The E8 Network of Expertise for the Global Environment
Deployment of new technologies
American Electric Power
American Electric Power (AEP) has been a leader in advancing new approaches to converting coal into electricity, such as Integrated Gasification Combined Cycle (IGCC) and FutureGen. Originally born out of the intent to turn coal into electricity with fewer environmental impacts, AEP’s attention to these coal-based power generation technologies have spurred industry realignments, public policy innovations, and public/private partnerships.
Description
IGCC and FutureGen refer to related, but different, approaches to converting coal into electricity. IGCC involves partially combusting coal under high pressure to produce a synthetic natural gas (syngas), which is then turned into electricity via combined cycle combustion. The syngas generated by IGCC can be cleaned of substances such as sulfur and mercury prior to combustion, and it is relatively cost-effective to do so in comparison to conventional pulverised coal-fired technologies, which require post-combustion pollution control technologies. The technologies associated with FutureGen take the aforementioned process of coal gasification even further by emphasising capturing carbon dioxide before combustion and giving additional priority to using syngas to produce products other than just electricity, such as liquid fuels and hydrogen for fuel cell operation. To differentiate the two, IGCC is a proven technology that AEP is working to translate into commercial-scale, baseload operation to meet electricity demand in the near future, whereas FutureGen is a public/private partnership to demonstrate and develop experience with a host of prototype technologies across a wider range of energy products with a goal of zero-emissions for the more distant future.
Results
Although AEP is awaiting regulatory approvals for its proposal to build an IGCC power plant in Ohio, and despite the fact that the FutureGen project remains in an nascent stage of development, several important changes have been motivated by AEP’s commitment to these new power generation technologies. With regard to IGCC, AEP’s announcement of its intent to scale this technology up to commercial operation has helped to bring about recent corporate acquisitions and spurred new industry alliances that have dramatically reduced the risk associated with coal gasification for power generation. Specifically, turnkey engineering, procurement & construction (EPC) solutions have emerged to replace the disconnected array of intellectual property owners, equipment vendors and construction services suppliers that had previously rendered project accountability all but impossible. AEP’s proposal for financing its IGCC plant also has introduce innovations in public policy that seek to integrate the best aspects of both the traditional regulated approach and the more recent attempts at market competition. The scale and risk of the ten-year, US$1 billion FutureGen project has necessitated large-scale, public/private cooperation between government and myriad industry stakeholders to share in the ambitious task of developing technologies that can decouple coal-based energy from emissions of regulated emissions and greenhouse gases.
EDF
EDF contributes to reducing emissions by giving priority to technologies that emit no, or little, CO2 (nuclear, hydro, new and renewable energies). The company consistently researches innovative technologies, seeks optimal integration of clean energy solutions in its electrical systems, and helps its customers to manage their energy consumption efficiently.
Nuclear power, along with hydropower, is the best means of generating large amounts of electricity without emitting greenhouse gases. In view of renewing its nuclear fleet, EDF has decided, in agreement with the French government, to begin construction of an initial-run, European pressurised water reactor (EPR – 1,600 MW) in Flamanville, Normandy.
Based on the estimated life span of 40 years for the nuclear plants now operating, the first plant retirement is expected in 2015. Retirement of other units will follow accordingly, requiring preparation in advance.
The EPR is the fruit of cooperation between French and German engineers. An improvement over existing PWR reactors, the new model reinforces safety and energy efficiency standards while lowering volumes of waste per kWh generated. In 2003, Finland also announced its intention to build an EPR. The new reactor does not sign a total break with past technology, so EDF will be able to capitalise on experience gained from existing
reactors. EDF will ensure plant engineering, integrating operator requirements into construction. Cost is estimated at €3 billion. The EPR has an estimated life span of 60 years.
EPR, Site Flamanville, in France
ENEL
'Archimedes Project': the new frontier of renewable energy plant
In 2003 ENEL and ENEA studied the possibility of integrating existing thermoelectric plants, especially combined cycle plants, with concentrating solar fields featuring linear parabolic collectors using the most recent technological innovations (solar collector, heat collector elements, thermal fluid and thermal storage) developed by ENEA in the Research & development framework.
In particular the project foresee the carrying out of renewable power plant that utilize solar energy to produce steam :
the steam will be forwarded near by Enel gas-fired combined cycle power plant.
This project represents a unique pilot implementation and it is part the initiatives that Enel is carrying out to pursue :
- The development of renewable energy in tune with the European directive 2001/77/CE;
- The security of energy supplying as indicated within green book of European Union;
- The carbon dioxide emissions reduction in compliance with the National Allocation Plan that the Italian Government has predisposed to meet the Kyoto target.
Project Description
The project deals with the integration of a solar plant with the latest generation of ENEL combined cycle power plant consisting of two 380 MWe groups. This CCGT power plant is located in Priolo Gargallo in the province of Siracusa on East coast of the Sicily: it has been chosen for its good meteorological conditions, a good solar radiation and availability of suitable surrounding land.
The solar part will contribute with peak electric power of around 30 MWe, added to the nominal pre-existing capacity of the plant, and will use the existing system and services for the thermodynamic cycle (plant, staff, infrastructure, etc.), the technical characteristics of which were found to be compatible with the project specifications.
The solar energy collected is used to produce steam to be fed to the existing plant turbo-generator groups as a supplement to that produced by the steam recovery generators, to increase the total electric production for a given fuel consumption (figure 1).
Figure 1
The technology for capturing solar energy is based on the use of linear parabolic collectors, consisting of a parabolic shaped reflectors (a common glass mirror) which, through a specific control system, continually concentrate the direct radiation from the sun onto absorption tubes (heat collector elements) situated at the parabola focus. Fluid used to capture the solar energy is circulated inside these heat collector elements.
Description of the solar plant
The main elements of the plant are :
- The solar field;
- The storage system;
- The steam generator;
- The auxiliary systems for plant start up and control.
The solar field represents the heart of the plant, it is here that the solar energy is collected, concentrated and the solar radiation absorbed to become the substitute for fuel and the thermal energy generator in conventional plants. It consists of linear parabolic collectors arranged in parallel rows, each of which is formed from several elements in series to form a single solar collector assembly or string. The solar field therefore presents a modular structure: the number of solar collector assemblies determine the thermal energy collected and therefore the power of the plant.
The collectors have a parabolic section reflector which continuously collect and concentrate the direct radiation from the sun through a specific control system onto a linear heat collection element situated on the parabola focus, inside which a fluid is circulated to capture the solar energy. The thermal fluid used is a binary mixture of molten salts (40% KNO3, 60% NaNO3).
The storage system consists of two storage tanks operating at two different temperatures: its own task is to store the thermal energy absorbed from the solar field and render it continuously available, independent of the variations in the solar source. The accumulation system is linked to the solar field through a distribution network that allows the transport of thermal energy from the solar collectors to the storage tanks.
The steam generator is the system that uses the stored thermal energy and consists of “tube and shell” heat exchangers in which the considerable heat generated by the process fluid is transferred to the water to produce superheated steam suitable for use in the thermoelectric plant turbines. When electric energy is required, the salts from the hot tank are sent to the heat exchanger, where high pressure and high temperature steam is produced for use in the thermal cycle of the ENEL plant, and then pumped back to the cold tank.
The main auxiliary systems required by the salt plant are those relating to the process fluid preparation, its circulation through the plant, heating of the pipe work and components and movement of the solar collectors.
Photo: Solar collector
Table of main parameters of the Priolo solar plant
| u.m. | ||
|---|---|---|
| Number of collectors | 318 | |
| Collector surface | 104 m2 | 17.91 |
| Peak power of the solar field [1] | MWt | 136.1 |
| Temperature of the hot – cold tanks | °C | 550 - 290 |
| Salt flowrate through the solar field at peak power | kg/s | 345.6 |
| Maximum solar energy(DNI) | GWht/y | 313.1 |
| Solar energy at the collector level | GWht/y | 253.4 |
| Solar energy transferred to the fluid | GWht/y | 156.5 |
| Annual average efficiency [2] | % | 61.8 |
| Maximum storable solar energy | GWht/y | 151.3 |
| Storage capacity | MWh | 500 |
| Maximum thermal power of the GV | MWt | 64.4 |
| Stored thermal energy | GWht/y | 149.9 |
| Thermal energy utilised | GWht/y | 130.6 |
| Fraction wrt that stored | % | 87.2 |
| Fraction wrt that available at collector level | % | 51.6 |
| Nominal capacity | MWe | 28.8 |
| Efficiency at nominal power | % | 43.6 |
| Gross electric energy produced [3] | GWhe/y | 55.9 |
| Expected functioning hours per year | h/y | 5,110 |
| Effective functioning hours | h/y | 2,774 |
| Plant utilisation factor [4] | % | 38.9 |
| Average annual electric efficiency net wrt the DNI | % | 17.3 |
| Saving in primary energy [5] | TEP | 11,835 |
| CO2 emissions avoided | t | 36,306 |
Hydro-Québec
** Contribution to be determined **
Kansai
Kansai Electric built its new headquarters building in December 2004 to function as the strategic core center of its group companies. The headquarters building was built based on the concepts of functioning as the “hub for the promotion of efficient management”, “place for harmony and sympathy with the society”, and a “model building for environmental symbiosis”.
The building has columns and beams protruding 1.8 m from the windows called “eco frame” that effectively block sunlight in summer season and directly leads natural breeze into the office rooms to reduce the air-conditioning load. The building is also equipped with total 100kW solar panels that are set on the “eco frames” on the south sides of each floor and on the roof of the building to actively utilise natural energy.
In addition, to promote energy conservation, the building uses light and motion sensors, thereby efficiently using daylight in work areas and dimming lights in office areas where nobody is working. The building also aims at both conserving energy and providing amenity for the office workers by, for example, setting lower air conditioning temperature around the office desk areas, whereas ambient room temperature is set higher.
The building is also equipped with a large-scale ice thermal storage district heating and cooling plant that uses untapped river water and exhaust heat from a substation to contribute to load-levelling and prevent the heat island phenomenon locally.
As a result of these measures, Kansai Electric expects a reduction of approximately 30% of primary energy consumption from office floors of the building compared to conventional office buildings.
The building is attracting attention as a leading example of a countermeasure against global warming and emergence of heat island phenomenon.
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RWE
In conventional pulverised coal-fired power plants, a further rise in efficiency is possible mainly by increasing the steam parameters, pressure and temperature. In the case of lignite-fired power plants, pre-drying of the raw lignite is an additional option.
In the past, efficiency increases in coal-fired power plants were obtained mainly by :
- improving internal turbine efficiencies
- optimising the cold end or the entire water/steam cycle by multiple reheat recovery steps
- reducing auxiliary power requirements
These potentials have been largely exhausted today. In future, increasing the steam parameters will play a decisive role.
In 2002, the latest state-of the-art supercritical lignite-fired plant in Germany (BoA 1) went on stream at the RWE site in Niederaussem. Steam outlet temperatures were raised to 580°C in the high-pressure section and to 600°C in the reheater. The increase of steam parameters and the optimized design result in a plant efficiency of more than 43%.
Better utilisation of lignite leads to lower specific fuel consumption, i.e. for the same amount of power less coal is burned. This translates into much lower fuel-related emissions. CO2 emissions are reduced by as much as 3 million t/a without reducing power output. Dust, sulphur dioxide (SO2) and nitrogen dioxide (NOx) emissions are some 30 % lower than with former plant design.
For lignite-fired power plants, pre-drying of raw lignite increases efficiency by an additional 4%. Drying the raw coal with low-pressure steam in a fluidized bed provides the necessary drying energy without using additional fuel. At the same time, the energy of the released vapours is used internally in the process. RWE has systematically developed its own fluidized-bed drying technology (WTA) over the last 10 years. The commercial-scale reliability of coarse-grain drying has been successfully proven from 1993 on. WTA Frechen demonstration plant worked without major problems with a throughput of 50 t/h of raw lignite. The breakthrough came in 2002 with the operation of fine-grain drying at a throughput of 30 t/h. In fine-grain drying, the raw lignite is ground to a grain size of 2 mm prior to being fed to the fluidized-bed drier. Fine-grain drying technology increases plant efficiency at constant costs for electricity production.
[1] With a solar flux of 1.000 Watt/m2 and a collector peak efficiency of 76%.
[2] Calculated for the solar energy on the surface of the collectors
[3] To obtain the net production, the absorption by the auxiliaries relating to the solar part, estimated at 3% of the produced energy, is subtracted.
[4] Relation between the energy produced and that that would be produced if the plant operated at the nominal power for the total number of foreseen functioning hours.
[5] An average specific thermal consumption of 2.184 kcal/kWh and a specific emission of 670 g CO2/kWh, average ENEL 2003 data for thermoelectric production.
Global environment and sustainable energy development
The e8, comprising ten leading electricity companies from the G8 countries, was formed in 1992 following the Rio Summit to examine and co-operate on major global electricity-related issues, with an emphasis on the global environment and sustainable energy development.