As we work to rapidly cut our carbon emissions in the coming years, buildings represent one of the next big challenges of tackling climate change, especially the energy we use to heat them (as covered in a previous article). Taking on this challenge will require a combination of innovative technology, policy, and programming. Looking at Germany’s well-known Energiewende can provide a good framework for US cities, states, and regions in thinking about decarbonizing buildings.
Much has been written about Energiewende, Germany’s national set of strategies for the energy transition. A key part of the country’s climate commitments, Energiewende receives a lot of attention, both positive and critical, and it continues to be adapted and iterated in response to changing needs. Energiewende consists of many different policies, strategies, and industry initiatives under a broad umbrella. Included under this umbrella is the much-debated set of approaches to cutting the carbon out of heat — the Wärmewende, or heat transition. Together, they provide a look at building a pathway to a low-carbon energy future.
A national strategy for energy transformation
2010 marked the first legislative commitment to Energiewende (though the term had been used for many years before), thereby creating a national strategy for changing how energy is generated and used. This in turn spurred the enactment of laws and funding to support renewable energy generation, increase building performance, and boost energy efficiency. All of these measures are closely connected with the development of the national climate plans, Climate Protection Plan 2030 and 2050.
The result has been a coordinated strategy defined by a national conversation on energy efficiency and renewable energy, providing guidance on objectives and next steps to states, industry, and research institutions.
But how is it all organized? The foundational approach of Energiewende can be defined in three key pillars (BMWi Energiewende Direct).
First and foremost, Efficiency First
Efficiency First is the first pillar of Energiewende: cut wasteful energy use before needing to supply it all with renewables. Concretely, this means a target of cutting 30% of primary energy use by 2030 (from a 2008 baseline) and 50% by 2050.
This is a broad, economy-wide objective: the recently enacted National Energy Efficiency Plan (NAPE 2.0) encompasses all sectors, including not just buildings and appliances, but also industry, transportation, and energy systems. If the plan is fully implemented, Germany would save twice as much energy as is currently generated by all wind and solar in the country.
To implement this ambitious program, the federal government adopted Energy Efficiency Strategy 2050, with NAPE 2.0 comprising the nearer-term programs. In addition to establishing the targets above, these strategies lay out an approach of first thoroughly identifying energy efficiency opportunities, then investing public and private funds in efficiency, and then potential requirements. For buildings, this includes energy advising programs, carbon-focused building renovation programs, green lending for building upgrades, and potential mandates for energy audits or a carbon fee. The adoption of the strategy also launched a two-year dialogue on designing energy efficiency programs from 2030 to 2050, working with stakeholders on what they see as key technical and political challenges.
What’s notable about this approach is the framing principle: that energy efficiency after 2030 will be needed, not so much to displace fossil fuel use, but rather to make the best use of the limited resource of renewable energy. Indeed, given the challenges of siting new wind farms and building transmission lines in a way that communities accept, energy efficiency is seen as a way to reduce the demand on new, occasionally controversial renewable energy facilities (BMWi Energieeffizienzstrategie 2050).
To date, primary energy use is down 5.5% as of 2017, so there’s still a steep path to 30% by 2030. Nonetheless, building efficiency has been successful, in comparison to increased overall energy use in heavy industry and transportation (BMWi Energieeffizienz in Zahlen 2019).
The forward charge of renewable energy
The second pillar of Energiewende is the direct use of renewable energy: using renewable energy to cover the energy use after it’s been made efficient, and using it in a way that ties to end-use as closely as possible.
Renewable energy has been one of the biggest and best-known success stories of Energiewende. To provide a broad perspective, last year, 42.1% of Germany’s electricity use was provided by renewable energy. The largest share of this is onshore wind, at over 14% of total power production; solar and biomass are at about 7% each. A total of 112 gigawatts of renewable capacity feed into the grid, which itself sees extremely high levels of reliability (BMWi Strommarkt der Zukunft).
Just as notable is the enactment of an ecosystem of laws to enable renewable energy: an act to ensure market-based pricing of renewable power delivery and transmission capacity, another to drive the digitalization of the grid, and other similar, foundational laws. To boost renewable energy use on-site, a 2017 law also specifically incentivizes the generation of solar energy on buildings with tenants.
Still, renewable energy expansion is hotly debated today, especially with the siting of wind turbines and limits on solar incentives. Most challengingly, the amount of heating and cooling, as opposed to electricity alone, that’s powered by renewables lags behind at 13.9% (BMWi Erneuerbare Energien).
Sektorkopplung: connecting it all together
The third pillar, and perhaps the most important for building decarbonization, is the focus on Sektorkopplung, or the strategic coupling of energy across sectors. The idea is that, after boosting energy efficiency and utilizing direct renewable energy use, the targeted coupling of sectors can provide renewable energy where it’s needed and when it’s needed. In other words, it is the optimized allocation of scarce renewable energy (Energieeffizienzstrategie 2050).
What does this look like? A broad spectrum of ideas fit into the Sektorkopplung approach. A simple example is the use of waste heat, such as that emitted from a commercial production process, and using it to heat homes nearby.
Perhaps more sophisticated is the use of renewable electricity for heating in a way that optimizes its use: for example, using wind energy to provide heat to urban neighborhoods. At night, when demand is low and wind power is cheaply available, the electricity can be used to heat water in an insulated tank, and the hot water is then distributed through the district heating system during the day. This is the exact goal of the Karoline Hamburg project, where a storage tank for the district heat network will hold an impressive 45 megawatts of heat energy. The tank will be charged up with heat by utilizing excess wind electricity from Northern Germany.
This approach has been called Power-to-Heat: coupling the sectors of clean power and heat. There is another power-to-heat approach in the Sektorkopplung space, and that’s using hydrogen as an energy carrier. By using clean power to electrolyze water into hydrogen, it can serve as a clean source of fuel for heating, industry, and power. While this might seem futuristic, there are several clean hydrogen projects underway today. (And, at the time of writing, hydrogen [#wasserstoff] is one of the top Twitter hashtags in Germany.) I hope to explore more about the fascinating space of Sektorkopplung in upcoming posts.
A framework for experimentation and transformation
Looking at Energiewende offers insight into how the energy transformation can happen in concrete steps. While energy policy and climate strategies are continuously debated, the framework offers a way to structure the conversation and the iteration of ideas. Indeed, Energiewende could perhaps be thought of as a framework for experimentation in the energy transition. After all, the openness to new ideas and reworking of existing systems is going to be an essential part of the road to a low-carbon future.
Nikhil Nadkarni is an urban planner specializing in climate, energy, and building decarbonization strategy. He is currently living in Berlin.