A PUSH FOR GREEN ENERGY

Transcription

1 TEXT: STEVE ROMAN PHOTO: WÄRTSILÄ [ SOLUTION ] A PUSH FOR GREEN ENERGY Cheap oil or no cheap oil, the move toward clean, renewable energy sources is picking up pace in the US, especially in the windswept Midwest and sunshine states like Hawaii. 54 Twentyfour

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3 The US has plenty of wind and sun. The headache for electricity producers comes from trying to integrate these intermittent, weather-dependent inputs into their systems. To solve the problem, operators are turning to internal combustion engines (ICEs). The past decade has seen the rise of the first ICE built on a scale large enough to be used on a power grid, and it just so happens that these quick-starting engines are amazingly good at doing what the traditional turbine generators can t: smoothing out the input peaks and troughs created by wind and solar power. It s no coincidence that the windiest part of the continental US the corridor stretching from Minnesota in the north to Texas in the south is where the interest in these engines has started to mushroom. When the Stillwater Utilities Authority, which serves a city of 46,000 in Oklahoma, was looking to update its power generation setup, balancing the fluctuating power coming in from wind plants had to be part of the equation. What they needed was a generator that could start quickly, run efficiently, and ramp up and down whenever needed. The solution that Stillwater settled on was a 56 MW power station that will consist of three 18.7 MW ICEs running on natural gas. Last September the company signed a contract with Wärtsilä to provide the plant. Gary Groninger, Business Development Manager for Power Plant Sales at Wärtsilä North America, explains why Stillwater chose this technology over the more traditional combustion turbines. Number one is that these engine generators start fast. They start in as little as five minutes and you can shut them down and start them up again in as little as five minutes. There s just nothing that compares to that in the industry, he said. If you have a big combustion turbine or a coal plant, that s 500 or 1000 MW, a big lump that you can t start and stop easily or efficiently. Other utilities in the region are turning to Wärtsilä for the same reason. In December, for instance, the company was contracted by Midwest Energy Inc. to supply an extension to its Goodman Energy Center in Kansas, specifically to handle increased input from wind farms. BALANCING ACT Interest is also high in Hawaii, the state that leads the US in solar photovoltaic (PV) capacity. As with wind, PV input is frustratingly volatile it can drop at a moment s notice when the sun goes behind a cloud. Like their counterparts in the Midwest, the Hawaiian Electric Company has opted for Wärtsilä s fast-starting engines to fill the gaps. Their new power project on Oahu, agreed in July 2014 and now awaiting regulatory approval, will use six Wärtsilä 34DF engines with combined output of 50 MW. Wind and solar balancing, as it s called in the industry, requires not only having another power source that you can switch on and switch off, but also one you can reasonably ramp up and ramp down within a few minutes to keep the supply of electricity feeding into the grid steady. Most ICE plants are modular, consisting of several independent engines that can be turned on or off independently, so changing output levels is basically a matter of throwing the right number of switches. And just as importantly, each, or all, can be ramped up and The Pearsall power plant in Texas has been in use since 2009 to balance the variability caused by wind. 56 Twentyfour

4 YOU CAN START AND SHUT DOWN THESE ENGINE GENERATORS IN AS LITTLE AS FIVE MINUTES. Twentyfour

5 ICE PLANTS RUN WELL AT HIGH ALTITUDES AND IN HOT WEATHER. The Pearsall power plant in Texas is among Wärtsilä s largest US projects. TRACK RECORD Among Wärtsilä s largest US projects to date is the South Texas Electric Cooperative s 203 MW Pearsall Power Plant, better known as The Wind Enabler. This milestone plant, equipped with 24 Wärtsilä 34SG engines, was completed in The next year, Wärtsilä supplied the equipment for the MW Humboldt Bay Power Plant in Northern California, replacing Pacific Gas & Electric s existing 50-year-old plant. Wärtsilä s total installed capacity in the United States currently stands at approximately 2400 MW. down without much change in the efficiency level, or heat rate. The loss from running an engine at half power is about 8 percent, far less than the 30 percent that s typical of turbine generators. But as Wayne Elmore, Director of Regional Sales for Wärtsilä North America, notes, this technology is not competing with combined cycle power, coal or nuclear power. The latter should still be used for base load while the internal combustion engines handle the peaks and valleys. The idea would be to use your combined cycle the way it was intended, which is run it flat out at its most efficient operating point. Don t turn it off and don t turn it down, because it s not very efficient if you do that. Whereas this technology is perfect for those types of things, he said. POWER PLANT PERKS In addition to being relatively easy to engineer and construct, which means they can be installed in as little as a year, ICE plants are creating a stir among utilities providers for the technical advantages they have over combined cycle turbine plants. Namely, they don t need huge amounts of water, turning them on and off multiple times a day doesn t affect the maintenance cycle, and they run well at high altitudes and in hot weather. Add that to the fact that they have significantly lower carbon and NO x emissions compared with other types of generators and it s easy to see why these engines, even though they re based on 150-year-old technology, are taking a lead role in making US electricity production leaner and greener. 58 Twentyfour