A simple chart that tells you the future of wind and solar.

It is not rocket science, even the dumbest politician should be able to understand this.

Leaving aside the talk of transmission costs, grid balancing, reliability and synchronous inertia, I present here one simple chart that tells you everything you need to know about the future of wind and solar as a means of de-carbonizing the electricity supply. It is a chart that even the dumbest of politicians should be able to understand.

It shows the proportion of wind and solar generation that can be directly used by electricity consumers at various levels of wind and solar penetration.

This version of the chart has been developed by a group of scientists from The Royal Society. It is based on an analysis of 37 years of wind and solar data from the UK. The chart for another country will of course, be different, but the general shape of the chart will be the same for most countries in temperate climates that have similar weather patterns.

The Y-axis of the chart shows the amount of energy generated by wind and solar as a proportion of demand, and the X-axis is the portion that can be directly used. The remainder must be curtailed or stored.

I have added three circles to the chart. The green circle is the point at which wind and solar are generating the equivalent of 50% of the annual energy demand. Everything looks great, it’s green for GO, every kilowatt-hour of energy is going straight to the consumer.

The fossil fuel plants that backup the wind and solar are seeing a diminished load, but they are still needed. The cost of providing electricity from those plants has gone up because their fixed costs must be distributed over a lower volume.

Extra transmission lines are needed because the new power is coming from a mix of locations that are not close to the end users.

Those extra costs, which are a direct result of the addition of wind and solar to the grid, are never allocated to the cost of wind and solar. By not allocating those costs the government has been able to persuade the electricity ratepayer that wind and solar are cheap, even though the ratepayer has seen a sharp increase in his power bill.

But look ahead to the next circle, it’s amber, it’s telling you to slow down and be ready to stop. At that point, wind and solar are generating the equivalent of 100% of the demand, but only 78% is directly usable. Wait a minute here! The second 50% of wind and solar generation has cost more than the first 50% because all the best locations were taken, but it is only providing just over half as much usable electricity!!

The plan of course is to put the oversupply into storage and use it during periods when the wind isn’t blowing, and the sun isn’t shining. However, there is no known storage technology that can do that at reasonable cost.

Batteries are hideously expensive and can never provide the storage volumes needed to overcome seasonal variations in either wind or solar.

Converting the electricity to hydrogen is being proposed as a solution, but it is not only costly, it is grossly inefficient, requiring 3 kWh of input power for every 1 kWh of output. Proponents of hydrogen argue that it can use electricity that would otherwise be curtailed and could be provided at no cost to the hydrogen plant. That, of course, leaves the electricity ratepayer to pick up the bill since wind and solar suppliers won’t build anything unless they are paid for their entire production.

Energy supplied via that hydrogen conversion, storage and regeneration will be at least five times as expensive as energy used directly.

Any attempt to move forward with even more wind and solar makes the situation worse. Another batch of wind and solar built to generate an equivalent of another 50% of demand gets you to the red circle, at which point you should very definitely have stopped building. That last 50%, which costs at least as much as the first 50% only gets you an extra 9% of directly usable electricity.

At this point, you have a very unreliable and very expensive electricity system in which gas plants sit mostly idle, waiting for a lull in the wind or a cloudy day but the whole gas supply train must be maintained and ready for action, at

But that’s where the traffic light analogy ends. You can’t sit and wait for the light to change before proceeding. It doesn’t change, there is no magic cheap electricity storage system that will allow you to proceed to that elusive net zero, and there never will be. You can’t mandate changes to the laws of physics.

It’s at this point that even the most adamant supporter of renewable energy must realize that they should have been building nuclear power 30 years ago. But wind, solar and nuclear are not compatible. A nuclear plant provides the best return if it is operated continuously at full power, it should not be expected to follow the intermittent whims of the wind and sun. In a system with nuclear power the wind and solar serve no useful purpose, the expenditure on wind and solar will have been wasted, so the best approach would be stop building now.