The changes in U.S. electricity supply and usage levels are rapidly reshaping utility load profiles and thus generation and transmission requirements for both new and existing resources.
The recent discovery of relatively cheap natural gas in the U.S. and growing use of the fuel as a baseload power generation source has also coincided with the rapid adoption of renewable resources in many parts of the U.S. These new components of the electricity supply stack continue to displace more traditional and older forms of baseload power generation, coal and nuclear units, for both economic and public policy motivations. Unfortunately, these growing pieces of the U.S. generation supply side all are subject to weather related intermittency.
The market for liquefied natural gas (LNG) is booming. International LNG trade is expected to exceed $120 billion this year, making it second only to oil as the most valuable world commodity, according to Goldman Sachs Group.
Demand for the product positions the United States – with its abundant natural gas — nicely to build an LNG export market. This is a big switch from a decade ago when the U.S. was experiencing tight energy supplies and thought by now it would rely on foreign LNG imports.
As a result of the industry shift, we are seeing keen market interest in development of liquefaction plants in the U.S. (and other parts of the world). The nation now has plants under construction to produce 44.1 million tons per annum (MTPA) of LNG and has proposed an additional 268 MTPA of capacity.
LNG plants can cost in excess of $8 billion to site, develop and build. So efforts are underway to make these new plants as cost-effective as possible – which is one of the reasons why the LNG industry is examining Turbine Inlet Air Chilling (TIAC).
In an ideal world, the most efficient equipment would also cost the least to buy and install. But in the real world that’s usually not the case.
Equipment often runs more efficiently because it’s made from higher grade materials. Higher grade materials cost more.
Anyone who has priced home air conditioning systems is aware of this. But as Energy Star labels often reveal, lower electric bills offset the higher cost to purchase the AC system over time. The efficiency pays off by making the house cheaper to operate.
A similar principle applies to turbine inlet air chilling (TIAC) systems for power plants, but on a much larger financial scale. Lower capital costs (capex) may mean higher operating expenses (opex). That’s why it’s important to consider the total lifecycle costs — and how to minimize them — when investing in a TIAC system.
If you’re outside working on a hot summer day, it’s inevitable that moisture will appear on your brow. A dry breeze evaporates the perspiration and cools down your body. This is nature’s way of keeping you productive because no one works efficiently when they are too hot. Nature’s cooling technique is effective — as far as it goes. But clearly, you’ll cool down more in an air conditioned room than by relying on outdoor breezes. This is especially true when it is humid, since damp air cannot absorb as much moisture as dry air.
So AC is more effective and predictable than nature to remove the sweat off your brow on a hot August day.
How does this apply to power generation? Like us, the gas turbines used in power plants operate less efficiently when the air is too hot.
And interestingly, the two most common technologies for cooling power plants — evaporative cooling and mechanical chilling – mirror the way we cool down our bodies. They even share similar pros and cons.
Here is a more detailed description of the two cooling technologies, as they are used in power production.
This paper was delivered at Power-Gen International, December 2015.
Power demand is often greatest at the extreme temperatures due to an inherent desire (or required need) to maintain a steady, comfortable condition. The additional energy required to offset extreme ambient conditions, whether running an air conditioner or a heater, creates additional power demand. Unfortunately, a combustion turbine performance is highly sensitive to ambient air conditions and thus extreme hot and cold temperatures negatively impacts a generating unit’s performance and operation. Coil-based inlet air-conditioning systems are designed and operated to counteract these challenging conditions and maintain a combustion turbine performance and reliability throughout the ambient temperature range.