Hmm.... It appears there are no forecasts for this.
It seems that energy futures analysis is being complicated, mostly by transitory geo-political issues, and overly hyped environmental issues.
The things we are fairly certain will happen:
1) Petroleum will still exist, and should be near current values.
2) Biofuels will see an increased use, with additional farmland being pressed into service.
3) Despite government efforts to push hydrogen fueled vehicles, the technology has already reached its maximum potential, and will fail for various economic, environmental, and physical reasons. The idea of a hydrogen fueled car will become something of a throw-back, just like personal air vehicles and the robotic kitchen.
4) Additional research, and the trials of time, will show that the hysteria over global warming was largely unjustified. Some policies may be in place to limit CO2, but they will not be as extreme as what currently exists. New oil sources will be opened to drilling, and formerly "depleted" sources will be revisited.
5) With lighter body materials and slightly more advanced batteries, electric (battery) vehicles may see an increase in range towards 200 miles, with a recharge time of a few hours. However, they will still cost about the same, in comparison to combustion vehicles.
The problems are that we have no ideas when the public opinions and government policies will change. We know they will change, but the number of electric cars will be influenced by when, which will be influenced by who wins elections and what-not.
For example, if Republicans maintain a strong presence in Congress and keep the Presidency, then it is likely that government will have a largely "hands-off" approach. This will leave the industry at the will of market forces, which will favor the continued use of combustion vehicles, well into 2030, although many multi-car families may start buying electric commuting cars.
If Democrats gain control of Congress and the Presidency, they will move government to being much more intrusive. Large sums of money will be spent on a hydrogen infrastructure (which will ultimately go unused), and new oil finds will remain untapped, drastically increasing the price of oil. In an attempt to reduce the price, they will drain the strategic reserve, setting the United States up for an energy catastrophe. They will also implement a carbon credit trading scheme which will further increase the cost of energy. The end result is that gasoline will reach roughly $6 per gallon by 2012, and $10 per gallon by 2016. People will rapidly adopt electric cars at that time. Inevitably, people are not stupid, and will recognize the failures of the Democrat Congress and President, and they will be replaced with Republicans who will counter many of the destructive policies. Gasoline will rapidly drop back to $4 - $5 per gallon. However, people will probably continue to use electric cars for their normal commuting, although the number on the road will decline starting from 2018.
So you see, there are two scenarios which have drastically different outcomes. In one scenario, market forces cause a gradual adoption, while in the other scenario, government interference will cause a rapid adoption followed by a decline as market forces are reasserted.
The thing you really need to focus on though, is that in 2030 the energy sources will be pretty much the same as they are today, but with more potential for biofuels. Battery powered vehicles will also have the same disadvantages as they have today. Similar market forces usually mean a similar outcome.