Water Engine Fallacy

 

Some Historical Claims 

Multiple "inventors" worldwide have claimed the invenction of engines which run on water alone.

1970 patent

Even nowadays some companys claim they can do it.

These are some of the claims:

• With the water engine you don't need batteries.
• You don't need to carry hydrogen cells.
• All you need is water.
• Vested interests of large fosil fuel multinationals are making sure water engine doesn't succeed.

An engine that runs just on water

Obtain Hydrogen from Water

Using electrolysis you can break the water molecule H₂O into hydrogen and oxygen. 

Obviously, apart from water you also need an electrical current which has to be supplied by a batttery. 

Electrolysis Energy Requirements

To obtain 1 kilogram of hydrogen from water through electrolysis, it typically requires around 50 to 55 kilowatt-hours (kWh) of electric energy.

Here's a breakdown of the calculation:

Energy Required for Electrolysis: The electrolysis of water to produce hydrogen involves splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂). The theoretical minimum energy required is about 39.4 kWh per kilogram of hydrogen under ideal conditions.

Efficiency of the Electrolyzer: In practice, electrolyzers are not 100% efficient. Modern electrolyzers usually have efficiencies between 65% and 80%. So, to account for inefficiencies, you multiply the theoretical energy requirement by the inverse of the efficiency.

$$\text{Practical energy requirement: }49.25\text{ to }60.6\text{ kWh}$$

This range accounts for different types of electrolyzers and their varying efficiencies.

Run an Internal Combustion Engine with Hydrogen

The amount of energy an internal combustion engine (ICE) can deliver from 1 kilogram of hydrogen depends on several factors, including the efficiency of the engine and the energy content of hydrogen.

Key Points:

1. Energy Content of Hydrogen:
• Hydrogen has a high energy content by weight, with a lower heating value (LHV) of approximately 33.33 kWh per kilogram.
2. Efficiency of an Internal Combustion Engine (ICE):
• Internal combustion engines are typically less efficient than fuel cells. The efficiency of a hydrogen-powered ICE can vary, but it is usually between 20% and 30%.

Calculation:

To find out how many kilowatt-hours an ICE can deliver from 1 kg of hydrogen:

• Energy delivered by the engine = Energy content of hydrogen × Efficiency of the ICE
• Using a typical efficiency range:

Energy delivered = 33.33 kWh/kg×(0.20 to 0.30) = 6.67 to 10kWh

 

Efficiency of the Water Engine

We can obtain 1 Kg of hydrogen from water by means of electrolysis consuming 50 kWh of electricity.

By burning this hydrogen in an internal combustion engine we obtain 10 kWh of actual mechanical energy in the car. 

Therefore with 50 kWh of electrical energy we have obtained 10 kWh of actual mechanical energy: this gives us an efficiency of 20%

Current Efficiency of an Electric Car

An electric car has an efficiency above 85%. This means four times as much as the "Water engine".

Fuel Cell Alternative

An alternative for the water engine is to use a fuel cell that converts hydrogen to electricity to power an electric car:

This solution would provide a small improvement. 

Now the efficiency would be 34%. 

Still much lower than just an electric car (85%)

Conclusions:

1. The so called "Water Engine" doesn't run on water but on electricity.
2. The "Water Engine" is, therefore, a very poor performance electric engine.
3. The efficiency of this "Water Engine" is 25% of normal electric engines.
4. Therefore this "Water Engine" requires to carry batteries 4 times larger than an electric car.
5. The folly of water-fuelled vehicles