Radiation powered battery-free energy-burst source for wireless weather stations and home-climate systems

Abstract

The power of a complete picture of energy-weather information can be used for novel energy saving algorithms in home-climate systems. Exploiting the human biological clock, we recently proposed to optimize climate systems by allowing for a correlation between inside and outside temperatures, while preserving maximal comfort. Following our earlier disclosure on a Gas Energy Observatory, we here disclose a detailed description of a battery-free wireless weather station for reliable, long-term and maintenance-free measurements. It is solar powered. Combined with energy storage in high-voltage capacitors using recently introduced low-cost step-up and step-down DC-DC converters, a versatile energy burst-source is created. Energies of a few J per day suffice for measurement, data-collection and wireless data transmission in bursts to a central data-processing device inside a nearby home. Provided as a high-volume consumer product, residential weather data can be gathered over the internet for creating a climate observation system with unprecedented areal coverage and spatial resolution at no additional cost—serving modern climate research and studies on global warming.

Description

SURVEY OF THE DRAWINGS

FIG. 1. Shown is a block diagram the complete wireless home-climate system, comprising gas-energy observatory (gray shaded region) linked with one or more home-climate monitors, a home-climate control system and a central heating system. Here, the dashed lines represent wireless data-transmission links. The gas-energy observatory consists of a local weather station, a remote display and a gas-meter. Here, the gas-meter houses a CPU, memory for data-archiving, sensor electronics for monitoring the gas-energy consumption through the residential gas-connection, a display and two wireless interfaces. One interface is integrated with the wireless consumer network and the other interface provides a data-link to the gas-supplier. The first mediates residential energy-weather data, whereas the second mediates compatible financial energy data. Both are encrypted for privacy and security.

FIG. 2. Shown is a block diagram of the solar radiation powered battery-free energy burst-source serving as a power supply to a wireless weather station. The energy burst-source comprises solar cells for harvesting radiation energy, a step-up DC-DC converter for storage into a capacitor, a step-down DC-DC converter for retrieving energy from the capacitor in terms of a constant voltage power supply to the weather station. The weather station comprises multiple sensors, such as temperature, pressure, humidity and other sensors, a multi-channel analogue-to-digital converter (ADC), a CPU with data-buffer, and low-power display such as an LCD, and a wireless interface for burst data-transmission. Note that the ADC also monitors the voltage, and hence the energy of the capacitor. In this fashion, the CPU is informed, when the capacitor is sufficiently charged to permit burst data-transmission of the data stored in its buffer. Such transmissions are subject to the condition that afterwards, there remains sufficient residual energy in the capacitor to enable continuing monitoring, even during nighttime periods up to Sunrise.

PREFERRED EMBODIMENTS

The preferred embodiment follows current trends in small, smart and easy-to-use, while paying attention to safety, reliability, data-integrity and battery-free operation to facilitate decade-long observations.

The complete wireless climate-control system is preferrably realized in a wireless local area network which is compatible with mainstream data-transmission protocols, to enable compatibility with commercially available products. In particular, Bluetooth appears to be a viable option, which is increasingly implemented in a wide variety of commercial products such as laptops, PDAs and mobile phones.

In the preferred embodiment, the wireless link has the lowest energy consumption in the idle mode and is time-efficient is establishing or re-awakening a data-link. For this reason, the wireless connection of the solar powered weather station may be realized using a dedicated single-channel wireless link, which requires no overhead during the initiation and closing of a burst data-transmission. In general terms, it is difficult to forecast the optimal choice of wireless link, as the commercially available technologies are rapidly evolving, and new ones are always on the horizon.

The preferred embodiment for the step-up and step-down DC-DC converters are variable converters, which optimize their operations along with the variable capacitor voltage. Charging of the capacitor is optimal when performed slowly, using a voltage-controlled step-up converter, whose output voltage leads the capacitor voltage by a small positive difference. The preferred choice of capacitor aims at having low self-discharge, to permit efficient storage of the energy, especially during time-periods of little or no radiation. Furthermore, high-voltage capacitors may be used, to maximize the energy storage in a small volume.

SUMMARY

The power of modern information technology in measurement and computation can be used to introduce novel energy saving strategies and algorithms. We recently disclosed a gas-energy observatory which presents the complete picture of real-time residential gas-energy usage in combination with local weather data. These energy-weather data provide direct feedback to the user, and can be used as input to novel energy-saving algorithms for home-climate systems, continuous home energy audits and validation of home-improvements. To facilitate maintenance-free operation of the weather station, we here describe a battery-free, solar powered wireless method of operation for long-term monitoring. Gathering these local weather data over the internet further creates a wide-area climate observation system for climate research and studies on global warming.

Claims

1. A radiation powered battery-free energy burst-source for powering a remote wireless device with the property that the daily harvest of radiation energy is stored in a capacitor, where the device and its wireless data-transmissions are powered by energy retrieved from said capacitor, where the storage of said energy is made efficient using a step-up DC-DC converter, where the retrieval of said energy is made efficient using a step-down DC-DC converter, where said wireless data-transmission is intermittent in burst-mode to transmit data stored in buffer to a remote host, subject to the constraint that said data-transmission occur while leaving sufficient residual energy stored to maintain sensing capability and local data-logging in a buffer.

2. A solar powered battery-free energy bursts source according to claim 1 with the property that said efficient energy storage to said capacitor is made possible using a voltage-controlled DC-DC step-up converter, where said voltage control maintains a small positive voltage difference between its open-terminal output and said capacitor, where said small positive voltage difference serves to store energy in the capacitor at a rate which most closely matches the power received from the solar cells.

3. A solar powered battery-free energy bursts source according to claim 1 with the property that said efficient energy storage to said capacitor is made possible using a DC-DC step-up converter, whose output is a current source, where the current is regulated to store energy in the capacitor at a rate which most closely matches the power received from the solar cells.

4. A solar powered battery-free energy bursts source according to claim 1 with the property that said weather station uses solar cells of GaAs for optimal efficiency.

5. A solar powered battery-free energy bursts source according to claim 1 with the property that said device uses Bluetooth for the wireless link.

6. A solar powered battery-free energy bursts source according to claim 1 with the property that said device contains a temperature sensor for observing local weather or located inside for monitoring room-climate in homes and buildings.

7. A solar powered battery-free energy bursts source according to claim 5 with the property that said data-transmission is directly into the internet to a remote central data-bank, where the gathering of said data is used to create a wide-area high spatial resolution climate observation system.

8. A solar powered battery-free energy bursts source according to claim 1 with the property that said device controls a heating system as part of a local wireless sensing and control network.

9. A home-climate system comprising a gas-energy meter, a local weather station, a home-climate control system, a heating system and a remote display all connected over a wireless network, where said gas-energy meter and local weather station comprise a gas-energy observatory producing energy-weather data and correlations between gas-energy usage and local weather, where said energy-weather information is transmitted to said home-climate system and to said display, where said home-climate system controls said heating system.

10. A home-climate system according to claim 7 with the property that said display provides the complete picture in high-resolution energy-weather data for visual feedback to the consumer in using residential facilities and heating, where said climate control system provides optimal control for maximal energy-savings and climate comfort allowing for correlations of room-temperature with local weather and the human biological clock.

11. A home-climate system according to claim 7 with the property that said local weather station and home-climate control system are radiation powered and battery free, where said battery-free operation is made possible using an energy-burst source on the basis of efficient energy storage and retrieval in and from a capacitor by the application of modern step-up and step-down DC-DC converters.