Jürgen Kern

The use of fossil fuels is the main cause of greenhouse gas emissions and a major driver of climate change. Although direct electrification can replace fossil fuels in many applications, certain sectors will continue to require high-density energy sources in the future, such as long-distance aviation, maritime shipping, and some high-temperature processes in the industry. For these applications, electricity-based synthetic gases and fuels, produced from renewable energies through Power-to-X (PtX) processes, represent a sustainable solution. This paper presents a novel approach for the large-scale estimation of PtX production costs and potentials, considering regional solar and wind power conditions. At its core is the DLR_ITEMS GlobalFuel framework, which calculates local production costs using temporally and spatially resolved data. The framework uses linear optimization to design cost-optimal systems by dimensioning the components for maximal efficiency. It accommodates various converter and storage technologies, enabling high utilization rates even with fluctuating renewable electricity supply. The methodology supports the analysis of multiple pathways by integrating different technologies and assumptions, including wind power, photovoltaics or concentrated solar power, electrolysis, and synthesis. This analysis provides a spatially detailed overview of future PtX generation potential and its levelized production costs. Additionally, the inclusion of domestic demand for renewable energy (RE) and green fuels enables realistic estimates of the export potentials of individual countries, highlighting production and export hot spots. This work focuses on the cost potentials of Fischer–Tropsch fuel production in the Middle East and North Africa (MENA) region. The findings indicate that domestic demand in large territorial countries has a moderate impact on the increase in levelized production costs for export potential. In contrast, small countries often have to fully utilize their limited renewable energy resources for domestic supply of electricity and green fuels. The analysis identifies the most favorable fuel potentials in the MENA region, with cost-optimal ranges between 190 and 220 €/MWh and an estimated annual production potential of 3,400 TWh in 2030. Of this, approximately 3,100 TWh could be available for export markets.

Synthetic fuels play an important role in the defossilization of future aviation transport. To reduce the ecological impact of remote airports due to the long-range transportation of kerosene, decentralized on-site production of synthetic paraffinic kerosene is applicable, preferably as a near-drop-in fuel or, alternatively, as a blend. One possible solution for such a production of synthetic kerosene is the power-to-liquid process. We describe the basic development of a simplified plant layout addressing the specific challenges of decentralized kerosene production that differs from most of the current approaches for infrastructural well-connected regions. The decisive influence of the Fischer–Tropsch synthesis on the power-to-liquid (PtL) process is shown by means of a steady-state reactor model, which was developed in Python and serves as a basis for the further development of a modular environment able to represent entire process chains. The reactor model is based on reaction kinetics according to the current literature. The effects of adjustments of the main operation parameters on the reactor behavior were evaluated, and the impacts on the up- and downstream processes are described. The results prove the governing influence of the Fischer–Tropsch reactor on the PtL process and show its flexibility regarding the desired product fraction output, which makes it an appropriate solution for decentralized kerosene production.

Synthetic fuels play an important role in the defossilization of future aviation transport. To reduce the ecological impact of remote airports due to long range transportation of kerosene, a decentralized on-site-production of synthetic paraffinic kerosene is applicable, preferably as near-drop-in fuel or alternatively as blend. One possible solution for such a production of synthetic kerosene is the Power-to-Liquid process. The basic development of a simplified plant layout addressing the specific challenges of a decentralized kerosene production which differ from most current approaches for infrastructural well-connected regions is described. The decisive influence of the Fischer-Tropsch synthesis on the PtL process is shown by means of a steady-state reactor model which was developed in Python and serves as basis for further development of a modular environment able to represent entire process chains. The reactor model is based on reaction kinetics according current literature. The effects of adjustments of the main operation parameters on the reactor behavior are evaluated and the impacts on up- and downstream processes are described. The results prove the governing influence of the Fischer-Tropsch reactor on the PtL process and show its flexibility regarding the desired product fraction output, which makes it an appropriate solution for a decentralized kerosene production.

DLR developed the optimization model REMix-CEM (Renewable Energy Mix - Capacity Expansion Model). REMix CEM to generate a cost-effective expansion planning of thermal and renewable assets with respect to a use optimization (dispatch) of various types of power plants for the energy system. Working closely with the Moroccan Ministry of Energy energy scenarios are created to support Morocco in the medium to long-term energy planning to develop cost-effective, and technically feasible expansion plans for renewable energy and better coordinate the interaction between different forms of electricity generation.

MESSAGE, TIMES and REMIX-CEM are potential tools for modelling a larger penetration of variable renewable energy (VRE) into the Brazilian power system. They also allow devising the opportunities that concentrated solar power (CSP) plants offer to the power system and to the wider energy system. There are different opportunities for CSP in Brazil in the short and medium term, consolidating this technology as a feasible alternative for greenhouse gas (GHG) mitigation in Brazil. This work verified that CSP is a cost-effective option only under very stringent mitigation scenarios (4DS and 2DS) and when carbon capture and storage (CCS) is not available. Still, according to the findings of REMIX-CEM-B, CSP can provide firm energy and dispatchable capacity in the Northeast region of Brazil, optimally complementing wind and PV generation. Moreover, CSP can offer additional flexibility to the Northeast power system, especially during winter and after 2030.

One of the major difficulties in the assessment of costs of desalination projects is that key investment parameters and operation-related parameters are project-specific data. This information is commonly not in the public domain and is generally available only to the general contractor. In addition, the interpretation of published data is complicated by the fact that often plant boundaries are not clearly indicated (e.g. if the intake cost and the pipeline cost to and from the plant are included in the evaluation). Finally, the analysis involves an elevate number of design parameters, such as plant capacity and configuration, metal and other material prices, and very site-specific conditions (seawater quality, feed water intake, and brine discharge). In the end, these issues result in difficult comparability of data from different sources about the cost of the desalinated water. This paper deals with the implementation of a flexible techno-economic model for the assessment of desalination plants on system analysis level. Thereby, the focus is given to units driven by different technologies (conventional steam turbines and concentrating solar power). The model is applied in a case study in order to evaluate and compare the performance and the costs of different desalination technologies (multiple effect distillation and reverse osmosis). Finally, a sensitivity analysis of the results with respect to selected key design parameters is carried out.

The increasing water demand and the impacts of climate change call for the construction of a large number of new desalination capacities, causing—besides environmental impacts—a relevant amount of additional power consumption. Consequently, new power plants need to be installed and operated as base load plants in order to supply power continuously to the desalination units. As fossil fuel prices are characterized by high volatility and a clear trend upwards, the use of renewable energies allows for saving fossil fuels and therewith reducing risks related to energy price escalation along the whole desalination life cycle. However, the fluctuant nature of renewable energies conflicts with the—ideally—continuous operation of desalination plants. In contrast to technologies such as photovoltaic (PV) and wind power, which are prone to fluctuating and intermittent power generation, concentrating solar power (CSP) is able to supply firm capacity on demand and can be fully integrated into conventional power utilities. On the other hand, CSP is currently considered to be more expensive than other renewable energy technologies. This work highlights the key importance of comparing technology options with equal quality of supply in order to obtain resilient results. Within this work, a representative site in the Middle East and North Africa Region has been analyzed by two different methodologies in order to demonstrate the potential large difference of results. The first method assumes that any variations of renewable energy supply can be compensated by the electricity grid, while the second method assumes that the addition of load to the electricity grid will require the addition of an equivalent firm power supply capacity. Hourly solar and wind data of a typical meteorological year have been used as inputs for a techno-economic simulation. Different options for CSP solar field layout, thermal energy storage, PV, and wind installed capacity, are analyzed and compared in terms of power and water cost for reverse osmosis and multieffect distillation plants.

Within the MED-CSD project, feasibility studies of integrated hybrid concentrating solar power (CSP) and seawater desalination (DES) plants were carried out in selected locations in Morocco, Italy, Cyprus, Egypt and Gaza/West Bank. After a review on CSP and desalination technologies, ten typical sites within the five partner countries have been selected. For each location, a CSP-DES plant was modeled. The model bases on hourly time series of solar irradiance, ambient temperature, as well as wind speed and includes local seasonal and hourly load curves for power and water. Surplus thermal energy from the solar field is fed into the energy storage, so that operation is possible at night and during cloud transients; gaps between demand and solar power production are covered by cofiring with fossil fuel. Different plant components (solar field collectors and desalination technologies) have been compared. A techno-economic model is applied in order to analyze the economic feasibility and the required financial framework conditions of the projects. Furthermore, an analysis of the market potential of concentrating solar power for sea water desalination in the Mediterranean Region and socio-economic and environmental impact analyses were implemented.