Publications

2025

Do organic farming policies need to be more target-oriented to achieve sustainability?
Rey Vicario, D., Kremmydas, D., Baldoni, E., Ciaian, P., & Tillie, P. Journal of environmental management, 394, 127342 doi.org/10.1016/j.jenvman.2025.127342.

Compares three EU organic conversion strategies (action-based, result-based, and combined) using IFM-CAP. Result-oriented policy delivers higher GHG reductions per euro by targeting high‑emitting livestock farms but is costlier and may miss the 25% area target. Action‑oriented policy is cheaper and closer to the 25% area goal but achieves lower emission reductions. Recommendation: target farms with greater emission‑reduction potential rather than only expanding converted area. Download

2024

Closing the EU protein gap – drivers, synergies and trade-offs
Hristov, J., Tassinari, G., Himics, M., Beber, C., Barbosa, A.L., Isbasoiu, A., Klinnert, A., Kremmydas, D., Tillie, P., & Fellmann, T., JRC Report, Publications Office of the European Union, ISBΝ dx.doi.org/10.2760/84255

The report argues that EU protein policy must link plant-protein supply with food- and feed-sector demand. It evaluates four scenarios: supporting protein crops, changing feed practices, restructuring livestock, and shifting to plant-based diets. Results show that combining supply- and demand-side changes brings the largest environmental gains and reduces reliance on imported protein. An integrated strategy is needed to support farmers, strengthen resilience, and manage impacts during the transition.

The EU target for organic farming: Potential economic and environmental impacts Kremmydas, D., Beber, C., Baldoni, E., Ciaian, P., Fellmann, T., Gocht, A., Hristov, J., Pignotti, D., Rey Vicario, D., Stepanyan, D., & Tillie, P. Applied Economic Perspectives and Policy, 47(2), 602-623 doi.org/10.1002/aepp.13470

The EU aims to reach 25% of the total agricultural area under organic farming by 2030. Interlinking a farm-level and agro-economic market model, we assess impacts of achieving the target either at Member State or aggregated EU level. Results show that flexible budget allocation across Member States would be more cost-efficient and less detrimental to EU production. Conversely, targeting at Member State level proves more effective in generating greater aggregated and more evenly distributed environmental benefits across EU regions. The results indicate the importance of leveraging tailored approaches to optimize organic farming outcomes across the EU. Download

2023

Modeling conversion to organic agriculture with an EU-wide farm model
Kremmydas, D.; Ciaian, P.; Baldoni, E.
Bio-Based and Applied Economics, 12(4), 261–304. doi.org/10.36253/bae-13925

The paper evaluates the EU Farm to Fork target of reaching 25% organic farmland by 2030 using a farm-level model. It compares two ways of modelling conversions to organic farming: an endogenous approach, where farmers decide based on utility differences, and an exogenous approach, based on econometric estimates of conversion likelihood. Results differ by method: farm income changes range from a 3.8% increase (endogenous) to a 1.3% decrease (exogenous). Both approaches, however, predict lower agricultural production (between 0.5% and 15%) for most crops and livestock products if the target is met. Download

Farm-level impacts of the CAP post-2020 reform: A scenario-based analysis
Petsakos, A., Ciaian, P., Espinosa, M., Perni, A., & Kremmydas, D.
Applied Economic Perspectives and Policy, 45(2), 1168–1188. doi.org/10.1002/aepp.13257

The paper analyzes the farm-level economic and environmental impacts of the post-2020 reform of the Common Agricultural Policy (CAP) of the European Union, examining six scenarios constructed around the budget allocated to eco-schemes and the stringency of enhanced conditionality. Results suggest that the CAP post-2020 can improve environmental performance but at a cost for farms. Enhanced conditionality appears to play a greater role than eco-schemes in delivering environmental improvements. The new CAP provides the Member States ample options to choose among different measures. The optimal policy mix will depend on the balancing of income support versus environmental performance that reflects policy priorities. Download

Agro-economic–environmental modelling in the context of the Green Deal
Fellmann, T.; Genovese, G.; Antonioli, F.; et al., incl. Kremmydas, D.
JRC Report, Publications Office of the European Union, ISBΝ 978-92-68-10181-0 (online) dx.doi.org/10.2760/123978

iMAP is a modelling platform supporting the European Commission in assessing policies for sustainable food systems, with major development driven by DG AGRI. The report presents iMAP’s expanded capacity to analyse production, environmental, and Green Deal–related policy impacts, thanks to integration of biophysical models and satellite data. Despite these advances, modelling environmental and consumer-related aspects remains limited by data gaps and biological complexity. Overall, iMAP—enhanced through interdisciplinary tools—offers a strong framework for evaluating Green Deal policies, though key uncertainties still constrain full assessment of the transition to sustainable food systems.

2022

Redistribution and the abolishment of historical entitlements in the CAP Strategic Plans
Kremmydas, D., & Tsiboukas, K.
Sustainability, 14(2), 735. doi.org/10.3390/su14020735

A key issue in CAP strategic planning in Greece is the treatment of historical entitlements. An unequal level of payments per hectare is difficult to justify in terms of the CAP’s rationale, and so the abolishment of these entitlements seems to be the most reasonable option. However, for historical reasons, this abolishment may result in a transfer of payments from smaller to larger farms and between different agricultural sub-sectors which could in turn lead to negative effects on the incomes of small farms and lead to farmers leaving the sector. We simulate the change to a flat rate payment in order to quantify these effects, then explore the possibility of employing the new obligatory redistribution measure, termed complementary income support, to mitigate any negative effects. We conclude that redistribution is, indeed, a powerful tool for fine-tuning decoupled payments if historical entitlements are to be abolished. Download

2021

The EU-Wide Individual Farm Model for CAP Analysis (IFM-CAP v.2)
Kremmydas, D., Petsakos, A., Ciaian, P., Baldoni, E., & Tillie, P.
JRC Report, Publications Office of the European Union, ISBΝ 1831-9424 (online) dx.doi.org/10.2760/248136

The report presents IFM-CAP V.2, an EU-wide individual farm-level model used to assess post-2020 CAP reform impacts on farm economics and the environment. It addresses the need for a micro-simulation tool that captures farm-specific policies and the heterogeneity of EU farms. Using Positive Mathematical Programming, the model improves policy assessment quality and analyzes distributional effects across 83,292 FADN farms. The report details the model’s design, mathematical structure, data preparation, livestock modelling, input allocation, CAP modelling, and calibration, along with its theoretical basis and output capabilities.

The Evolution of Decision Support Systems for Agriculture
Kremmydas, D.; Konstantinis, A.; Rozakis, S.
In EURO Working Group on DSS, Springer. doi.org/10.1007/978-3-030-70377-6_6

We use the Scopus database and naïve Bayes text classification to identify almost a thousand and a half DSS papers targeting problems in agriculture during the last three decades. We then use bibliometric network analysis to establish the chronological trends regarding the methodologies, the technologies, the topics, and their interrelation. We also provide insights into the evolution of international research and academic community cooperation and specialization. Download

A design for a generic and modular bio-economic farm model
Britz, W.; Ciaian, P.; Gocht, A.; Kanellopoulos, A.; Kremmydas, D. et al.
Agricultural Systems, 191, 103133. doi.org/10.1016/j.agsy.2021.103133

Past assessments highlight the need for a generic, modular BEFM that can be maintained by a network of modellers. Current project-based funding leads to many case-specific models instead of robust, comparable ones. This paper identifies required features and design principles for such a modular tool through literature and model reviews. It proposes concrete steps and a research agenda to build a flexible, network-maintained BEFM for future policy analysis. Download

2020

The Matthew effect of a journal’s ranking
Drivas, K., & Kremmydas, D.
Research Policy, 49(4), 103951. doi.org/10.1016/j.respol.2020.10395

The paper examines the impact of a journal’s ranking on the citations its papers garner. Our testbed is journals included in the early annual publications of the Academic Journal Guide, published by the Association of Business Schools from 2007 to 2010. By focusing on a small subset of these journals, we provide causal evidence that an increase in a journal’s ranking will increase citations to its papers. We argue that this increase can be attributed to (i) more authors learning about and viewing these outlets and their publications and (ii) researchers signalling their paper’s own impact by citing highly ranked journals. We find some evidence for the former, though not robust, and substantial evidence for the latter. Given that signalling is deliberate and associated with incentives to publish in highly ranked journals, we decompose this channel by citing researchers’ characteristics. Except for senior academics, all types of researchers are consistent with signalling. The policy implications of our results relate to the pervasive use of journal rankings and recent initiatives to evaluate research. Download

2018

A review of agent-based modeling for agricultural policy evaluation
Kremmydas, D.; Athanasiadis, I.N.; Rozakis, S.
Agricultural Systems, 164, 95–106. doi.org/10.1016/j.agsy.2018.03.010

Farm level scale policy analysis is receiving increased attention due to a changing agricultural policy orientation. Agent based models (ABM) are farm level models that have appeared in the end of 1990’s, having several differences from traditional farm level models, like the consideration of interactions between farms, the way markets are simulated, the inclusion of agents’ bounded rationality, behavioral heterogeneity, etc. Considering the potential of ABMs to complement existing farm level models and that they are a relatively recent approach with a growing demand for new models and modelers, we perform a systematic literature review to (a) consolidate in a consistent and transparent way the literature status on policy evaluation ABMs; (b) examine the status of the literature regarding model transparency; the modeling of the agents’ decision processes; and the creation of the initial population. Download

Allocating Shadow Prices in a Multi-objective Chance Constrained Problem of Biodiesel Blending
Caldeira, C., Dias, L., Freire, F., Kremmydas, D., & Rozakis, S.
In Multicriteria Analysis in Agriculture, Springer. dx.doi.org/10.1007/978-3-319-76929-5_5

Biodiesel can be made from different mixes of vegetable oils, and choosing the right blend strongly affects both cost and environmental impact. This chapter introduces a model that finds the optimal oil blend to minimize production costs and greenhouse gas (GHG) emissions, while respecting technical constraints related to biodiesel quality and feedstock composition. Using shadow prices, the model identifies which technical limits most restrict cost savings and GHG reductions. It can therefore be used to assess how technological improvements or policy requirements would influence biodiesel costs and emissions. Download

2016

The impact of different energy policy options on feedstock price and land demand
Bartoli, A.; Cavicchioli, D.; Kremmydas, D.; Rozakis, S.; Olper, A.
Energy Policy, 96, 351–363. doi.org/10.1016/j.enpol.2016.06.018

The aim of this work is to quantify the extent to which the rapid spread of biogas raised the maize price at regional level, increasing the demand of land for energy crops. For this purpose we applied a partial-equilibrium framework simulating the agricultural sector and the biogas industry in Lombardy, under two alternative schemes of subsidization policy. Results show that policy measures implemented in 2013 – reducing the average subsidy per kWh – may contribute to enforce the complementarity of the sector with agri-food chains, decreasing the competition between energy and non-energy uses. Compared to the old scheme, maize demand for biogas would decrease, lessening the market clearing price (as well as feed opportunity cost for livestock sector) and reducing land demand for energy purposes. Download

Data warehouse technology for agricultural policy data: a Greek case study
Maliappis, M.T.; & Kremmydas, D.
International Journal of Sustainable Agricultural Management and Informatics, 2(2–4), 243–262. https://doi.org/10.1504/IJSAMI.2016.082002

Statistical data for agricultural policy analysis has certain unique features: a multitude of sources of very different nature, a variety of dimensional granularity and different end user requirements. The utilisation of data warehouse (DW) technology is valuable for tackling the above issues and successfully offering data to policy stakeholders and modellers. In this paper, we briefly introduce the DW technology, discuss the DW design issues in the context of policy related data and investigate the several difficulties identified on building and using a DW for monitoring crop responses to climate change for two Greek regions. Download

2015 and before

Food Inflation in the European Union: Distribution Analysis and Spatial Effects
Liontakis, A., & Kremmydas, D.
Geographical Analysis, 46(2), 148–164. dx.doi.org/10.1111/gean.12033

The issue of inflation convergence in the EU, has gained increasing attention by both academics and policy makers in Europe. This study explores the evolving distribution of food inflation rates in the EU-25 member states using distribution dynamics analysis and covering the period from January 1997 to March 2011. We show that spatial autocorrelation prevails inside the EU-25, and, therefore, the independency assumption is violated. The results of this analysis confirm the existence of convergence trends, which are even clearer after the spatial filtering procedure, indicating, on the one hand, the influence of spatial effects on food inflation and, on the other hand, the effectiveness of the Getis spatial filtering technique. Download

Straw potential for energy purposes in Poland
Rozakis, S.; Kremmydas, D.; Pudełko, R.; Borzęcka-Walker, M.; Faber, A.
Biomass and Bioenergy, 58, 275–285. doi.org/10.1016/j.biombioe.2013.06.011

Based on statistical data from the Polish Central Statistical Office (CSU) the actual production of straw was modelled on a scale of local districts (NUTS-5) as well as the needs of its local use and the possibility of redistribution of excessive quantities to regions with a deficit of straw. As a result, the straw surplus that could be used in the energy sector was obtained along with its geographical distribution. Next, a cost-minimising transport model is used to optimise the straw’s allocation among main power plants all over the country, taking into account capacities and technical constraints of co-firing biomass with coal. The results are detailed at the municipal level indicating excess capacity for biomass co-firing by plant and regions to be satisfied by additional biomass sources such as biomass from forest or energy plantations. Download

Highly scalable parallelization of standard simplex method
Mamalis, B.; Pantziou, G.; Dimitropoulos, G.; Kremmydas, D.
International Journal of Computers and Applications, 35(4), 152–161. doi.org/10.2316/Journal.202.2013.4.202-3691

In this paper we present a highly scalable parallel implementation framework of the standard full tableau simplex method on a highly parallel (distributed memory) environment. Specifically, we have designed and implemented a suitable column distribution scheme as well as a row distribution scheme and we have entirely tested our implementations over a considerably powerful distributed platform (linux cluster with myrinet interface). We then compare our approaches (a) among each other for variable number of problem size (number of rows and columns) and (b) to other recent and valuable corresponding efforts in the literature. In most cases, the column distribution scheme performs quite/much better than the row distribution scheme. Moreover, both schemes (even the row distribution scheme over large-scale problems) lead to particularly high speedup and efficiency values, which are considerably better in all cases than the ones achieved in other similar research efforts and implementations. Moreover, we further evaluate our basic parallelization scheme over very large LPs in order to validate more reliably the high efficiency and scalability achieved. Download

Parametric Optimization of Linear and Non-Linear Models via Parallel Computing
Kremmydas, D.; Petsakos, A.; Rozakis, S.
International Journal of Decision Support System Technology, 4(1), 14–29. doi.org/10.4018/jdsst.2012010102

A web based Spatial Decision Support System (web SDSS) has been implemented in Thessaly, the most significant arable cropping region in Greece, to evaluate energy crop supply. The web SDSS uses an optimization module to support the decision process launching mathematical programming (MP) profit maximizing farm models. Energy to biomass raw material cost is provided in supply curve form incorporating physical land suitability for crops, farm structure, and Common Agricultural Policy (CAP) scenarios. To generate biomass supply curves, the optimization problem is parametrically solved for a number of steps within a price range determined by the user. The more advanced technique used to solve the MP model, the higher the delay of response to the user. In this paper, the authors examine how effectively the web SDSS response time can be reduced to the user requests using parallel solving of the corresponding optimization problem. The results are encouraging, since the total solution time drops significantly as the problem’s size increases, improving the users’ experience even when the underlying optimization models use advanced, time demanding modeling techniques. These statements are illustrated by comparing linear and non-linear agricultural sector models. Download

Support and protection of Greek agriculture
Karanikolas, P.; Bourdaras, D.; Kremmydas, D.; Martinos, N.
South-Eastern Europe Journal of Economics, 6(2).

This paper aims at determining the level of support for Greek agriculture. The calculations are performed on a commodity basis over the period 1989-2006. By using an adapted OECD methodology, research findings indicate that the overall support level for Greek agriculture is similar to that of the EU, though after 2002 diverging trends are observed. A redistribution of the various parts of support is ascertained, whereas livestock production is more supported than crop production. The ratio of market price support to the total value of production seems to explain variations in support levels between Greece and the EU. The need for a critical reappraisal of OECD methodology is stressed. Download