The future of the gas-fuelled power sector looks promising, especially with growing concerns over the ability to balance the grid because of the greater integration of renewables. This is a key finding of a survey of power industry professionals.
Furthermore, a robust bottom line will depend on the effectiveness with which operational flexibility and efficiency are combined, meaning an even more critical role for maintenance professionals.
The survey also revealed that 65 per cent of respondents believe that turbine lubrication has a key part to play here, hence the following report also looks at how the latest oil technology can help maintain operational efficiency.
One of the major shifts taking place in the global power generation market is the rapidly increasing share of renewable energy resources as we seek to reduce carbon dioxide emissions over the long-term.
According to the latest Renewables Global Status Report from REN21, renewables accounted for approximately half of the estimated 194 GW of new capacity added globally in 2010, with installed renewable power capacity hitting an estimated 1320 GW. This represents an increase of almost 8 per cent from 2009.
Renewable energy now represents approximately a quarter of total global electricity capacity and delivered close to 20 per cent of the global power supply, primarily from hydropower.
However, unlike conventional providers of baseload power, such as fossil fuel plants, the feed-in of renewables-based power into the grid depends strongly on the day/night cycle and weather conditions. This means that the availability of wind and solar power at any given time is not predictable, so renewable energies do not lend themselves to the all-important grid control and stabilisation.
Thus to ensure grid stability and a secure supply of electricity, it is realistic to say that fossil fuel power plants will continue to be a key part of the world’s power generation mix.
However, to be able to compensate for the fluctuating availability of power from a growing renewable energy base conventional power plants will need to exhibit greater operational flexibility, i.e. quick and frequent starts and stops, and operating at part load to supplement renewables will become the norm for power generation companies.
One of the most operationally flexible power plant types currently available on the market is the combined-cycle gas turbine (CCGT) plant, which manufacturers are now claiming can offer thermal efficiencies that exceed 60 per cent.
Earlier this year Credit Suisse estimated gas fired power plants would make up about 25 per cent of global capacity additions in the next five years, boosting orders for gas turbines by 50 per cent to 63 GW.
More recently, at the launch of the International Energy Agency’s (IEA) latest edition of its World Energy Outlook, Fatih Birol, IEA’s chief economist said “we are entering a golden age for gas, which will make gas markets much less challenging”.
The IEA forecasts that global consumption of natural gas will catch up with coal by 2035, with unconventional gas resources, such as shale gas and coal-bed methane, playing a pivotal role.
Clearly it is no exaggeration to say that the future of the gas fuelled power sector is looking extremely positive.
To explore this power generation sector in a bit more detail, Power Engineering International magazine, working with Shell Lubricants, recently conducted an online research survey. Power industry professionals from right across the globe were quizzed on where they believe the sector is headed, and on what opportunities and threats exist for the industrial sector’s development.
Approximately half of the respondents were directly involved in the maintenance of gas turbines, either in a decision-making/managerial capacity or as a direct maintenance operative. Thus, the survey also explored the industry’s perception of the importance of an effective lubrication regime in the efficient operation of a gas turbine, as well as determining the impact on overall plant productivity.
We present the research’s main findings below.
Opportunities & Threats
In terms of providing opportunities for the future development of gas power plant, most of those polled cited the growing installed base of renewables.
Almost 92 per cent of the respondents strongly agreed or agreed with the statement that the greater integration of renewable energy generation and the accompanying concern over the ability to effectively balance the grid means there will be a greater need for power generated by natural gas, primarily gas turbines.
According to REN21, among all renewables wind power increased the most in 2010, by an impressive 39 GW, bringing the total global wind capacity close to 198 MW by the end of last year.
In recent years, most countries have announced some sort of renewables development plan. The IEA predicts continued significant growth of the renewable energy sector, accounting for 18 per cent of the global energy mix by 2035. However, the required support, which would need to rise from $64 billion last year to $250 billion in 2035, may not be sustainable in this “age of fiscal austerity”, says the IEA.
The vast majority polled also see that the perceived retreat from nuclear power presents a growth opportunity for gas fired power generation. Eighty-nine per cent believe that the current global uncertainty over nuclear following this year’s Fukushima incident will result in an increase in the number of gas fired power plants built, and in particular CCGT plants.
Some countries have made it very clear that they no longer wish to have a nuclear base, Germany being the most significant, with more recently Belgium turning its back on new nuclear and instigating a phase-out of its existing nuclear assets. This decision, although largely supported by the public, is seen as unwise by many in the industry, not least by the large European utilities. If we look at Germany prior to Fukushima, nuclear supplied almost a quarter of its electricity; so what will make up this significant shortfall – the last nuclear plant is due to shutdown in 2022?
The Merkel government is pinning its hopes on renewable energy, and in particular increasing wind power’s share. Whether this is achievable remains to be seen, but regardless, natural gas fuelled generation is likely to benefit. However, as in life, nothing is certain, least of all that we will be enjoying a new ‘dash for gas’ in the near future. When asked what were the main threats to the future development of the gas power generation sector over half (54.1 per cent) of respondents said gas price volatility.
With the price of natural gas historically linked to oil prices, volatility in the former’s price in commonplace, and after a period of relatively low prices in 2009 (one assumes due to the global recession) prices are on the rise again – so far this year the price of wholesale gas has risen by a third.
The second biggest threat to the future growth of gas power generation was cited as concerns over security of supply – almost 36 per cent of those polled. This was experienced at first hand by Central and Eastern Europe in early 2009, when Russia essentially turned off Europe’s gas tap because of a price dispute with Ukraine.
However, a relatively recent discovery promises to make concerns over price volatility and security of supply a thing of the past. It is of course shale gas. It has already transformed the US from a gas importer into a potential gas exporter. With Europe more recently finding significant reserves in both Poland and the UK, it is beginning to play catch-up. China, unsurprisingly, is also well and truly on the shale gas bandwagon.
According to the World Energy Outlook 2011, global consumption of natural gas will catch up with coal by 2035, with shale gas playing a role, providing environmental concerns over its extraction can be addressed. The other main threat identified by a third of respondents (33.9%). is the introduction of ever more stringent environmental regulation, particularly governing emissions from power plant stacks.
In particular in Europe, legally-binding carbon reduction targets – the European Union’s 2020 target of cutting greenhouse gas emissions by 20 per cent – as well as legislation governing NOx and SOx emissions – the newly introduced Industrial Emissions Directive – both present challenges for fossil fuel power stations.
On the plus side for the gas power sector, a power station fuelled by natural gas produces half as much carbon dioxide and a third of the NOx that a coal fired power plant does. Further, a high efficiency CCGT plant can produce up to 70 per cent lower greenhouse gas emissions.
Flexibility versus Efficiency
As mentioned above, advances in gas turbine technology have resulted in the development of machines that in combined-cycle mode can top more than 60 per cent thermal efficiency – a target the industry has been chasing for years.
Early summer 2011 saw four of the world’s biggest turbine manufacturers launch their next-generation gas turbines; which all promised greater efficiency – Siemens’ SGT5-8000H; GE Energy’s FlexEfficiency 50 concept; Mitsubishi Heavy Industries’ J Series; and the latest version of Alstom’s GT26 CCGT.
Interestingly, although much was made of achieving a thermal efficiency greater than 60 per cent, arguably greater attention focused on the machines’ capability to operate in a highly flexible manner.
For example, GE claims its FlexEfficiency 50 plant can ramp-up at a rate of 51 MW per minute, twice the industry norm, and can go from a hot start to full rated power in 28 minutes. Similarly, Siemens’ pioneering gas turbine, which underwent a rigorous testing process over 3–4 years, was specifically designed to be fast starting and flexible, providing the option of running the H class efficiently whether it is in a base, intermediate or peak load range.
In today’s market, where fuel prices are once again on the rise and environmental considerations are becoming increasingly important, power utilities need to operate their fleet so that they can get the best price for the electricity they produce,
This all begs the question, has ‘operational flexibility’ overtaken ‘efficiency’ as the main priority of a power plant operator? Not according to those polled, a resounding majority (61 per cent) said that plant efficiency and flexible operation were equally important in today’s marketplace.
Ronald Bakker, senior product application specialist at Shell says: “The power generation sector is clearly under increased pressure to perform, both in terms of efficiency and flexibility. This has been accentuated by the shift from state to private operators in many markets. In fact the results of this research are closely aligned with what we are already hearing from our customers around the world, and which has already been shaping our R&D focus to develop products that help improve both the efficiency and flexibility of operations.”
However, operating under high efficiency, and in a flexible manner, mean that these power plants are subjected to unprecedented stresses and strains. This makes having an effective maintenance strategy essential in ensuring a long, trouble-free operation life. Arguably one of the most important aspects of preventative maintenance, and one that is often overlooked in the grand scheme of things, is gas turbine lubrication.
Lubricants Can Save You Money
One of the most significant and unexpected findings of the survey was that over 65 per cent of respondents said that the maintenance of the lubrication system of their gas turbines had either a moderate or major impact on their company’s profitability.
This is undoubtedly an interesting result, but should we be surprised by the fact that by conducting an effective lubrication maintenance regime you can markedly benefit your company’s bottom line? If looked at rationally, probably not when you consider the well-documented inter-relationship between lubricant efficiency and plant performance.
Lubricant efficiency depends heavily on the ability to form and maintain an oil film of adequate thickness. If this is not achieved in a machine then problems such as unit alarms, trips or even fail-to-starts can occur, and if your gas turbine is not turning you are not making money. In a similar vein, 77 per cent of those polled confirmed that lubricant efficiency had a moderate to major effect on their gas turbine operating costs. All the main lubricant suppliers make significant investments in tribology, or the ‘science of lubricants’, as lubrication is a key component in the overall value chain, and can have a crucial impact on efficiency and productivity, and therefore the economics of a gas turbine power plant.
When asked to rank from very important to insignificant the benefits of a lubricant utilised in a gas turbine, almost 91 per cent of respondents said greater machine uptime was the most important, closely followed by longer intervals between oil changes (88.6 per cent).
The ratio of turbine uptime to downtime is essential to the power production process. Any downtime resulting from a required turbine oil drain obviously impacts on the machine’s uptime. Thus, although the aim of preventive maintenance is to extend turbine life by guarding against component failure, and thereby maintaining operating efficiency, the economic impact of a temporary shutdown in order to carry out an oil drain should not be under-estimated.
Bakker continues: “Lubricants should be considered a vital engineering component of any power operation. They have a direct impact on equipment performance and reliability, and given that the economic case for avoiding unplanned downtime is extremely strong, applying the right lubricant technology according to the unique demands of a particular operation can deliver significant efficiencies.
“At Shell we have been undertaking lubrication research continuously since 1940 and working in close partnership with OEMs to help our customers tackle productivity and efficiency challenges in their operations. We then take the expertise we develop through these partnerships and apply it in a way that benefits all our customers.”
Wear reduction of moving parts and prevention of bearings failure top the ranking of the most important issues related to the lubrication of gas turbines – 93.8 per cent of respondents.
This finding is not surprising considering the essential role a lubricant plays in any turbomachine, i.e. to effectively enable parts, such as bearings, to move against other components/surfaces without resulting in degradation of either.
Over recent years turbine users have reported issues related to mild to severe lube oil ‘varnishing’ in their systems. Varnish can appear as a thin orange, brown or black film deposit on the interior of lubricant systems. The problem has been seen in most types of turbines using many different turbine oils. Varnish formation in turbine oils represents a serious performance problem for end users. A costly concern is the formation of varnish on thrust or journal bearings, which can cause increased wear rates and potentially a change in lubrication regimes, increasing the severity of the oil stress and potentially accelerating oil degradation.
Interestingly, 87.3 per cent of those polled also said improving turbine efficiency and performance was another ‘very important’ or ‘important’ deliverable from a gas turbine lubricant.
The survey also asked what qualities they looked for in a lubricant supplier. Ninety-one percent said reliable delivery, closely followed by good customer service (84.1 per cent). Offering oil conditioning monitoring services also ranked highly. With an increasing number of utilities outsourcing their plant maintenance it is not surprising to find that customer service and the offer of additional value-added services have become a priority.
Effective lubrication is key
Although the research survey cannot be described as scientific it does throw up some interesting findings.
The majority polled are clearly very upbeat about the opportunities that exist for the rapid growth of the gas fired power generation sector – primarily driven by the greater grid integration of renewables and the high level of uncertainty that the global nuclear power sector is currently experiencing.
Shale gas and other unconventional gas resources, such as coal-bed methane, look set to allay concerns over the continued volatility of wholesale gas prices and security of supply that threaten gas power’s expansion.
Another interesting finding, is the key role that turbine lubricants have in ensuring the economic running of a gas turbine came out loud and clear, as well as their importance when it comes to protecting a company’s bottom line.
Commenting on the survey results, Bakker said: “It is reassuring to see that the industry trends and issues related to lubrication that the end-users see as important are the same ones that drive our product development, particularly in the area of high-quality formulations.
1. REN21, which is the Renewable Energy Policy Network for the 21st Century, is a policy network that provides a forum for international thought leadership in renewable energy.
2. The term ‘Shell Lubricants’ collectively refers to Shell Group companies engaged in the lubricants business.
The research survey, which was sent to readers of Power Engineering International magazine, was sponsored by Shell Lubricants.
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