I moved to Germany this year from Canada, and I've been incredibly impressed with the speed and aggressiveness with which Germany has been pursuing renewable energy sources[1]. This is great news because it's happening despite the fact that Germany is really not an ideally situated country for any of the major renewable energy sources, so these advances are applicable to other countries in ways that e.g. the experiences in Denmark or South Australia might not.

The buildout of renewable energy sources in Germany has been so widespread and so successful that they're no longer the interesting part of the problem. Now that the electrical grid here is averaging 60-70% renewable electricity in any month of the year, the limiting factors now are energy storage, and long-distance flexible transmission of electricity.

Transmission lines are a not-so-sexy, but totally vital part of running a grid with so much intermittent electricity production that's only accurately forcastable a few days in advance. There's been a lot of HVDC lines build connecting Germany to the UK and various scandinavian countries, but one of the biggest things we're still waiting on is a new link from the north of the country to the south. The south has more solar resources, and the north has more wind resources, so there needs to be way more capacity to share.

Storage is going to be a very hard problem to tackle and has a less clear path forward. Batteries are going to play an important role, but in the near term they're likely only to be valuable for smoothing out supply and demand over a two to three day window.

Something that doesn't get discussed very much though is how much bio-gas Germany generates. German farmer collective, landfill operators, and wastewater operators actually make quite a bit of money by using specialized bacteria to compost organic material and generate methane.

Bio-gas is responsible for around 8-9% of German electricity generation. It's currently used in a very consistent way, with the same amount being burned nearly every hour of every day, but eventually when wind, solar, battery, and HVDC electricity sources are able to take over most day-to-day electricity needs, this bio-gas could instead be stored and used as a backup power source, as well as being sold to industry for hard-to-electrify industrial processes.

Afterall, if all that gas were stored instead of used up immediately, it'd only take 11-12 days of storage to store enough gas to power the whole grid for a day. This is really important, because the amount of solar and wind energy being produced can vary huge amounts from week-to-week.

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[1] Yes, I know, Germany made a gigantic mistake decomissioning their nuclear reactors early. I strongly disagree with that choice, and I think there's a deeply rooted misunderstanding and fear of nuclear power in this country which is a big shame. Despite this, good progress is being made however.