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CHP supports renewable energy. But who should pay?

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Chris Marsland, Technical Director for ENER-G Group explains how combined heat and power could play an integral part for more renewable energy to be brought onto the grid. But the added complexity of doing so is costly, so who should pay?  


Strange as it may seem, the UK gas combined heat and power (CHP) fleet, in addition to reducing carbon emissions by generating our energy more efficiently, is also providing invaluable support for the growing renewables industry.

This is great, you might think, as we need to move to a new order of sustainable energy and reduced carbon emissions. But what extra cost burden will the increase in wind and solar supply add to CHP generation in the near future, and who should pay for it?

You might be familiar with the European Union's work on grid codes. New codes are being put in place and are designed to prepare and improve the EU wide electricity network for the future.

Several of these new codes deal with the need to provide certainty of supply and manage the grid, addressing the increasing penetration of intermittent renewable energy sources.

Firstly, most of the country's renewable energy supply (which accounted for 15% of total supply in 2013)  is intermittent and dependent on wind or sunlight, and so dispatchable power supplies are necessary as back up.

A further little-known challenge of increasing renewable penetration is the concept of system inertia. Traditional power stations have large rotating lumps of copper - the generator. These have rotating momentum which helps stabilise the network when power output from other sources fluctuates. Renewable energy sources tend to connect to the grid using high tech electronics, which have no rotating mass and cannot provide this inertia.

So intermittency and loss of inertia require those in control of the system to request more and more capabilities from our CHPs, to help ensure a secure and stable network. It is a big responsibility for CHP, but our sector is more than capable of providing these essential system features to even out supply.  Indeed, we have been doing so successfully for many years in response to market and system financial signals.

The big shift found in these new EU codes is the possible mandatory requirement for CHP to have significant technology features fitted before they are allowed to connect to the grid. These new requirements are potentially increasing the cost and complexity of CHP.

These technology requirements include improved control systems, larger/different generators and an ability to permit greater interaction with and control by the system operators. These aren't merely technology tweaks – they would require major capital costs, R&D, and engineering and manufacturing investment that could add large extra costs to CHP developments and threaten the competitiveness of the industry. 

It is right and necessary that we move to a low carbon energy system, but we need all the tools in place to facilitate it. Energy users subsidise the wind and solar technologies that are necessary to meet our climate change commitments. However, the new EU proposals are recommending that the CHP industry pays for the challenges such a new system brings.

Without CHP (with their rotating mass), which provide the technical ability to manage grid stresses when faults occur in the system, the massive growth of wind and solar generation would not be possible.

CHP providers, owners and operators should be proud that we are playing our part in helping to bring about the rightful change to a sustainable energy system. But is it right that we, as a major contributor to carbon reduction, should pay the cost for problems that we solve?  Surely the network owners and operators should instead be paying generators  for the cost of helping them keep the system stable.

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  • Guest
    Marcel Geers Sunday, 16 November 2014

    Power electronics CAN supply the equivalent of "rotating mass". Look for example at the EU funded project VSYNC.

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Guest Monday, 18 February 2019