Understanding the effects of carbon trading from institutional characteristics of electricity markets functioning in the EU and China

Award date: 17 June 2022. Supervisor: Professor Jos Marie R. Delbeke, European University InstituteThe increasing carbon price and the unstable energy supply have precipitated concern about affordable energy prices and energy security. How do different national institutional arrangements, specifically state-led and market-led electricity market design, mediate the impact of the CO2 emissions trading on electricity price? This paper adopts qualitative comparative analysis in investigating the interrelationship between EU and China’s electricity markets, carbon markets, and how electricity markets reflect input costs (of fuels and carbon costs). And find out that there are important differences in designing and operating these markets, reflecting different economic arrangements. Despite the differences, whether in China or the EU, governments will have to involve themselves more in energy markets to ensure that the energy transition meets not only its environmental goals but also energy security and industrial goals – while ensuring the transition is affordable for consumers. The ultimate goal of fuel switching to renewables would intensify this situation

Size-dependent characterisation of deep UV micro-light-emitting diodes

Deep UV Micro LEDs (DUV-µLEDs) are attractive for optical wireless communications, however not much is known about their size-dependent characteristics. Here we study spectra, power output and bandwidth as a function of device size and achieve a bandwidth of 570MHz with a 20µm diameter device

Experimental study of coal and gas outburst processes influenced by gas pressure, ground stress and coal properties

With the continuous increase of mining depth, coal and gas outburst poses a significant threat to mining safety. Conducting research on the mechanisms of coal and gas outbursts contributes to understanding the evolutionary process of such incidents, thus enabling accurate prediction and prevention of coal and gas outbursts during mining operations. This paper has developed a comprehensive visual experimental system that is specifically tailored to simulate diverse coal body conditions, ground stress and gas pressures. By monitoring and analyzing the real-time progression of coal fissures during the outburst process, we can obtain valuable insights into the evolution and mechanisms of coal and gas outbursts. Additionally, this study introduces a method to determine the critical threshold for predicting coal and gas outbursts, and the critical gas pressure threshold for Jiulishan Coal Mine (Jiaozuo City, Henan Province, China) is established at 0.6 MPa

Over 10 Gbps VLC for long-distance applications using a GaN-based series-biased micro-LED array

By employing a GaN-based series-biased micro-light emitting diode (µLED) array and orthogonal frequency division multiplexing modulation format, a high-speed free-space visible light communication system for long-distance applications has been demonstrated. The blue series-biased µLED array, which consists of 3×3, 20 µm-diameter µLED elements, presents promising performance with an optical power and -6dB electrical modulation bandwidth of over 10 mW and 980 MHz, respectively. Record data transmission rates have been successfully achieved at different free-space distances. Within 5 m transmission distances, over 10 Gbps data rates at the forward error correction (FEC) floor of 3.8×10-3are accomplished. Extending the transmission distances to 20m, the data rates are maintained at the Gbps level at the FEC floor

Gb/s Underwater Wireless Optical Communications Using Series-Connected GaN Micro-LED Arrays

High speed wireless communications are highly desirable for many industrial and scientific underwater applications. Acoustic communications suffer from high latency and limited data rates, while Radio Frequency communications are severely limited by attenuation in seawater. Optical communications are a promising alternative, offering high transmission rates (up to Gb/s), while water has relatively low attenuation at visible wavelengths. Here we demonstrate the use of series-connected micro-light-emitting-diode (μLED) arrays consisting of 6 μLED pixels either 60 μm or 80 μm in diameter and operating at 450 nm. These devices increase the output power whilst maintaining relatively high modulation bandwidth. Using orthogonal frequency division multiplexing (OFDM) we demonstrate underwater wireless data transmission at rates of up to 4.92 Gb/s, 3.22 Gb/s and 3.4 Gb/s over 1.5 m, 3 m and 4.5 m, respectively, with corresponding bit error ratios (BERs) of 1.5×10-3, 1.1×10-3 and 3.1×10-3, through clear tap water, and Mb/s rates through >5 attenuation lengths (ALs) in turbid waters

High-speed visible light communication based on a III-nitride series-biased micro-LED array

Visible light communication (VLC) using III-nitride light-emitting diodes (LEDs) offers many advantages such as license-free operation, high spatial diversity and innate security. In particular, micro-LEDs (μLEDs) are strong candidates for VLC due to their high modulation bandwidths. However, the low optical power of a single μLED is a key factor limiting VLC performance. In this paper, we report an optimized series-biased μLED array to achieve higher optical power while retaining high modulation bandwidth for high-speed VLC. An example array consisting of 3 × 3 40 μm-in-diameter μLED elements is presented here. At a current density of 3200 A/cm 2 in direct-current operation, the optical power and small signal 6-dB electrical modulation bandwidth of a blue-emitting series-biased μLED array are over 18.0 mW and 285 MHz, respectively. The data transmission capabilities of this μLED array are demonstrated by using on-off keying, pulse-amplitude modulation, and orthogonal frequency division multiplexing modulation formats over free space with the error-free data transmission rates of 1.95, 2.37, and 4.81 Gb/s, respectively

Design, fabrication and application of GaN-based micro-LED arrays with individual addressing by n-electrodes

We demonstrate the development, performance and application of a GaN-based micro-light emitting diode (μLED) array sharing a common p-electrode (anode), and with individually addressable nelectrodes (cathodes). Compared to conventional GaN-based LED arrays, this array design employs a reversed structure of common and individual electrodes, which makes it innovative and compatible with n-type metal-oxide-semiconductor (NMOS) transistor-based drivers for faster modulation. Excellent performance characteristics are illustrated by an example array emitting at 450 nm. At a current density of 17.7 kA/cm2 in direct-current operation, the optical power and small signal electrical-to-optical modulation bandwidth of a single LED element with 24 μm diameter are over 2.0 mW and 440 MHz, respectively. The optimized fabrication process also ensures a high yield of working μLED elements per array, and excellent element-to-element uniformity of electrical/optical characteristics. Results on visible light communication are presented as an application of an array integrated with an NMOS driver. Data transmission at several hundred Mbps without bit error is achieved for single and multiple-μLED-element operations, under an on-off-keying modulation scheme. Transmission of stepped sawtooth waveforms is also demonstrated to confirm that the μLED elements can transmit discrete multi-level signals

Design, fabrication and application of GaN-based micro-LED arrays with individual addressing by n-electrodes

We demonstrate the development, performance and application of a GaN-based micro-light emitting diode (μLED) array sharing a common p-electrode (anode), and with individually addressable nelectrodes (cathodes). Compared to conventional GaN-based LED arrays, this array design employs a reversed structure of common and individual electrodes, which makes it innovative and compatible with n-type metal-oxide-semiconductor (NMOS) transistor-based drivers for faster modulation. Excellent performance characteristics are illustrated by an example array emitting at 450 nm. At a current density of 17.7 kA/cm2 in direct-current operation, the optical power and small signal electrical-to-optical modulation bandwidth of a single LED element with 24 μm diameter are over 2.0 mW and 440 MHz, respectively. The optimized fabrication process also ensures a high yield of working μLED elements per array, and excellent element-to-element uniformity of electrical/optical characteristics. Results on visible light communication are presented as an application of an array integrated with an NMOS driver. Data transmission at several hundred Mbps without bit error is achieved for single and multiple-μLED-element operations, under an on-off-keying modulation scheme. Transmission of stepped sawtooth waveforms is also demonstrated to confirm that the μLED elements can transmit discrete multi-level signals

Deep UV micro-LED arrays for optical communications

Deep ultraviolet (UV) optical communications have attracted considerable attention recently. As most of the Sun's ultraviolet radiation is absorbed by the ozone layer in Earth's stratosphere, UV optical communications offer not only a high-security communication link between satellites in the upper atmosphere, but also data transmission with low solar background noise for outdoor communication on the ground. Furthermore, deep UV light is strongly scattered in the air caused by abundant molecules and aerosols, which enables non-line-of-sight short-range optical communication. However, in comparison with visible light communications, the data transmission rate based on deep UV light emitting diodes (LEDs) has been little explored and is still quite low. This is mainly due to the low modulation speed of conventional deep UV-LEDs. Therefore, developing high speed deep UV-LEDs is of paramount importance. In recent years, we have developed the micro-LEDs (µLEDs) as novel high-speed transmitters for visible light communications.1 These µLEDs, of edge dimension/diameter typically in the 10-100µm range, have extremely high modulation bandwidths due to their high operating current densities. Based on these studies, we report here the first III-nitride deep UV-µLED array emitting at around 262 nm to demonstrate its full potential for deep UV optical communications. This array consists of 15 µLED elements with a flip-chip configuration. With an emission area of 565.5 µm2, each µLED element is individually addressable. The UV optical power of a single µLED element is 196 µW at 3.4 kA/cm2 direct-current (DC) operating current density. We are currently measuring the modulation bandwidth of these deep UV-µLEDs. As they can sustain such a high DC operating current density, we expect a high modulation bandwidth and, in turn, a high data transmission rate for fast free-space optical communication. These results will be presented in the conference

Development, performance and application of novel GaN-based micro-LED arrays with individually addressable n-electrodes

We demonstrate the development, performance and application of a GaN-based micro-light emitting diode array sharing a common p-electrode with individual-addressed n-electrodes. These individually-addressed n-electrodes minimize the series-resistance difference from conductive paths, and offer compatibility with n-type metal-oxide-semiconductor transistor-based drivers for faster modulation