Stuart McCarthy, Thermal Energy International Inc, Nepean, Canada
Coal enjoys a substantially lower cost and greater availability than either natural gas or oil, with far greater reserves than either, to supply future generations. Coal remains the king of power production with 55 per cent of electric power in the USA produced from coal and some states, such as Kentucky, Indiana and West Virginia, deriving almost 100 per cent of their power from coal. Other parts of the world, such as China, also receive over 90 per cent of their power supplies from coal-fired facilities. However, the upside of the cost equation has its downside in higher rates of unwanted emissions than other fossil fuels.
Figure 1. The US EPA has set new NOx emission targets under the State Implementation Plan
In Europe and the USA, environmental agencies have for some time been implementing stiffer regulations on the energy and industrial sectors when it comes to emissions from coal-fired power generation or industrial boilers using coal.
One of the latest targets for regulators on both sides of the ocean is nitrogen oxides (NOx), which have been identified as one of the primary contributors to ground level ozone formation. Combined with Volatile Organic Compounds (VOCs) and activated by the sun’s rays during warm weather, this chemical soup turns to smog with damage ranging from crop destruction to respiratory ailments in humans.
In the USA, the Environmental Protection Agency (EPA) has set new targets for reduced NOx emissions in 22 states and the District of Columbia, under the State Implementation Plan or “NOx SIP Call”. Starting in 2003 for some states and 2004 for others, power producers must reduce their NOx emissions to 0.068 kg/mmBTU from current US Clean Air Act Title 4 limits of 0.2 kg/mmBTU. These reductions must occur during the smog season or the five hottest months of the year. While the SIP Call affects 22 states, just four of those states – Ohio, Indiana, West Virginia and Illinois, account for 47 per cent of the targeted NOx reduction.
Similar targets exist in Europe where the European Commission has mandated a reduction in NOx emissions by 2010 of 44 per cent from 1990 levels. Coal-fired power generation used to provide power for 380 million EU residents and accounted for 37 per cent of all EU NOx emissions. Industry, transportation and even natural formations account for the balance.
The five primary contributing nations to NOx emissions in the EU are the United Kingdom (22.94 per cent), Germany (21.29 per cent), Italy (16.94 per cent), Spain (10.44 per cent), and France (7.28 per cent).
To comply with previous regulations for reducing acid rain emissions such as sulphur dioxide (SO2), power producers undertook a number of initiatives. Some switched to low sulphur coal, which while hitting SO2 targets, has a reduced heating rate, requiring greater consumption of coal. Others decided to do nothing, purchasing SO2 credits because the cost of credits were cheaper than implementing compliance measures.
Others deployed scrubbing equipment, the most common being classed as wet flue gas desulphurization (WFGD) scrubbers. In the USA, approximately 20 per cent of coal-fired power stations are equipped with WFGD scrubbers, while in Europe, 70 per cent of coal-fired power plants are scrubbed.
It is into the immediate market opportunity and the future growth market that Thermal Energy International Inc. of Ottawa, Canada, has developed a revolutionary new NOx control technology called Thermalonox.
Figure 2. Thermal Energy and AEP will install and test Thermalonox at the Conesville power plant in Ohio
Thermal Energy president and chief executive officer Thomas Hinke and his father Dr. Joseph Hinke, an eminent Canadian cell physicist and professor, created Thermalonox. Thermalonox is now patented or patent-pending in 42 countries.
Thermalonox has been developed to efficiently and safely reduce NOx emissions by up to 90 per cent and at 75 per cent lower cost than existing technology. The primary target market is the coal-fired power market where facilities are already equipped with WFGD or other scrubbers. However, Thermalonox is also designed to efficiently remove NOx from any flue gas stream including those from gas turbines and oil-fired boilers.
Until now, the primary mass NOx reduction technology being employed was Selective Catalytic Reduction (SCR), which is a capital-intensive technology, requires mass storage of ammonia and super heating of flue gas. A typical SCR installation can take up to two years with substantial power station downtime. A number of communities in the US have expressed concern over the issue of potential leaks from pressurized ammonia storage and have sought to ban SCR implementation in their communities.
Testing the technology
Recently, American Electric Power (AEP), one of the largest US investor-owned electric power utilities, entered into a strategic alliance with Thermal Energy. AEP operates 38 000 MW of power generation assets, approximately 26 000 of them from coal. AEP also owns two electricity distribution companies in the UK and has ownership in coal-fired assets in China.
The alliance will see Thermal Energy and AEP install the first commercial-scale demonstration of Thermalonox at the utility’s Conesville, Ohio power station. The Conesville plant has six units generating a total of 2000 MW, with two of its 375 MW units equipped with WFGD scrubbers.
One of these units will host the $15 million project on which construction is expected to be completed by the end of May 2001, followed by eight to 12 weeks of testing. The NOx emissions at Conesville are currently 0.2 kg/mmBTU and the Thermalonox project is designed to achieve a minimum 75 per cent reduction in NOx emissions at Conesville to exceed compliance with the new EPA target of 0.068 kg/mmBTU.
Martin Mearhoff, AEP’s vice president of renewable energy and advanced technologies views the successful demonstration of Thermalonox as “very important to AEP and for that matter, to the US utility industry”. The Thermal Energy-AEP alliance extends well beyond the demonstration project. In addition to funding the project, AEP has acquired an option to obtain up to 20 per cent of Thermal Energy in exchange for the exclusive rights to licence Thermalonox in North America for deployment at coal-fired power generation stations currently equipped, or to be equipped with WFGD scrubbers. AEP’s subsidiary AEP Pro Serv, Inc. will lead the Thermalonox charge. Thermal Energy is also interested in establishing similar relationships in other industrial sectors and other parts of the world to complement the existing alliance with AEP.
The two-step process
Thermalonox is a two-step process. The first step is to initiate a gas phase chemical reaction in the flue gas converting NOx to NO2. This is done through installing a compact injection system in the flue duct before the WFGD scrubber. The NO2 is water-soluble and can be extracted in the WFGD scrubber to the same efficiency as the SO2 scrubbing, typically anywhere from 75 per cent to 95 per cent.
“There are hundreds of different WFGD products around the world. The first step can easily be adapted to any WFGD system, turning it into a low NOx FGD system,” said Thomas Hinke.
The first phase reaction is accomplished by the direct injection of elemental phosphorus (P4) into the exhaust gas stream at the existing temperature range, typically 121-280°C. The P4 reacts simultaneously with oxygen (O2) to form ozone (O3) that immediately reacts with NO to form NO2.
The second phase employs the existing WFGD scrubber circuitry to absorb and dissolve up to 90 per cent of the NO2, which is absorbed and dissolved into water and removed. Once in solution form, NO2 hydrolyzes with relative ease to form nitrite and nitrate ions.
While most scrubbers can adequately handle the NO2 removal and power plant operators may be satisfied with the levels obtained, others may wish to increase NOx removal efficiency even further, possibly for excess compliance and the generation of NOx emission credits. Thermal Energy’s Flu-Ace technology can be added after the scrubber to increase the removal efficiency and turn the Thermalonox/DeSOx scrubbing system into a full multi-pollutant removal system.
Flu-Ace is a system developed in the late 1980s and deployed by Thermal Energy at a number of institutional and industrial settings, for waste energy recovery from any flue gas stream. The Flu-Ace towers were refined to accomplish one of the highest rates of efficient heat recovery in the form of clean, hot process water, plus highly effective air pollution control.
By adding a Flu-Ace tower as a polishing scrubber to a Thermalonox equipped WFGD system, a power producer can increase NOx and SOx removal to between 95 per cent and 99 per cent. The Flu-Ace system can also capture particulate matter as small as 0.3 microns, and remove up to 99 per cent of heavy metals in emissions such as mercury. In the USA, the EPA recently announced its intention to set mercury emission targets for the power industry commencing in 2004. Flu-Ace presents an opportunity for the power industry to enter into district heating arrangements with nearby institutions, provide process water or even simply offset internal heating or water requirements.
Transportation of goods
The phosphorus used in Thermalonox is typically shipped by rail in specially designed cars called “isotainers”. The P4 is shipped as a solid and is stored under water. On arrival, heating units within the car raise the temperature of the P4 until it liquefies. For the Conesville demonstration, the rail cars will serve as the on-site P4 storage facility. Upon successful completion of the demonstration, it is anticipated that AEP will convert the system to permanent usage at which time a more permanent storage system will be built.
The P4 is then transported through specially designed lines to a stage where it will be diluted in emulsion form for spraying into the duct system.
The impact on scrubber by-products is seen to be quite positive. First, for those who are producing gypsum for wallboard, Thermal Energy sees no detriment, whereas with SCR as little as 4 ppm of ammonia can ruin the setting time. Furthermore, there are no toxic by-products from Thermalonox and combined with the WFGD technology, valuable inorganic chemical by-products can be retrieved such as calcium phosphates for use in the fertilizer industry to further offset compliance costs. In cases where the by-products are simply used for landfill, again, no problems are foreseen.
Figure 3. Thermalonox uses a compact injection system and the existing WFGD scrubber to reduce emissions
One of the critical components of Thermalonox is elemental phosphorus. Phosphorus is the eleventh most abundant solid element on the planet. The US Geological Survey estimates that phosphorus reserves are ample enough for at least 130 years of supply.
To ensure a supply of phosphorus is available for Thermalonox users, Thermal Energy has entered into an alliance with Astaris LLC of St. Louis, one of the world’s largest producers of phosphorus and phosphorus derivatives. This new alliance brings more than just a supply of phosphorus. Astaris also brings engineering expertise in the creation of phosphorus injection and delivery systems, as well as a full safety and handling regimen that is second to none.
While phosphorus can be a flash fire hazard because of its instant combustibility on contact with oxygen, it is this precise quality which makes it so effective in Thermalonox. To this end, Astaris is assisting Thermal Energy and AEP, as well as future clients, with the development and deployment of full safety systems. These safety systems not only ensure the secure storage of phosphorus and utility assets, but more importantly are designed to protect the workers and create the optimum safe environment.
Such systems have been in use for decades as phosphorus and phosphates are widely used in everything from food and fertilizers to dyes and antibiotics. While the innovation behind Thermalonox is clearly new and revolutionary, the underlying technology is proven and sound.
Thermalonox versus SCR
At the end of the day, the cost for any environmental compliance technology must be borne by the consumer, be they residential or business. In this regard, Thermalonox has some clear advantages over SCR. One factor in the economics is the minimal downtime for power producers in implementing Thermalonox.
In SCR installations, power station units may be forced offline for several months during the extensive retrofit process. This impacts revenues for the utility or power producer from lost sales of energy into the grid, or in cases of deregulation, directly to end-users. There is a double whammy here for power suppliers who have energy commitments or contracts with clients and must therefore source alternative supplies of electricity to meet those commitments.
Thermal Energy commissioned US energy analysts GenerSys Inc. of Albany, New York, to do a study comparing the cost of Thermalonox to SCR in the EPA NOx SIP Call area. GenerSys screened the scrubbed units in the EPA NOx SIP Call territory and concluded that Thermalonox consistently beat SCR as an investment. In 135 of 140 units screened, the return on equity versus SCR was greater than 16 per cent with a number of units exceeding 100 per cent ROE, with Thermalonox being installed for as little as $35/kW, compared to $75 to $100/kW for SCR.
GenerSys concluded that Thermalonox and SCR are the only two mass NOx reduction technologies available for existing coal-fired utilities. Only empowering with alternative fuels will generate significant NOx reductions. GenerSys based the financial parameters for Thermalonox and SCR against the “do nothing” approach, which anticipates the availability of NOx emission credits in the market. GenerSys, a number of utilities and other analysts anticipate NOx credits trading in the $2500 to $3500/t range and the analysis examined the 140 units against a credit range of $1500 to $5500.
The study treated compliance options as an investment opportunity, mitigating the up-front capital cost, ongoing operations and maintenance costs and capital additions against the avoidance cost of purchasing emissions credits. At the $3500 per credit range, virtually every scenario showed Thermalonox as a hands-down winner. As the GenerSys report concludes, “Thermalonox is now available as a better choice for your compliance needs than SCR.”