This is Roger Pham's Typepad Profile.
Join Typepad and start following Roger Pham's activity
Join Now!
Already a member? Sign In
Roger Pham
Recent Activity
@Dursun Sakarya, "Hydrogen infrastructure –the pillar of energy transition--The practical conversion of long-distance gas networks to hydrogen operation" "RATP beginning tests of Solaris Urbino 12 hydrogen bus in Paris 23 October 2020"
@Dursun Sakarya, The abstract of that paper is as followed: " In this paper the energy needs of a hydrogen economy are quantified. Only 20%-25% of the source energy needed to synthesized hydrogen from natural compounds can be recovered for end use by efficient fuel cells. " Reply: Well, if the end result of H2 utilization is heat, or combined heat and power, then we can pretty much recover almost 100% of the input energy, minus the 15% loss in the electrolysis process and may be 2% loss in pipeline transportation. This means that the H2 made in Springs and Falls will be used in Winters for heating and combined electricity and heating using the waste heat of the Fuel Cell (FC). 1.. You can charge your EV on a winter night using a home-based FC while the waste heat of the FC will keep you warm. 2.. Daytime solar energy is used to make H2 which will be used to make home electricity by the FC while the waste heat will make hot water for bathing, dish washing and laundry. 3.. Of course, batteries will be used for storage of electricity when waste heat is not required. For example, a Plug-in FCV will have 50-mile-range on battery for daily driving for 80-90% of total milefage, and only needing H2-FC for occasional long trips "Because of the high energy losses within a hydrogen economy the synthetic energy carrier cannot compete with electricity. As the fundamental laws of physics cannot be chanced by research, politics or investments, a hydrogen economy will never make sense." Reply: It is WRONG to use Hydrogen to compete with Electricity, either from the grid or from Battery, but Hydrogen is a great way to complement grid Electricity AND Battery Electricity whenever those 2 sources aren't available or aren't practical. For example: Long-haul trucking and shipping can use Battery, but the weight of battery is too much and cuts down too much on payload capacity, thus Hydrogen will be used to maximize payload and maximize revenue.
@gryf, Geared hub is a necessity in order to reduce the size, weight, and cost of the e-motor by allowing it to spin much faster than the slow rotational speed of the wheel, hence producing much more power and torque at the wheel. AGM Lead Acid battery is cheaper than Li-ion batteries to keep cost down, but they should provide an option for LiFePo batteries for those wanting more performance and reliability. I would never choose Lead Acid battery since Li-ion is much longer lasting and much lighter.
@mahonj, We don't know what is the frontal area and the Cd. If the frontal area is 0.9 M^2 and the Cd is 0.2, rolling coefficient at 0.008, and weight at 250 kg, then it only takes 1 kW of power to travel at 64 kph, which is pretty close to the stated specs of 70 kph maximum speed at 1 kW of power. Its range at top speed of 64 kph would be 64 km, but could be a lot higher at lower cruising speeds. It looks as if the Cd could be 0.2 because the rear of the vehicle tapers to a much thinner section width than the front of the vehicle. This is a good looking design and would be great for the crowded inner city. Why need any more power? Keep it light and affordable.
@SJC, IMHO, the advantage of H2 usage in the open sea is mainly due to its renewable nature, because diesel engine pollution in the open sea is not an issue. However, for long-haul trucking, diesel fuel reformation to H2 can serve as a source of backup energy when H2 is not available.
@mahonj, Local H2 piping system that are of low-pressures can be made from polyethylene or iron that can tolerate low-pressure H2, instead of steel. Thus, existing low-pressure residential piping for natural gas can take 100% H2 as-is. Thus, a local electrolyzer can serve the entire city, to ensure economy of scale.
"Type 316/316L austenitic stainless steels are considered the benchmark for resistance to hydrogen embrittlement in gaseous hydrogen environments. Type 316/316L alloys are used extensively in handling systems for gaseous hydrogen, which has created engineering basis for its use. This material class, however, is relatively expensive compared to other structural metals including other austenitic stainless steels, thus the hydrogen fuel cell community seeks lower-cost alternatives. " From: Another way to cut cost would be to make H2 locally and store it locally to avoid using long pipelines as with natural gas or petroleum.
@gryf, No, this will not lead to any great development. This does not prove anything except just for bragging right. Lucid Motor has already achieve very pwerful e-motor Going fast in an airplane requires a lot of energy that battery simply does not have. In an electric car, the power is only needed for a few second short burst to get to speed limit. Still, even cruising at the speed limit at 75 mph drops the range of the Model S from 402 miles down to the low 200 miles, as Car & Driver magazine has tested. For environmental sustainability, Rolls Royce needs to work on using Green hydrogen for air transportation, working on all angles and ramification of the issue, from the supply chain to airframe optimization to power plants using Green H2.
@mahonj, 136 kW is around 180 hp. The Honda Civic hatchback 1.5-L Turbo is putting out 180 hp from an 1.5-liter turbocharged engine as well, so this is not extraordiary.
This is also the most viable way to bio-synthesize food in space , in the Moon, and in Mars. At the cost of $2,500 to launch a pound of payload into space, carrying enough food for extra-terrestrial colonies for extended periods of time is out of the question. Photosynthetic plants and algae at a few % efficiency would be too inefficient and too vulnerable to the cosmic radiation of deep space, in the Moon and in Mars. Would be much lighter and cheaper to carry instead solar panels having around 40% efficiency into space colonies to make H2 as fuel and as means for synthesizing food from recycled CO2 and ammonia from human wastes. In Mars, human colonies would live underground for the most part to avoid cosmic radiation, and can't depend on plants, neither, so must collect solar energy on the surface to make H2 and bring it down underground to synthesize food in bio-reactors.
sd stated: "....40% efficiency with hydrolysis/fuel cell generation." Reply: For that reason, use more efficient means of e-storage first before resorting to Hydrogen. The problem is that batter, pump-storage, and ice storage are severely limited in capacity and can only hold a few days' worth of energy and not seasonal quantity. A Plug-in FCV with 40-50-mile of plug-in range can satisfy 80-90% of total energy using grid-electricity, and only needing H2 for long trips. A Plug-in FCV only requires 1/5th the battery capacity of an equivalent long-range BEV, thus freeing up a lot of battery to make 5x the number of plug-in EV's. It so happens that above certain latitude, winters are cold and requiring heat energy to keep warm, and this is where H2 will be most efficient, and solar energy is lacking in the winters. Plug-in FCV can also use the waste heat of FC for winter driving. Summers also require a lot of energy for cooling, but solar energy is plentiful in the summers, and ice storage can cheaply hold enough energy for a day or so, for evening and night cooling need. So, H2 cannot be a sole solution, but can provide seasonal quantity of e-storage for the entire society, in conjunction with battery, pump-storage, and ice storage.
@sd, The efficiency of H2 is greatly improved with waste heat utilization, amount to 80% round-trip efficiency, to rival any other means of e-storage like pump-storage.. For example, during the winters, home-based Fuel Cell can provide electricity to charge your EV at night, while providing waste heat to keep you warm. Second example: Grid-excess Solar electricity during the day can be used to make H2, for used to provide home power later in the evening, with waste heat used for hot water., at 80% round-trip efficiency. Of course, in the summers, ice can be made to store solar energy for home cooling later in the evening, with around 80% round-trip efficiency, the same as pump-storage.
Nikola has the correct vision: Battery Electric + Fuel Cell when applications require long-range and extended operations. Nikola has shown undestanding of the market and is receiving larger orders. Nikola stock could become the next Tesla stock. By contrast, Tesla has shown lack of understanding of the Renewable Energy picture by going against H2-FC and against PHEV.
@sd, I really respect that you use the Bolt for daily driving and not the 2 other HD pickup trucks. We really would like to see other owners of big SUV's and PU trucks drive Plug-in Vehicles daily, and leave their gas-guzzling monster at home and only drive 'em on special occasions when they are really needed. There are far too many full-size SUV's and PU trucks on the roads. Yes, the Bolt is far more beautiful than the Leaf, Rouge, BMW i3, and the Element..etc...but I wish that GM would send a version of the Velite 6 here to the USA. It sure would beat the Prius Prime in the beauty department and in performance as well. 135 kW power of the Velite 6 is weak in comparison to the Tesla M3 LR, but 135 kW is much more powerful than the Prius Prime at only 90 kW of total power and the Hyundai Ioniq PHEV at 104 kW. Everything is relative!
@sd, Your Bolt doesn't have the additional advantage of using gasoline for long-distance driving, with super-quick energy fill-up, and the doubling in range between energy fill-up in a PHEV. As such, the Bolt is inferior to the Velite 6 PHEV. Also, the Bolt is much uglier. The Velite 6 is a very beautiful design, but too bad, it is limited in power, with only 135 kW of power, thus not competitive with the Model 3. Plus, the power-split device is bulky and complicated, and is NOT needed in a PHEV. A PHEV simply needs to drive the front wheel as directly-coupled to the front axle with only a clutch, similar to those of Honda 2-motor hybrids, because the rear axle can be driven by the e-motor to drive the vehicle at low speeds. To boost low-speed torque, the engine can be coupled to a hydraulic torque converter to boost engine torque 2 folds to provide additional torque to combine with the rear e-motor when launching the vehicle at rest, for maximum 0-60 time. With this setup, we can add the 80-kW power of the front engine to the 120 kW power of the rear e-motor to come up with 200 kW of total power, which should greatly improve acceleration performance.
Tom, you again have ignored the calendar life issue completely. Calendar life means battery aging even WITHOUT any cycling at all. Calendar life applies to ALL types of batteries. Calendar life is shortened for Li-ion batteries when kept fully charged, when kept at very low charge, and when kept at high temperatures above 104 degree F or 40 degree C, even in the absence of use. In those conditions, calendar life of Li-ion battery is just a few years even when NOT cycled at all.. Optimally-kept Li-ion batteries can last for over 10 years with careful usage of keeping the charging cycles at under 80% of capacity and at moderate temperatures. Lead-acid batteries don't age nearly as well. All of my UPS battery power back up devices using Lead-acid batteries will need to have the battery changed in about 5 years, even when the batteries are NOT cycled at all. The batteries just went bad even when kept at optimal charge level all the times. For more details on the Calendar Aging issue, refer to this link: So, it is most economical to have a small Li-ion battery pack with just enough capacity for daily driving, and change it every 10 years...instead of having a battery pack 5 times larger than what you need for daily driving, and still having to change it every 10 years, due to calendar aging. GM charged around $5,000 for a new Volt's battery pack, while the Model 3 battery pack will cost above $20,000.
Currently automotive Li-ion batteries are known to be capable of 3,000 charging/discharging cycles if each cycle is kept to within 80% of its rated capacity. So, if the Volt's battery is cycled to 80% roughly once daily, then it will hold up for about TEN (10) years, which sorta coincide with its calendar lifespan. So, it would make more sense to spend $5,000 to change the 18-kWh battery pack of the Volt rather than to spend $20,000 to change the 75-kWh battery pack of the Model 3 Long Range.
Thomas Paine stated: "It makes more sense to have the life of the battery last at least the life of the car. " Reply: While the revolutionary Thomas Paine was well known for his "Common Sense" pamphlet, the later-day Thomas Paine is notably lacking in common sense. Well, Tom, NO known battery in existing cars can last for the life of the car, EXCEPT for the hybrid traction battery in the Prius and other Toyota's hybrids. The lead-acid batteries typically last for 5-7 years and must be replaced, even though it is has VERY shallow duty cycle and is always kept at optimal charge level, while the car can last for 15-20 years, so existing non-hybrid gasoline cars must go through FOUR battery changes. during its life span. Li-ion batteries last around 10 years, and so is the warranty of these new Li-ion batteries. A current BEV or PHEV using Li-ion batteries will probably need at least ONE battery change during its lifespan. Fortunately, changing battery packs can be very quick, as Tesla has demonstrated with its battery swapping, and Nio cars in China routinely having their batteries swapped in THREE minutes at hundreds of battery swapping stations in China for extended-range driving. So, after 10 years, would you rather spend a small sum of money to change the 18-kWh battery pack of the Volt, or spend a huge sum of money to change the 75-kWh battery pack of the Model 3? There is such a thing as Calendar-Life-Aging which cause battery degradation even if the battery is rarely used and is always kept in optimal charge level, which keep practical life span of current Li-ion batteries to around 10 years, even if rarely used.
@Yoatmon, No heat pump nor heat engine can exceed Carnot limit. This is the second law of Thermodynamic that cannot be violated. The current vapor-compression AC and heat pump is as efficient as it can get. Peltier junction heat pump is far less efficient. It is not possible to store a season's worth of energy using battery. Hydrogen permits seasonal scale e-storage, from the energy surplus of Springs and Falls for use in Winters and Summers. Many car makers are having problem with enough battery supply to make PHEV, because making enough battery for only 500,000 long-range BEV requires $5 Billion investment into the Battery GigaFactory. If we will make PHEV and Plug-in FCV instead, we will be able to make 2.5 millions to 3 millions of those Plug-in vehicles for the same $5 Billion investment. So, PFCV represents far more efficiency for the money invested in battery production facility.
@yoatmon, Batteries will be used for applications that doesn't need heat. FC will be used for application that can also use the waste heat of the FC unit, such as providing for home electricity during sun down period with waste heat from the FC used for home water heating, with the potential for 100% efficiency of utilization. In the winter when the solar energy is very weak, the FC can provide power all day while supplying waste heat for office and home heating. Winter driving in FCV can use the waste heat from the FC for cabin heating and windshield defrosting. A plug-in FCV (PFCV) can take advantage of both the efficiency of battery and the rapid fill-up of the H2 storage, as well as the battery-sparing advantage of a H2 storage system, permitting a PFCV to have superior range to a long-range FCV, yet using only 1/5 to 1/6 of the battery capacity.
@SJC, Flow batteries can store energy for many hours to 1-2 days maximum, not enough for seasonal-scale e-storage. From the article: "Hydrogen serves as one of the leading alternatives for energy storage and seems to be favoured as a low-cost alternative for storing huge quantities of electricity over days, week and also months. Hydrogen fuel can be stored for long periods, in quantities limited only by the size of storage facilities... When it comes to long-term and large-scale energy storage, hydrogen—in the form of compressed gas, ammonia (NH3) or synthetic methane—has a role to play in balancing seasonal variations in electricity supply and demand from renewable energy sources."
Nice-looking design, better looking than a typical SUV or CUV, and better aerodynamic. IMHO, perhaps the 1.4-TSI engine was chosen over the 1.5 TSI Millerized due to higher power of the 1.4 at 156 hp vs 128 hp of the 1.5 Millerized, and lower cost for the 1.4, because the 1.5 is a more complicated engine with more advanced variable valve and cylinder deactivation for higher part-load efficiency, which is not needed in a PHEV.
@sd--Ultimately, the most efficient and viable option for adequate-range-and-payload would be the use of liquid-hydrogen (LH2) and fuel cells (FC). LH2 has 1/3rd the weight of petroleum and when used in FC with efficiency of 60-70% vs 25% efficiency in small gas turbines would result in very low fuel weight per mile traveled. Fuel cell is modular and can be sourced from those developed for FCV cars and trucks in order to obtain very cost-effective power solution due to economy of scale when produced by the millions of units yearly and not merely a few hundred yearly for aero engines. The additional weight of the FC can be partially compensated for by the weight saving of direct-drive e-motor that can even double the power to weight ratio of turboprop power plants. @Mahonj--your concern is true for battery powered aircraft, but for LH2-FC aircraft with far higher energy density and far higher energy efficiency, any existing aircraft would be able to double or triple the range with LH2-FC vs its petroleum version. So, all existing aircraft can be retrofitted with LH2-FC-e-motor and enjoy massive gain in energy efficiency, range and payload capacity. @Gryf--Of course, electric aviation will work, but even more so with LH2-FC as energy medium, as detailed above. @SJC--It would be far more efficient to use ultra-light Liquid Hydrogen-FC instead of using 3x heavier liquid fuel and having to carry bulky and heavy reformer as well. For large jetliners, the turbofan can approach the efficiency of FC-e-motor, so no need for FC-e-motor, because the turbofan can be powered by LH2 directly.
>>>>>>>"If you have a source of biogas, why not just that for your energy needs?" The goal is decarbonization of energy consumption. The CO2 waste stream of steam reformation of both natural gas and biogas can be sequestered underground for zero-emission energy consumption. Also, H2-FC is a zero-emission electricity source, unlike biogas combustion.
Why not just have a separate fueling island in larger gas stations that contains a dispenser for pure gasoline without ethanol nor aromatics, and a separate dispenser for ethanol + aromatics? Why not devise a way to retrofit existing cars to contain a separate tank for ethanol + aromatics, having a built-in second fuel pump to piggy back onto the main fuel rail in order to supply high-octane additive on on-demand basis? I can guarantee that power and low-end- torque as well as high-end-torque would increase to provide more satisfying drive, plus a gain in cruise fuel economy, due to faster and more efficient combustion with the start of combustion nearer to TDC. This would also be great for turbocharged engines.