Flexibility of thermal power generation for RES supply in Germany until 2020

Abstract

EC Directives (EC in SEC 85/3, 2008; EP, EC in COM 19, 2008) give individual targets in emission reduction and renewable energy share to the member states of the European Union. Germany is obligated to reduce its green house gas emissions by 14 % until the year 2020 related to the year 2005 and to increase its share of renewable energy in the final energy consumption to 18 %. For electrical energywhich is the main topic of this paperthe portion of electricity based on renewable energy sources (RES) is projected to increased from 15 % in 2008 to 40 % until 2020 (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit, 2012). Because of the short period of time, this ambiguous target represents a big challenge in development of adequate renewable generation. The high shares of wind or PV in the supply system necessitates to expand the storage capacities, extend the transmission and distribution grids and improve flexible operation of the entire energy system, star ting with generation and ending with demand side. Long term scenarios of electricity generation and demand in Europe until 2040 can be found in Eurel (2012). To maintain the high standard of security of supply in the German grid, a Task Force of VDE has investigated the needs to balance the German energy system under the aspect of high penetration of RES. For the analysis of the consequences for the non-renewable power generation, a simulation model of the German energy system had been elaborated, which considers the development of RES shown in the reference scenario (VDE AT40, 2012), for the following development of RES until the year 2020: wind 60 GW, PV 60 GW, run-of-river hydro 5 GW (constant) and biomass 7 GW. In total the installed power of RES might achieve 130 GW. Considering the coincidence of RES generation, it will touch the grid load many times over the year and to a small extend overshoot the existing demand. The system simulations show, that the thermal fleet will be facing load gradients of up to 15 GW/h over 1 h in the year 2020. These high gradients will need flexible thermal power plants, which will be able to respond to fast changing

Fuel Cell Electric Vehicle‐to‐Grid: Experimental Feasibility and Operational Performance as Balancing Power Plant

“…We contend that grid‐connected FCEVs are indeed capable of meeting the requirements for future balancing power plants identified by Brauner et al. . With a maximum V2G DC power output of 10 kW, the maximum downward and upward power gradients of the FC were –47 kW s −1 (–470 % s −1 ) and +73 kW s −1 (+730 % s −1 ) respectively, at the sample frequency of 5 Hz.…”

“…As shares of intermittent renewable energy sources increase , stationary back‐up power plants will face even lower utilization factors in coming years and require expensive back‐up power , , . Passenger cars also face low utilization factors and could be put to better use while parked.…”

“…Brauner et al. identified the following operational requirements for balancing power plants in the future, once high shares of intermittent renewables have been achieved, and particularly in cases where large‐scale pumped storage is limited or unavailable: ability to perform high power gradients (≥ 0.05 % s −1 of all plants in the grid combined); ability to be operated at low minimal generation (e.g., 15–20 % instead of 40 %); high efficiency under partial load as well as nominal load (e.g., 25 % instead of 50 % partial load); high number of start‐ups and shutdowns (e.g., 0.5 start‐ups and shutdowns per day instead of 0.25 start‐ups and shutdowns per day); ability to schedule cars in the face of an insecure day ahead energy prognosis. …”

“…Brauner et al. stated that, for a load gradient of 15 GW h −1 in the grid, approximately 25 GW of flexible power plants with 0.0167 % s −1 of power capacity must be available for the German electricity system in 2020. However, the available capacity could be reduced to 8 GW, if an ability of 0.05 % s −1 could be achieved.…”

“…Aeroderivative open‐cycle gas turbines and gas engines can reach 1.67 % s −1 under hot start conditions , reducing the available capacity to 0.25 GW – this amount corresponds to 25,000 cars at a rated capacity of 10 kW. Increasing the ability to perform high power gradients reduces the number of power plants in hot standby and economizes energy .…”