly of industrial hydrogen pipeline transport and hydrogen-equipped filling stations. Hydrogen stations which were not situated near a hydrogen pipeline would get supply via hydrogen tanks, compressed hydrogen tube trailers , liquid hydrogen trailers , liquid hydrogen tank trucks or dedicated onsite production. Pipelines are
15795-408: The same mission, in most cases, a very much better [payload-to-weight ratio]. Only when the structural factor approaches zero [very little vehicle structure weight] does the payload/weight ratio of a single-stage rocket approach that of a two-stage. A slight miscalculation and the single-stage rocket winds up with no payload. To get any at all, technology needs to be stretched to the limit. Squeezing out
15930-429: The second half of the twentieth century, very little research was conducted into space travel. During the 1960s, some of the first concept designs for this kind of craft began to emerge. One of the earliest SSTO concepts was the expendable One stage Orbital Space Truck (OOST) proposed by Philip Bono , an engineer for Douglas Aircraft Company . A reusable version named ROOST was also proposed. Another early SSTO concept
16065-453: The slight oblateness of the Earth , or by relativistic effects , thereby changing the gravitational field's behavior with distance) will cause the orbit's shape to depart from the closed ellipses characteristic of Newtonian two-body motion . The two-body solutions were published by Newton in Principia in 1687. In 1912, Karl Fritiof Sundman developed a converging infinite series that solves
16200-440: The smaller, as in the case of a satellite or small moon orbiting a planet or for the Earth orbiting the Sun, it is accurate enough and convenient to describe the motion in terms of a coordinate system that is centered on the heavier body, and we say that the lighter body is in orbit around the heavier. For the case where the masses of two bodies are comparable, an exact Newtonian solution is still sufficient and can be had by placing
16335-449: The spheres and was developed without any understanding of gravity. After the planets' motions were more accurately measured, theoretical mechanisms such as deferent and epicycles were added. Although the model was capable of reasonably accurately predicting the planets' positions in the sky, more and more epicycles were required as the measurements became more accurate, hence the model became increasingly unwieldy. Originally geocentric , it
16470-730: The standard Euclidean bases and let r ^ = cos ( θ ) x ^ + sin ( θ ) y ^ {\displaystyle {\hat {\mathbf {r} }}=\cos(\theta ){\hat {\mathbf {x} }}+\sin(\theta ){\hat {\mathbf {y} }}} and θ ^ = − sin ( θ ) x ^ + cos ( θ ) y ^ {\displaystyle {\hat {\boldsymbol {\theta }}}=-\sin(\theta ){\hat {\mathbf {x} }}+\cos(\theta ){\hat {\mathbf {y} }}} be
16605-412: The standard derivatives of how this distance and angle change over time. We take the derivative of a vector to see how it changes over time by subtracting its location at time t {\displaystyle t} from that at time t + δ t {\displaystyle t+\delta t} and dividing by δ t {\displaystyle \delta t} . The result
16740-443: The subscripts can be dropped. We assume that the central body is massive enough that it can be considered to be stationary and we ignore the more subtle effects of general relativity . When a pendulum or an object attached to a spring swings in an ellipse, the inward acceleration/force is proportional to the distance A = F / m = − k r . {\displaystyle A=F/m=-kr.} Due to
16875-463: The system's barycenter in elliptical orbits . A comet in a parabolic or hyperbolic orbit about a barycenter is not gravitationally bound to the star and therefore is not considered part of the star's planetary system. Bodies that are gravitationally bound to one of the planets in a planetary system, either natural or artificial satellites , follow orbits about a barycenter near or within that planet. Owing to mutual gravitational perturbations ,
17010-498: The use of an electric heat pump with a hydrogen boiler, may play a role in residential heating in areas where upgrading networks to meet peak electrical demand would otherwise be costly. The widespread use of hydrogen for heating buildings would entail higher energy system costs, higher heating costs and higher environmental impacts than the alternatives, although a niche role may be appropriate in specific contexts and geographies. If deployed, using hydrogen in buildings would drive up
17145-436: The vehicle has to hold itself up on rocket power until it reaches orbit. The lower excess thrust of the hydrogen engines due to the lower thrust/weight ratio means that the vehicle must ascend more steeply, and so less thrust acts horizontally. Less horizontal thrust results in taking longer to reach orbit, and gravity losses are increased by at least 300 metres per second (1,100 km/h; 670 mph). While not appearing large,
17280-498: The way vectors add, the component of the force in the x ^ {\displaystyle {\hat {\mathbf {x} }}} or in the y ^ {\displaystyle {\hat {\mathbf {y} }}} directions are also proportionate to the respective components of the distances, r x ″ = A x = − k r x {\displaystyle r''_{x}=A_{x}=-kr_{x}} . Hence,
17415-398: The world's current supply of hydrogen is created from fossil fuels. Most hydrogen is gray hydrogen made through steam methane reforming . In this process, hydrogen is produced from a chemical reaction between steam and methane , the main component of natural gas. Producing one tonne of hydrogen through this process emits 6.6–9.3 tonnes of carbon dioxide. When carbon capture and storage
17550-403: Was a reusable launch vehicle named NEXUS which was proposed by Krafft Arnold Ehricke in the early 1960s. It was one of the largest spacecraft ever conceptualized with a diameter of over 50 metres and the capability to lift up to 2000 short tons into Earth orbit, intended for missions to further out locations in the Solar System such as Mars . The North American Air Augmented VTOVL from 1963
17685-510: Was a similarly large craft which would have used ramjets to decrease the liftoff mass of the vehicle by removing the need for large amounts of liquid oxygen while traveling through the atmosphere. From 1965, Robert Salkeld investigated various single stage to orbit winged spaceplane concepts. He proposed a vehicle which would burn hydrocarbon fuel while in the atmosphere and then switch to hydrogen fuel for increasing efficiency once in space. Further examples of Bono's early concepts (prior to
17820-803: Was lost when it landed with only three of its four landing pads deployed, which caused it to tip over on its side and explode. The project has not been continued since. From 1999 to 2001 Rotary Rocket attempted to build a SSTO vehicle called the Roton. It received a large amount of media attention and a working sub-scale prototype was completed, but the design was largely impractical. There have been various approaches to SSTO, including pure rockets that are launched and land vertically, air-breathing scramjet -powered vehicles that are launched and land horizontally, nuclear-powered vehicles, and even jet-engine -powered vehicles that can fly into orbit and return landing like an airliner, completely intact. For rocket-powered SSTO,
17955-516: Was modified by Copernicus to place the Sun at the centre to help simplify the model. The model was further challenged during the 16th century, as comets were observed traversing the spheres. The basis for the modern understanding of orbits was first formulated by Johannes Kepler whose results are summarised in his three laws of planetary motion. First, he found that the orbits of the planets in our Solar System are elliptical, not circular (or epicyclic ), as had previously been believed, and that
18090-686: Was not suitable. A hydrogen economy was proposed by the University of Michigan to solve some of the negative effects of using hydrocarbon fuels where the carbon is released to the atmosphere (as carbon dioxide, carbon monoxide, unburnt hydrocarbons, etc.). Modern interest in the hydrogen economy can generally be traced to a 1970 technical report by Lawrence W. Jones of the University of Michigan, in which he echoed Bockris' dual rationale of addressing energy security and environmental challenges. Unlike Haldane and Bockris, Jones only focused on nuclear power as
18225-579: Was valued at over US$ 155 billion in 2022 and is expected to grow over 9% annually through 2030. In 2021, 94 million tonnes (Mt) of molecular hydrogen ( H 2 ) was produced. Of this total, approximately one sixth was as a by-product of petrochemical industry processes. Most hydrogen comes from dedicated production facilities, over 99% of which is from fossil fuels, mainly via steam reforming of natural gas (70%) and coal gasification (30%, almost all of which in China). Less than 1% of dedicated hydrogen production
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