The climate crisis is here, and to prevent the average temperature from rising further, we need to stop increasing the amount of carbon dioxide and other greenhouse gases in the atmosphere. Doing so requires us to transition our energy system. In discussions about this transition in public forums like Twitter, I feel that many people don’t have a deep understanding of the topic. They might say things like “it’s impossible to produce enough electricity” for electric cars while suggesting synthetic fuels as an alternative or insist that we can’t store electricity from renewables and need a complete fossil fuel backup. I don’t claim to be an expert on the topic, but I’ve read quite a bit and will try to reproduce my understanding in a short blog article that aims to clarify some misconceptions. I may also make some mistakes along the way, so if you see any, let me know.
In a nutshell, modern civilization requires energy. We can save some of it through increased efficiency or sufficiency, but we can’t do without it. Our society uses energy in roughly two forms: fuels and electricity. For this purpose, “fuel” shall mean liquids, gases, and solids (e.g., wood and coal) that we burn. Let’s look at the origins of these two forms separately.
The vast amount of fuels is fossils, meaning we burn substances stored in the ground for a very long time. The problem: our current climate relies on their carbon remaining buried instead of released into the atmosphere. There is a consensus that we eventually need to stop burning them. The two alternatives are biofuels and synthetic fuels. Biofuels come from plants that bind CO2 from the atmosphere during growth, making them climate-neutral. We can create some of those from organic waste products, but to produce them at a large scale, we need to grow monocultures of fuel crops which take up a lot of space. Hence, experts generally consider it impossible to replace all fossil fuels with biofuels. For synthetic fuels, we use electrolysis, which requires electrical energy as its input. We’ll get back to those in a bit.
Electricity can come from three sources: we can burn fuels, we can harvest energy from nature (e.g., in the form of sunlight, wind, or streaming water), or we can split atoms. Burning fossil and organic fuels comes with the abovementioned problems, so they are no longer an option. Renewables like solar and wind aren’t reliable because their output depends on the weather. Nuclear power is climate-neutral, but it’s considered risky because of radioactive radiation in its waste products or released by accident. Outside of climate denier circles, there seem to be two groups: those who want to implement a fully renewable system and those who prefer to add nuclear power to the mix. I don’t want to argue in favor or against nuclear in this article, but I want to focus on overcoming the challenges of renewables.
Our electricity demands aren’t constant but follow a curve throughout the day and the year. Electricity production for the public grid must ensure that the production curve matches the consumption curve. If production is higher than consumption, we need to either decrease it or store the excess energy. If production is lower than consumption, we need to either increase it, release energy from storage or reduce consumption (I’ll get to that point later).
We cannot control the production curve for renewables (though we can make some predictions), and we cannot easily handle it for coal and nuclear, which only work efficiently with a steady output. However, natural gas plants can usually ramp up and down production quickly. The combination of renewables and gas works like this: renewables have immediate access to the grid. If their output isn’t enough, we switch on gas-burning plants (called “peakers”) to produce the remaining electricity demand. Our electrical system already does this. And ideally, the more renewables we add to the grid, the less fossil gas we need to burn because there will be smaller peaks to fill. Our current electrical grids already do this, which is why gas considers itself a “transition technology,” and the EU taxonomy for sustainability includes it.
Now, wait, you may now say that the argument that renewables need a fossil backup is indeed correct. However, you don’t need a full backup, and that’s for two reasons. First, renewable availability fluctuates, but not too much, especially if you combine a lot of solar and wind on a large, geographically distributed grid and include running-water and geothermal plants. The latter two provide constant output, and there’s always wind somewhere, especially offshore. So you don’t need to plan for zero. Second, this works with the assumption that we have no storage, which isn’t true. Even today, we have an extensive pump storage system. Admittedly, there is limited space to expand it, but other storage technologies exist, including, but not limited to, electrolysis and fuel production.
You may think we need to build more storage right now, but I’d argue it’s not yet the right time. We must first focus on building additional renewables and expanding the grid to bring them across vast distances from sunny and windy regions to consumers. Storing electricity is expensive and generally incurs losses, meaning you don’t get back the same amount of energy. It is always better to use it immediately, in other words, to control consumption. I understand this can invoke dystopian thoughts of power rationing and blackouts for crucial systems like medical infrastructure. Do we need to drop the idea that we can plug appliances into a power socket whenever we want?!
Control of consumption can comprise pricing strategies that make electricity cheaper when more renewables are available and expensive when there are fewer, ideally shifting loads. It’s called yield management, and it’s pretty standard in a market economy. For industrial use, it can make economic sense to implement the ability to stop production lines in exchange for cheaper electricity prices occasionally. Cars spend a lot of their time parked. They can charge whenever it is most affordable if you keep them plugged in. There are other examples, and a smart grid can manage them without inconveniencing consumers. Cars and commercial applications could probably cover it, so private households have no change (unless they want to leverage it as a discount). However, let’s get back to storage once more.
Due to the losses I’ve mentioned, storage doesn’t make much sense as long as there are fossil peaker plants on the grid. Please read that again because it’s essential. Burning fuel to produce electricity for storage requires more than if you just kept it and burned it later when needed. It’s neither economically nor ecologically sound. It also means that if you build an electrolyzer to produce green hydrogen and synthetic fuel, you should only turn it on when there’s an excess of renewable (or nuclear) energy and switch off all fossil fuel plants first. With the currently deployed renewables, this situation does occur, but it happens so rarely that it wouldn’t be viable to build electrolyzers and other storage systems for those occasions. At worst, we disconnect the electricity surplus and let it go to waste. We likely move through a phase where we have enough excess that it seems we’re wasting it but not yet enough to make it economically viable to deploy more storage. It’s the nature of transition, though, and not a flaw in the system. At some point, storage becomes more viable than fuel-burning plants, and we can dismantle the latter.
After talking so much about electricity, what about the situations where we use fuels directly? One option is synthetic fuels, but they are a form of electricity storage that incurs losses, so it seems evident that using electricity directly is the better option whenever possible. That’s why we should replace gas heaters with electric heat pumps and petrol and diesel cars with electric cars. Often this seems counterintuitive because if, on the one hand, we want to increase efficiency and save electricity whenever possible, why should we add more consumers to the electric grid?
The answer is straightforward, though. Yes, we add electric consumers, but at the same time, we reduce fuel-based energy consumption. Once we’ve accepted that fossil fuels are no longer an option and we don’t have enough biofuels to replace them, we can only choose between using electricity directly or producing fuels from electricity. In this battle, electricity wins practically all the time. Even when disconnected from the grid, such as in vehicles, batteries seem to be more efficient storage than fuels. There are exceptions where the higher energy density and lower fuel weight probably win over batteries, such as in jet fuel for airplanes. For cars and likely for trucks, the decision for batteries is clear.
In summary, to decarbonize our energy system, we need to electrify whatever we can and build a well-connected smart grid. We first must deploy as many renewables as possible on the grid to get regular excess energy. At that point, we need additional storage methods to capture the surplus and feed it back during low production. They gradually replace fossil gas peakers (if the form of storage is hydrogen or another gas, we can repurpose the same plants). The better we keep consumption aligned with production (e.g., through dynamic pricing), the less storage we need. If we decide to keep nuclear power alongside renewables, it can also provide some baseload. It doesn’t mean it solves the challenges in building the renewable-centered system because nuclear is not a peaker technology.
This post outlines my understanding of the coming energy transition. As I said in the beginning, I’m not an expert, just a curious mind. I hope it was helpful. If you find any flaws in my reasoning, please point them out.