Abstract

Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements to milliwatts and microwatt range. Consequently, many complex electronic systems and devices such as wearable medical and autonomous devices consume power in the range less than 200 μW, and wireless sensor networks in the range μW to 100 mW are operated on battery power. Due to the salient limitations of battery power, such as longevity of charge and where applicable, the requirement for periodic recharging, possibilities for utilization of autonomous energy sources is critical for operation of such devices. Ambient energy sources, such as vibrations (1 μW to 20 mW), motion (wide range in power outputs), temperature gradient (0.5–10 mW), radiofrequency waves (>180 μW/cm2), light (100 μW/cm2 to 100 mW/cm2), acoustics (0.003–0.11 μW/cm2), and many other, have the potential to directly power the electronic device. Ambient energy harvesting, when used separately or in conjunction with batteries, will enhance the longevity of equipment operations requiring portable or autonomous power supply. This paper reviews the state of the art in energy-harvesting techniques, power conversion, and characterization of mini- and microscale self-sustaining power generation systems in the range 600 μW to 5 W, specifically focusing on low-power system applications, for personal assistive and mobile technology devices.

Abstract

South Africas Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private investment, and electricity prices of wind power falling by 46% and solar PV electricity prices by 71%, in nominal terms. Competitive tenders were introduced after an unsuccessful attempt to implement feed-in tariffs. The tenders incorporated standard, nonnegotiable contract documents, including 20-year Power Purchase Agreements and an Implementation Agreement whereby the Government of South Africa back-stops IPP payments by the national utility, Eskom. All of these projects have reached financial close to date and some are already delivering power to the grid. The financing success has been due in part to the requirements for commercial banks to undertake a thorough due diligence of projects prior to bids being offered. The details of the policy package described may be useful for other policy makers in countries developing policies for renewable energy deployment.

Abstract

In recent years, research about the application and optimization of PV panels has grown rapidly. Especially for stand-alone solar systems there have been some problems related to first stages of design and application. Finding the optimum slope of PV panels in order to maximize the absorbed solar radiation is considered as one of the major obstacles. Although in Malaysia there have been some research works about finding of optimal tilt angle, however, this research work aims to start investigation about slope of PV panels for three villages without electricity and prior research. The Liu and Jordan model is applied to find the monthly optimal tilt angle and fixed tilt angle for the application of solar energy in these rural locations. The results demonstrate that the optimal tilt angle in these locations is less than 5°.