The 100% RE grid dream

Yesterday while riding the high-speed train to Roma with a colleague, I posted on LinkedIn this article reporting how Denmark had overshot its electrical energy consumption on wind alone – for two days in a row.

On the train back in the evening I was amazed to see how many impressions that post had achieved, and the amount of comments (positive but also negative) it had prompted.

Given the horrendous thread management offered by LinkedIn, I quickly realised it wasn’t possible for me to respond to criticism, something I am keen to do in the interest of mutual learning. So, even at risk of downgrading the performance of the post (now fast approaching the 100k impressions mark), I thought of summing up my counter-arguments here, grouping critique in representative “buckets” and liberally stealing comments and sources provided by other readers.

Bucket 1 – yeah, but it’s only two days

This is true, but Denmark averages 80% RE over the 12 months (thanks, Kristoffer Vinterlaerke): although 80% is not 100%, it shows that deriving 100% of energy from renewable sources is possible through a mix of overbuilding, grid storage and thick energy exchange with nearby territories. This point is important because we have consistently been told that intermittent sources like wind or sun CANNOT support the “baseload” i.e. the amount of energy that a country or territory requires on a continuous basis.

In a recent study, prof. Mark Jacobson of Stanford argued not only that this is an unfounded statement, but moreover that the amount of grid storage might be far less than what we think.

Examples like this rephrase the bumblebee paradox in energy terms: Science claims baseload cannot be supported by 100% RE, but nobody told Denmark and they do.

Bucket 2 – does not apply to my country

True, Denmark has a very long coastline and has been an early adopter for RE, and it’s a small country with <6M population…. there are, however, other countries with much richer endowments e.g. in solar or pumped hydro potential.

This charts (sourced from Eurostat) represents the combined generation from the EU 27 members of renewable energy, should we ramp up PV installations by a measly 50%: since the peaks and valleys of wind and solar are essentially in opposition, you can see the aggregate energy generated is not at all as variable as we’ve been lead to think.

A strong, coherent, common energy policy that generates wind power where there is more wind and solar power where the sun shines stronger would add up to a much more energy-independent Europe, something which, as we are painfully learning, should also be a national/union security issue.

Bucket 3 – Energy vs. Power

A number of critics schooled me on the difference between Energy and Power; of course they don’t know I graduated in Nuclear Engineering and my company builds charging parks for fleets of last-mile delivery vans, so I sort of know what I’m talking about.

But it’s a good point to make for those with a different background and experience.

“Energy” and “Power” (= energy / time) are not the same thing, even though in the English language they’re sometimes used interchangeably; in fact, they’re measured with different units: Joules (symbol: J) for energy (or equivalently, kiloWatt-hours, symbol: kWh) and Watts (symbol: W) for power.

I will illustrate the practical difference using the example of my house and its PV system:

The red curve represents the energy we use, the blue one the energy we generate: during the winter months we use more than we generate (pink areas) while in the rest of the year we make more than we use (light blue area). It so happens that the blue and pink areas are roughly the same surface, i.e. my solar panels generate 100% of the electrical energy we consume, yet during the winter days, they are not sufficient to meet our “power” requirement, i.e. they do not generate enough energy per hour.

To shift energy from the “excess” periods to the “needy” ones you need storage; in my case, storage is provided by the grid itself which buys my excess production and resells it to me when I need it. Otherwise it can be stored in batteries or in pumped hydro reservoirs etc.

To sum up, meeting the “energy” requirement is only half the job, and – frankly – the easier bit: meeting the “power” requirement means a slightly more complex (but still fully feasible) system.

Bucket 4 – so what ? What’s the point?

Well, if you haven’t gotten it by now, it does not reflect well on my prose which is obviously not as clear as I thought (else you’re a troll, but trolls don’t read, so we’ll discard that option).

The point is that a 100% RE grid is absolutely NOT technically impossible, and some lucky and forward-thinking communities are already approaching this goal.

It will cost money, yes, but far less money than will cost the damage we’re inflicting on our planet.

Is this the first time?

No, it’s not, it happened before in multiple instances and locations (thanks Michael Birinbom):

No, it’s not impossible, and every time someone says so, remind them of the bumblebee:


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