Hybrid Cars (What to do about climate change, part 1)
Since I've talked in past episodes about climate change, and the risks it poses to us -- thought it only fair to use some episodes to discuss potential approaches to mitigating (if not yet solving) the problem. This is the first episode in what should be a series of about a half dozen such episodes, scattered out over the next few months.
Lots of talk about hybrid vehicles in terms of reducing carbon emissions & reducing fuel usage -- but just what is a hybrid car?
Problem -- lots of flavors of this technology, and "hybrid" has now become a marketing buzzword. Tough to tell what's the truth, and what's "sales truth."
Compounding the issue -- advertised mileage estimates have been overstated.
In 2006, the marketing firm J.D. Power & Assoc. surveyed prospective car buyers
More than half said they were considering buying a hybrid, but most had no clue how much they cost, or what they'd gain from one.
At its most basic level, a hybrid vehicle uses two or more energy sources to propel it.
For hybrid cars, one of the energy sources is an internal combustion engine (ICE) running on something flammable. ICE's have been primary power source for cars & trucks since early in the 20th century -- but it wasn't always the case. First cars had either electric motors or steam engines -- but the advent of cheap petroleum left them in the dust, and the tide is only now turning back.
Use of ICEs leads to emissions of carbon dioxide (as well as other potentially problematic gasses), subsidizes some very rough neighborhoods on the planet, but has fantastic energy density -- equating to range on a given volume of fuel. Energy storage density will be a big theme in this episode, so hold on to that...
ICEs are also quick & easy to refuel -- just pull up to a filling station, and refill your vehicle's tank within a few minutes. Other energy sources aren't necessarily that convenient.
One of the bigger differences between all the flavors of hybrid cars is what the second energy source is. Key to this is energy storage, and density of energy storage. Also, your choice of second energy source will bring with it other plusses & minuses -- safety, ease of handling, etc.
Second energy source -- so far, primarily a choice of hydraulic vs. electric
Regardless of second energy source, have two basic configurations -- series vs. parallel. Can think of all the flavors of hybrid technologies on sort of a matrix, with energy source on one axis and configuration on the other.
Parallel hybrid (dominant type so far)
Combined hybrid -- a mix of parallel & series, with some sort of power splitting device allowing various ways of getting ICE power to the wheels.
Issues in work -- battery problems
Household gadgets (cordless drills, etc.) -- progression: NiCad -> NiMH -> LiIon batteries
Current gas-electric hybrids are based on NiMH batteries; everybody wants to make the jump to LiIon for greater storage capacity = range.
Hybrids only good for the environment to the degree that they cut gas consumption -- so real world gas mileage is the key.
Much of this also a function of how much you drive, what kind of driving you do.
Hybrids make more sense (currently) for city driving.
Meanwhile, other interesting technologies are coming online that have the potential to increase fuel efficiency as much as hybrids, but at lower cost.
Coming up: plug-in hybrids
Essentially, are gas-electric hybrid cars with really big battery packs, and ability to easily charge at home.
Would be more widely applicable, but battery stability & capacity issues have to get worked.
Fully electric cars also waiting on better batteries.
Just as fully electric cars will likely be the eventual successor of electric hybrids, is a proposal for a fully hydraulic car.
Auto manufacturers finally getting behind need for "greener" vehicles -- should see some interesting things for sale in the next two or three years.
Sources and other links
Mild (electric) hybrids
Full (electric) hybrids
Serial vs. parallel configurations
Other helpful technologies
GM: two-mode hybrid