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Roger Pham
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Continued from above: So, the easiest way to decarbonize fossil fuel and even waste biomass would be to steam reform them at nearby oil and gas fields, whereby the waste high-pressure and highly-concentrated CO2 stream is already ready to be sequestered down into depleted oil and gas wells nearby. The H2 produced at nearby the oil and gas fields would be pumped in pipelines to reach end-users, analogous to what would be done for natural gas. Just substituting zero-carbon H2 gas for the natural gas,for use by the end-users, that's all. The UK is considering going that route, to replace natural gas with H2, with CO2 sequestration if the H2 is made from hydrocarbon sources.
The two most energy-consuming and expensive steps in CO2 sequestration are: 1) separate the CO2 from very diluted l level in the air, and, 2) Compress the CO2 from atmospheric pressure to thousands of psi for sequestration. The use of higher-CO2 concentration in power-plant exhaust would make it less expensive than CO2 from the air, but still requires the costly compression step from atmospheric pressure to thousands of psi. However, the use of almost-pure CO2 from the process of steam reformation of natural gas, coupled with the very high pressures at thousands of psi already existed in the steam-reformation vessels means that: the use of H2 by end-users, when the H2 is produced from reformation of fossil fuel, would result in by far the easiest and least costly CO2 sequestration.
Good point, E-P regarding the use of synchronous motors fed by the frequency of the alternators to avoid the efficiency loss and the weight associated with AC to DC and then to AC conversion. So, we may have one turboshaft connected to one alternator to power one side of the aircraft, while the other turboshaft will do the same for the other side of the aircraft, with rapid switching to all motors power by one alternator should there be failure of one turboshaft. This setup may be competitive weight-wise and cost-wise with existing high-bypass turbofans, while exceeding in term of efficiency, especially much improved single-engine operation. Regarding your concern about having airflow over the tail surfaces, why not have some e-motors and props mounted on the tail surfaces also? In this way, we will have very positive attitude control of the aircraft regardless of airspeeds and wind gust. The use of ultra-capacitor to help spool up the turboshaft engines and the props rapidly coupled with very positive attitude control at all airspeeds can allow for rapid response to down-burst cells, wind gusts, and will increase safety. Furthermore, there will no longer be the problem of thrust asymmetry in the event of failure of one turboshaft engine, thus will further enhance safety and reduce pilot training time. Perhaps the Boeing 737-Max 8 should be the first airliner to be experimented with this new electro-turboshaft propulsion method, since it will solve the handling issue with the too big fan nacelles hanging way in front of the leading edges, as well as providing the efficiency needed to be competitive in the market. Go, Boeing, Go! Regarding the use of microwave energy beamed up from the ground, there might be issues with the effect of very high-energy microwave on the passengers and on avionics and on airframe heating. Perhaps you can enlighten us on these issues.
This is actually a very good way to improve efficiency of even large turbofan transport planes. This is how: Large turbofan transport planes need ridiculously-large nacelles to obtain ultra-high bypass ratio, but the large nacelles add drags and weight, plus the big heavy fans are also heavy and requiring another low-pressure turbine with shaft, and even another gear drive unit like the most recent Pratt&Whitney geared fan. The Airbus A400M turboprop transport that can cruise at 485 mph is proof that turboprop can fly fast. However, large propellers produce more vibration, noise, and more prone to failure due to their humongous size, and the mechanical gear boxes are also their weak link, that require more maintenance and higher failure risk. Much smaller and more numerous propellers driven by e-motors along wing leading edges can overcome the disadvantages of big gear-driven turboprops. So, we can a 10 or more smaller e-motor driven propellers all along the wing leading edges to obtain ultra-high bypass ratio without requiring humongous fan nacelles. We will only need two turboshaft units coupled with high-speed generators mounted in the nose of the aircraft. So, even with failure of one turboshaft unit, all the e-motors would be still functioning and can still generate 66% of the original thrust, thus single-engine climb performance would be far better than the failure of one turbofan unit in a twin-fan wing-mounted plane. Seems to be a promising concept.
ECI asked if it would be competitive for the electrolyzer equipment to operate at part-time basis? Answer: Electrolyzers are getting cheaper in production cost now, and also, you would want to use the ultra-pure electrolytic Hydrogen as transportation fuel whereby higher prices are allowable, instead of as replacement for natural gas in power generation. ECI further asked "Would it be cost competitive with pumped hydro....?" Answer: Dunno about pumped-hydro, but it is difficult to compete with natural gas as back-up power generation fuel, so transportation fuel will fetch higher prices. Pumped-hydro can still be used as short-term e-storage, while H2 from natural gas with CO2 sequestration at the source can be used for longer-term RE back-up. ECI further stated: "Given the low round-trip efficiency, it seems unlikely." Answer: The round-trip efficiency of H2 from grid-excess RE can match that of battery IF the Hydrogen will be used for heating, or combined power and heat applications. Efficiency of electrolysis if calculated on the HHV (Higher Heating Value) of H2 can be as high as 85%, and when used for space heating can result in nearly 100% efficiency, so the round-trip efficiency can be above 80%, which can match the round-trip efficiency of batteries and pumped-hydro.
Paroway stated: "This plan is meant to keep the oil industry as our masters. " Of course, the oil industry is already our master...what can we do about it? That 's why the US gov has no plan to combat GW, while raising the speed limits to 70-80 mph, and putting no additional taxes nor restriction on the sales of low-mpg SUV's and trucks, and has no plan for public transportation...etc... Short of a revolution in the USA and other oil-producing countries, our most realistic option would be to negotiate for the energy industry to move toward the Hydrogen Economy by at least producing hydrogen from fossil fuels at near oil and gas fields, and then immediately sequester the CO2 waste stream down in depleted oil and gas wells. Then, the Hydrogen can flow in pipeline systems to the end users, who will then use the Hydrogen for transportation, for combined power and heating in FC or combustion engines in distributed power generation due to the emission-free nature of H2, ...and for production of steel, concrete, fertilizer, and other industrial chemicals. It is FAR EASIER to decarbonize at the source than at the end users. E-P has reservation regarding storing H2 in underground natural gas reservoirs. However, due to the vast size of these formations with very high volume to surface ratio, we can simply coat the walls of these underground caverns with a thick coating to prevent leakage of H2 into the sulfur-based rock formation. That's all. So, to sum up, we can easily and cost-effectively achieve CO2-free energy by moving to the Hydrogen Economy, NO MATTER how the Hydrogen will be produced.
Indeed, the major selling points for long-range BEV's like Tesla are high performance and novelty, and not really about environmentalism. Most people don't much care about the environment. A hybrid (HEV) has been known to be cost-saving over a comparable non-hybrid, yet hybrids has not really been growing in sales, perhaps due to the higher initial cost and the fear of high cost of battery replacement and of repairs of the hybrid power train. The higher cost of a HEV will be more than offset by lower fuel cost, however, it is the fear of battery replacement and of repairs of the hybrid power train that has kept most people from purchasing HEV's, even though in the majority of cases, HV battery packs have been known to last for the life of the car, and that overall repairs for HEV power train have been a lot lower than repair costs of a transmission unit. Better public education will greatly help in this regard, if the governments want to protect the environment and energy security seriously, and NOT any budget-draining subsidies for cars with huge battery packs that can do more harms for the environment than helping it, especially when the Lithium is not even recycled due to the cost of recycling Lithium from Li-ion batteries..
@lad, The first gas turbines ever made ran on hydrogen. Future gas turbine using Liquid H2 can have precooling of intake air to gain efficiency by 25%. In combination with the lightness of LH2, future jet planes using LH2 can use 2.5 x less fuel per pound of payload.
@sd 6 kg of H2 would give an energy equivalent of 132 kWh of Li-ion battery. The 6-kg H2 tank should cost around $3,000 and 26 kWh of FC should cost around $200 x 26 = $5,200. So, the FC and H2 tank combined would cost around $8,200. On the other hand, 132 kWh Li-ion battery at $300 per kWh would have a price tag of $39,600. Ouch!!! So, the smart thing to have is the FC and H2 tank for range extension, instead of an additional 132 kWh of Li-ion battery. Just do a little math, my friend.
@EP and HD Whatever socio-racial problems there are in the USA, the horse has left the barn, the genie has gotten out of the bottle...We will have to endure for a while... THE number 1 peaceful solution for the long-term future of the USA is to limit welfare support to ONLY ONE child per mother. A welfare mother cannot keep reproducing illegitimate children one after another when taking advantage of hard-earned taxpayers' money. Any women on welfare should be on verifiable birth control like the IUD that can be identified via sonography scan, or a Norplant that can be verified physically. At the same time, the fertility rates for tax-paying parents should be boosted, in the form of lower income tax % for each additional child in the family. This would benefit tax-paying parents and give the incentive to have more kids, while lower incentive for fertility for non-tax-paying families. This will lead to social prosperity and improving social sustainability. The current welfare situation and the demographic trend are not sustainable. Over time, the lower fertility rate of welfare mothers in comparison to that of non-welfare mother will reduce the proportion of troublesome population. As far as dealing with increase in VMT, we will have to push for rapid decarbonization of transportation...The horse has left the barn for 7-8 decades now, ever since GM-Oil conglomerate bought electrolley lines and cars and crushed them, while urban planning policies allowed huge urban sprawls, including zoning policies that forbid mingling of business district with residential area, plus socio-racial disharmony leading to abandoning of inner cities of the middle class . Let's guess who's the boss...who's in control of the goverment, eh? Where I came from, many people lived right above their shops, offices, or small businesses, thus significantly reduces commuting requirement. We used to live on a 3-story house that the 1st floor was used for business office, thus no commuting for my parents. Why can't that be done for the USA's?
@EP--You're a good aero-engineer to consider the weight distribution of the fuel in an aircraft. Yes, the concentrated weight in the fuselage can increase the wing's structural weight, but since the fuel only weighs merely 12% of MTOW, the increase in wing's structural weight won't be much . NASA has used low-density polyurethane foam as insulation for H2-containing sphere with success. A spherical container of 1 foot diameter and 1 inch-thick polyurethane foam can hold LH2 for about 10 hrs. If we would extrapolate this to the vast size of a jumbo-jet's fuselage with much higher volume-to-surface ratio, then we won't need more than 1-inch thick polyurethane foam as insulation, which is very light and can also confer structural strength as well. So, a modern carbon-fiber composite aircraft fuselage can have an 1-inch thick foam in between two layers of carbon-fiber composite skin for both strength and insulation. So, the aircraft fuselage skin can serve as LH2 tank as well, with the internal bulkheads of the fuselage will serve as the transverse walls of the LH2 tanks. When the LH2-plane is on the ground, the on-board fuel cell can use the LH2 boil-off to produce electricity to serve the air-conditioning an lighting requirement of the cabin, and can be plugged-in the power grid to release any excess electricity not needed by the cabin. In this way, there will be no waste of energy, and no H2 released in the atmosphere. Indeed, the SABRE engine has illustrated the concept of using LH2 for cooling intake air, thus achieving higher engine performance and even higher fuel efficiency due to lower compression work and higher pressure ratio possible. I would predict thermal efficiency increase from 50% of current core-turbine to go up to 65% efficiency as the result of pre-cooling, and this would further reduce the mass and volume of LH2 required. Thus, an LH2 plane can achieve 2.5 times the fuel efficiency per lb of payload in comparison the current jets. So, if jet fuel now costs $2.25 per gallon, then we can tolerate LH2 costing $5.6 per kg. From Wikipedia "Hydrogen economy", "As of 2002, most hydrogen is produced on site and the cost is approximately $0.70/kg and, if not produced on site, the cost of liquid hydrogen is about $2.20/kg to $3.08/kg.[33]" So, even adjusting to today's $, it is not too far-fetch to produce LH2 profitably at $5 per kg using Solar or Wind electricity at $0.02-$0.03 per kWh. Producing LH2 from electrolysis requires about 60 kWh per kg, so at 3 cents per kWh electricity, the electricity cost will be $1.80. Adding other costs and we can achieve a cost of $4 per kg, and adding $1 of profit on top of that will give us $5 /kg for LH2 at the airport gate.
@EP--You have to design a LH2 plane with a clean-sheet approach in order to appreciate the lightness of LH2. Keep in mind that the latest jet engines are far more fuel -efficient than the low-bypass engines of several decades ago. Look in Wikipedia for the specs of the Boeing 787-9: Max Takeoff Wt (MTOW): 560,500 lbs with a max fuel load of 223,378 lbs. This means that the fuel weight is almost HALF of the MTOW, with Max payload of 116,000 lbs only, with range of 7,635 nmi. Now, with LH2 weighing a third that of jet fuel, your fuel load will be only 74,000 lbs, giving you additional 148,000 lbs of pay load on top of the 116,000 lb payload, we can increase the pay load almost 2.5 times. But we can't, because we don't have the room for additional passengers. So, we will design the plane with smaller wings and tail planes, smaller engines, and smaller landing gears...and these components weigh about ~ 2/3 the empty weight of the plane. The weight of the empty 787-9 is around 221,000 lbs, and 2/3 of this weight would be 147,000 lbs. Take this and divided by 2 ( due to 50%- reduction in MTOW) = 73,000 lbs. So, the MTOW of the new 787-9 using LH2 would be fuselage weight of 73,000 lbs + Wings tail engine LG wt of 73,000 lbs + fuel weight of 37,000 lbs + payload of 116,000 lbs = 299,000 lbs...or a little more than HALF of the MTOW of the jetfuelled version. So, now we are able to reduce the LH2 fuel weight to ~ HALF of the previous 74,000-lb fuel load due to a complete clean-sheet design approach. Density of LH2 = 70 kg per M^3. Total fuel weight is 37,000 lbs or 16,818 kg would take up a volume of 240 M^3. Cabin width of 5.5 m and cabin length of ~50 m, would give you a volume of V = pi x r^2 x length = 1187 M^3. Passenger floor of this plane would take space 1/2 way up the height of the fuselage, thus taking up only 1/2 of the total internal space of the fuselage, which is around 600 M^3, giving space of almost 600 M^3 underneath the seating floor for fuel and cargo, of which, the LH2 fuel only takes up around 240 M^3 of space. Entirely doable!
Longer into the future, we will have jet planes using liquid hydrogen for fuel, that will be much lighter than existing jet fuel and the planes thus will be built with smaller wings, smaller engines, smaller landing gears and will be far more energy efficient than existing jet planes. At the same time, high-speed electric train capable of 230 mph can serve high-density routes profitably, and can use RE directly without conversion to a fuel, which should boost efficiency of traveling significantly. So, conversion of H2 into liquid hydrocarbon fuel will be only a transitional step and will be phased out, to be replaced by H2 and RE directly.
Another winner of the Darwin's Award. "Fool me once, shame on you...Fool me twice, shame on me."
Biomass gasification or fermentation will be the best source of CO2.
Why not get CO2 from fossil fuel power plants and from sea water? Or just use the H2 directly?
>>>>>>>"With low-cost batteries and an electric powertrain, you wouldn't need hydrogen, .." But you will still have Hydrogen made from grid-excess Solar and Wind energy from Springs and Falls that you'll have to do something with it. Might as well use those in vehicles as high-value transportation fuel instead of as substitution for low-value natural gas or coal in power generation.
>>>>>>"...the chief problem with hydrogen combustion engines hasn't been efficiency, but low power density." Correct. However, this can be overcome by strong electric hybridization. With the advent of strong electric power train and low-cost batteries, we can have bigger battery pack to provide acceleration power and generation of braking energy. So, the engine is there mainly to provide base-load power. The use of turbocharging will further alleviate the low power density, best for trucks which must require extended high power for climbing long grades. The low exhaust temperature will allow turbochargers to be cheap and durable.
@ECI--The cost of H2 infrastructure will come down with scaling up. By contrast, a lot was already invested in fossil fuel supply chains and power generation and power transmission and distribution for petrol and BEV's.
A "simple" BEV with thousands of battery cells and thousands of Battery Management System (BMS) components and battery and motor cooling system...isn't so simple after all...it's just an illusion. Have you ever taken apart a Tesla's battery pack before? Very complicated inside with thousands of parts and interconnection. Go to "Rich Rebuilds" channel on Youtube to see how complicated inside a Tesla car, with zillions of wires and components... and a very complicated maze inside a Tesla's battery pack.
What is Green about high-fuel-consumption supersonic jet engine?
@E-P, Hydrogen is a gas, thus it can be stored in existing natural gas reservoirs, depleted oil and gas wells, and in salt caverns wherever available. Hydrogen can be supplied to each house in existing natural gas piping. We're simply replacing natural gas with Hydrogen, that's all. Renewable-energy Methanol is also viable wherever there are no local residential gas piping, kinda like heating oil right now, but renewable-energy Hydrogen should be cheaper to produce and more efficient from source to end-user applications.
@E-P, Hydrogen is a gas, and thus can be stored in existing Natural Gas reservoirs and depleted Oil and NG wells, also in salt caverns.
sd stated: "...clean energy which is not really clean as long as you are using power that would otherwise displace electric power produced burning coal or natural gas." Grid electricity fetches much better pricing for a given amount of energy than the equivalence in fuel energy, so no one is stupid enough to use Renewable Energy to make Hydrogen when that same RE can be fed to the electric grid to fetch much higher prices. Maximum profitability would dictate the use of Grid-EXCESS RE to make Hydrogen, while feeding as much RE into the grid as the grid can handle to maximize revenue.
@sd--You can have a Tesla or a Bolt to be charged during sunlight hours, then any excess solar PV or wind electricity can be used to make Hydrogen to power FCV. With a market for grid-excess Solar and Wind electricity to make high-value H2 for transportation, this will incentivise more investment in Solar and Wind energy, and BEV enthusiasts and FCV enthusiasts will benefit. You can have it all.