Best Energy Storage

One part of the challenge of distributed energy grids is the ability to store excess energy. For example solar panels can only produce energy during day time but where does the energy come from at night? We have to either use other energy sources at night or discharge some form of battery.

All forms of energy are either potential energy (e.g. heat up water) or kinetic energy (e.g. spin a fly-wheel). Batteries are a way to store potential energy. Unfortunately are common batteries not very high in energy density. Energy density is the amount of energy that can be stored in a given volume or mass.

Here is a list of energy densities of common energy storage materials

  • Hydrogene: 33.3 kWh/kg
  • Natural gas: 13.9 kWh/kg
  • Fuel: 12.7 kWh/kg
  • Lithium-ion battery: 0.22 kWh/kg
  • Lead-acid battery: 0.05 kWh/kg

To give you a more practical example of what this list means: to light up one 100W bulb for an hour you would roughly need:

  • 3g (0.1oz) Hydrogene
  • 7g (0.25oz) Natural gas
  • 7g (0.25oz) Fuel
  • 0.45kg (1 pound) Lithium-ion battery
  • 2kg (4 pounds) Lead-acid battery

It seems obvious that hydrogen is the appropriate way to overcome the energy storage problem. There are two reason:

  1. hydrogen is available everywhere (can be made from water by using electrolysis)
  2. conversion from hydrogen back to energy just produces water and heat as the only byproducts

There is some momentum building up on the battery market and already Apple announced plans for a hydrogen Fuel Cell Battery. Also electronic giant Samsung is is putting in efforts to bring this technology to the market. I have high hopes that the auto industry will be one of the driving forces to mature this technology. We need hydrogen batteries to build the energy grid of the future.

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