Variable forecast

Gunning Wind Farm
Gunning Wind Farm

Wind power generation is the most cost-effective form of commercial-scale renewable energy available. With a mandated renewable target and carbon price mechanism channeling investment towards renewables, Energy Source & Distribution’s James Dillon talked to ROAM Consulting policy principal Dr Jenny riesz about the opportunities and challenges associated with building wind farms.

Wind power generated more than 6400GWh of electricity in Australia in the past year, with investment in wind power totalling $1.16 billion during the 2010-11 financial year. The Clean Energy Council’s recent renewable energy report shows that the amount of wind power in Australia has grown by an average of 35 per cent per year over the past five years, with the efficiency and power output of turbines quickly evolving. South Australia alone may have 4.405GW of wind installed by 2030, resulting in significant numbers of hours where wind energy production is expected to exceed demand. With a predicted fourfold increase to the existing 1.75GW of wind over the next 20 years, the National Electricity Market (NEM) is facing a potential dramatic increase in wind energy.

Integrating the variable, intermittent and asynchronous nature of wind power into the NEM brings a host of technical challenges. For generators looking to build wind farms and gain access or connection agreements with network providers, the negotiation process can be challenging. Community concerns must also be addressed, with the South Australian Opposition’s recent 2km exclusion zone policy proposal for wind farms causing the Clean Energy Council to label it a major threat to investment. But the uncertainty and cost involved in building wind farms continue to reduce as state and federal legislation drives investment towards renewable energy.

Renewable legislation

Contributing to technical knowledge around wind farm integration is ROAM Consulting renewable energy and climate policy principal Dr Jenny Riesz. Dr Riesz works with clients to develop wind models and explain the implications of climate policy. On the other side of the coin, she has also worked with governments on how to set policy and the implications they will have on the industry. Dr Riesz believes Australia now has the right mix of renewable energy legislation in place to ramp up wind generation considerably over the next decade.

“I think we are in a really good place now. We’ve got the 20 per cent by 2020 renewable energy target, and that’s really important legislation. It seems now that they have done the split (into small and large) the scheme is working very effectively,” Dr Riesz explained to Energy Source & Distribution.

“And the carbon price that just came through is another very important piece of legislation. You really do need both of those pieces of legislation together in order to get renewable energy coming into Australia. So now that we have that we are in a very good place. I think companies do still need to be concerned about this public approval; the community support aspect is very important, so they do need to be consistently working on that.”

Australia’s total energy generation currently sits on 3 per cent wind energy, with 6 per cent hydro and a few percentages for solar, biomass and other forms of energy. While it seems that investors will have a brief hiatus for the short term as the RET scheme sorts itself out, Dr Riesz believes it will be rectified in the next year or two and will lead to a very large ramp up of wind power, culminating in 10 per cent of Australia’s power by 2020.

“It’s not a huge target to achieve, but it will much more then what we have now and that means at that level, wind is contributing large amounts of energy,” Dr Riesz said.

“It’s an important part of our system. I don’t think its at all unachievable, but it’s something that will be quite a shift in how our system operates, and that shift is already happening now in terms of people thinking about that system, setting up the right schemes, the right rules to work with that.”

Technical integration

Wind generation’s trickiness is mostly due its variability as a power source, causing interesting challenges around network voltages. As synchronous generation is displaced with electronic-coupled asynchronous generation, the total inertial response is reduced, resulting in larger speed changes for the same power imbalances. According to the AER’s State of the Energy Market 2011, the Australian Energy Market Operator (AEMO) has identified concerns about the adequacy of frequency control during periods of high wind generation and is working on this issue.

“You have these sorts of issues with other types of generation too, but with wind generation the affects it is having can vary as the output of the wind turbine varies,” Dr Riesz said.

“So you might then have to have more sophisticated electronic components coming into the system with it to match the voltage.”

Wind variability is managed through forecasting systems that can be predicated reasonably well when looking up to one-to-two hours in advance. As the market already deals with a large amount of variability, Dr Riesz said the asynchronous nature of wind can be absorbed well by a balanced system, maintaining supply and demand at every point in time.

“The models we have up for wind forecasting are pretty good and they’re getting better all the time as well. So you can use that to manage when you might think there’s a sudden drop off in wind, making sure you’ve got enough other generation on the system,” Dr Riesz said.

Australia’s five-minute interval spot market is also a major benefit, allowing quick changes to be made in accordance with the power and flow of the wind.

“International markets sometimes have hourly or day-ahead. So that makes it much more difficult for other systems to integrate wind because they have to forecast the wind a whole day ahead, whereas we don’t. We only have to forecast the next five minutes. It works much more smoothly for us,” she said.

With an efficient system in place, Dr Riesz expects the system can be scaled up over time to cope with new wind generation input.

“It will get a little more expensive but we will probably see more of the conventional-type generators starting to participate in that market more actively. But we don’t anticipate that will be a huge problem. It’s something that we need to be aware of to make sure that we can meet their requirements. So at this stage nothing suggests it’s going to be a big problem.”

In order to understand the technical issues that might arise when integrating wind into the NEM, AEMO is conducting a number of studies into maximising the benefits of wind power. According to AEMO managing director and chief executive officer Matt Zema, the market operator has been looking at how the NEM can accommodate the expected increase in wind and assessing how overseas power systems have managed integration.

“Where relevant to the Australian context, AEMO will use this information, with additional studies to analyse what changes, if any, need to be made to the market, technical standards, operations and planning to maximise the benefits of this new technology,” Mr Zema said.

New transmission capacity is generally required to integrate wind into grids, but according to AEMO’s Wind Integration In Electricity Grids: International Practice And Experience there is opposition to traditional alternating current (AC) overhead lines and economically justifying the transmission investment for a low-capacity factor resource like wind is challenging.

“It is well recognised that dealing with a number of wind energy projects together and grouping them into one technical solution has a lot of advantages and there are good practical examples of this in Texas and Ireland,” the report states.

With increasing wind penetration levels, state-of-the-art forecasting systems will need to be integrated into new electricity market designs. Horizontally propagating wind features have been found to be a major cause of large rapid changes in wind power for Australian wind farms. In recent years AEMO established the Australian Wind Energy Forecasting (AWEF) system, which utilises two different weather forecasts and can forecast the wind production of every wind farm in the national electricity market. This project provides a vehicle for improving the research, development and application for forecasting of intermittent energy. AWEF recently trialed Wind Insight, a software that fits into the AWEF system and looks to forecast sudden rapid changes.

“You can have displacement effects such that a sudden drop off might path to the right or the left of the wind farm, but not actually hit it in the point forecast or line forecast,” Dr Riesz said.

The software designer for Wind Insight has since joined ROAM Consulting and Dr Riesz hopes the program will eventually be implemented with AWEF in AEMO’s systems.

State of difference

Australian states have each treated wind power differently, with South Australia seen as leading the charge on growth. South Australia has the highest wind farm capacity in the country with more than half of Australia’s installed wind capacity. South Australia has reduced its carbon emissions by 18 per cent over the past five years and most of this can be attributed to wind power, which now produces more than 20 per cent of the state’s electricity, according to the Clean Energy Council’s latest report.

“The government there is very supportive of wind power, so you see a lot of proponents wanting to go there because the planning approval process is easier,” Dr Riesz said.

“But they do have some problems with their network. It’s starting to reach the point where they are starting to need some very serious augmentations to get larger quantities of wind coming in. So they are looking at addressing those, they are looking quite hard to squeeze every last drop out of their network.”

Congestion is now starting to emerge on South Australian transmitter ElectraNet’s network, and executive manager network strategy and regulatory affairs Rainer Korte said the company is now pursuing an upgrade of the Heywood interconnector between South Australia and Victoria. A regulatory investment process is underway, and if successful, will lead to a 40 per cent increase in capacity.

“This interconnector upgrade not only helps South Australia export for wind energy, we tend to export at times of low demand,” Mr Korte told Energy Source & Distribution.

“It will also help to support South Australia at times of high demand when energy comes the other way. So we’re very committed to pursuing that as quickly as we can, because I think there are a lot of people out there on the national market looking for a stronger interconnector and we are pushing this one through.”

In New South Wales, Acciona Energy’s Gunning wind farm added 47MW of capacity to the Yass-Goulburn transmission lines and was completed at a capital cost of $147 million. New South Wales has many new wind projects underway, with the Australian Bureau of Resources and Energy Economics Major electricity generation projects November 2011 report showing almost half of all new wind coming from the state. Total planned capacity for these projects is 3543MW, with an average capacity of 322MW. The Silverton wind farm, to be located 25km north-west of Broken Hill, will be Australia’s largest, with new capacity of 1000MW.

While many new wind projects have been slated to begin in Victoria, some have been put on hold due to recent changes in the state’s planning approvals process, specifically a two-kilometre setback rule. According to Dr Reisz, the rule has had quite a significant affect.

“What that means is that any projects that already had planning are actually going ahead full-speed to get them through the process but they cant make any changes to those projects now. And those projects that don’t have planning approvals have been discarded permanently because they don’t think they will be able to get those planning approvals with the new rules,” she said.

Many of these proponents are now looking to invest north to New South Wales or possibly Queensland. The Victorian determination is a very real demonstration of how significant public approval is in terms of projects going forward.

Community concerns

As generators working in Victoria have discovered, one of the most important issues potentially holding back wind farms is legislation made in response to community concerns. Backlash from a single community in Victoria caused the government to change the planning approval.

“What that means for Victorians going ahead is that they’re probably going to have to pay a lot more for their power importing that wind energy from South Australia and from New South Wales,” Dr Reisz said.

“Meanwhile, they’re going to be using coal-fired generation mostly, which has a very high carbon emission and they have to pay for that with a carbon price coming. I would say for Victorians, overall, it’s a fairly bad outcome.”

While the intention of the rules are to protect communities that feel they are being negatively affected by the wind farms, Dr Riesz believes the people who have the wind farms on their land are quite happy with the situation.

“It’s mostly the neighbours who aren’t being financially compensated and feel that their visual amenity has been detrimentally affected. That’s something that is a personal sort of thing to quantify that.”

The environmental impacts include looking at native species in the area. There are some locations where wind farms have not been allowed because they are in the middle of migratory routes of birds, or where there are endangered species nearby.

“On the whole, however, when they look at the actual number of birds that are harmed by the wind, it’s much much less then birds that get harmed by other things (such as windows or cats).”

While the growth of solar power was one of the major stories of 2011, the right legislation mix is now in place for wind power to become a dominant generation source in the coming decade.