(CNN)Today, German President Frank-Walter Steinmeier will receive "the last piece of black coal" dug from a German mine, as a symbolic gesture marking the end of the country's bituminous coal production.
Germany hands over last black coal, but struggles to curb its emissions
Hard black coal provides more heat than soft brown lignite, which also means it generates less CO2 for the heat produced. But Germany has vast reserves of lignite, which can be sourced from open-cast mines, making it cheaper.
The government announced in 2007 that it would close all the country's black coal mines, which couldn't compete with cheaper imports. But despite its image as a champion of green energy, Germany still depends on coal.
Coal accounts for more than a third of its energy mix and Germany is by far the biggest producer of lignite (brown coal) in the EU. Despite a target to cut greenhouse gas emissions by 40% of 1990 levels by 2020, the country is still Europe's biggest emitter of greenhouse gases.
In an effort to get its "Energiewende," or energy transition to renewables, back on track, earlier this year Germany announced it will completely phase out coal power plants by 2038 at the latest, while continuing its program of shutting all its nuclear power plants by 2022, in response to the Fukushima disaster.
But on Monday, Germany's energy industry association BDEW warned that the closure of coal and nuclear plants means the country faces a shortfall in power supply by 2023.
Currently, Germany produces excess electricity -- enough to export to neighboring countries. But one difficulty is that the supply of renewable energy is variable.
"The biggest issue in terms of security of supply is when the wind doesn't blow and the sun doesn't shine," said Hanns Koenig, of energy market analysis firm Aurora Energy Research.
He says by the mid 2020s Germany may need to import electricity to meet peak demand, beyond what can be supplied by renewables.
"But to some extent that's fine," he added. "We're building a European power market coupled between countries, so just because we're dependent on capacity from abroad to meet our own peak demand, it's not a failure of the system but in a sense its part of the design."
Claudia Kemfert, head of energy and transport at The German Institute for Economic Research, is confident there will be no energy shortfall in the short term.
But she says one factor limiting the growth of clean energy is Germany's renewables auction system.
In the past, Germany operated a feed-in tariff system, guaranteeing renewable energy providers an above market price for their power, in order to support renewables at a time when they were expensive to set up.
The system helped reduce the costs of installing renewable capacity, but consumers have footed the bill, leading to some of the highest household energy prices in Europe.
In response, in 2017 Germany introduced an auction system, where the government decides how much new renewable capacity is to be built and companies bid to provide it, with the cheapest bid winning.
However, Kemfert believes that the government should set higher capacity levels to increase the amount of renewable energy produced.
"Now that costs for renewables are so low, it doesn't make sense to limit them to a low level," she said. "We have to double the capacity that we auction in order to get the increase in renewables that we need."
Koenig adds that despite widespread public support for the energy transition, there is often local opposition to new onshore wind farms, which slows down development and adds to its cost. As a result, auctions for onshore wind projects have been undersubscribed.
Germany is set to miss its 2020 climate targets. In 2017, renewables made up around 13% of all energy consumption, well short of the 20% target set for 2020, while greenhouse gas emissions have fallen by 28% since 1990, compared to the 40% target -- although emissions fell 4.2% last year, the result of high coal prices and hot weather reducing heating demand.
Experts say that's not only because of the continued use of coal, but also down to the transport sector, which has around the same emissions levels as in 1990.
"In the electricity sector, we have 20 years of policies going in the right direction -- in the transportation sector we didn't even start," said Kemfert. "We need to change to more sustainable transportation, including electromobility, renewable fuels, and so on."
By way of comparison, renewables account for more than half of Sweden's energy, around 17% in Spain, and 10% in the UK.
Germany has a host of more ambitious climate targets for the coming years, reducing emissions by 55% by 2030, and 80 to 95% by 2050. But Kemfert believes Germany is no longer the champion of green energy.
"We had a good start 20 years ago. Increasing the share of renewables from almost zero to approximately 40% is quite good," she said. "We have invested heavily in these technologies and now they're becoming more and more competitive -- I think that's also a German success.
"But others are doing more and investing more in renewables than we do. We are not leading anymore."