Bias in energy system models with uniform cost of capital assumption

Several studies have recently evaluated the feasibility of 100% renewable energy-based energy systems in different world regions. In a recent article, Bogdanov et al.1 contribute to this literature, by using an energy system model that takes into account the unique conditions of 145 global subregions, including factors such as renewable energy (RE) resource conditions, structure and age of existing capacities, demand patterns, etc. Based on their results, they discuss transition pathways and calculate the 2050 levelized cost of electricity generation (LCOE) of 100% RE-based energy systems in those 145 subregions. While the paper provides a new high-resolution analysis of 100% RE systems, we believe that it falls short of adequately considering large differences in the cost of capital (CoC) when comparing the LCOE between countries. As a result, Fig. 2 in Bogdanov et al. shows the lowest LCOEs for solar photovoltaic (PV)-based systems in countries such as the Democratic Republic of Congo (DRC) and Sudan, which seems at odds with the high investment risks and very low installed capacity in both countries2. Accounting for CoC differences between countries changes the results dramatically, as we show in Fig. 1. We therefore argue that using uniform CoC can lead to distorted policy recommendations.

Written by Florian Egli, Bjarne Steffen and Tobias S. Schmidt

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We must accelerate transitions for sustainability and climate change, experts say

We must move faster towards a low-carbon world if we are to limit global warming to 2oC this century, experts have warned.

Changes in electricity, heat, buildings, industry and transport are needed rapidly and must happen all together, according to research from our partners at the Universities of Sussex. The new study, published in the journal Science, was co-authored by INNOPATHS’ Benjamin K. Sovacool.

To provide a reasonable (66%) chance of limiting global temperature increases to below 2oC, the International Energy Agency and International Renewable Energy Agency suggest that global energy-related carbon emissions must peak by 2020 and fall by more than 70% in the next 35 years. This implies a tripling of the annual rate of energy efficiency improvement, retrofitting the entire building stock, generating 95% of electricity from low-carbon sources by 2050 and shifting almost entirely towards electric cars.

This elemental challenge necessitates “deep decarbonisation” of electricity, transport, heat, industrial, forestry and agricultural systems across the world.  But despite the recent rapid growth in renewable electricity generation, the rate of progress towards this wider goal remains slow.

Moreover, many energy and climate researchers remain wedded to disciplinary approaches that focus on a single piece of the low-carbon transition puzzle. A case in point is a recent Science Policy Forum proposing a ‘carbon law’ that will guarantee that zero-emissions are reached. This model-based prescription emphasizes a single policy instrument, but neglects the wider political, cultural, business, and social drivers of low carbon transitions.

A new, interdisciplinary study published in Science presents a ‘sociotechnical’ framework that explains how these different drivers can interlink and mutually reinforce one another and how the pace of the low carbon transition can be accelerated.

Professor Benjamin K. Sovacool from the University of Sussex, a co-author on the study, says:

“Current rates of change are simply not enough. We need to accelerate transitions, deepen their speed and broaden their reach. Otherwise there can be no hope of reaching a 2 degree target, let alone 1.5 degrees. This piece reveals that the acceleration of transitions across the sociotechnical systems of electricity, heat, buildings, manufacturing, and transport requires new conceptual approaches, analytical foci, and research methods.”

The Policy Forum provides four key lessons for how to accelerate sustainability transitions.

Lesson 1: Focus on socio-technical systems rather than individual elements

Rapid and deep decarbonization requires a transformation of ‘sociotechnical systems’ – the interlinked mix of technologies, infrastructures, organizations, markets, regulations and user practices that together deliver societal functions such as personal mobility.  Previous systems have developed over many decades, and the alignment and co-evolution of their elements makes them resistant to change.

Accelerated low-carbon transitions therefore depend on both techno-economic improvements, and social, political and cultural processes, including the development of positive or negative discourses. Professor Steve Sorrell from the University of Sussex, a coauthor of the study, states: “In this policy forum we describe how transformational changes in energy and transport systems occur, and how they may be accelerated. Traditional policy approaches emphasizing a single technology will not be enough.”

Lesson 2: Align multiple innovations and systems

Socio-technical transitions gain momentum when multiple innovations are linked together, improving the functionality of each and acting in combination to reconfigure systems.  The shale gas revolution, for instance, accelerated when seismic imaging, horizontal drilling, and hydraulic fracturing were combined.   Likewise, accelerated low-carbon transitions in electricity depend not only on the momentum of renewable energy innovations like wind, solar-PV and bio-energy, but also on complementary innovations including energy storage and demand response.  These need aligned and then linked so that innovations are harmonized.

Prof. EU INNOPATHS consortium researching low-carbon transitions for Europe, comments: “One of the great strengths of this study is the equal emphasis it accords to technological, social, business and policy innovation, in all of which governments as well as the private sector have a key role to play.

“European countries will become low-carbon societies not only when the required low-carbon technologies have been developed but when new business models and more sustainable consumer aspirations are driving their deployment at scale. Public policy has an enormous role to play at every step in the creation of these changed conditions.”

Lesson 3: Offer societal and business support

Public support is crucial for effective transition policies. Low-carbon transitions in mobility, agro-food, heat and buildings will also involve millions of citizens who need to modify their purchase decisions, user practices, beliefs, cultural conventions and skills. To motivate citizens, financial incentives and information about climate change threats need to be complemented by positive discourses about the economic, social and cultural benefits of low-carbon innovations.

Furthermore, business support is essential because the development and deployment of low-carbon innovations depends upon the technical skills, organizational capabilities and financial resources of the private sector. Green industries and supply chains can solidify political coalitions supporting ambitious climate policies and provide a counterweight to incumbents.  Technological progress can drive climate policy by providing solutions or altering economic interests. Shale gas and solar-PV developments, for instance, altered the US and Chinese positions in the international climate negotiations.

Lesson 4: Phase out existing systems

Socio-technical transitions can be accelerated by actively phasing out existing technologies, supply chains, and systems that lock-in emissions for decades. Professor Sovacool comments that: “All too often, analysists and even policymakers focus on new incentives, on the phasing in of low-carbon technologies. This study reminds us that phasing out existing systems can be just as important as stimulating novel innovations.”

For instance, the UK transition to smokeless solid fuels and gas was accelerated by the 1956 Clean Air Act, which allowed cities to create smokeless zones where coal use was banned. Another example is the 2009 European Commission decision to phase-out incandescent light bulbs, which accelerated the shift to compact fluorescents and LEDs. French and UK governments have announced plans to phase-out petrol and diesel cars by 2040. Moreover, the UK intends to phase out unabated coal-fired power generation by 2025 (if feasible alternatives are available).

Phasing out existing systems accelerates transitions by creating space for niche-innovations and removing barriers to their diffusion. The phase-out of carbon-intensive systems is also essential to prevent the bulk of fossil fuel reserves from being burned, which would obliterate the 2oC target. This phase-out will be challenging since it threatens the largest and most powerful global industries (e.g. oil, automobiles, electric utilities, agro-food, steel), which will fight to protect their vested economic and political interests.


Deep decarbonization requires complementing model-based analysis with socio-technical research. While the former analyzes technically feasible least-cost pathways, the latter addresses innovation processes, business strategies, social acceptance, cultural discourses and political struggles, which are difficult to model but crucial in real-world transitions. As Professor Geels notes, an enduring lesson is that “to accelerate low-carbon transitions, policymakers should not only stimulate techno-economic developments, but also build political coalitions, enhance business involvement, and engage civil society.”

Additionally, the research underscores the non-technical, or social, elements of transitions.  Dr. Tim Schwanen from the University of Oxford, a coauthor, states that “the approach described in this Policy Forum demonstrates the importance of heeding insights from across the social sciences in thinking about low-carbon transitions.”

While full integration of both approaches is not possible, productive bridging strategies may enable policy strategies that are both cost-effective and socio-politically feasible.

Further links

This article was originally posted on the University of Sussex website.

Click here to read the full paper in Science

The EU energy system towards 2050: The case of scenarios using the PRIMES model

By P. Capros, M. Kannavou, S. Evangelopoulou, A. Petropolos, P. Siskos, N. Tasios, G. Zazias and A. DeVita


In November 2016, the European Commission presented the ‘Clean Energy for all Europeans’, (i.e. ‘Winter package’), a set of measures to keep the European Union competitive as the clean energy transition is changing global energy markets. The package proposes policies in line with the 2030 targets agreed by the European Council in 2014 regarding GHG emissions reduction, renewable energy and energy efficiency.

The PRIMES model, developed by E3M, has been used to build the EU Reference Scenario 2016 and support the Impact Assessment studies that accompany the Winter Package [1-4]. Figure 1 shows schematically that individual parts of the Winter Package where the PRIMES model has been used and the various scenarios considered. In addition to the proposals included in the Winter Package, additional framework related to the decarbonisation of transport and the effort sharing amongst Member States towards the reduction of GHG emissions has also been proposed in the context of the targets set by the European Council. PRIMES was also used in those assessments.

PRIMES is a partial equilibrium modelling system that simulates an energy market equilibrium in the European Union and in each of its Member States. The model includes consistent EU carbon price trajectories. It proceeds in five-year steps and uses Eurostat data.

Scenario description

Several scenarios were considered.  The main scenario, EUCO27 is in line 2014 European Council. It considers at least 40% cuts in greenhouse gas emissions (from 1990 levels), at least 27% share for renewable energy and at least 27% improvement in energy efficiency. Four variants to the EUCO27, considering different levels of energy efficiency improvements (30, 33, 35 and 40%) were also considered to assess the impact of the proposed legal framework on energy efficiency. Other scenarios related to the integration of Renewable Energy Sources (RES) and the functioning of the internal energy market were also developed and used to assess the various implications of the winter package.

All EUCO scenarios are decarbonisation scenarios, i.e. they are compatible with a 2oC trajectory and the EU INDC [5] submitted following the COP21 meeting in Paris in 2015. They achieve above 80% GHG emissions reduction in 2050 compared to 1990 levels, in line with the European Commission ‘Energy Roadmap 2050’.

Figure 1: Illustration of European Commission studies which used the EUCO scenarios

The main elements of the EUCO27 and EUCO20 scenarios are shown in Figure 2:

Figure 2: Climate and energy targets used for the EUCO scenarios

Table 1 shows the main policies used for delivering the climate and energy targets in all scenarios.

Policies ETS Increase of ETS linear factor to 2.2% for 2021-30 (2015/148 (COD)
Market Stability Reserve (2014/0011/COD)
Policies RES RES-E policies: new guidelines for auctions
Policies promoting the use of biofuels
Support of RES in heating
Policies efficiency Energy efficiency of buildings: new EED, enhancement of article 7
More stringent eco-design
Support of heat pumps
Best available techniques in industry
Policies transport CO2 car standards (70-75gCO2/km in 2030, 25 in 2050) and for Vans (120 in 2030, 60 in 2050)
Efficiency standards (1.5% increase per year) for trucks
Measures improving the efficiency of the transport system

Key findings

The projections obtained through the various scenarios reveal the following:

(A) Impacts on GHG Emissions (EUCO27)

The energy related CO2 emissions decrease primarily in the energy supply sectors, notably in the power sector, but also in the demand sectors.

The remaining non-abated emissions by 2050 are by order of magnitude due to  the non-CO2 GHG, the residual use of oil in transport and various small scale uses of gas in the domestic sector and industry

The reductions of emissions in the sectors that participate in the Emissions Trading System (ETS)  exceed those in the non-ETS sectors

The ETS drives strong emission reductions in the power sector and promotes the development of RES which benefit from learning-by-doing requiring low or no out-of-the-market support.


(B) RES penetration

Variable renewables (e.g. wind and solar)_ are expected to dominate the power generation sector. The projection shows variable RES capacity to more than double in 2030, from 2015 levels, and quadruple by 2050.

RES in heating and cooling also develop, albeit at a slower pace, driven by heat pumps and RES-based production of heat.

The biofuels in transport constitute the main growing market for bioenergy, as biofuels are essential for reducing emissions in non-electrified transport segments (the RES-T includes for electricity used in transport the RES used in power sector).

(C) Electricity supply mix

Due to the increased penetration of intermittent RES, gas-firing capacities acquire a strategic role for balancing and reserve, a role increasingly performed by storage technologies in the long term. Nuclear plant retrofitting is essential to maintain total nuclear capacity, as investment in new nuclear plants suffers from limitations (sites, financing, etc.).

Coal-firing generation is under strong decline with CCS not becoming a major option.

The model results confirm the importance of sharing balancing and reserve resources across the EU countries and the advantages of market coupling in the day-ahead, intra-day and real-time balancing. The scenarios assume minimization of costs over the pan-European market, which in the mid-term becomes fully integrated.

(D) Energy Efficiency

(E)    Renovation of houses and buildings, the Eco-design regulation, the application of the Best Available Technologies (BAT) in the industry are significant enablers to energy efficiency.

(F)     Electricity consumption hardly increases until 2030.  The energy efficiency improvement drives electricity savings in the short/medium term, and energy savings overall.   Transport electrification and increased use of electricity for heat purposes add significant load, but only after 2030.



(G) Developments in the transport sector

Advanced car technologies (mainly plug-in hybrids and battery electric vehicles) dominate the car market as a result of the CO2 car standards, which continuously tighten.

The biofuels, mostly advanced lignocellulose-based fungible biofuels in the long term, get a significant market share in the non-electrified segments of the transport sector (trucks, ships, aircrafts).

(H) Investments and electricity prices

Investment expenditures are likely to rise considerably in the decade 2020-2030 and beyond.

The projections do not see significant pressures on electricity prices in the medium term, but prices are likely to considerably increase in the long term, mainly due to increasing costs of grids and system services.

Moderate increase in total costs relative to the Reference in EUCO27 and EUCO30. There’s considerable increase in investment in the demand sectors when the energy efficiency ambition increases.  The induced technology progress can offset the increase in the energy costs in the long term. The investment expenditures are likely to rise considerably in the decade 2020-30, a crucial decade for the energy transition, also because of the necessity to extend power grids, upgrade power distribution, build vehicle recharging infrastructure and develop advanced biofuels.

The investment requirements in gas-fired plants are significant after 2025 and until 2050, in contrast to the continuous decrease in the rate of use. The investment in nuclear both for extension of lifetime and new plants is also significant.  The investment outlook is dominated by the massive development of variable RES, notably wind and solar.

On average, the prices of electricity in the EUCO scenarios do not increase in 2030 compared to the Reference projection.  The projections do not see significant pressures on electricity prices in the medium term. The electricity sector restructuring, the sharing of resources in the integrated EU market and the technology learning offset the impacts of ETS. The projection of rising electricity prices in the long term is mainly due to the increasing costs of grids, smart systems and system services. However, the prices increase significantly after 2030.

More information on the winter package scenarios is available online at

By Pantelis Capros, Professor in the School of Electrical and Computer Engineering, National Technical University of Athens and Director of the E3Mlab/ ICCS.


[1] European Commission (2016).

[2] European Commission, COM(2016) 767 final/2, 0382 (COD) (2017) 1–116.

[3] European Commission, COM(2016) 761 final.

[4] European Commission, Impact assessment on the revised rules for the electricity market, risk preparedness and ACER, Eur. Comm. Winter Packag. 5 (2016).

[5] The EU’s Intended Nationally Determined Contribution to the UNFCCC.