Some say Electric Cars are the future, others say Hydrogen. Who is right? Well there is no contest really, here is the explanation.
I recently watched a top gear episode which reviewed two electric vehicles, and clearly demonstrated that there were tasks for which these cars were clearly unsuited. Now it could be said the episode was a trifle unfair, since it did not look at other tasks for which the vehicles would be suited.
(The episode screen July 31 I believe and had a Nissan Leaf and a Peugeot iOn if you wish to search for it.)
The test cars ran out of power, and with recharging both taking time and no recharge points established in the area of the test the result was most inconvenient. The program did demonstrate neither of these cars was a good choice for a weekend away. The reality is those same cars might well be suitable for a regular commute, where the distance to be traveled is both known and typically quite short, and recharging can be planned.
The conclusion of the show suggested that Hydrogen power cars, as tested once on a previous occasion, provide the perfect answer.
The arguments I heard put forward for the hydrogen car are:
1) With power coming from combustion, the car would feel like current cars.
2) The only tailpipe pollution is water!
3) Hydrogen is the most abundant substance in the universe, so it will never run out!
This all sounds compelling, but looking lets look at the claims.
1) We can make powered by combustion. This can actually be true, but I would suggest having combustion in a car is not actually a good thing. Even the potential for combustion means carrying fuel that burns and thus is a safety hazard. As we will see, in truth, the inefficiency of the combustion process is the Achilles heel of the whole idea. So instead hydrogen cars produce electricity via a fuel cell, and we then use the electricity to drive electric motors. Search for the Honda Clarity and you will find this is how this car, and all other proposals work.
2) The only tailpipe pollution is water. Again this is true, but it is because, like all electric cars, the pollution is moved to elsewhere, not eliminated. Remember, conventional battery electric cars have no tailpipe pollution at all.
3) Hydrogen is the most abundant substance in the universe. Again true, however with a large 'but'. Here on earth Hydrogen floats away and does not stay on the ground, or even in the atmosphere. I refer to the article on Wikipedia 'Atmospheric escape', but in summary, Hydrogen is so light if eventually floats away from a planet the size of the Earth. To get hydrogen to use to power cars, we have to extract it from compounds, We can extract if from fossil fuels, particularly natural gas, but we can be truly sustainable and extract hydrogen from water. This means no reliance on fossil fuels, and a closed loop since burning the hydrogen produces water again. Any other source than water and we are changing the world and making more water, so in the long run creating an imbalance. If we really need more water we could melt the ice caps a little....or did someone already think of that?
So our cycle becomes, put energy in to extract the hydrogen, transport the hydrogen both to the car an in the car, then burn the hydrogen to get back the energy we put in. The hydrogen is not a source of energy, since we have to put energy in to extract it. If we use water to extract hydrogen, we need at least the exact same amount of energy in the extraction as we get back. Going from fossils fuels gives only a slight gain, more than offset by other problems in the long term, but workable while we are digging up the fossil fuels anyway. Overall, hydrogen becomes a way to carry energy, not a source of energy.
But it is not easy to carry energy in the form of hydrogen. As the smallest atom it escapes very easy and is very light, so to carry hydrogen you need highly compress it. Transferring, refueling and transport are all expensive using hydrogen. All to get back the electricity we started with.
But the biggest problem is that to get our energy back, we use combustion. With combustion we produce heat and every bit of heat that is not turned into motion is lost energy. Think how hot our current engines get. All that heat is lost energy and we produce so much we need to power a cooling system to get heat away from the energy. When you had to add the energy in the fist place, you really notice that you lose most of it to heat in the engine.
This is why all proposed hydrogen cars do not combust the hydrogen. They use an alternative method called a fuel cell, which is far more efficient than combustion and produces not heat, but electricity. All proposed hydrogen cars use fuel cells and are, in effect, an electric car with a hydrogen fuel cell in place of a battery. So the comparison becomes a battery electric car vs a fuel cell electric car.
Since now we are comparing two types of electric car, the drive system is identical. The choice is charging by refilling plugging in, or charging by refilling hydrogen.
The 'refilling hydrogen' is like conventional refuelling, the conventional battery takes hours. The conventional battery is efficient and easily provides adequate range for most driving requirement, the hydrogen fuel cell is a more complex inefficient system but can more easily provide a much greater range.
So hydrogen fuel cell to produce electric = long driving range but reduced efficiency.
The most logical answer is a plug in hydrogen 'hybrid'. It is really only two sources of electric power, so can have less total bulk than a plug in hybrid gasoline/diesel vehicle. This gives the ultimate efficiency from the battery direct electrical storage,
and the additional range on demand from the fuel cell. The best of both worlds.
Such a car could in theory be an improvement on the cars of today for refuelling. If we have can refuel the hydrogen as we today refuel gasoline or diesel, isn't the same? Well... no! Since we can also drive on plug in power, and in fact on most daily trips only need 'plug in' power. We can go far, far longer without a refuel stop. An important step is that 'plug in' can mean just leaving the car in the garage, and charging by induction with no actual plug in at all.
While fuel cells are expensive and hydrogen refuelling uncommon, the plug in hybrid gasoline/diesel makes a great interim step and achieves are large percentage of the gains- if not all while we still get hydrogen from fossil fuel.
So there is no hydrogen vs electric - it is just conventional battery vs fuel cell with an electric car in both cases. And a combination of both power sources is probably the ultimate solution. In the interim, the plug in internal combustion engine hybrid is a great solution.
