Generating Electricity from Excess Heat
The power sector may have another tool in its kit to meet tomorrow's energy demand. It is the recycling of wasted energy that scientists say could supply much-need generation capacity while also limiting the release of heat-trapping emissions.
Consider that for every BTU of coal or natural gas burned in a combustion turbine only 35 percent of that is converted into useful power. The other 65 percent is lost forever in the form of waste heat that is discharged into the environment. Interestingly, the technology exists to modify that waste heat -- a tool that could gain ever-increasing credence if natural gas and coal prices turn volatile
"Generating electricity from waste energy is similar to renewable generation because it is a use-it-or-lose-it source, much like catching wind, sunlight, or falling water," says Melissa Mullarkey, a public policy associate at Recycled Energy Development, in a formal paper she authored.
In the end, she says that while the process does not require the use of any more fuel it does boost the efficiency levels to at least 65 percent. At the same time, far fewer greenhouse gas emissions are released, although the government has expressed concerned that more nitrogen oxide will be created.
With the U.S. Energy Information Administration saying that the expected demand for power will rise by 50 percent over the next two decades, the country will need every resource possible. Along those lines, the Oakridge National Laboratory issued a study that says an expansion of co-generation could provide 20 percent of the nation's generation capacity by 2030. Doing so would also generate $234 billion in new investment and create 1 million new jobs.
Recycling energy falls under the category of combined heat and power, which generates and uses both electricity and thermal heat - a technology that is now eligible to receive 10 percent investment tax credits from the U.S. government. Combined heat and power units produce about 12 percent of all electricity in this country.
Because the recycling process requires no added fuels, there's a huge window of opportunity to capture energy in those refineries and industries where the wasted heat is released at 300-700 degrees Fahrenheit. Put simply, it is like boiling water and then using the steam to power other things in the house. But for all practical purposes, the steam is just released and lost forever.
Consider ArcelorMittal Steel USA: It says that international competition has caused it to find ways to cut drastically its energy consumption, and that it will continue to do so. To that end, it has implemented a process at one of its steel plants in Chicago whereby it re-uses heat to make electricity and thereby saves it $100 million a year.
Up in Smoke
That is a practice popular among European industrials with many of them producing as much as 20 percent of their power this way. But Mullarkey with the Recycled Energy Development says that there are some regulatory barriers to overcome in this country before businesses here could achieve such results.
For starters, she points to the New Source Review provision under the Clean Air Act. That rule is intended mainly to prevent older coal-fired power plants from equipping those units to produce more energy so as to minimize pollutants. Tough enforcement of the law, in fact, has resulted in a number of settlements with utilities - deals that have required them to spend millions to modernize their coal facilities.
But according to Mullarkey, some power operators fear that that they will get sued if they equip their facilities so that they could capture excess heat. She writes that these projects could alter the generation process and thus violate the New Source Review. Even though the technology may cut carbon levels it could increase nitrogen oxide levels as more energy is generated.
"Energy policy should promote using industrial off gas to generate power instead of flaring it, but because of potential changes in emissions that could trigger New Source Review, these projects are not pursued," writes Mullarkey. "Given that waste energy recovery represents the quickest, easiest, and most profitable way to reduce carbon dioxide emissions, it is essential to address the regulatory barriers to these projects."
Furthermore, cost is a deterrent. Central generation last year was reported to be notably less expensive per kilowatt than that of local generation, which is at the core of the recycling process. However, with a big plant, there's a need for transmission and distribution -- all of which adds to the expense of building a central power facility and which makes on-site power more attractive.
Recycled Energy Development is involved with a silicon maker in West Virginia. The silicon production process entails the use high temperatures and those exceeding 3,000 degrees. The goal is to take the heat that would otherwise just evaporate and to use it to create clean electricity that increases the efficiency of the silicon plant. Doing so not only minimizes pollution levels but it also limit expenses and create jobs.
"What we are doing in West Virginia shows that it's possible to cut manufacturing costs and carbon emissions at the same time," says Sean Casten, the energy development president. "If used widely throughout the industrial sector, energy recycling could be the key to restoring American manufacturing."
Energy is wasted daily. And a marketplace void now exists to recapture waste heat and to apply it to create electricity. Proponents of the concept say that the technology is available today to do just that but that high costs and regulatory impediments stand in the way. If the federal government gets more involved, then they say that fewer power plants will ultimately be necessary and that the air will be much cleaner.
To subscribe or visit go to: http://www.energybiz.com