ESC News

Hydrogen and e-fuels and their potential role in future energy systems are hotly debated topics. Using The modelling platform Nexus-e, a team of researchers at the Energy Science Center at ETH has looked at the potential role of imported or domestic hydrogen or e-methane for the Swiss electricity system guided by three main research questions.

On 31 January 2024, the PATHFNDR consortium participated at the dissemination workshop, where researchers presented the PATHFNDR scenario results and provided insights on sector-coupling.  

For Anthony Patt, Europe’s ambitious plans for a hydrogen economy may be too ambitious, tipping the scales towards the interests of the fossil fuel industry, rather than energy consumers and the climate. Switzerland should be careful before jumping fully on board, he argues. Read more on the Energy Blog @ ETH.

The Energy Science Center (ESC) is very pleased to welcome Rebecca Lordan-Perret to the executive team. Rebecca joined the ESC as Science Outreach Manager in December 2023. 

Eine klimafreundliche Zukunft in den Themengebieten Energie und Mobilität gemeinsam angehen, sich zu bestehende Entwicklungen, Herausforderungen und Erkenntnissen mit Akteuren aus Wissenschaft, Wirtschaft und Gesellschaft kurzschliessen sowie praxisnahe Lösungsansätze erarbeiten: Diese zahlreichen Aktivitäten werden nun in dem neu gegründete Reallabor Sisslerfeld gebündelt.

The Energy Science Center (ESC) is very pleased to welcome Yvonne Wisianowsky to the executive team. Yvonne joined the ESC in October 2023 as maternity replacement for Annina von Mentlen. She will be in charge of communication activities and event organisation at the ESC.

Harnessing the sun’s energy to generate electricity through building envelopes presents an opportunity for us to contribute to a better future. But what is the energy generation potential of your building, and how can you estimate it? Beyond energy generation and savings, what should you keep in mind before integrating photovoltaic systems (PVs)?  

In September 2023, Anna Knörr started working as research assistant for the Joint Initiative SPEED2ZERO. The ESC is excited to welcome Anna to its executive team!

In this study, the Nexus-e team assesses the role of the existing and new nuclear power plants for the Swiss electricity system. They use the Nexus-e modeling platform to develop three scenarios with different operating time of existing and construction of new nuclear power plants.

After a week of interactive keynotes, torrential rain, case study analysis, thunderstorms, and captivating poster presentations, the 2023 Summer School on Energy Technology, Policy, and Politics has officially come to a close.  

Jonas Savelsberg joined the Energy Science Center as a senior project manager for Nexus-e in August 2023.

Matthieu Boubat joined the Energy Science Center (ESC) in July 2023 as a scientific assistant. He is working on scenario developments for various projects at ESC and collaborating toward making the Nexus-e platform open source.

Upon application of ETH President Joël Mesot, the ETH Board promoted three ETH professors who are also members of the Energy Science Center.

You are probably aware that your daily commute contributes to climate change. But just how much? In the latest post on the Energy Blog @ ETH Zurich, the authors offer a detailed look at the carbon footprint of various transport modes, from bicycles and scooters to cars and public transit. Learn how everyday choices can significantly affect your impact on the environment and discover more sustainable options for urban mobility.  

Christian Schaffner im SRF-Newsbeitrag zu Strompreisen im Minus.

Are you passionate about making science accessible to all? Do you excel at communicating and connecting with diverse audiences? We have an exciting opportunity for a dynamic and enthusiastic individual like you to join our team as a Scientific Outreach Manager.

Auctions for renewable energy support have become the standard way to give out subsidies to solar energy projects and other renewables in Europe. In an auction, investors usually compete to receive the subsidy based on their offered support price, where the bidders with the lowest offered prices win. The Swiss government has started using auctions to award investment subsidies to larger PV projects. Are the auctions designed well and fit for purpose? How have the auctions performed until now?

Navigating the complexities of bioenergy, its potential for carbon neutrality, and its conflicts with land, food, and feed resources is a pressing issue. What if we could circumvent these issues and focus solely on land-free bioenergy, similar to growing mushrooms on waste coffee grounds for a delicious dish? Waste and byproducts can generate valuable bioenergy, playing strategic roles in a future sustainable energy system.

The weather couldn't have been more perfect, setting the stage for a memorable celebration of 15 years of MEST ( Master in Energy Science and Technology).  

ETH Zurich and EPFL want to work with partners from politics, science and industry to push innovative storage and transport solutions for renewable energy carriers. The overall goal is to create a climate-​neutral and flexible energy system for Switzerland. Around 20 partners and industrial companies have already voiced their interest in a collaboration.

Gabriela Hug and Christian Schaffner argue that securing an affordable energy supply from renewable sources is not a utopian ideal for Switzerland, but rather a practical and feasible necessity.

The Energy Science Center (ESC) welcomes Prof. Dr. Victor Mougel as a new member of the competence center.

Wir haben alle Voraussetzungen, um den Wandel hin zu einer sicheren, nachhaltigen und bezahlbaren Energieversorgung zu realisieren. Zu diesem Schluss kommen Energiefachleute der ETH.

Community solar systems, defined as medium to large-scale PV installations co-owned by multiple building owners and/or tenants, offer one option to increase PV adoption in cities. This blogpost summarizes the findings of our recent paper that explores if, by how much and under which conditions community solar could help accelerate PV adoption in cities

To decarbonize our economy, electricity will replace oil and natural gas as the primary energy carrier. Where should that power come from? Many people argue that all of it should be produced domestically. Careful analysis suggests some share of it should be imported, says Anthony Patt.

Every time we calculate the environmental impacts of an electric vehicle, we use data from the lithium carbonate production at the Salar de Atacama in Chile. To meet soaring lithium demand, other, more polluting mining pathways are emerging. However, poor data availability is preventing proper accounting, leading to underestimated environmental damages. What we need are more transparent supply chains for a low-carbon society.

Massive investment in low-carbon infrastructure is required to put Europe on a path to net zero by 2050. While this is no big surprise, it is astonishing that investments are still growing rather slowly, even for market-ready technologies such as onshore wind or solar PV. This Energy Blog post quantifies current investment gaps in Europe’s energy infrastructure and discusses the hurdles that must be urgently overcome to reach the required investment levels.

The Energy Science Center (ESC) welcomes Dr. Stefano Moret as a new member of the competence center.

How can we educate the public about energy in Switzerland? What exactly will the future of energy look like? A new exhibition at Verkehrshaus aims to sensitise the public to new approaches to our energy supply. One of the exhibits was developed by "Energy Science for Tomorrow", a joint initiative of the ETH Board – comprising ETH Zurich, EPFL, Empa, and PSI, in collaboration with NCCR Automation, Design++ and SATW.

Based on interviews with stakeholders such as architects, engineers, and the city of Zurich, this blog post on the Energy Blog @ ETH Zurich suggests various PV implementations and their benefits at four different scales: Bus shelters, Parking lots, Plazas and Bridges.

The Energy Science Center (ESC) is delighted to welcome Prof. Adrienne Grêt-Regamey, Dr. Viola Becattini and Dr. Paolo Gabrielli as new members of the competence center.

In an increasingly decentralized and electrified energy system, electric vehicle users and their diverse behaviors could both drastically hinder or substantially support current energy transition efforts in many regions globally. The negative or positive effect depends on how users are integrated into the system.  

Eyvonne Ranjan joins the Energy Science Center (ESC) as project coordinator for PATHFNDR and SPEED2ZERO. The ESC is very excited to welcome Eyvonne to its executive team.

Electricity systems require more and more flexibility to integrate increasing shares of variable renewable electricity and avoid costly grid expansion. The demand side – involving electricity end-users – will be key in providing relatively cheap flexibility. Looking beyond the technical aspects is crucial to leverage this potential; namely, by addressing social and regulatory challenges.  

In this blog post, editors Kate, Churchill, and Leopold identify five global energy conversations they will be following in 2023, which they believe will be of interest to you. Check out their picks to stay informed and engaged in these important discussions.

To meet net-zero targets by mid-century, gigatons of carbon dioxide (CO2) per year must be removed through direct air capture and storage (DACS). However, current deployment is low, requiring DACS technologies to be deployed at an unprecedented pace. The blog post explores the two most advanced capture methods used in DACS, compares their scalability, and stresses the significance of investing in multiple technologies over the next decade instead of solely relying on existing approaches.

America’s recently passed climate law provides strong support for accelerated adoption of clean vehicles in the US. Subsidies are generous for consumers looking to go electric, but only for vehicles that meet strict geographic requirements for critical mineral sourcing, battery manufacturing and vehicle assembly. Unabashedly, the US is seeking to shift the EV supply chain from China to North America, but at what cost?

Security of electricity supply and electricity costs have become major business concerns for the Swiss industry sector. On the current trajectory towards a clean energy system, situations in winter with reduced availability of electricity followed by soaring prices may occur more regularly. With Switzerland establishing a strategic reserve to overcome electricity shortage situations, we argue in this blog post that demand-side measures should be part of such a reserve.

The secret to getting through the energy crisis is that everyone in Europe does their part. And a bit of luck. In this post on the Energy Blog @ ETH Zurich, the author highlights some preliminary results from his investigation of the gas shortage in Europe – because winter is here but Russian gas is not. He models the optimal response to the gas crisis to outline a potential strategy for European countries to get through this daunting situation.

The joint initiative "SPEED2ZERO" contributes to halving greenhouse gas emissions by 2030, preparing the infrastructure needed to achieve this, building a resilient energy system and safeguarding biodiversity.

ESC member Aldo Steinfeld, professor and head of the Professorship of Renewable Energy Carriers, receives the 2022 Sustainable Engineering Research Award by the American Institute of Chemical Engineers, for pioneering and visionary contributions in renewable energy carriers, and leadership in clean energy research and education, and solar power technologies. Congratulations!

While the economic impacts of climate policy are generally perceived as costs, Anthony Patt proposes the opposite perspective. For Switzerland, converting the energy system and reaching the net-​zero target may net benefit the economy, he finds

Electricity consumption is closely and positively related with global economic and human development across different geographical, social, and cultural contexts. As a Sustainable Development Goal and as an integral part of the water-energy-food nexus, access to electricity is vital to our individual and collective security and well-being. Despite the importance, access to electricity is not explicitly recognized as a universal human right.  

How much energy do buildings consume per canton, per municipality? How big is the heating demand? How much electricity did Switzerland consume yesterday? How many Smart Meters are installed per municipality? In terms of data freely available on the energy sector – so called Open Energy Data -, Switzerland has a lot of catching up to do compared to other countries. Why is that? What are the obstacles?

The latest blogpost on the Energy Blog @ ETH Zurich discusses a key shortcoming in electrification models used by policymakers and international organizations to chart electricity access pathways in sub-Saharan Africa –  unrealistic financing cost assumptions. It highlights why this often overlooked flaw in electrification models could slacken efforts to reach universal electricity access by 2030 and explains why it matters.

Regina Moser joins the Energy Science Center (ESC) as a project manager. The ESC is very pleased to welcome Regina Moser as a new member of the ESC team. Regina will lead the project "Engage everyone with Energy" (E3TOTO).

The global energy transition requires a dramatic shift towards renewable and low-carbon energy technologies. Hydrogen is one of these and can be used to store intermittent solar and wind power. As well as being produced from green electricity by electrolysis, it can also be manufactured by capturing and storing carbon dioxide during the conversion of natural gas.  

On 16-17 September 2022, the PATHFNDR team from the Energy Science Center presented a challenge at the Energy Data Hackdays at the Technopark Aargau in Brugg. The challenge was to develop a decision-making tool for policy-makers to explore and compare multiple energy scenarios.  

On 14-15 September 2022, the PATHFNDR research team, industry partners, and policy-makers discussed the challenges and opportunities of four topics: energy independence, hydrogen, system flexibility, and sector coupling.

Ingmar Schlecht (Principal Investigator in the PATHFNDR consortium) spoke on SRF's news program "10vor10" on September 1, 2022 about how financial incentives for private individuals could help reduce energy consumption. The interview builds on the concept of "supplier-financed energy savings bonuses”, which is also explained in a Handelsblatt article (in German) by Silvana Tiedemann, Lion Hirth and Axel Ockenfels.

The PATHFNDR team presented to the review panel the first results after one year of work and the outlook for the coming year. The discussion focused on energy scenarios and the technologies needed to enable flexibility and sector integration. The meeting ended with a tour of the NEST, move and Ehub demonstrators at Empa. We thank the review panel and BFE SWEET office for their valuable feedback! A big thank you also to Empa for hosting the meeting!

The Energy Science Center (ESC) is very pleased to welcome Arijit Upadhyay as new member of the ESC team. Arijit joined the existing team of the Nexus-​e research project in July 2022.

There is a danger of blackouts, nuclear power capacity has to be boosted again, an electric car is no cleaner than a petrol car, and Switzerland is too small to make a difference in the climate crisis – statements like these and politically charged terms are dominating the discussion about the energy of the future. In a four-part special series of the ETH Podcast, we take a closer look at these claims. The Energy Science Center supported the Podcast team in their search for answers.

Up until now, energy system modeling using bottom-up capacity expansion models has primarily focused on investigating cost-optimal transition pathways of national energy systems. Now that the transition is accelerating, it is time for this modeling community to start investigating the question of "How do we get to net zero?" by focusing more strongly on how policies can accelerate or impede the transition. Read the whole article in the Energy Blog @ ETH Zurich.

For sustainable energy systems the innovative technologies are existing, but we have to combine them in the most sustainable way to decarbonize our future. The questions are what business model change, political regulations and societal adaptation are needed and inevitable and helped us to answer the questions “What steps we should take?”, and “Who will lead the way?”

Oil and gas prices are currently on the rise, raising questions about the security of Switzerland’s energy supply. A policy brief from the Energy Science Center shows how Switzerland can achieve independence from fossil fuels for its energy system.

Derzeit steigen die Öl- und Gaspreise, und es stellt sich die Frage, wie sicher die Energieversorgung in der Schweiz ist. In einem Positionspapier zeigen nun Forschende des Energy Science Center der ETH Zürich auf, was die Schweiz tun kann, um ihr Energiesystem von fossilen Energieträgern wie Öl und Gas unabhängig zu machen.

The Energy Science Center (ESC) is delighted to welcome Prof. Annalisa Manera as member of the competence center. Annalisa Manera is a Professor of Nuclear Systems and Multiphase Flows at ETH Zurich.

During two semesters, the Master in Energy Science and Technology (MEST) students had the opportunity to work on real-​world problems currently faced by companies within the energy sector.

Building retrofits are increasingly assessed from an environmental perspective. Standard assessment methods, however, largely do not consider future developments and fail to take into account the state of climate emergency where the time horizon is substantially shorter than the expected building lifetime. Therefore a more forward-looking analysis is required.

Earlier this year, the Swiss Agency for Development and Cooperation (SDC) organised the first International Cooperation Forum in Geneva to address poverty and climate change. Two editors of the Energy Blog @ ETH highlight their key takeaways about electricity access from the event.

So the Energy Blog @ ETH just turned 50 articles old! Through the support of the ETH Energy Science Center (ESC), the Energy Blog @ ETH team, consisting mostly of PhD students, along with professors and ESC staff, has worked to create a space where anyone working in energy at ETH Zurich can showcase their research or give informed opinions on pertinent energy topics of our time.

High gas prices can help the transition to a renewable energy system, but European decision makers must now consider policies to decrease the price volatility exposure of renewables to safeguard the transition. In an analysis recently published in Nature Energy, we show that such policies can strengthen the political support for long-term carbon prices.

Congratulation to Dr. Anselma Wörner, former Doctoral Student of our Energy Science Center, ETH Zurich Member Prof. Elgar Fleisch, for being awarded with the ETH Medal for her outstanding doctoral theses.        

In the video series "Ask the Expert" Prof. Gabriela Hug, Chair of the Energy Science Center, answers questions from the community on the topic of energy Supply.

The application window for the upcoming CAS in Applied Technology and Energy (CAS ATE) is now online.  See what the 2021 participants have to say about their experience in the new video.

Congratulations to Dr. Nicolas Schmid, doctoral student of our Energy Science Center member Prof. Tobias Schmidt, for receiving the "Silver Medal for Outstanding Doctoral Theses" from ETH Zürich.

Our ESC member Prof. Horst-Michael Prasser will give his farewell lecture at ETH Zurich on 15 December 2021 17.15 - 19.00h on the topic "Innovation auf dem Gebiet der Kernenergie jenseits der öffentlichen Wahrnehmung ". We would like to thank Prof. Prasser for his many years of contribution and support to the ESC. We wish him all the best for the future and to exciting new challenges ahead.

The Energy Science Center (ESC) of ETH Zurich once again organized a major energy symposium, this year for four days in an hybrid format. The motto was "Climate Neutral Switzerland 2050: What Energy System Do We Need?" For those who were not able to attend the event live, all presentations and video recordings are now available online

Increasing shared transport supply raises the question how users decide between these and their private car or public transport. So, what is important to them? Konstantin Krauss gives a brief overview about  mode choice in the Energy Blog

Congratulations to the ESC Member Maria Lukatskaya for being recognized as a Highly Cited Researcher in 2021 by Clarivate Analytics! Of the world’s scientists and social scientists, Highly Cited Researchers are one in 1,000.

Congratulations to our ESC member Prof. Aldo Steinfeld and his team for receiving the Energy Globe World Award 2021 for their EU project "Sun-to-Liquid".

The ETH Energy Apéro, Autumn 2021, was a social event for anyone involved in the ETH energy community, held in the ETH Dozentenfoyer. Professors, researchers, doctoral students and masters students were invited.

The Energy Science Center (ESC) is very pleased to welcome Kirsten Oswald to the executive team. Kirsten joined the ESC as Science Outreach Manager responsible for knowledge transfer activities.

Our founding member Prof. Konstantinos Boulouchos will give his farewell lecture at ETH Zurich on the Oct. 5th, 2021 17.15 - 19.00h on the topic "Shaping the path(s) to a Sustainable Energy Future". We would like to thank Kostas for his many years of contribution and support to the ESC with his progressive view of the energy system. We wish him all the best for the future and to exciting new challenges ahead.

The Energy Science Center (ESC) is delighted to announce that Prof. Gabriela Hug will take over the Chair of the Managing Board (October 1, 2021) from Prof. Dimos Poulikakos whose 4-year tenure has ended.  

In September 2021, the Energy Data Hackdays will take place for the fourth time at the Hightech Zentrum Aargau. The ESC research project "Nexus-e" will participate and provide a challenge on identifying key changes in the Swiss energy system on its path to achieve 2050 net-zero decarbonization targets.  

Climate change is pressing and we need fast decarbonisation of all aspects of life. As a multi-purpose technology, batteries play a central role in the reduction of carbon emissions. However, the current supply chain of Lithium-ion batteries is often associated with environmental and social burdens. Thus, some voices are advocating alternative mining: potato-sized rocks, rich in critical metals.  

Switzerland has set itself the goal of net-zero greenhouse gas emissions by 2050. Achieving this goal will require major changes in the energy system. In the Joint Activity Scenarios and Modelling (JASM), researchers from the eight Swiss Competence Centers for Energy Research (SCCERs) worked together to build a modelling framework and develop concrete scenarios for how Switzerland can achieve the net-zero goal. Gianfranco Guidati, Head of the Joint Activity, explains the key results in an interview.

Wood is an ancient construction material, but it has been gradually substituted with concrete and steel. However, the advantages of wood are now being (re)discovered as sustainability becomes a global interest and advanced manufacturing technologies become available. This article focuses on its advantages in carbon capture, digital construction, and prefabrication.

Marco Mazzotti, Professor of Process Engineering at the Department of Mechanical and Process Engineering (D-​MAVT), receives the 2021 SINTEF and NTNU CCS Award for his research on carbon dioxide capture and storage systems.

In May 2021, the students from the Master's programme Energy Science and Technology successfully completed their interdisciplinary case studies. In six groups and over two semesters, they worked on real-​​world problems currently faced by companies within the energy sector.

It is estimated that buildings are responsible for 36% of global final energy use and 40% of the energy-related greenhouse gas emissions in Europe. Buildings are also complex machines with long life cycles, which include regular maintenance and updates. Thus, buildings and particularly building refurbishments provide manifold and exciting opportunities to address climate change issues at low cost and with (free) co-benefits.

On 31 May, the successful kick-off of the PATHFNDR project took place. PATHFNDR is one of four consortia selected in the first call "Integration of renewables" and funded by the SFOE under the funding programme SWiss Energy research for the Energy Transition (SWEET). Besides the leading house ETH Zurich, teams from Empa, PSI, ZHAW, HSLU, UniGE, EPFL, and also 25 industry partners will investigate how the Swiss energy system has to be transformed to absorb a much higher share of renewable energy sources.

Das Newsportal nau.ch berichtet: "Nicht das E-Auto, sondern Wasserstoff-Fahrzeuge sollen die Zukunft sein. Das behaupten Gegner des CO2-Gesetzes immer wieder." Christian Schaffner vom Energy Science Center (ESC) widerspricht.

The Energy Science Center (ESC) is very pleased to welcome Adriana Marcucci to the executive team. Adriana joined the ESC in June 2021 as manager for the coordination of the scenarios for the SWEET program.

The Energy Science Center congratulates Johanna Vorwerk on receiving the Best Presentation Award in the seminar “Frontiers in Energy Research”.

The SWEET funding programme is not only aimed at the technical and natural sciences, but also encourages the participation of the social sciences and humanities in consortia. The objectives of the Energy Strategy 2050 can only be achieved through the interaction of these scientific fields. In an interview on Energeia+, Yasmine Calisesi, Energy Center EPF Lausanne, and Christian Schaffner, Energy Science Center, ETH Zurich, give their views on the important aspects of interdisciplinary collaboration.

Today is National Climate Day in Switzerland. We don’t have much time left to reach our climate goals and to implement our promised share in the fight against global warming – but we already have concrete ways to contribute today! Be it in the choice of our next car, the refurbishment of our own home, or the choice of our vacation destination. Switzerland could become a showcase country for technically, economically and socially feasible solutions for a sustainable energy supply. Let’s do it!

On the recommendation of ETH President, Joël Mesot, the ETH Board appointed nine new professors. Among the appointed professors is Tobias Schmidt, who has been  Tenure Track Assistant Professor at ETH Zurich since 2015. He was promoted to Associate Professor of Energy and Technology Policy in the Department of Humanities, Social and Political Sciences.  

Today, only a minority of Swiss households have air conditioners installed for cooling. This might change due to the warming climate and the growing integration of heat pumps to new buildings, which can be used for heating and cooling. The Swiss cooling energy demand may reach a similar order of magnitude compared to the heating demand by mid-century onwards, which could have a significant impact on the energy system.

The Energy Science Center (ESC) is very pleased to welcome Lea Ruefenacht to the executive team. Lea joined the ESC as project manager for the SWEET research project PATHFNDR.

Our goal is not to predict the future, rather to shape it. Net-zero scenarios for the energy system help us do that. Although they deliver only a blurred view of the future, they allow us to guess the shape of things to come, and most importantly to formulate actions for today that will put us on the right track.

The Energy Science Center (ESC) is delighted to welcome Dr. Petrissa Eckle and Dr. Turhan Demiray as members of the competence center. Petrissa Eckle leads the Sustainability in Business Lab (sus.lab) at ETH Zurich and Dr. Turhan Demiray is research director of the Research Center for Energy Networks (FEN).

To help keep global warming in check, Switzerland has committed to a net-zero emissions target by the mid-century. The required energy transition will likely give rise to costs, but it will also yield large co-benefits in terms of, for instance, improved health outcomes from less pollution. These are, however, often overlooked. The latest post argues that to take sound decisions related to the energy transition, it is important to consider all the associated costs as well as benefits.

Energy storage is required to reliably and sustainably integrate renewable energy into the energy system. Diverse storage technology options are necessary to deal with the variability of energy generation and demand at different time scales, ranging from mere seconds to seasonal shifts. However, only a few technologies are capable of offsetting the long-term (seasonal) mismatch between renewable generation and energy demand.

Futaba, host of the Fukushima prefecture TEPCO Daiichi nuclear power plant, was evacuated in March, 2011. It has since remained empty. Only recently reopened to the public, Futaba now resembles that of a forgotten ghost town, waiting quietly for life to resume. For Matsueda Atsushi, a once proud Futaba resident, a return home is ridden with doubt and unease.

Since the 1960’s, Japan has aggressively built its nuclear power industry to be one of the best in the world. The Fukushima nuclear disaster of March 11, 2011 changed all of that. Today, the incumbent nuclear institutions in Japan struggle to maintain both political support and shares of the power supply as they compete with rapidly expanding renewable energies.

With the decarbonization and decentralization of energy production, Switzerland faces two mammoth tasks in the coming years and decades. The restructuring of the energy supply requires political and investment decisions. Scientists at ETH Zurich have now created the modeling platform Nexus-e. It enables to create scenarios for the electricity sector and, in particular, also includes economic and grid-related issues.