ALL Are Here to Stay

Today, in the energy discourse there are constant skirmishes between the proponents of different types of energy.

Depending on the respective camp, people want to eliminate (pick one) fossil fuels, nuclear, wind, solar, what have you.

Well, we have news for all the groups: NONE of the current energy sources is going away, at least not this century. Whether we like it or not, on a global scale, we'll have to learn to live with them.

Now, after saying the above, it doesn't mean we should write a blank check to any particular technology without FIRST doing our homework.

As an example, let's analyse solar photo-voltaic (PV).

What is the highest PV penetration that makes economic / environmental sense in a national grid?*

Since PV is intermittent, it probably makes no sense to go much above low single digits. Why? Let's do our homework with an example:

Say a country uses, on average, 40 GW of electricity. At peak hour, they consume 40% more than the average, in other words, 56 GW.

Thus, the maximum output of the solar panels at any particular moment should not exceed 56 GW (unless we want to embark in expensive / environmentally challenging massive storage which today is not ready for prime time).

Consequently, the PV installed capacity in this country should be capped at 56 GW.

If the solar annual capacity factor in this country is 15%, then the average annual production of the PV installation will be: 56 GW x 0.15 = 8.4 GW.

The country itself consumes 40 GW average, so the PV component would be: 8.4 / 40 = 21%.**

The above means that at peak solar production ALL other generating capacity would need to be idled / shut down. At night (and to a lesser extent during cloudy days), the other types of generators would have to supply the electricity requirements.***

Non intermittent power sources such as fossil fuels and nuclear are not constrained by the above mentioned "cap."

Hydro is somewhere in the middle since its intermittency is not daily but seasonal or from year to year.

Conclussion: intermittent energy has a "natural" cap that would make no economic / environmental sense to exceed.

Feel free to add to the conversation on Twitter: @luisbaram


Notes:
* Sure, one country could "dump" excess power into another, but if that second country uses the same type of technology to produce its electricity, they would have surpluses at the same time.

** This is really an optimistic number since, for example, in Europe more electricity is required in winter when solar produces the least energy. I propose the "rule of thumb" for solar should be to cap it at the annual capacity factor. e.g. if the annual capacity factor is 15%, then at the most 15% of the annual electricity should be solar. However, even this number might be too high.

*** The costs per GWh of the modulated / idled / shut down power plants are higher than if they could produce continually at their capacity. These costs ultimately affect the overall prices of the electricity in the grid.