An Introduction to New Energy Technologies Essay

New energy refers to various forms of energy other than traditional energy. I have organized a brief discussion of new energy technology essay, welcome to read!

An Introduction to New Energy Technology Paper I

On New Energy Power Generation Technology

Abstract: This paper introduces the application of China's energy power generation technology from the current situation of global energy, and finds that China's new energy power generation is of great strategic significance for modernization. Two new energy generation technologies, wind power generation system and fuel cell power generation system, are further introduced. Wind power generation is the most mature technology, the most conditions for large-scale development and commercialization prospect in today's non-water renewable energy power generation, and it is also the focus of recent development. Fuel cell is a device that converts chemical energy directly into electrical energy, which has high energy conversion efficiency and almost no emission of nitrogen oxides and sulfur oxides.

Keywords: new energy; wind energy; fuel cell; power generation technology

Classification number: F206 Literature identification code: A

Energy shortage has become a bottleneck restricting the economic development of all countries, how to develop advanced and safe new energy technology, how to improve the energy utilization rate has also become the world's countries concerned about the subject. The European Union was the first to put forward the 20-20-20 plan: by 2020, renewable energy accounted for 20% of the EU's total energy consumption. December 2007, former U.S. President George W. Bush also signed the Energy Independence and Security Act (EISA), which vigorously promotes the use of new energy and energy conservation programs. In addition, from the environmental point of view, in order to protect the earth on which people depend, the development of new energy is also the way to go.

First, the current situation of China's energy and power generation technology

In 2011, China's new energy power generation continued to maintain a rapid development trend, the installed capacity of grid-connected continues to grow, and power generation continues to increase. As of the end of 2011, China's new energy installed capacity reached 70 million kW, ranking first in the world, and the grid-connected new energy installed capacity reached 54.09 million kW, a year-on-year increase of 47.4%, accounting for about 5.1% of the total installed power generation capacity. Among them, the grid-connected capacity of wind power accounted for about 85.5% of the total installed capacity of grid-connected new energy; the installed capacity of grid-connected solar photovoltaic accounted for about 4.4% of the total installed capacity of grid-connected new energy; the installed capacity of biomass and other new energy power generation accounted for about 10.1% of the total installed capacity of grid-connected new energy.

In 2011, China's new energy generation capacity of about 101.6 billion kW?h, an increase of 29.9% year-on-year, accounting for about 2.2% of all power generation. Among them, wind power generation accounted for about 72.0% of the total new energy power generation; solar photovoltaic power generation accounted for about 0.9%; biomass and other new energy power generation accounted for about 27.1%. 2011 China's new energy power generation according to the power generation of coal consumption of 320g/(kW?h), equivalent to saving 32.41 million tce, reduce carbon dioxide emissions 90.3 million t.

Electricity is the national life and production foundation. and production of the foundation, both from the energy point of view, or the power system itself, the study of new energy generation technology for China's modernization and people's lives have considerable practical significance and strategic significance.

Second, wind power generation technology

Wind energy resources mainly include land-based resources and offshore resources in two parts. Wind power is today's non-water renewable energy generation in the most mature technology, the most large-scale development conditions and commercialization prospects of power generation, but also the new energy development focus direction.

1. Development Status

In recent years, China's wind power industry has made great progress, which is inextricably linked to China's rich wind energy resources. According to relevant information, on land from the ground at a height of 10 meters, China's wind energy resources theoretical reserves of about 4.3 billion kilowatts, technology can be developed for about 300 million kilowatts, 50 meters from the ground, it is estimated that may be doubled; offshore resources of 10 meters high economic development of about 750 million kilowatts, 50 meters high about 1.5 billion kilowatts. From the total installed capacity of China's networked wind farms, by the end of 2006, China has built about 91 wind farms, with a total installed capacity of about 2.6 million kilowatts, 1.34 million kilowatts more than the 2005 new installed capacity, a growth rate of 105%. According to the national medium- and long-term plan, wind power generation should reach 15 million kilowatts in 2015 and 30 million kilowatts in 2020. However, compared with the wind power developed countries, China's development scale is still very small, and the development speed is also slow. Important factors constraining the development of wind power in China include both technical and institutional aspects. Technology, wind turbine manufacturing level is low, wind turbine performance testing equipment and technology is also relatively backward, and the lack of corresponding certification bodies; system, the level of operation and maintenance of wind farms and systems and foreign wind farms and domestic thermal power production compared to the obvious gap, the lack of detailed records of problems and failures in the operation process, analysis.

2. Impact on the power system

Wind turbine is the wind as the prime mover, the wind's random volatility and intermittency determines the wind turbine power output is also fluctuating and intermittent. Therefore, large-scale access to wind farms will bring fluctuations in power, which will increase the burden on the power grid, affecting the quality of power supply and grid stability.

(1) Impact on power quality. Air flow movement caused by the wind speed fluctuation cycle is generally a few seconds to a few minutes, this short cycle of wind speed fluctuations and the operating characteristics of the wind turbine itself may affect the power quality of the grid. First of all, it will have an impact on the frequency: wind power generation active power fluctuations caused by electromagnetic power fluctuations, due to the rotor inertia of the generator set, the regulation system is difficult to keep up with the instantaneous changes in electromagnetic power, resulting in a power imbalance, so that the generator speed changes, the frequency of the system will also change. In addition, wind power will also have an impact on the voltage: fluctuations in the output power of grid-connected wind turbines lead to fluctuations in voltage, and the frequency range of its output power is within the range of the voltage flicker (25Hz), so it will cause voltage flicker, and finally will produce harmonic voltages and harmonic currents.

(2) The impact on grid stability. For weaker grids, wind power fluctuations will lead to instantaneous voltage dips as well as frequent dropouts of wind turbines. After the fault is cleared, the magnetization of the generator and the increase in the turndown rate will consume a large amount of reactive power, leading to difficulties in restoring the grid voltage.

(3) Impact on FM peaking capacity. Airflow for a long time, seasonal movement caused by the wind speed fluctuation cycle is generally a few hours, or even days, months, this long period of wind speed fluctuations will increase the existing grid frequency regulation peak burden. The trough of the load curve often corresponds to the peak of the wind power output, the wind farms on the grid to make the equivalent load of the grid peak and valley difference increases, greatly increasing the grid frequency regulation peak burden.

Third, solar photovoltaic cell power generation technology

1. 1 solar photovoltaic cells

Solar photovoltaic cell power generation is also referred to as solar photovoltaic power generation, is considered to be the future of the world's fastest-growing and the most promising of a renewable new energy technology. The basic principle of solar photovoltaic cells is to use the semiconductor "photovoltaic effect" (photovoltaic effect) to convert the sun's light energy directly into electrical energy. Materials that can generate electricity using the photovoltaic effect are called photovoltaic materials. A device that uses the photovoltaic effect to convert solar energy directly into electricity is called a solar photovoltaic cell or photovoltaic battery. Photovoltaic cells are the core components of solar photovoltaic power generation.

In 1839, the French physicist Edmond Bec-qurel found: two pieces of metal immersed in the electrolytic solution of the voltaic cell, when receiving sunlight irradiation when the voltage rises, he published a paper on this phenomenon is called "photovoltaic effect ( PhotovohaicEffect)". Photovohaic Effect". "The Photovohaic Effect is a phenomenon in which an uneven semiconductor or a semiconductor-metal hybrid material under the action of light changes the distribution state and concentration of carriers that can conduct current within the material, resulting in a potential difference between different parts of the material. 1941, Auer discovered the photovoltaic effect on silicon, thus laying the foundation for the use of semiconducting silicon in the widespread application of solar photovoltaics. In 1954, the United States Bell Labs scientists Chapin (Darryl Chapin) and Pearson (Gerald Pearson) developed the world's first practical monocrystalline silicon photovoltaic cells. In the same year, Weikel found that gallium arsenide has a photovoltaic effect, and cadmium sulfide film deposited on the glass, made the world's first thin-film photovoltaic cells. The Dafeng 20 MW photovoltaic power plant, which was put into operation in December 2010, is currently the largest thin-film photovoltaic power plant in the country, with an annual generation capacity of 23 million kW-h.

The principle of operation of solar photovoltaic cells is shown in Figure 1.

In the semiconductor doped impurities made of PN junction, to form in the equilibrium state of the built-in electric field, the built-in electric field under the action of the separation of excess carriers generated by the external excitation, thus forming an external voltage. Under light conditions, electrons in the semiconductor absorb photon energy and jump from the valence band into the conduction band, forming electron-hole pairs that become carriers. The minimum energy required to generate carriers is the forbidden bandwidth of the semiconductor Eg, solar cells made using materials with smaller forbidden bandwidths can form larger currents.

Monocrystalline silicon based on the first generation of photovoltaic cells is currently the mainstream of the solar photovoltaic cell market, its photoelectric conversion rate has reached 24. 7%; based on thin-film technology, the second generation of photovoltaic cells photoelectric conversion efficiency has reached 16. 5% ~ 18. 8%. Due to the thin film photovoltaic cells greatly reduce the consumption of semiconductor materials, and therefore has good prospects for development. It should be noted that photovoltaic cells in the photovoltaic conversion process, photovoltaic materials do not undergo any chemical changes, nor does it produce any mechanical wear and tear, so solar photovoltaic cells are a kind of noiseless, odorless, non-polluting ideal clean energy. 2006, China's total production of solar cells for the first time to reach 400 MW, thus exceeding the United States as the world's third largest producer, but also the world's fastest growing country. The company is also the fastest-growing country in the world.

1. 2 Solar photovoltaic power plant

Solar photovoltaic power plant is a number of photovoltaic conversion devices, that is, photovoltaic cells encapsulated into photovoltaic modules, and then according to the needs of a number of components into a certain power of photovoltaic arrays, and with the energy storage, measurement, and control devices to match, constituting solar photovoltaic power plant.

Solar photovoltaic cells have a great deal of flexibility, not only can they be used to build sporadic specifications of the power station, but also can be composed of solar photovoltaic power generation systems applied to small, decentralized power users. This independent operation of solar photovoltaic power generation system called off-grid solar photovoltaic power generation system.

Due to the influence of diurnal insolation and weather, off-grid photovoltaic power generation systems usually need to be used in conjunction with other forms of power supply, such as diesel generator sets and battery packs, which increases the investment and maintenance costs of the power plant. Off-grid PV systems are often built in remote mountainous and desert areas far from the grid to supply power to independent regional users.

The off-grid solar PV power plant system is shown in Figure 2.

The power generation system of the power station consists of solar photovoltaic cell arrays, battery packs, DC controllers, DC-AC inverters, AC distribution cabinets, and backup power supply systems (including diesel generator sets and rectifier charging cabinets), etc. The working principle is that the solar photovoltaic cell arrays can be used to generate electricity. Its working principle is that the solar photovoltaic cell array supplies power to the battery pack through the DC control cabinet, and the upper and lower voltage limits of the battery pack are adjusted according to the needs, and the charging is automatically controlled by the DC control cabinet. The battery bank supplies power to the DC-AC inverter through the DC control cabinet, and the DC power is converted into three-phase AC power through the inverter, and then the power is supplied to the user through the AC distribution cabinet under the three-phase four-wire system. When the voltage of the battery pack drops to the lower limit voltage, in order not to cause the battery pack to be over-discharged, the DC control cabinet will automatically cut off its output circuit, so that the DC-AC inverter stops working. The diesel generator set is the backup power source of the power station, which will charge the battery bank through the rectifier charging cabinet if necessary, or supply power to the users directly through the AC power distribution cabinet when the PV power generation system fails or stops operation. DC - AC inverters and diesel generator sets can not be supplied to the user at the same time, for this reason must be set in the AC distribution cabinet interlocking device to ensure the uniqueness of the power supply.

When the capacity of the solar PV plant reaches a certain size, it can also be connected to the grid, the so-called grid-connected PV plant. At this point, if the local load is insufficient, the excess power can be delivered to the grid. When the local solar power generation is insufficient, the grid will provide electricity to the users. Therefore, grid-connected PV plants can eliminate the need for energy storage devices, reducing system investment and maintenance costs. At the same time, due to the mutual aid with the power grid, improve the utilization rate of power generation equipment and the safety and reliability of power supply and electricity, is the inevitable trend of large-scale development of solar power generation technology. China's first grid-connected photovoltaic power plant is a 100 kW high-pressure grid-connected photovoltaic power plant in Tibet's Yangbajing Renewable Energy Base, which was put into operation in 2006. 2 × 10 MW of photovoltaic power projects were put into operation in Dunhuang at the end of 2010, which was the first grid-connected photovoltaic project in the country.

Conclusion and Prospect

This paper analyzes and explains that new energy power generation technology is an urgent and practical research topic from the global and China's energy status, and then introduces the characteristics of wind power generation system and fuel cell power generation system as well as China's development status in these two aspects. New energy does not only refer to wind energy and fuel cells, but also includes biomass energy, ocean energy, geothermal energy and photovoltaic cells. The potential for the development of new energy power generation technology in our country and even in the whole world is enormous. In the stage of human tomorrow, new energy will replace fossil fuels and play an important role.

References:

[1] Xu Dehong . Introduction to New Energy Power Electronics [D]. Hangzhou : Zhejiang University ,2009.

[2] Hao Wei, Shu Jun, Zhang Particle. An overview of new energy power generation technologies [C]. The Fifth Annual Conference on Graduate Student Academic Exchange, North China Electric Power University , 2007.

[3] Shi Tao. Modeling and simulation of fuel cell power generation system [D]. Nanjing:Southeast University,2007:5-6,63-64.

Click on the next page for more >>> > Introduction to New Energy Technology Paper