Hydrogen economy

The hydrogen economy is a proposed system of delivering energy using hydrogen. The term hydrogen economy was coined by John Bockris during a talk he gave in 1970 at General Motors (GM) Technical Center. Wikipedia

Like steam and electricity, Hydrogen can carry energy but is hard to store. It can power transport, generate electricity, cook as gas, make steel, all without releasing CO2.

 

Using Hydrogen

If the Hydrogen or natural gas is fed into a fuel cell it will give off twice the power that can be released by burning.

Hydrogen has always made up 50% of towns gas, with CO. Natural gas used nowadays is mostly methane.  Hydrogen could easily be injected into this gas to make a towns gas with higher heating value and producing less CO2.

There are different fuel cells for hydrogen and natural gas. Hydrogen can be used in either.

If a town's gas was changed to 100% hydrogen, then stove jets would need to be changed.

In Iceland where there is a lot of geothermal heat, the government has a plan to convert the country to a hydrogen based energy system.

It will be possible to export hydrogen but the costs may be high. The process of liquefaction uses about 30% of the energy in the hydrogen, so it will always be preferable to transport compressed hydrogen as a gas in a pipeline.

  MJ/KG
Hydrogen    143
Methane CH4    50
Petrol, etc    47
Fat (animal/vegetable) 37
Coal    24
Carbohydrates - sugars, wood, peat 17
Carbon monoxide - CO 10.3

Efficiency of hydrogen

Cars can use hydrogen either in an internal combustion engine, or in a fuel cell.

An internal combustion engine is 38% efficient with hydrogen. Petrol / gasoline is only 30%.

A fuel cell with electric motor is 40-60% efficient. If the waste heat is used, then itcan be 85% efficient.

 

Problems with hydrogen

Hydrogen is very difficult to store as it is not very dense. See page on hydrogen storage. It must be cooled to -240oC become a liquid.

Hydrogen makes steel brittle, so pipes must be made with stainless steel.

Hydrogen being a small molecule is a great escape artists. It will leak through rubber or joints other gases cannot. A town's gas line may start out 50:50 H2 and CO, but will often end up all CO by the end. The H2 leaks out.

Fuel cells are expensive, and  purity of hydrogen needs to be as high as 99.999%.

The round trip efficiency of AC electricity to hydrogen, then back to AC is only 20%. 80% of the energy is lost.