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Solar intermittency: Australia's clean energy challenge

16 June 2012

REVE

Intermittency is one of the biggest barriers to the uptake of solar energy, however a new CSIRO report demonstrates that this challenge can be overcome.

Sunshine is difficult to accurately forecast, can change rapidly due to moving clouds, cannot be controlled and is not a source of energy 24 hours a day.

However, CSIRO and partners are now on the path to solving the intermittency challenge with the completion of a world-first analysis of solar intermittency in the Australian context.

The study provides a greater understanding of the effects of solar intermittency on electricity grids, directly addressing the concerns of market and grid operators, solar installers and investors. Furthermore, the project found that:

We can ‘fix’ intermittency. With knowledge and tools, such as solar forecasting and energy management, CSIRO can provide the information required to manage solar intermittency.

We need a customised approach. Solar intermittency is not uniform, different sites, regions and countries require individual solutions. Local research and demonstration pilots are required. Australia has a unique electricity network and we need unique solutions.

We need a highly flexible electricity grid. If large amounts of solar energy are to be used as a power source in the near future we need a grid designed with renewable energy sources in mind.

The project was made possible with funding from the Australian Solar institute (ASI) with in-kind support from CSIRO, Australian Energy Market Operator, and Energy Networks Association.

Solar intermittency will always exist given the impact of weather conditions on the level of solar radiation reaching the earth’s surface.

For these very reasons it is challenging to integrate renewable energy into the electricity grid.

The grid requires a stable, consistent supply of electricity otherwise blackouts and inefficiencies can occur and the grid becomes very difficult to manage.

However by gaining a better understanding of intermittency CSIRO can provide the tools, system and information required to cost effectively manage the issue.

There are a number of reasons why solar intermittency is creating barriers for the renewable energy industry:

Uncertainty: if you do not know what electricity your system can produce hour to hour or day to day it is very hard to provide a consistent and stable service.

Grid management: an irregular electricity supply with great spikes and troughs can cause all sorts of problems for electricity grids, including possibility of black-outs in extreme cases.

Increasing costs: Much time and money can be spent dealing with the irregular supply, inflating the costs of solar energy.

CSIRO’s study aims to create certainty, provide solutions for a stable grid supply and through these solutions, allow increased uptake and decrease the cost of solar energy.

CSIRO partnered with Australian Energy Market Operator and the Energy Networks Association to conduct the world first study on solar intermittency and we are now one step closer to ensuring this challenge is a manageable variable rather than a daunting unknown.

The 12-month study, funded by the Australian Solar Institute (ASI), provides a greater understanding of the effects of solar intermittency on electricity grids, directly addressing the concerns of market and grid operators, solar installers and investors.

As part of the research the following was carried out:

Industry consultation. CSIRO brought together over 40 key industry experts from utilities, power system operators, large-scale renewable system operators and other industry players from around Australia to jointly report on the effects of renewable generation intermittency on electricity grids and identify the key concerns regarding intermittency in Australia.

Literature review. We assessed the current state of worldwide research on renewable generation intermittency and determined how it applies to the Australian context. We were surprised at the contradicting findings, with many sources disagreeing with each other.

Data collection. We gathered high resolution solar data, including irradiance and output power, at three different scales (utility-scale, commercial-scale and residential-scale), from three major solar power research facilities around Australia including the Desert Knowledge Australia Solar Centre in Alice Springs and Australia’s largest flat panel PV system at the University of Queensland.

Data analysis. We analysed the high-resolution solar data collected from these three sites around Australia to evaluate output power fluctuation ramp rates in order to study and understand the variability of Australian solar power installations.

Network impacts simulation. We simulated the likely impacts of solar output power fluctuations on various types of Australian electricity networks at different penetration levels. Four different scenarios were considered and modelled.

Model developed. We developed a PV output power estimation model to study the effect of a particular PV array upon the local network.

This project produced several critical findings that help to understand the challenges and opportunities behind intermittency and grid integration

Solar deployment is heavily dependent on mitigating intermittency. Rigorous analysis of both network simulations and trial deployments in the context of Australian electricity transmission and distribution systems is needed

We defined high penetration intermittent generation. A statistically-rigorous mathematical definition of high-penetration intermittent renewable generation was established.

There is considerable intermittency in the existing electricity system. The existing electrical power system already incorporates significant load intermittency which is managed through generator dispatch and ancillary services mechanisms. As solar penetration levels increase, additional measures such as those already in place to manage load intermittency may be needed (for example, additional ancillary services).

The effect of solar intermittency is not uniform. The effect of solar generation intermittency on the power system is context specific and currently must be considered on a case-by-case basis. As a result, the amount of solar generation that can be integrated into utility power systems varies widely.

Solar intermittency can be managed. The effectiveness of a number of mechanisms that can be employed both individually and cooperatively requires further investigation via modelling and experimental analysis as well as real-world Australian trials.

Existing research has conflicting outcomes. There is significant disagreement between studies around the world on intermittency and its effects. Some results directly contradict each other and it is clear further research and consensus is needed.

Accurate solar forecasting is essential. Intermittency can be planned for and managed more cost-effectively with appropriate long (years: addressing system capacity), medium (months/days: addressing system dispatch) and short term (minutes/seconds: addressing power quality) forecasts.

Research and demonstration work is required in Australia. In assessing future high solar penetration scenarios, it is necessary for analysis that has been carried out in other countries to be performed within an Australian context.

Australia is unique. Australia’s electricity infrastructure, operation schema and usage patterns are different to other countries and require appropriate system testing and development locally.

Australian Energy Market Operator (AEMO) operates across the electricity and gas markets across southern and eastern Australia. AEMO contributed a wealth of expertise in the connection, planning, forecasting and operating of renewable energy.

Energy Networks Association (ENA) is the peak national body for Australia’s energy networks, and guided our research on the effects of solar intermittency on electricity networks.

The project was supported by a grant from the Australian Government’s Australian Solar Institute (ASI). The ASI is supporting Australian research and development to help solar energy become cost competitive with other energy sources.

From this study, CSIRO now has the foundation research required to provide the tools, systems and information to help Australia’s electricity and solar industries cost effectively manage solar intermittency.

The key areas of development will be solar forecasting and energy management.

CSIRO’s Energy Transformed Flagship has a team of 30 engineers, social and computer scientists, mathematicians and control engineers dedicated to creating the tools, systems and knowledge to achieve a low-carbon, highly efficient, national energy system that lets Australia retain its economic competitiveness and quality of life.

The team is working with industry and government on a range of ‘Smart Grid’ solutions that will be essential to reducing Australia’s dependence on fossil fuels.

The benefits of a smarter electricity network will also include reduced energy system losses, improved power quality and help slow price increases.

It will also bring an exciting new range of energy services into our homes and businesses that can automatically help improve comfort, cost-savings and overall efficiency

The Flagship’s Renewable Energy Integration Facility, based at the CSIRO Energy Centre in Newcastle, NSW, is a world-class facility able to test real-world grid integration scenarios that include a multitude of traditional and renewable energy sources.

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