Germany energy model with 39% Renewable Energy

 Germany Models its Transmission System for 39% Renewable Energy 
Major upgrading of the German electricity transmission system to incorporate technologies such as flexible line management or high temperature-resistant aluminium conductors would not be cost effective, according to a report from the German Energy Agency, DENA GmbH.
The study looks at the transmission requirements of a German grid that guarantees security of supply, while operating in a liberalized European energy market, when 39% of power is supplied from renewable energy sources. (Germany plans to generate 39% from renewable sources in 2020.)
Modelling a series of options, DENA’s Grid Study II considers the benefits and costs of upgrading to new transmission technologies such as HVDC and high temperature conductors, as well as the effects of grid management measures, the addition of storage capacities and demand-side management for load shifting. The study team considered the environmental impact and public acceptability of these technologies as well as their effects on availability and economic efficiency.
To maximise the accuracy of estimates of wind power availability in 2020, a 15-minute time series of wind conditions for Germany was developed from historic records. The effects of intermittency on system services, voltage support and short-circuit power, as well as islanding and system restoration were covered in detail. 
Role of capacity-enhancing technologies
The installation of flexible line management technologies that monitor the temperature of conductors could increase the current-carrying capacity of overhead lines in Northern Germany by approximately 30% and in Southern Germany by 15%. High temperature-resistant aluminium conductors that are designed to operate at higher temperatures allow 50% greater load capacities in some cases. Both technologies would be cost-effective on specific lines that are needed for the additional transmission demands from new wind generation. But the study found comprehensive use of neither technology was economically efficient.
A basic scenario where there is little upgrading of existing transmission lines and no addition of power storage facilities, would require 3,600km of new routes and would cost €946 million per annum to 2020. That would increase the transmission tariff for domestic customers from 5.8 cents per kWh to 6.2 cents per kWh.
A solution using flexible line management would reduce the new routes needed by 100 km, but line upgrading costs would make the solution slightly more expensive than the basic scenario – at €985 billion, or a transmission tariff to domestic customers of 6.3 cents per kWh.
Modifications would be needed on 5,700 km of existing routes as well as the addition of 1,700 km of new routes if high temperature resistant aluminium conductors were used, costing €1.6 billion. 
Storage motivations
The study team found that storage facilities operated according to the existing market regulations made only a minor contribution to the grid integration of non-transmittable power trapped behind regional bottlenecks. As the electricity market and the grid operation are economically separate, the economically optimal behaviour of storage facilities to maximise prices in the electricity market do not necessarily result in behaviour which relieves grid bottlenecks.
The study team also modelled the potential for greater use of demand side management in 2020 and found that 60% of positive balancing energy and 2% of negative balancing energy could be covered by demand side management. Load smoothing via demand side management could reduce peak load demand by around 800 MW, a saving of €481 million. The study is based on an assumption that Germany’s electricity demand will fall by 8% in the ten years between 2010 and 2020. Onshore wind is expected to grow to 37 GW and offshore wind will reach 14 GW. By 2015 PV will have reached a generation capacity of 13 GW and will grow a further 4.9 GW to 2020. Biomass is expected to add 900 MW between 2015 and 2020, to reach 6.2 GW.
After the original study period, the authors were asked to look at the effects of a delayed phase-out of nuclear energy. They found that it would not affect the future expansion of renewable energy sources.
(source : Leonardo-energy )