Technology Monitor 2021 Hydrogen green energy and Smart roofs

Roland Ortt and Florian Schmidt, Delft University of Technology

Datum 21 december 2021
Toekomstonderzoeker STT


Dr. Patrick van der Duin, managing director STT

This is already the third Technology Monitor to be released by STT. Once again, TU Delft, under the project leadership of Dr. Roland Ortt, has made an in-depth analysis of two technologies on which many have pinned their hopes, but for which it is as yet uncertain whether they will be labeled as a technological breakthrough at some point in the future. For the 2021 version, the choice was made for 'green hydrogen' and 'smart roofs'. Two technologies (or technological systems) that are different but, as the report will show, also have similarities and even can be complementary.

The systemic nature of both technologies is an important similarity. An agreement they share with almost all contemporary technologies. Virtually no technology can be developed in isolation these days. System technologies and system innovations are no longer the exception, but are now the rule. This does not make it any easier to make strategic policy for both government and companies with regard to the further development of the relevant technologies. Whether this is good or bad news I leave to the reader. But it does shed some light on how fast technological developments and the diffusion of the resulting products and services are going. I mean, the systemic nature of technology and innovation means developers can no longer do it on their own. Technology development and innovation are 'distributed processes' (as it is so beautifully called) that are becoming increasingly complex. Collaboration is good and necessary, but does not automatically lead to acceleration. Who does not know the African saying:

'If you want to go fast, go alone; but if you want to go far, go together'.

The speed of technological developments should therefore not be exaggerated. For example, the Technology Monitor states that in 1895 (!) the first experiments with hydrogen were carried out in Denmark. And as for smart (green) roofs, I refer the reader to the famous Hanging Gardens of Babylon. What does go faster is the diffusion of new products and services (based on technology). Here we do see exponential curves describing the diffusion (market acceptance) of innovations. An interesting question that arises is what relationship there is between technological development and innovation diffusion curves. A possible hypothesis is that technological collaboration is not only stimulated by increasingly necessary collaboration, but that the steeper diffusion curves lead to shorter payback times, i.e. more business risks and that these can be limited if the development trajectories are shared (i.e. more collaboration). Perhaps this question can be addressed in follow-up research by STT. ‘All things may change’ (‘Het kan verkeren’), the poet Bredero once said. For example, hydrogen was not so 'hot' a few years ago, but in 2021 it is considered promising. It is therefore important to keep a cool head, not to overestimate the pace of technological development and, above all, to continue to analyse well. This Technology Monitor is exactly intended for that: an analysis of the current status of the development of hydrogen and 'smart roofs' and based on this determine what needs to be done to give these technologies a serious chance. In my humble opinion, this report provides the right background and the right tools for this.

dr. Patrick van der Duin, managing director STT


The Netherlands Study Centre for Technology Trends (STT) conducts broad futures studies on the crossroads of technology and society. Those crossroads can be approached from a societal perspective. Society is a large unit to study, which is why it is divided into various domains. In most cases, the foresight studies are conducted from the point of view of such societal domains, like education, healthcare, industry and security. STT’s reports often include an exploration in one of those domains, as a building block of a multidisciplinary picture of society as a whole. In each domain, technological developments play a role. The interplay of the broader social influences and developments in specific domains is an important basis for an exploration at the crossroads of technology and society in the existing work at STT.

The crossroads of technology and society however, can also be approached from the perspective of new technological developments. As such, new technological developments together present a large unit of research, which is why they are divided into separate technologies, like gene therapy, robotics, blockchain and self-driving cars. Each of these technologies typically develops and diffuses over a longer time period, in which the technologies are often applied in various domains. The interplay of the broader social influences and the developments in specific domains, and their joint effect on the development and diffusion of a technology are an important basis for an exploration at the crossroads of technology and society that complements the existing work at STT.

In domains like education or healthcare, different technologies are applied that set changes in motion. In turn, new technologies like the Internet, developed and diffused by being applied in various consecutive domains. In some cases, technologies even create new social domains or combinations of domains. In short, if we want to examine the crossroads of technology and society, we need complementary perspectives, including social domains as well as new technological developments.

In this Technology Monitor two societally significant new technological developments, ‘Green hydrogen’ and ‘Smart roofs’, are examined. Earlier versions of the ‘Technology Monitor’ were released in 2018 and 2020 (See Ortt and Dees, 2018; Ortt, 2020).

This report focuses on two research questions:

  1. What is the current status regarding the development and diffusion of two potential breakthrough technologies, notably ‘Green hydrogen’ and ‘Smart roofs’?
  2. What conditions have to be met for these technologies to become actual breakthroughs?

Reading guide

Chapter 1 will start with defining green hydrogen. Green hydrogen is a type of hydrogen that is created in a sustainable way. Hydrogen is a feedstock for the chemical industry, a fuel and a carrier of energy. We focus on the latter application and discuss in what stage of the pattern green hydrogen currently is and what actors and factors do either block or stimulate large-scale use of green hydrogen. Chapter 2 will show a similar line of reasoning in describing smart sustainable roofs. Smart (sustainable) roofs are systems that combine and connect different technologies in a smart way. Chapter 3 will summarize the answer to the research questions and will discuss differences and commonalities between the two technologies.


Hydrogen is green when it is produced using sustainable electricity sources such as wind turbines or PV-panels. We focus on hydrogen as a mobility solution or as an energy storage and discard hydrogen as feedstock for processes in the chemical industry.

Roofs are smart and sustainable when they interconnect sustainable energy sources fitted on the roof (such as wind turbines, solar PV panels or solar thermal panels) with the appliances using electricity. Smart roofs usually also contain a subsystem for storing energy and a connection with the public grid. Such smart roofs are also referred to as rooftop microgrids. Micro-grids that are disconnected from the public electricity grid need to be able to store electricity because energy supply and use are usually not synchronized in the case of local rooftop sustainable energy sources. If the usage of energy in the household can be managed (shifted over time), then a smart control unit can be useful to decide when to store energy and when to use it and how to schedule the use of electric appliances. Micro-grids that have a local storage unit and are connected to the grid definitely require a control system to see when it is most economic to store locally generated electricity or to feed it back into the public grid.

This report explored the status of development and diffusion of both technologies. Are they just experimental technologies, are they applied on a small scale in specific niche market applications only, or are they already applied on a large scale in a mainstream market?

Two breakthrough technologies ‘Green hydrogen’ and ‘Smart roofs’

Green hydrogen, an energy source and carrier, and Smart roofs, a combination of different innovations that can be fitted on or integrated with the roof of buildings, have a few things in common. Both represent examples of sustainable technological innovations that help in managing the stability of the electric grid. Both may turn out to become breakthrough technologies. Breakthrough technologies are technologies that can be applied in several domains in society and that have the potential to initiate a structural change in those domains. Another thing that both technologies have in common is the fact that their wide-scale use requires a change in the larger system of energy provision and use. A final commonality is that they consist of parts or modules most of which are already available. It is the combination of the parts and the necessary changes in the larger system that still need to be implemented.

The technologies are seen as important parts of the transition towards sustainable energy provision and use. Interestingly, the two cases also have a direct link because hydrogen can be used to store energy for a rooftop micro-grid. This is why we decided to choose these technologies for the current version of the Technology Monitor for STT.

“Green hydrogen and smart roofs are important for the transition towards sustainable energy provision and use.” — Technology Monitor 2021

Green hydrogen

Green hydrogen refers to a system composed of interconnected subsystems which require coordination. If we look at the subsystems for production, transportation, storage and usage of green hydrogen, we see that some of the subsystems are already in place, yet other subsystems and their combination in one interconnected system are still lagging behind.

Hydrogen is already produced on a large scale, and there is more and more sustainable (wind or solar) electric energy available, yet the portion of hydrogen production that is green is still marginally small. Regarding transportation we see that pipelines for gas are available, some of which are idle and can possibly be re-used for hydrogen. Yet, a full public wide-scale hydrogen transportation and distribution system is not in place. Storage of hydrogen is possible but largescale storage required to balance out the peaks in sustainable energy production and thereby align the available energy with the fluctuations in demand, is not yet available. Local storage systems, for example in consumer households, are available. In fact, experimental systems are used already for more than a century. Yet, mainstream energy storage systems using hydrogen are not yet in place on a large scale in the market. A final bottleneck seems to be adapting all the systems required to use green hydrogen as a mobility solution or energy carrier. Hydrogen cars, for example, are commercially available, but these cars represent a very specific and small niche only.

As an answer to the first research question, we conclude that green hydrogen (as mobility
solution and energy carrier) is in the adaptation phase, it is applied on a small scale in specific
niche applications. The reason that green hydrogen is not yet applied on a large scale as an
energy carrier or fuel is visible in the status of the conditions. These conditions provide an answer to research question 2.

The main barriers to large-scale diffusion can be found in the green production of hydrogen
as fuel or energy carrier and in the availability of complementary products and services. The
complementary products and services lack in terms of a wide-scale transportation network
and local connections to that network but also appliances to use the green hydrogen as fuel or
energy carrier are not yet widely available. The performance and price (especially for the use of
green hydrogen as a mobility solution) are not yet competitive.

Rooftop micro-grids

Rooftop micro-grids also represent systems of interconnected subsystems, like green
hydrogen. In contrast to the wide-scale system for green hydrogen, the rooftop
micro-grid is a local system situated in one building. The rooftop micro-grid consists of
subsystems, most of which are also produced and used on a large-scale on buildings, meaning
these subsystems are in the stabilization phase. That is true for solar PV panels, solar thermal
systems and wind turbines. These systems started to diffuse on a large scale before the
turn of the century. Most locally fitted Solar PV panels are connected to the public grid. Yet,
local systems to store electric energy are experimental and in the adaptation phase and so are
the control units connecting the subsystems and optimizing the production and usage of
electricity over time. Rooftop micro-grids are in the adaptation phase.

In contrast to green hydrogen, the main subsystems for rooftop micro-grids are available, they
should become more economic in operation and standard control units are required when
interconnecting the subsystems. Finally, subsystems should be made compatible. In short, the
main barriers to large-scale diffusion refer to the product price of some of the subsystems and
the availability of complementary compatible subsystems. To interconnect subsystems close
collaboration or coordination between a range of market actors is required. Although both technologies are in the so-called adaptation phase, the status of the conditions do reveal that the barriers for large-scale diffusion for smart roofs are lower than for green hydrogen. We thus expect that large-scale diffusion for smart roofs is more likely in the near future than for green hydrogen. See chapter 3 for recommendations and discussion.

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