It's a question of scale of production.
The basic problem with alternatives to oil thus far devised is one of scale. Sure we can produce ethanol, biodiesel, hydrogen and so on but to do so on a scale that would substantially replace present oil use just isn't a goer with the resources we have available. Your car "eats" many times more than you do. Hence the impracticality of replacing petrol with ethanol from wheat etc - there simply isn't enough land to grow it and then there's water, fertilizers etc. Same with biodiesel - sensible use of waste animal and vegetable oils but they aren't available on anywhere near the scale that we use diesel fuel today. An order of magnitude difference.
Realistically, ethanol etc would suffice to keep ambulances and essential deliveries running but basically nothing else. No long distance freight trucks, no aviation, no private cars and not many buses either. Scale is the problem.
Electricity (batteries) would work for relatively short distance travel but not for long distance without major innovation in battery technology. And then there's a possible issue with the supply of whatever such high tech batteries would be made from. All the batteries you have in your house powering various gadgets, wouldn't get your car out of the driveway. Even the car battery itself wouldn't get you much beyond the local corner store. So again it's a scale issue but at least batteries are acceptably efficient at storing energy.
If algae could be made to grow rapidly enough on an industrial scale then it would overcome such scale problems. Whether or not that is possible is a good question but it does seem to be one of the more promising technologies. Electric (not hydrogen since they are relatively inefficient) cars for commuter trips and algae derived fuels for aviation, long distance travel etc could be a goer. Genetic engineering could have a use in making the algae growth more productive?