lots of choices, lots of problems
Oil is a hard act to follow... it's been relatively cheap and plentiful, it packs a lot of energy and it's a liquid at ordinary temperatures and pressures. Unfortunately, it's getting expensive and scarcer and it's dirty.
Hydrogen sounds ideal but has serious problems. You can't liquify it at any sustainable temperature so it has to be shipped and dispensed as a high-pressure gas. It's more dangerous than gasoline in that it is colorless and odorless and burns with an almost invisible flame, but mostly, a vehicle would have to have a tank of it at high pressure which, in itself, is dangerous. It may be possible to absorb it onto something to store it, but that does no look to be able to store enough for a car. It also needs to be generated, which requires more energy than will be recovered by using it as fuel. With a fuel cell, efficiency may be high enough for it to be viable for some cars, but I don't see it as a widespread solution. It's upside is that it is almost non-polluting. Burning anything in air can generate oxides of nitrogen. A fuel cell may be truly non-polluting.
Battery power can be as clean as hydrogen overall and produces no emission from the vehicle itself, but can be very dirty if the power is generated that way, such as from coal. Battery technology continues to advance and for many uses, an electric car can be a viable choice. Batteries will need to be recyclable or much of the advantage is lost. I suspect we may be able to more than double the energy density of batteries, but that will still produce a car with a range of 400 miles or less (right now, a lot less). I'd buy one if the batteries could be guaranteed to last long enough to be economical and if the range hit aroung 200 miles in a car that cost similar to a gas-powered one. Charging isn't as much of a problem as you might think. Most would be charged overnight, when demand is lower. They will probably never be practical for long trips.
Biodiesel is probably the best choice for large trucks. It may be the best choice for cars that need to have more range than batteries can provide. It should be carbon-neutral on a global scale, but locally, it's still burning a carbon-based fuel. 100 square miles of Iowa may have better air from growing crops to make fuel for New York City, but NYC's air will still have a surplus of CO2. I think the biggest challenge here is to grow the crops without doing more environmental harm than burning fossil fuels does, but it can be done and it's currently workable technology.
Ethanol might help but I don't see it as a long-term solution. Production from crops is very inefficient and it needs to be distilled, which is a very energy intensive process. It also packs less energy than petroleum based fuels, but it burns a lot cleaner and should also be carbon-neutral.
Nuclear energy should probably be ranked with matter-antimatter generators. Sounds nice but is almost certainly not a viable mobile energy source as the radiation shielding needed would be prohibitively big and heavy and reactors are just too potentially dangerous to be in any place as risky as a vehicle.
Hybrids, using biodiesel or hydrogen are possibilites with all the disadvantages of the fuels involved. LNG and LPG are fossil fuels and will never be major players in the mobile market.
Short term, I think we'll see someone produce a successful, economical electric car with sufficient range that it sells enough to spur the major automakers to follow suit, and I think we'll see biodiesel replace petroleum diesel in many places. It's possible someone will produce bio-gasoline, but not until oil gets a lot more expensive.
Long term, we have to get away from burning oil and coal and we probably need to get away from needing motor vehicles so much. This will take a major realignment in our society making public transportation and walking as practical as it once was. The motor vehicle changed our world in the 20th century. We may have to change again in the 21st. Remember, even if the environment wasn't an issue, so much of the stuff we've come to expect is made from these materials. Most plastic is made from oil.
Was this reply helpful? (0) (0)