“Now, we can”, 100% renewable energy !

A few decades ago, making a statement as the title above, in my engineering environment, would not have been good to build your credibility. Now, things have changed. Wind and solar energy have reached a stage where their installation is economically viable.

Could we go all the way, thinking about a society where only renewable energy would be acceptable?

When I was a kid, I wanted to invent a car driving on water. I truly believed that this would be a reality by the year 2000. Now, in 2018, we start to take electric cars seriously. Cars powered by renewable energy are driving on sun, wind or water, not?

Tesla has contributed a lot to the positive imagine of electric cars. Elon Musk now wants to extrapolate lithium-ion batteries from cars to batteries providing grid storage & services on a big scale. The first 100 MW battery farm was installed in record time in Australia. This solves a problem that unpredictable renewable energy, like wind a solar, poses to the grid. If you cannot balance energy consumption and production, you can’t have a stable grid. You need to be able to absorb excess wind and solar energy when not all is consumed. Equally, when there is peak demand, you need to be able to bring rapidly that extra bit.

As a grown-up now, I dream of batteries on water… but, wait a minute, hasn’t this been invented yet?

Since more than 50 years, the only substantial grid storage capacity has been provided by pumped-storage power plants. These don’t actually generate energy but pump water from a lower to an upper reservoir and turbine it back at a cycle efficiency of 75-80%. Historically, by pumping during night time and turbining during day time, they have been paired with nuclear power plants to make their combination follow daily electricity consumption cycles. These pumped-storage plants have evolved technically, providing lower mode change times (shifts between standstill-turbine-pump) and higher flexibility, making them perfect to pair with wind and solar.

If we expand wind and solar to cover the entire electricity consumption, we also need huge storage capacities (or back-up thermal power plants; but that’s not what we want). For a country like France, creating new hydro power plants may be overly ambitious. But transforming existing reservoirs and hydro power plants into pumped-storage plants should be possible. Several rivers have cascades of power plants with the water, naturally, only flowing towards the sea. Such reservoirs have huge capacities and could be used by pumping water in the opposite direction. Sun shines more in summer than winter. Electric heating drastically increases consumption in winter. Yearly storage cycles from photo-voltaic (PV) can only be handled by pumped-storage plants. PV will evolve ever more with transparent panels that will replace our current windows, road integrated solutions, massive rooftop covering etc.

Now we can ! Let’s do the necessary transformation to our hydro power plants to have cheap and massive storage capacity and avoid any excuses to integrate all the solar and wind energy we aspire. And, in parallel, let’s start driving electric cars. @Elon Musk, please put all that lithium-ion in car batteries and let’s store with water.