Wind Power Issues from Tyndall Center

From Tyndall Center for Climate Change Research

Security of decarbonised electricity systems

Research Theme:

2. Decarbonising Modern Societies

Project ID

T2.24

Full project title:

Ensuring new and renewable energy can meet electricity demand: security of decarbonised electricity systems

Project status:

completed

Project Duration:

18 months - March 2003 to September 2004
Contact:

Goran Strbac, Electrical Engineering and Electronics, UMIST
Dr Jim Watson, SPRU, University of Sussex.

Other researchers involved in this project:
Dr. Dusko P. Nedic – Ipsa-Power Anser A. Shakoor—University of Manchester Professor Goran Strbac- University of Manchester Dr. Mary Black- University of Manchester Dr Jim Watson, SPRU, University of Sussex. Dr. Catherine Mitchell, Warwick Business School

Final Report Nedic, D. P., Shakoor, A. A., Strbac, G., Black, M., Watson, J., and Mitchell, C. (2005) Security assessment of futures electricity scenarios, Tyndall Centre Technical Report 30
(PDF, 52 pages 620Kb)
Project overview

In the context of reducing CO2 emissions, the UK Government's 2010 targets for Renewables and CHP will make only a small (if symbolically important) contribution. A considerably larger proportion of renewable and other low carbon energy sources (e.g. fuel cells, micro CHP and possibly nuclear) will be required in order to respond to the climate change challenge over the longer time horizon. This new generation will displace the energy produced by large conventional plant, raising serious questions about the ability of such a system to manage the balance between supply and demand, and hence, to maintain the security of the electricity system. Currently, large conventional centrally controlled generators (coal, oil and gas fired, but not nuclear) play a vital role in managing the balance between load and generation in the operation time scale, and hence maintaining a secure system.

Clearly, meeting variable demand with intermittent, and/or uncontrolled and/or inflexible generation will be a major challenge for secure operation of sustainable electricity systems of the future. Objectives: This project was identified for further work in the PIU Energy Review and is directly relevant to the Tyndall Research Strategy. This inter-disciplinary project is to investigate the security of decarbonised electricity systems with the following objectives:

1. Identification of alternative scenarios for decarbonised electricity systems
2. Security assessment of decarbonised electricity systems: Capacity and Balancing Aspects
3. Security assessment of decarbonised electricity systems: Environmental and Economic Aspects
4. Security assessment of decarbonised electricity systems: Regulatory Issues

Work undertaken
The project was conducted jointly by Manchester University (UMIST), SPRU and Warwick Business School. UMIST undertook the engineering investigation of possible future UK electricity scenarios and security assessment of these scenarios. SPRU contributed the social science expertise in developing these decarbonised scenarios. Dr. Catherine Mitchell of Warwick Business School contributed to the project as a consultant.

Throughout the project regular meetings were held with a number of important stakeholder organisations. These included DTI and OFGEM, Eddison Mission, Innogy, NGT, United Utilities, Powergen, and Alstom.

Results
1. In the context of our work on the security assessment of decarbonised systems the first task was to identify the plausible future scenarios for electricity demand as well as generation for the UK. Defining new scenarios being out of the scope of this project, we analysed some of the recently projected UK energy scenarios and deduced the possible medium and long-term UK electricity generation sector development schemes. Our analysis showed that wind power is expected to be a dominant renewable technology by 2020. Therefore, for the mid-term future UK electricity scenarios we assumed a wide range of wind penetrations up to 40GW. The long-term future UK electricity scenarios are derived from the projections given by the Royal Commission on Environmental Pollution and the PIU Energy Review.

2. Penetration of intermittent renewable resource will displace considerably the energy produced by large conventional plant. However, there are a number of concerns in relation to the ability of this new generation to replace the capacity of the conventional plant and in particular its flexibility. This raises a number of questions as to whether the future sustainable system will be able to operate securely, and how exactly the balance between generation and demand will be managed.

Novel probabilistic techniques were developed to assess capacity adequacy of both mid-term and long-term UK electricity scenarios.

The performed capacity adequacy studies for the mid-term future UK electricity scenarios clearly show that the capacity value of wind generation plant is limited. Analysis was carried out for a wide range of wind penetrations to examine the generating capacity of conventional plant that can be displaced by wind, while maintaining a specified security level. We observed that wind generation only displaces a relatively modest amount of conventional plant, which means that in order to maintain the same level of security, a significant capacity of conventional plant will still be required.

The performed capacity adequacy studies for the mid-term future UK electricity scenarios clearly show that the capacity value of wind generation plant is limited. Analysis was carried out for a wide range of wind penetrations to examine the generating capacity of conventional plant that can be displaced by wind, while maintaining a specified security level. We observed that wind generation only displaces a relatively modest amount of conventional plant, which means that in order to maintain the same level of security, a significant capacity of conventional plant will still be required.

One of the popular questions associated with capacity value of intermittent renewable resources is to what extent incidences such as anticyclone “cold snaps” which give high demand but little wind anywhere in the country could affect the ability of wind to displace conventional generation capacity. We carried out a series of studies assuming different incidence scenarios and calculated how they can affect the value of this contribution. Our studies demonstrate that a coincidence of very low wind power output in the whole country and peak winter days can significantly reduce wind power's contribution to the total generation capacity.

The performed capacity adequacy studies for the long-term future UK electricity scenarios demonstrate that the utilisation of the total supply energy is expected to be significantly reduced in the most of these scenarios compared to the 1998 utilisation level. Another concern is that during summer a significant renewable energy curtailment might be needed considering that the total renewable output is larger than total demand, especially for the scenarios where significant installations of PV solar panels are projected.

Apart from capacity adequacy another important security question for these future decarbonised electricity system will be balancing of system load and generation. Our analysis shows that in order to maintain the integrity of a low-carbon electricity system, there will be a need to develop new forms of flexibility in both supply and demand sides. The amount of flexibility required will depend on the plant mix and in particular on the total capacity of intermittent renewables and reserve allocation. In this project, using a simple snapshot analysis, we discuss the impact of system flexibility, sudden losses of generation and reserve allocation on managing load-generation imbalances.

3. In a low-carbon electricity energy based system, with renewable generation producing the vast majority of electricity, considerable capacity of conventional plant may still be required. This would mean that the conventional power system might be acting as a backup or standby system, which obviously may reduce the overall value of renewable generation.

Due to a disproportion between the conventional capacity and the energy substitution by the wind source, a considerable number of thermal plants will be running at low output levels over a significant proportion of their operational time in order to accommodate wind energy. Consequently these plants will have to compromise on their efficiency, resulting in increased levels of fuel consumption as well as emissions per unit of electricity produced.

A simulation technique was developed to evaluate (i) reduction in fuel cost associated with system balancing, (ii) corresponding reduction in CO2 emissions and (iii) reduction in energy produced by conventional generating units for generation systems with different generation flexibilities and reserve allocation.

Relevance to Tyndall Centre Strategy and Overall Centre Objectives
The results of this project hold direct relevance to the Tyndall Theme 2 project IT1.30 – “Connecting new and renewable energy sources to the UK electricity system”. This study complements the other Theme 2 projects, looking at renewables, fuel cells and micro-grids, which together cover some of the key options that can contribute to a low carbon society.

Outputs from project “Security of Decarbonised Electricity Systems”

Papers published or accepted for publications
UK Electricity Scenarios for 2050 – Jim Watson, November 2003, TWP41

G Bathurst, G Strbac, “Value of Combining Energy Storage and Wind in Short-Term Energy and Balancing Markets”, Electric Power System Research, June 2003.

L Dale, D Milborrow, R Slark, G Strbac, “The Shift to Wind is Not Infeasible”, Power UK, April 2003.

L Dale, D Milborrow, R Slark, G Strbac, “Total Cost Estimates for Large-Scale Wind Scenarios in UK”, Energy Policy, July 2003.

Final report:
Nedic, D. P., Shakoor, A. A., Strbac, G., Black, M., Watson, J., and Mitchell, C. (2005) Security assessment of futures electricity scenarios, Tyndall Centre Technical Report 30

(PDF, 52 pages 620Kb)

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Last modified: Tuesday, 11-Dec-2007 13:21:49 GMT