A new JRC lead-authored report on transmission network planning, Inputs for a vision on the future European energy infrastructure, highlights that a radical change in coordinated network planning and operation is needed to accommodate market liberalisation and the increasing integration of renewable power sources. It finds that the key issues to obtain a reliable and effective European grid are integrated strategic planning and cross-border coordination.
The importance of electricity transmission grids - the backbone of the EU's economy - is higher than ever. These networks are getting older, are confronted with complex market liberalisation processes and have to host increasing amounts of renewable energy sources. Furthermore, in order to address the challenges of energy security and climate change, transmission grids need to become more interconnected and smarter by seamlessly integrating a wide range of users such as generators, consumers and/or other grids.
In the EU, electricity grids are included among the low carbon energy technologies assessed as part of the strategy to achieve the energy and climate change policy targets. These include a 20 per cent reduction of carbon dioxide emissions and a 20 per cent share of renewables in overall EU energy consumption by 2020. In turn, this translates to 30-35 per cent of electricity consumption covered by renewable energy sources.
According to SETIS, if the maximum potential is realised, the EU's electricity grids could reduce carbon dioxide emissions by up to 30m t/y in 2020 and 60m t/y in 2030. The corresponding maximum cumulative carbon dioxide emissions avoided for the period 2010 to 2030 would be up to 600m t/y.
However, the report notes that such a strategy relies totally on better planning: "Existing transmission planning methods commonly make use of a worst-case scenario approach: power flow analysis is performed for a small number of cases selected by experienced network planners. With the increased uncertainty and the many assumptions necessary for the analysis, the need to include more combinations of load, (renewable) generation and international exchange is becoming essential and a probabilistic approach to deal with such uncertainties is needed."
In terms of the way forward, the reports calls for a rethink on the planning criteria for expanding the transmission and distribution grids together with more robust methodologies for network planning.
Current transmission and distribution systems in Europe do not talk to each other. It is therefore critical to improve the two-way interactions between electricity transmission and distribution. The report cites the recent disturbance and disruption events in Europe, for example the 4th November 2006 problem which originated in Germany and then spread all over the continent. The reportsays: "One of the causes of the German problem was in fact the inadequate monitoring and control by transmission operators of small-sized generation units installed at distribution level. The uncoordinated action during the disturbance worsened the situation and introduced a risk of more severe instability. Such disturbances prove that, without properly coordinated system interfaces between transmission and distribution, and real-time information exchange - for example concerning generators connected to the distribution network - the consequences of a power disruption at the distribution level may also be suffered, if not amplified, at the transmission level.
The recent JRC review of existing methods for transmission planning and for grid connection of wind power plants presents the state of the art in this field and points the way for future developments. The report's findings and recommendations include:
- Transmission planning must change drastically to accommodate market liberalisation and increased integration of wind and other sources of renewable power.
- Grid expansion should focus on achieving better coordination between transmission system operators (TSOs) through integrated strategic planning and cross-border cooperation.
- Transmission planners should take a smarter approach to integrating 'variable' power sources such as wind, solar, hydro and wave, which do not generate consistent levels of power - for example by balancing the variable power with storage technologies.
- TSOs should prioritise the emerging challenge of integrating the future transmission system (hosting large-sized generation, both conventional and renewable) with smart distribution grids (embedding dispersed small sized energy sources and storage).
- A more harmonised and market-based framework is required to overcome planning and regulatory differences at national level, and to realise the potential synergies between offshore energy projects and cross-border trade in electricity.
In detail, future development of the EU grid might include further use of HVDC interconnections. Although these involve higher costs, the report notes that they use less land and have fewer decoupling disturbances. Wind generation could be connected with hydro reserves, for example those in Norway, while interconnecting several offshore wind projects would help reduce the impact when the wind speed is low in one particular area.
Another suggestion is the establishment of a set of super-grids - in effect a higher voltage European backbone - to reduce losses over long distances and facilitate long-distance transportation. This could also involve connecting wind power generators in NE Europe and the solar power generators in the Mediterranean basin with the major energy-intensive areas of the EU.
A case is also made for replacing existing aging transmission lines with new materials, which will extend their limits. Integrating these with new smart control methodologies will balance the flows, while evaluation of using buried cables could create a way of overcoming the difficult and time-consuming consent procedure needed for overhead lines.
The full Inputs for a vision on the future European energy infrastructure report can be found at
Meanwhile, many companies are already heavily-involved in smart grid technology development. For example, Intergraph has recently partnered with Siemens Power Transmission & Distribution in the US to provide Oncor Electric Delivery with integrated smart grid services that combine Intergraph outage management systems with distribution management solutions from Siemens.
Oncor operates the largest distribution and transmission system in Texas, delivering power to approximately three million homes and businesses and operating approximately 117,000 miles of distribution and transmission lines in the state.
