Scottish Islands Interconnections: Modelling the Impacts on the UK Electricity Network of Geographically Diverse Wind and Marine Energy

To meet climate change goals, the decarbonisation of the UK electricity supply is crucial. Increased geographic diversity and resource use could help provide grid and market stability and reduce CO2 intensive balancing actions. The main purpose of this research is to investigate the impact of geographic diversity and Scottish island renewable energy on the UK network. This has been done by using the energy market modelling software PLEXOS with results validated using data for 2017/18. The model considers spatial diversification and forecasting errors by modelling day-ahead and intra-day markets with nodes for each distribution network operator region and island group. It was concluded that Scottish island renewable capacity could have a stabilising effect on the variability of renewables in terms of electricity generated, prices and forecasting errors, from the timescale of the entire year down to hours. The ability of geographically diverse generators to receive a higher price for electricity generated was shown to decrease with increased island capacity. Instances of negative prices were reduced with supply diversity (wind and marine) but not geographic diversity. Day ahead errors showed most clearly the impact of diversity of supply, particularly given the predictability of tidal stream generation

Diameter and Chirality Dependence of Exciton Properties in Carbon Nanotubes

We calculate the diameter and chirality dependences of the binding energies, sizes, and bright-dark splittings of excitons in semiconducting single-wall carbon nanotubes (SWNTs). Using results and insights from {\it ab initio} calculations, we employ a symmetry-based, variational method based on the effective-mass and envelope-function approximations using tight-binding wavefunctions. Binding energies and spatial extents show a leading dependence with diameter as $1/d$ and $d$, respectively, with chirality corrections providing a spread of roughly 20% with a strong family behavior. Bright-dark exciton splittings show a $1/d^2$ leading dependence. We provide analytical expressions for the binding energies, sizes, and splittings that should be useful to guide future experiments

Past trends for the UK Energy Scenarios: How close are their predictions to reality?

This study provides an exploration of the future energy trends in the UK by assessing existing energy scenarios studies and their predictions compared with actual data. The criteria for inclusion were to be national in scope, backcasting and comprehensive (covering the electricity sector). The importance of assessing the historic energy system projections could conduct us to improvements in future energy scenarios. The three studies considered relate to the same four factors: growth indicators, fuel prices, new installations and power stations retirement. The scenarios review revealed several common and different themes although all were developed under the same national targets

Long Term analysis of submarine transmission grid extensions between the Greek islands and the mainland

Interconnections' infrastructure is considered fundamental to implement the common rules for the internal electricity market according to 2009/72/EU. Greece currently consists of 29 non-interconnected island systems, experiencing frequent forced outages and high generation costs. A number of interconnection plans are in the pipeline between the Greek islands in the Aegean Sea archipelago and the Greek bulk continental grid. This paper investigates interconnection scenarios and their impact in terms of security of supply, costs and renewable energy integration into the system. PLEXOS® Simulation Software by Energy Exemplar is used to simulate the Greek electricity system. The results show a twofold growth of renewables share between 2020 and 2040 while electricity generation costs recorded on the non-interconnected islands mirror continental costs following the grid extensions. Loss of load probability and unserved energy are eliminated, whilst greenhouse gas emissions are reduced by 73% (vs 1990) in 2040

Sustainable island power system – Scenario analysis for Crete under the energy trilemma index

Sustainable energy supply is an essential part for economic and social development in every society. Islands as geographical isolated regions have to confront a number of challenges to secure a reliable and clean energy system. Currently, electricity demand on the Greek island of Crete is supplied by oil-fired engines imposed to new emissions restrictions applied from 2020. Thus, a capacity upgrade is necessary and new solutions driven by renewable energy, energy storage and interconnections. This study investigates three scenarios: Business as Usual (BAU); Natural Gas (NG); and the Interconnection of Crete with the National Grid System (Int.) to assess the potential techno-economic and environmental impact of the required transition under the Energy Trilemma Index. A capacity expansion and operation optimisation process has been applied through a high resolution spatio-temporal analysis performed with PLEXOS Integrated Energy Model. It was concluded that no BAU Scenario could facilitate a future plan for the electricity system of Crete or any European island imposed to such constrains. The optimum scenario incorporates interconnectors and energy storage systems that manage to deliver 52% reduction in the total system costs (2020-2040), 79% in electricity prices and 48% reduction in GHG emissions by 2040, compared to the BAU

Modelling electrical interconnections for Rhodes island power system

Remote island power systems often fail to enjoy the right to secure, clean energy supply. This paper presents a short-term analysis for the electrical system of Rhodes-Halki in South Aegean, with the use of a mixed-integer dispatch module in PLEXOS® Simulation Software. While examining the impact of submarine grid extensions, the results show that following the interconnection of Rhodes' power system, rapid renewable energy deployment is recorded, allowing for electricity exports equal to 220 MWh by 2040. Power generation costs decline by 58.9% for the week recording MAX demand and 54.8% for the week recording MIN demand, compared to the BAU autonomous scenario. The scenario imposing generation restrictions according to directives 2010/75/EU and 2015/2193/EU shows high levels of unserved hourly energy equal to 70%-85%

Life Cycle Assessment of Domestic Heat Pumps with Gas Boilers and Hybrid Scenario Analysis in the UK

This research analyses the environmental impacts of domestic heat pumps with gas boilers and scenario analysis through a life cycle approach. The study analyses three scenarios (Transport (SK), 50% Hybrid and 75% Hybrid) to compare their results with a baseline model and also CE 2050 model which has a future outlook. The results show that changing the manufacturing location from Europe to South Korea doesn’t have a significant impact on both models as the weight of manufacturing and transport phases are relatively small compared to the use phase. Hybrid scenario results show increases in GHG emissions; however, the remaining categories have reductions. 50% Hybrid scenario results expect a reduction of 18% and 12% on average in ASHP and GSHP respectively in the baseline model. However, 75% Hybrid scenario results offer less reduction than the half-hybrid scenario in the same model with 8% and 5% decrease in ASHP and GSHP. In CE 2050 model, the results expect an increase of 27% and 21% on average in both heat pumps for 50% Hybrid scenario. On the other hand, CE 2050 model results offer less increase than the half-hybrid scenario for 75% Hybrid scenario with 18% and 13% increase in ASHP and GSHP respectivel

Modelling and forecasting hourly electricity demand in West African countries

The Economic Community of West African States aims to achieve 100% electrification rates by 2030 in all member countries. To achieve this ambitious target, electricity generation capacities need to be increased significantly. Forecasting hourly electricity demand is imperative for capacity planners in optimizing investment options and ensuring reliable electricity supply. However, modelling hourly electricity demand in developing countries can be a challenge due to paucity of historical demand data and methodological frameworks that adequately capture technology transitions and urban-rural communities. In this study, we address this gap by developing an hourly electricity demand model for 14 West African countries in the year 2016 and 2030. The model takes into account electrification rates, available household appliances, occupancy patterns of household members, type of day, available daylight hours and hourly weather conditions. Annual electricity demand in non-residential sectors and electricity access rates in urban and rural households are forecasted using multiple regression analysis. We validated the developed model using actual 2016 monthly and annual electricity demand data. The results show the seasonal variations of electricity demand, with hourly electricity demand in dry seasons relatively higher than demand in wet seasons. The results also indicate that in 2030, electricity demand in the West African region is estimated to be five times its 2016 level. The methodology presented in this study can be applicable for modelling hourly electricity demand in developing countries that have scarce historical hourly demand data, a significant electricity supply-demand gap, and varying electricity access rates in urban and rural areas

Quantifying the integration of renewable energy sources in West Africa’s interconnected electricity network

The West African Power Pool (WAPP) aims to provide access to affordable electricity to all countries in the region by installing electricity interconnections between countries and creating an integrated electricity market. In this study, we develop a multi-regional economic dispatch model of the West African power system, and quantify the impact of increasing cross-border electricity trading and renewable energy sources on: electricity generation cost, carbon emission, electricity supply and rapidly growing demand. Our results indicate that increasing cross-border electricity trading significantly reduces unserved electricity demand that comes from load shedding in the region. However, in the 2030 scenario where only existing and currently planned generation plants are operational, increased cross-border electricity trading increases electricity generation from heavy fuel and diesel power plants by 16% and 8% respectively. Consequently, this results in an increase in total electricity generation cost and carbon emission in the region. In two scenarios where all fourteen countries in the region are interconnected, average marginal costs in most of the net importing and net exporting countries decrease and increase respectively, due to insufficient generation capacities in several countries. A key finding from our study is that most of the planned interconnections by WAPP could be underutilized in 2030, thus providing an opportunity to integrate unexplored hydro and solar resources in the region