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Roger Pham
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@yoatmon: >>>>>"Personally, I need a PHEV as direly as I need a hole in my head." Reply: Wait until you're in a middle of a major snow storm with power outage and temperatures in the single-digit or below 0 dgr F and your 200-mi winter-range BEV will now deliver around 150 mi before needing a charge, and you can't since you have a power outage due to brown-out condition due to massive grid overload. This means that public fast-charging would be out of the question You'll be in for a lot of hurt! Cold, dark, and stuck!!! It is happening now for a lot of people. A big swath of the USA is now experiencing just that, with temperatures below 0 for Kansas, Nebraska, Colorado, Oklahoma, and in the single digit as far South as Texas and Mississippi, for10 days in a row! With a PHEV like the RAV4 Prime with a plug-out from the car, you can use the PHEV as the backup generator to power your house to get the central heater blower running to keep warm, have all the lights on and TV, computers, ovens and appliances ...With a range of over 500 miles, the PHEV will have enough of gas for several days of power backup for your home, with gas refill in 3 minutes.
@yoatmon, The future is PHEV, not long-range BEV (LR-BEV). 1..This is because LR-BEV packs so much battery capacity per vehicle, in reality ensuring that the rest of the vehicles in the market will not have enough battery and will continue to run on gasoline. 2.. Especially when it is still not cost-effective to recycle the Lithium in Li-ion batteries. 3.. Cold weather requires a lot of heat for defrosting and in reality, dropping the range of LR-BEV to half. It is not even possible to charge a Li-ion battery pack when its temperature drops below freezing. 4.. A LR-BEV rated at 300-mi EPA like Tesla in reality can only deliver around 200-mi when driven at 75-80 mph to keep up with traffic. UNACCEPTABLE, when one is pressing for time. 5.. Hot tropical climates year round will significantly reduce the calendar-life span of the Li-ion batteries, thus a big battery pack would be a big waste. A small battery pack in a PHEV that can be replaced at an affordable cost is much more sensible and practical. Heavy use of A/C in hot climates will drop the range of BEV. 6.. Even taking only 1/2 hour to "fast" charge a LR-BEV every 200 miles would still be far too long for most people in a hurry to get to destination in a long trip, and even worse when one must detour to find an available "fast" charging station that is not conveniently on the route. PHEV's would have no such problem. There are SO MANY things WRONG with LR-BEV the more we are digging into it.
@Lad: >>>>>>"...wonder why one would pay the extra costs associated with driving a complicated PHEV. " Reply: A PHEV can cost much less than a long-range BEV and can be simpler. That's the point of this article. Let's imagine a PHEV having a 15-kWh battery pack that can deliver 150 kW of power, and 2 electric motors with one on each axle, 60 kW (80 hp) each for a total of 120 kW (160 hp). With this much e-power, it will only need a 3-cylinder 1-liter engine of about 75 hp output in the front axle, which is very simple. No need for transmission, nor any starter nor any generator. The 60-kW e-motor in the front axle can be clutched to the engine via a simple synchro-clutch to act as a starter as well as a generator. In the all-electric mode, it will have 160 hp of power. In the hybrid mode, the engine can be clutched directly to the front axle to provide cruising power, while accelerating and decelerating power is provided by the e-motors. Combined power in the hybrid mode would be 160 hp + 75 hp = 235 hp. For more power in the hybrid mode, we could put a turbocharger on the 1-liter engine to raise its power to 140 hp. So, combining 140 hp of the engine to the 160 hp of the e-motors = 300 hp total. This is enough power to compete with comparable BEV's in the market, power-wise. In the engine-only mode, the two e-motors can also act as an e-CVT transmission, with the engine powering the front motor-generator to generate power to drive the rear e-motor, with maximum power of around 70 hp of the engine. The engine-only mode is rarely used, except in the case of complete depletion or complete malfunctioning of the battery pack. For a long trip, the battery will be charged full and kept at full charge in order to assist the engine when climbing mountains will be needed. When climbing mountains, the battery will assist the engine to climb, and during the descent, the down-hill energy will be returned back to the battery pack. The 1-liter engine weighs around 200 lbs with all associated hardware, yet can replace 1,000 lbs. of battery weight. The 1-liter 3-cylinder engine will costs around $1,500 to $2,000 yet can displace $15,000 to $20,000 of battery cost.
@Thomas, FF free HC fuel is very expensive to make and inefficient to use. Use H2 directly in Fuel Cell is more efficient and pollution-free. It is far better to turn FF into H2, and immediately sequester the resultant CO2 in oil and gas wells to avoid CO2 emission into the atmosphere. It is possible to use existing Natural Gas pipeline system for pure H2 in order to replace NG, Oil, and coal all together, thereby allowing us to jump start the transition to emission-free energy.
Albert E. Short asked: "When did liquefying and storing hydrogen become cheap and lightweight? " Answer: Ask NASA, who paid $3.66 per kg of LH2 in 2001. With inflation between 2002 and today = 45%, then $3.66 x 1.45 = $5.3 per kg. In regional airliners with PT6 turboprops, the FC system can double the efficiency propeller to propeller, thus we can divide this cost in 1/2 = $2.65 per GGe of jetfuel. Even better, the very lightness of LH2 permit gain in payload weight, even doubling the payload weight that is especially applicable to heavy cargo, so we can divide this $2.65 by half again, to $1. 325. In larger airliners with higher-efficiency gas-turbines, the efficiency gain using LH2 is not as dramatic as with smaller regional airliners, but at least the cost of LH2 can equal the cost of jetfuel per ton-mile of payload.
@E-P On the third thought, instead of lengthening the fuselage design in not-yet-build aircraft, the fuselage could be widened to accommodate larger volume instead of lengthening the aircraft. For example, the B 737 500 had fuselage width of 3.75 meter, and we want to widen it about 0.5 m to accommodate another passenger's row. With the length of the untapered fuselage being 26 m, the old volume is 287 m^3 vs the new volume to be 368 m^3 for a gain of 81 m^3. The plane carries about 15,000 kg of fuel, so with H2 weighing a third as much, will end up carrying ~5,000 kg of LH2. With a density of 71 kg per m^3, this would occupy a volume of 70 m^3, which is below the volume gained from widening the plane. Of course, due to the higher efficiency of the engine running on LH2 and the lower Max takeoff wt, we will need quite a bit less LH2 to travel the same distance, so some of the extra volume can end up as polyurethane insulation foam that can also add immense structure strength to the fuel tank as well, and any left-over can be used to increase payload to compensate for a lot lower fuel weight. With a fuselage width widened from 3.75 m to 4.25 m while keeping the length the same, there will be a 13% gain in skin surface area. Assuming that the skin surface area of the fuselage is only 40% of total skin surface area of the plane, then this gain = 40% x 13% = 5% increase in total skin surface area of the plane, so this is a negligible penalty in cruising drag that can be made up for by slightly decreasing cruising speed of about roughly 1%.
@EP On second thought, BOTH LH2 tanks, in front and in the rear are needed due to problem with weight balance as the fuel is being consumed. The front LH2 tank can be placed below the passenger floor, in the front cargo area, while the rear tank can be placed in the tail section, thus taking up less passenger seat space, though cargo space will be reduced and will have to take on denser cargo to make up for the loss of some cargo space, unless the fuselage is being lengthened as discussed. @gryf, Yes, smaller-aircraft turboprop engines have poor efficiency and would be better off replaced with FC that can double the fuel efficiency. Additionally, due to the much lighter fuel weight of LH2, payload can increase significantly, thus allowing LH2 price per BTU to be as high as 3 times the price of jet kerosene fuel. So, if jet fuel now costs $2 per gallon, then LH2 cost of $6 per kg would be tolerable. Back in 2001, NASA paid $3.66 per kg of LH2 and $0.16 per kg of LO2. Adding inflation and the bulk price of LH2 today would still be affordable to replace kerosene jet fuel.
@EP, Great point regarding the potential of tail-strike with lengthening of the fuselage. There are several potential solution short of lengthening the landing gear strut. 1.. No modification to the aircraft length and reduce seat count on existing aircraft, while accepting heavier cargo payload in the front cargo section to make up for lower seat count, because it would cost quite a bit to lengthen the fuselage existing aircraft. 2.. On aircraft not-yet-built, the fuselage would be designed to be lengthened BOTH in front of the wings AND behind the wings in order to maintain optimum balance. This would minimize the fuselage lengthening requirement behind the landing gear. 3.. Furthermore, the use of LH2 while carrying the same payload would mean much reduced Maximum Take Off Weight (MTOW) and hence no need for high angle of attack like before. 4.. If higher payload in the form of heavier cargo load is taken on to offset the much-lower fuel weight, then the aircraft will not be allowed to be used on short runways, only on longer runways, or higher flap angle will be used to reduce rotation angle requirement on takeoff on shorter runways, because takeoff distance is always longer than landing distance. 5.. In practice, building some extra speed before rotation would allow for reduction in angle of rotation and would enhance safety if runway is long enough.
For a mid-size to big airliner, the gas turbine engine is efficient enough when burning LH2 and therefore Fuel Cell is not necessary. With LH2 that is very cold, it can be used to cool the air intake charge before entering the compressor, thus significantly reducing the compression work and hence increase thermodynamic efficiency. Mid-size airliner turbine engine can see an increase in thermal efficiency by 10-20%, with similar gain in power density, as the result of using LH2 to cool the air intake charge. LH2 would best be placed in the rear of the aircraft in one big spherical tank in order to minimize the surface to volume ratio and hence reducing insulation weight and boil-off rate. The fuselage is simply lengthened enough accommodate the LH2 tank without reducing cargo and passenger space. An added advantage would be great reduction in post-crash fire hazard after impact-survivable crashes. The wing fuel tanks for kerosene could be left intact in order to have a jet-fuel capability in case of operating at airports that do not carry LH2. LH2 may not be available in many airports at the beginning of the Hydrogen Economy. This is an added advantage of using existing aircraft designs, existing gas turbine engines modified for use with LH2, and the fuselage will simply need lengthening, without having to replace the whole aircraft. With modern fly-by-wire controls in newer generations of aircraft, lengthening of the fuselage would be easier, by simply using longer electric cables to transmit control commands from the cockpit. Hydraulic controls can also be accommodated by simply using longer hydraulic piping.
The thermal efficiency of a small turboprop engine in the 600 hp range in the Cessna Caravan is around 20-22%. The bigger turboprop engine in the 1,200 hp range as in the PC12 has efficiency around 25%. The efficiency of the Kuznetsov NK-12 turboprop engine, 12,000 hp, in the Russian Bear bomber is around 33%. Large jetliner turbofans have the core turbine engine with efficiency around 45-50%, somewhat comparable to earlier generation of FC.
@bman, Thanks for your comment and feedback. 1.. Regarding the efficiency of FC, new generation of higher-temp FC is now able to reach 70% efficiency with temperature of 150 dgr C, thus allowing significant reduction in the size of the radiator and making higher power possible in aviation. Also, power density of as much as 6 kW per liter and 4 kW per kg is now possible, while motors having 5-6 kW per kg is now available, making the weight of the entire propulsion competitive with turboprop. Of course, peak power is only needed for a few minutes during takeoff at full gross weight, and can be throttled back to 75% during climb, and way back during cruise at altitude. 2.. Regarding the Challenger disaster, from Wikipedia: "The disintegration of the vehicle began after a joint in its right solid rocket booster (SRB) failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch. The seals' failure caused a breach in the SRB joint, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint attachment and the structural failure of the external tank. Aerodynamic forces broke up the orbiter." There is no mention of LH2 at all as having anything to do with this disaster. Just the solid boosters and aerodynamic forces the broke up the vehicle. 3.. With LH2, the very light nature of it and the thick polyurethane foam insulation required means that the fuel tank is very strong and big for the inertial force of the fuel and should hold up very well, far better than heavy petroleum fuel in flimsy aluminum skin fuel tanks inside the wings. Would a fuel tank leak cause fire? Since the fuel is so cold, no fire can happen adjacent to the aircraft, but much further behind and above the aircraft, as the LH2 has the chance to vaporize and gain heat and floats upward and mixed with air. A lot of steps must happen before the cryogenic LH2 can catch fire, well above and behind the aircraft.
Another way to look at LH2 fuel consumption per lb of payload is to realize that for the Cessna Caravan with 8,000 lbs gross weight, 4,700 lbs empty weight, and 3,300 lbs usefull load, with maximum fuel weight of 2,200 lbs, it has only 1,100 lbs of payload. Even if the aircraft is not downsized, then when subtracting the 244-lb of LH2 (2,200 lbs divided by 9 folds less fuel mass) from the 3,300 lbs of useful load, we would have 3,056 lbs of PAYLOAD available for the full range as with 2,200 lbs of jetfuel earlier, but now, with the huge PAYLOAD of 3,056 lbs, we almost TRIPLE the payload capacity for the LH2 in the non-downsized version of the Cessna Caravan as the result of using LH2-FC propulsion system. So, we have almost tripled the payload capacity, while using only 1/3 of the fuel caloric value due to 3 folds gain in thermal efficiency of the FC would means 9 folds gain in fuel efficiency of LH2 per lb of payload.
Correction to my posting above: "...and we are bound to achieve as much as 4 folds gain in fuel efficiency in comparison to petroleum fuel in small aircraft, ..." instead of "12 folds gain in fuel efficiency" as stated.
@yoatmon, Aircraft can use Liquid H2 (LH2) as fuel, which weighs 1/3 that of petroleum fuel for a given amount of BTU. Then, for 19-seat passenger aircraft, the FC is 3 x more efficient than an equivalent 400-600-kW gas turbine. So, already, we may end up with fuel weight about 1/9 that of the jetfuel weight just on the basis of 3x gains in thermal efficiency and 3x gain in gravimetric energy density. Ah, but there's more: Fuel weight is generally 1/2-2/3 of useful load of the aircraft, with the remaining for payload, and fuel weight can be as much as 1/3 to 1/2 of the gross takeoff weight.. Thus, the entire aircraft can be downsized to have smaller wings, smaller tails, smaller propulsion system, smaller landing gears which will save even more weight and would end up consuming 75% of the energy per mile per kg of payload. So, multiplying 3 folds thermal efficiency gain of the FC with 1.33 folds gain in energy efficiency per unit of payload due to weight and drag reduction = 4 folds gain in fuel efficiency when converted to LH2-FC propulsion system. So, the LH2 fuel weighs practically nothing when so little of it is being used, AND with 3 folds higher in energy content per unit of mass: 4 x 3 = 12 folds lower fuel mass per kg of payload. Let's say that the Cessna Caravan carries 2,200 lbs of jetfuel, then an equivalent-payload LH2-FC plane would carry only 183 lbs of fuel, or just the weight of ONE passenger. This extremely low fuel mass has major implication in the crash safety of the aircraft, with high percentages of deaths of current small plane crashes from post-crash fire from otherwise survivable crash. Jetfuel is placed in the wings, which is very likely to break up after even a low-impact crash, causing fuel rupture which will cause lethal fires. The LH2 fuel tank could be placed in well-protected insulation structures (thick polyurethane foam) in the rear of the fuselage whereupon the fuel tank holding very light fuel will very likely stay intact after a survivable crash. Rear section of aircraft always stay intact after impact-survivable crashes. So, LH2 is very advantageous for aviation, and we are bound to achieve as much as 12 folds gain in fuel efficiency in comparison to petroleum fuel in small aircraft, and much gain in safety at the same time from post-crash fires and from increase reliability of the propulsion system, with dual e-motors and dual FC system powering a single propeller.
@yoatmon stated: "Energy produced from renewables is a too valuable resource to be wasted in H2 infrastructure. " Reply: RE is used directly in the grid or stored in batteries whenever possible, and only the grid-surplus RE will be used to make H2. Grid electricity is only 1/3 to 1/4 of total energy consumption, so we will need to overbuild RE capacity to be 5 times higher than the grid's peak demand to meet all energy demand. As such, we will have grid-surplus energy for the majority of the time, except when RE output will be down to 1/5 of peak output. During which time, ALL of the RE output will be devoted to the grid. When RE output is below grid's demand, then gas turbines will have to be turned on burning H2 as fuel, but this is a rare event, due to the overwhelming RE capacity. Notice that due to the rare event of the grid needing power backup, grid-utility battery storage will NOT be cost-effective due to infrequent cycling. Battery need to be cycled every 1-2 days in order to use up all of its cycle life during its limited shelf life of 10-20 years. This is dispatchable demand scheme to take advantage of intermittency of RE in order to require very little grid-utility storage and very little wasteful use of H2 to generate electricity. Please note that for industrial use and for heating purposes, H2 has efficiency near 100%. New higher-temp steam electrolysis has efficiency of 90% on HHV basis even when accounted for the heat input, so we will have 90% round-trip efficiency, to rival any other e-storage media, comparable with battery's efficiency. For light vehicles, Plug-in FCV that can use grid electricity for 80% of total mileage will overcome the inefficiency of FCV, and only needing H2 for long trips. For Heavy-duty vehicles for long-distance, the use of H2 permit significant gain in payloads over the use of battery. Short-trip HDV can be battery powered. In summary, judicious use of RE which involves direct grid use, battery storage, and H2 for industrial and heating purposes and for long-trips in vehicles will make the most out of valuable RE resources. The true answer is the word AND instead of EITHER or OR, in the case of RE.
@sd, The problem with long-range BEV is that it is too battery intensive, taking up too much resources. It takes $5 Billions to invest in a GigaFactory that can produce 500,000 long-range BEV a year. Imagine all the investment in more mining operations world-wide to feed those monstrous GF that don't produce that many BEV's. The same GF can produce enough battery for 2,500,000 Plug-in FCV. Heck, Toyota currently has to severely limit the production of the RAV4 Prime PHEV due battery shortage. With a skeletal H2 network nation-wide, the hypothetical Plug-in FCV will sell well, due to much lower prices than a BEV with comparable range. With only 60 hp FC stack and 300-mi range on H2 and 40-50-mi range on battery, it will cost around $35k and will deliver the range of $70k-BEV costing twice as much, and the BEV is taking much longer to charge in comparison to the 3-5 minutes it take to fill-up with H2. Your Bolt does not have the range required for convenient long-distance trips.
@Davemart, I was discussing the US market, which seems to be the world's biggest market for FCV in spite of very limited availability of H2 stations and very expensive H2 at the pump. With a nation-wide skeleton network for Plug-in FCV, we will see a much bigger growth of Plug-in FCV, due to much less H2 required per Plug-in FCV, thus can be located much farther to the H2 station than a FCV, and much lower cost of H2 infrastructure per vehicle, because one H2 station can serve 5 times higher number of PFCV.
@ECI, The following will address your concern regarding current problems of FCV. Question: 2012 Mirai goes faster and farther, but is that enough? Answer: Kudos to Toyota for vastly improving the Mirai, but that is NOT enough. 1.. H2 fuel is still too expensive, and going up in prices now to $16.5 per kg or GGe. Fuel subsidy of $15,000 from Toyota every 3 years, meaning production number cannot be much due to money loss. 2.. Lacking a national H2 network in the US really limits the appeal and sale volume. To remedy the two issues above, Toyoda could make a Plug-in FCV version of the Mirai with about 50-mi battery range. If charged also at work, battery range for daily driving will increase to 100-mi. A... This means that H2 is used only less than 20% of the total mileage, thus major saving in fuel cost. Fuel subsidy could be reduced to $3,000 every 3 years for 3 to 6 years, or none at all, thus major saving for Toyota. B.. This also means that the H2 station could be located 30 miles away from home and it would still be practical, with less than once-a-month filling up, instead of 7 mile from home with weekly filling up. Thus a metroplex with 30-mi radius (60-mi diameter) would only need ONE H2 station in the center, at near the convergence of all of the InterStates Hwy for travelers passing thru to fill-up. Metroplexes that are farther than 250-mi apart will have a small H2 station in between. With about 50 major metroplexes in the USA, or 80 if we wanna cover all the state capitals in the USA, we will need around 80 H2 stations, plus about another 50 or so to cover for metroplexes that are further apart than 250 in total 130 H2 stations to cover the urban population, which is 80% of the population of the USA. C.. With total number of H2 stations reduced to 130 in the USA that covers 80% of population, then Toyota, Honda, Hyundai, Shell, Itawani, Linde, First Hydrogen, etc...could join together to build these with ease. Total cost at $2 million per station = $260 millions. Someone will ask: Where to find the room for a bigger PHEV battery pack when the current Mirai is already packed? Answer: Limit H2 range to 300 mi by removing the smallest rear H2 tank. Remove the very inefficient hybrid traction battery, and put in PHEV battery. Reduce Fuel Cell System capacity to half to save more weight and space. With more power from the PHEV battery pack, the FC system can be reduced by 1/2, or even to a 1/3, or around 60 hp, thus will save a lot of money on production cost. Battery is getting to be very cheap now.
@Darius, Green Hydrogen is not meant to replace Green Electricity nor to replace Battery, because green electricity and battery electricity will be used directly whenever available, and Green Hydrogen will be used as back up, AND for heating, combined heat and power, and industrial syntheses for which purposes, the efficiency of H2 utilization is nearly 100%. New method of steam electrolysis has raised the efficiency of H2 production to 94% based on HHV and 80% based on LHV of Hydrogen. This puts the round-trip efficiency of H2 to approach 90% by HHV for heating and industrial syntheses, to match the efficiency of battery e-storage.
@yoatmon, Please Google: "Repurposing gas infrastructure for hydrogen" As of 2019, 70 million tons of hydrogen is consumed yearly in industrial processing. Pipeline in Germany made from regular pipeline steel since 1938 has been transporting H2 at up to 200 bar pressure, and is still functioning. Handling of H2 is not an issue with current technology.
Bunker fuel is so goddamn cheap, costing only $0.03 per kWh. Even if Green Hydrogen at an incredibly-cheap price of $3 per kg, containing 33 kWh of energy = $0.09 per kWh, clearly 3 times more expensive than the so goddamn-cheap bunker fuel. To be cost-competitive, Green Hydrogen must cost only $1 per kg at the pump...clearly not possible at this point in time. May be in due time.
@gryf, Thanks for your reply. Indeed, the Clarity costs more than the hypothetical Insight PHEV, $33k vs $25.3k, because the Clarity is a bigger car with a bigger battery pack of 17 kWh vs 12 kWh of the Insight PHEV, bigger e-motor and bigger power-inverter as well...and perhaps the Clarity is still stuck with too-heavy battery tech, when more modern battery tech could offer a lighter battery pack. A near-future Insight that is optimized for PHEV will do much better, when the battery pack will be integrated into the body frame as structural component like in Tesla's design, and NOT just placed within the rear trunk compartment taking up valuable space and adding weight without adding strength, forcing more strengthening requirement of the body in front of the battery pack and thus adding further to the curb weight to the vehicle. Indeed, Honda could do MUCH better than its existing PHEV design.
Truck transport for H2 is for the transitional period. Eventually, H2 will flow in current Natural Gas piping system to be delivered to everywhere and no more H2 transport truck will be needed.
The governments should NOT micromanage and dictate which technologies to support. Instead, just gradually increase the Carbon Tax and let the people figure it out which technologies are most practical for them. The PHEV examples here are among the least efficient PHEV's on the market. Why not choose more efficient PHEV's to run the tests?
@yoatmon and @sd, You guys have missed the main point of the article which is the very high efficiency of electrolysis. Existing electrolysis is already 80%-85% efficient by HHV (Higher Heating Value) of Hydrogen. With even higher-efficiency electrode as detailed in this article, higher efficiency is now attained, which could be well over 90% efficiency of electrolysis. This matches the efficiency of battery electricity e-storage. Quoting from above: "The advanced noble electrocatalyst required only 180 mV (millivolt) overvoltage to attain a current density of 10 mA (milliampere) per cm2 of catalyst, while ruthenium oxide needed 298 mV. In addition, the single Ru atom-bimetallic alloy showed long-term stability for 100 hours without any change of structure." Green Solar and Wind energy is wasted everyday on vast empty fields and parking lots. If these wasted Solar and Wind (S&W) energy is captured to produce H2 to replace Fossil Fuel, then we will easily control Global Warming without complicated efforts. It only takes about 2% to 5% of total land surface area to capture enough solar energy to satisfy ALL energy requirement for the USA. There is NO shortage of land area, and there is NO shortage of solar PV materials. Please note that H2 is NOT anti battery. Those who favor battery can continue to use battery, but the bulk replacement of NG, Coal, and Petroleum by using Green Hydrogen will be needed to really control Global Warming.