in a hybrid once the car is up to cruising speed the electric power goes off and the gasoline motor goes back to recharging the battery ready for next time even better than that a hybrid has what's called regenerative braking when you put your foot on the brake in a conventional car when you put your foot on the brake brake pads are gripping the rotor the disc and your motion is being turned into friction heat so there goes more energy wasted as heat i don't know if you're aware of how much breaking a full-size car from 60 miles an hour to zero produces in like a few seconds enough heat to boil a pint of water when you think about a street with stop lights every half mile that's an awful lot of energy you keep throwing away okay so you threw all that energy away as heat as you break towards the light then you burn more fuel the same amount to get back up to speed on the green light in the hybrid as much as possible of that energy is retrieved turned into electricity as you're braking ready to use as you drive away again okay so do you see what's different about this diagram from the first one we've added this little loop in here we're basically recycling energy motion that we don't need is being turned into electricity to be turned back into motion again later on that's what the hybrid adds does the hybrid do anything about the heat being wasted from the gasoline motor another thing that's still being wasted the only good news is it's a smaller engine so it's producing less heat but because of that the hybrid is better but not that much better a good hybrid one designed from the ground up for energy efficiency like the toyota prius gets you from 10 to about 20 efficiency at all that's all but that does mean double the gas mileage so you know a conventional small sedan might if it's well designed and if you drive it carefully get you as much as 30 miles to the gallon a toyota prius might get you 60. okay it's a great improvement how can we do better than this well we could go to an all-electric car like a vault or a leaf or a tesla but you can't really make a meaningful comparison of one of those to a fuel vehicle because an electric car is only half the system with a conventional car you take the resource the chemical energy and you process it and wind up with motion with an electric car the processing of the resource takes place at an electric power plant and only the last part electricity to motion takes place in the car so the efficiency of an electric car even contribution to pollution and climate change depends on where the electricity came from if we're generating our electricity from coal burning power plants an electric car is not a wonderful thing to have if however your electricity is coming from solar power plants and wind farms awesome today the range of vehicle types available is getting bigger and bigger at one end of scale is the hybrid that we talked about already at the other end of the scale is the all-electric car but now they're intermediates there's the plug-in hybrid which still has both a gas motor and an electric motor both of which can drive the car but instead of a small battery that retrieves wasted energy it has a bigger battery and you can plug it in to the wall and charge up the batteries so that for shorter journeys you don't have to use the gas motor at all and then coming from the electric there's now the extended range electric which is all electric as long as the batteries last but it has a gasoline motor that can't drive the car but can cut in to charge the battery in case of need all of these are available on different vehicles on the market today anyway how can we do better than this using fuel in the car well the key problem is all of this lost heat and so the only way we can improve is to come up with a strategy where we don't burn the fuel we get the energy from the fuel without burning it and this can be done the device we need is called a fuel cell a fuel cell is not some sort of a battery it is a device for getting energy from fuel the only fuel we can actually use in a fuel cell turns out is hydrogen here's how it works fuel cell basically has two chambers with a membrane between we put hydrogen into one and we put oxygen into the other we could burn hydrogen oxygen flames explosions get heat light and sound but we'd waste all of that energy what we do here the this special membrane here is the key to the thing because it will let protons go through but it blocks electrons a hydrogen atom is made of one proton plus one electron so in here the protons go through to meet up with the oxygen the electrons can't do that so we provide an electric wire a metal wire and the electrons flow around the wire to rejoin their protons and combine with the oxygen and so we can put motors light bulbs anything we want into that wire and collect the energy as electricity not as heat okay so hydrogen combining with oxygen to produce waste product of water which is great no pollution the energy provided as electricity rather than heat same exact amount of energy doesn't matter how you combine a hydrogen with oxygen burn it put it in a fuel cell same chemical reaction same energy produced the difference is if you burn it and get the energy as heat light and sound much of it will escape and not do anything useful whereas if you get the energy as electricity electricity is confined it can only run down the wire you provide and so we can take it to an electric motor and convert it into motion much much more efficiently as i said we can't run a fuel cell vehicle on gasoline only hydrogen but for comparison purposes if we could a conventional car we said might if you're lucky get 30 miles to the gallon a hybrid could get 60. a fuel cell vehicle if it could run on gasoline could get between 100 and 150 miles out of that same yellow or even up to 300 miles to the gallon according to some promotional literature that's the difference between using 20 and wasting 80 versus using 80 and wasting 20. it's a huge difference there is presently one fuel cell vehicle on the road that you can go out and buy it's the toyota mirai here it is pictured at a hydrogen filling station when toyota introduced the mirai they sold it in japan first of all now they're available here in southern california there is of course a problem with hydrogen-powered vehicles where do you get the hydrogen from one good thing we can say about governor schwarzenegger he was a strong proponent of hydrogen here he is in his official governor's portrait now it's a little difficult to take seriously the green environmental claims of a man who drives a personal fleet of four hummers but when he took office governor schwarzenegger announced that he would have fun of his hummers converted to hydrogen that proved to be impossible but star power is a wonderful thing and general motors agreed to build a hydrogen-powered hammer especially for him here are governor schwarzenegger and the chairman of general motors showing off the hydrogen hummer at a press conference at lax now it's my understanding that this hydrogen hummer was not a fuel cell vehicle it burned the hydrogen in an internal combustion engine just like gasoline so that made it extremely inefficient heat lost in the same way as it would be with regular fuel and so the hummer couldn't actually go very far without running out of fuel the cameras did not see the hydrogen hummer being unloaded from a flatbed truck in a side street just around the corner but schwarzenegger was able to step in and zoom into view of the cameras for his press conference anyway before leaving office he ordered oversaw construction of a limited number of hydrogen fuelling stations in california mostly in the bay area and sacramento initially there were only three in southern california but the numbers have continued to grow this map shows the hydrogen filling stations available in california today from the la area you can get to san diego going north as long as you don't miss the one station in the central valley on interstate 5 you can get to the bay area from the bay area you can get to reno but don't try to go anywhere else in california and definitely don't try to go out of state outside of california there's one hydrogen station in connecticut oh and there are three in vancouver canada hydrogen development has a long way to go if you're going to purchase a hydrogen-powered car you have to know where the fueling stations are and you're limited on where you can travel to but that at least begins to break through this chicken and egg problem if there isn't any hydrogen why would you buy a hydrogen car but if there aren't any hydrogen cars why would you provide hydrogen we're starting to get through that barrier