Evolution towards the still poorly-defined ‘smart grid’ concept promises change for several aspects of Europe’s electricity system. Here, COGEN Europe’s Fiona Riddoch suggests that cogeneration, and particularly its role to help balance increased levels of renewable generation being placed on the system, can help meet several current policy goals.
The liberalization of the electricity and gas sectors in Europe has been a major focus of the European Union’s energy policy over the past years. In parallel to the efforts on opening the networks to competing electricity producers and dismantling the old state controlled energy companies, there is a drive to harmonization and standardization of procedures to allow better interaction across borders and within regions. Simultaneously this liberalization process is having to absorb a range of other changes driven by the energy and climate agenda which is impacting the primary energy and electricity supply market as it moves forward.
The 2020 energy and climate targets of a reduction in emissions of carbon dioxide, an increased proportion of renewable energy in the energy mix and increased energy savings are collectively changing Europe’s long term energy supply mix.
The EU has extended its energy vision horizon from 2020 to 2050 and is now actively engaged in discussions around the challenges and energy vision in this extended time frame. The balance between central and distributed generation and the requirements for energy storage in different parts of the overall supply system are shifting in response to the near and longer-term energy and climate goals. End use energy efficiency measures, such as the European Performance of Buildings Directive, are changing heat and electricity demand in buildings. The buildings sector’s demand for heat will decrease significantly over the period up to 2050. European environmental and energy policies, as well as the shift of the production sector to Asia, are impacting industrial energy use. Next to that, the scenarios governing the longer-term trajectory of electricity demand are currently being hotly debated.
The need to rethink the physical electricity supply network was a topic from early on in the climate and energy strategy development. However, the full need for a different approach to the grid was brought home to the EU by a real life demonstration of what could go wrong under the current structure and approach.
BLACKOUT PROMPTS REFORM
A serious blackout on the continental European electricity network on 4 November 2006 led to electricity cuts over Germany, France and Italy and involved 15 million electricity customers being disconnected. Although the disconnection was brief, its ultimate impact was permanent.
The 20 kWe EcoBlue micro-CHP unit from LichtBlick will help to balance wind in the German electricity network
In the reports which followed, it became clear that the electricity transmission system operator who was at the origin of the fault did not have the necessary security procedures in place. Moreover, he did not have adequate technical tools to verify that the system operated within the proper security limits when choosing to make a major change to its network. Other European transmission system operators did not receive information on the actions taken by the German transmission operator. Some mechanisms which protected the grid in traditional scenarios, such as disconnection of distributed generation, added to the problem in the system. The lack of sufficient investment both at the level of the reliability and of the operation of the grid were highlighted by the incident and the analysis which followed.
In summary the operation, management and hardware of the electricity network at the European level was inadequate for the 21st century demands. Faced with a very visible example of what could happen without reform of the grid, the European Commission intensified its efforts.
There is now activity around almost all aspects of transmission and distribution at the European policy level, with the electricity network reform leading the way. There has been much spoken and written in support of a new ‘smart grid’, although the exact definition of the term remains dangerously hazy. Dedicated working groups ensure that some of the main elements are being defined. The new smart grid must, by definition, provide reliable electricity supply to European consumers. It must do this efficiently in the context of the new low carbon fuel/general supply mix. It must allow simple cost-effective incorporation of new supply options, including principally increased capacity of distributed generation. It must also cope with the increased intermittency which will result from the incorporation of a significant capacity of renewable energy.
AN UPSIDE FOR COGENERATION
This new, more diverse, more distributed world offers some advantages for cogeneration.
Optimum fuel efficiency ticks all the 2020 boxes
Cogeneration is one of the few technologies which addresses all of the 2020 targets. Cogeneration is a highly effective primary energy saving technique for generating heat and electricity. Through energy efficiency, less primary fuel is required to be burned to meet a specific amount of heat and electricity demand. Hence less carbon dioxide is emitted.
Cogeneration helps meet the renewables target in two ways. By maximizing the efficiency in generating heat and electricity the sustainability is improved of the overall process, while by contributing to the overall fossil fuel primary energy savings, cogeneration makes it easier for Europe to achieve its renewables target. The industry employs over a hundred thousand people in Europe and reliably supplies 11% of Europe’s electricity.
Rapid starting, stopping and greatER efficiency over a wide load range.
Around 40% of Europe’s cogeneration uses natural gas, with an additional few percentage points running on other gases. Within the fuel choices in the electricity supply sector, gas plant has the advantage of being very fast to start, adjust and stop. This means in the absence of sufficient capacity to meet peak demand or, in the absence of transmission capacity, high efficiency cogeneration on gas is an effective way to adjust the supply to meet rapidly changing demand.
Gas engines (the main CHP technology in the size ranges up to 15 MWe), as well as exhibiting rapid response, operate very efficiently over a wide load variation – as illustrated in Figure 1.
|Figure 1: Ancillary services from cogeneration plants|
Balancing intermittency of renewables
The intermittency of renewables – of wind in particular – demands flexibility of response of operation from other suppliers on the grid. The successful combination of CHP and renewables is attracting increasing attention. Today, in Denmark when the wind speed drops by just one meter per second the country needs to find an additional 350 MW of electric power.
Gas CHP clearly has the response time to be able to adjust to such fluctuation. To maintain the necessary high efficiency of primary energy use, which is the advantage of cogeneration, the system must also have useful heat demand associated with the electricity demand, and traditional users are beginning to find new ways to meet this need for flexibility.
CHP MEETING MARKET NEEDS
There are already some gas-based CHP systems which are responding to the market needs and exhibiting more flexibility in their operating approach. Greenhouses in the Netherlands, for example, can respond to market demand by shifting their heat and electricity needs through the day. In Denmark – the country with the highest penetration of both CHP and wind in its supply system – the district heating companies which use cogeneration to maximize the efficiency of their fuel use, are increasingly providing the grid with balancing functions.
In Germany, micro-CHP has been identified as the solution to balancing wind in the network. LichtBlick is the largest independent energy supplier in Germany and has announced its goal to place 100,000 micro-CHP systems with an electric output of 20 kW each into homes and buildings in Germany. The property owner will be provided with the CHP unit and a heat storage unit and be guaranteed that the home will be supplied with heat as required. LichtBlick maintains ultimate control over the CHP unit, with remote capability to manage the unit. A large heat store de-couples the production of heat from that of electricity when necessary. The multiple small units give a sensitive and responsive network of immediate capacity to create a supply of up to 2 GW.
These bright spots in the market show the enterprising nature of the sector, combined with positive support, structures in member states with high ambitions for energy efficiency. Meanwhile, the EU policy around the smart grid and European wide structures is struggling to keep pace with the demand from both cogeneration and renewables for an enabling policy structure with a Europe wide relevance.
It is still very early days for the smart grid concept, and a session will be dedicated to this topic at the COGEN Europe and EuroHeat & Power joint conference this year (to be held on 2 June in Brussels). There is no clear definition of scope of the term and, currently, several actions at European level are collecting information and debating the topic. Some stakeholders seem to be talking of a far-reaching re-invention of the grid with extensive ambition into load management at the appliance level. Other stakeholder groups focus on the immediate and simpler needs for real-time information covering supply and demand status at both TSO and DSO level, the ability to respond flexibly, and a structure to allow distributed generation to connect with ease. One commentator observed ‘smartness is not an objective in itself, it is a set of tools for supporting the achievement of the 20/20/20 targets’.
There is no doubt the electricity sector faces a time of change:
- changing overall demand patterns
- scarce and costly fuels
- greenhouse gas emissions/sequestration
- fluctuating demand/production
- integration of wind, solar and tidal power
Faced with this range of challenges, cogeneration has a lot to offer the European smart grid. Cogeneration is a mature, available technology which is understood and supported. It fits into the new distributed generation role. It modernizes the grid and provides electricity and heat locally where it is needed, and balances the intermittency of renewables.
Dr Fiona Riddoch is managing director of COGEN Europe, Brussels, Belgium.