Intermittent energy storage is not so simple as it seems. Today, electricity produced by the wind or the sun is mostly stored in batteries. The problem is a storage cost higher than the energy production cost because of the low lifetime of the batteries: around 2.000 cycles.
The idea of ENERGIESTRO consists in associating photovoltaic electricity production with a reversible electric motor/generator and an inertia wheel... in concrete (1.7 ton)
The name of the system is VOOS for Volant de stockage solaire (Solar energy storage). Its cost is the same as the cheapest batteries' but with a longer lifetime:
- Cost of lead-acid-battery energy: 200 €/kWh for 2000 cycles => 0.10 €/kWh
- Cost of VOOS: 200 €/kWh for 10,000 cycles => 0.02 €/kWh (1 sun cycle per day during 30 years). Energy losses: 20 %.
An energy cost lower than the fossil fuels' make this system able to be widely implemented in desert areas in association with large photovoltaic plants .
VOOS won the international innovation contest in 2014.
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