Applying Sensor Networks to Evaluate Air Pollutant Emissions from Fugitive and Area Sources Office of Research and Development National Risk Management Research Laboratory, Air Pollution Prevention and Control Division 6/5/13 Karoline Johnson, Bill Mitchell, Gayle Hagler, Brian Gullett, Eben Thoma, Ram Vedantham WISeNet Workshop – June 5, 2013

Overview 1) Challenges with quantifying air emissions 2) Current EPA monitoring strategies 3) Sensor networking applications for quantifying air emissions 4) Deployment of sensor network at a field study 1

Air pollution variation Local air pollution is affected by local and regional sources. Spatial and temporal variation –Local source impacts (e.g., highways) –Meteorology (mixing height, wind direction) Certain sources especially hard to quantify including: –Area sources –Fugitive emissions 2

Fugitive source emissions Leaks and other unintended releases of gasses and vapors Emissions data are challenging to obtain. Emissions can be related to product loss In some situations potentially dangerous Current emission measurement strategies are expensive and challenging to employ. 3 imgs source: EPA.gov Tanks and transfer - sources of fugitive emissions

Area source emissions Emissions occur over large areas. Emissions are challenging and expensive to quantify. Examples: –Forest fires –Landfills –Industrial plants with a large number of fugitive emissions sources 4 Smoke from forest fire

5 Common field study approaches Data logged to on-station computers Off-site researcher can review streaming data Long-term multi-site set-ups: Cell modem per station communicates data to home station Short-term multi-site set-ups: Data may be logged on-board to multiple field computers or logged internally…time alignment, data download and transfer may be manual Data brought home, organized, analyzed…

Emerging sensor technology Very inexpensive Small Lightweight Direct sensing of pollutant Allow to have more monitoring stations 6 Reference analyzer $10,000s Metal oxide CO sensors <$10 Set up <$100 imgs source: Ecotech.com Optical particle counter <$20 Set up <$100 Img source: Shinyei.co.jp CO 2 Infrared sensor <$150 Img source: co2meter.com

7 Envisioned wireless sensor network application for air monitoring Large number of dispersed sensors Researcher can review data Short and long-term multi-site set-ups: Single cell modem or lab computer communicates data from all sensors to researcher …

ZigBee-based networks Zigbee = network XBee = data transmission module on Zigbee network imgs source: Mark Fickett A variety of types of Xbee modules: -Antennas vary -Communication range varies (indoor: XBee=40 m, XBee-Pro=90 m, outdoor line-of-site: XBee=120 m, XBee-Pro=3200 m) 8

9 ZigBee vs. Wi-Fi and Bluetooth ZigBee “…standards-based wireless technology designed to address the unique needs of low-cost, low-power wireless sensor and control networks…” ZigBeeWi-FiBluetooth Data rateLow ( kbps)High (Mbps) Power requirements Very lowHighMedium NetworkingAd-hoc, peer to peer, star, or mesh Point to hubAd-hoc, very small networks ApplicationsBuilding automation, industrial control/monitoring, sensor networks LAN connectivity, internet access Wireless connectivity between devices (“cable replacement”) Range3200 m (or longer with mesh) 100 m10 m Comparison of wireless networking protocols ZigBee complies with IEEE

ZigBee-based networks Low data rate transmission – for applications not including video streaming Neighborhood or facility-scale sampling – distance between points dependent on Xbee type and can be increased with repeater Xbees Highly scalable – can contain hundreds to thousands of nodes Self-healing – increases robustness of network 10 Self-healing Xbee Setup

Arduino Microcontroller Open source Low cost and power consumption Paired with Xbee and sensor for data transmission 11 Arduino UNO Arduino ADK imgs source: Arduino.cc

Application- Eglin AFB Controlled burn Two different types of forest burned Small four-node Xbee network deployed Lost communication for a short time first day without the relay Xbees 12 Network set up Burn 1

Open burn test facility 13 Comparison of carbon monoxide concentrations measured in a reference analyzer (a) and corresponding voltage readings obtained from a parallel low cost electrochemical sensor (b). ~$10K reference analyzer $20 CO sensor

Open burn test facility 14 Comparison of sensor and analyzer during single burn Linear regression leading and trailing edges

Eglin AFB data CO sensor signals from the field (a) Concentrations calculated with the leading and trailing edge linear regression equations (b) Particle concentrations (shown for reference) (c) 15

Benefits for forest fire applications Able to capture significant spatial and temporal variability in emissions Can encompass large spatial area Cost effective – loss of a sensor station due to fire an acceptable risk Avoided time-synchronizing many computers Benefits would multiply with increasing network size. 16

Future research Test larger networks with more area and nodes Further evaluation of sensor performance in laboratory and field settings Additional field studies Development of emissions models based upon wireless sensor network datasets 17

Conclusions Wide variety of applications of these air sensor networks in air pollution research –Short- or long-term evaluation of source emissions –Application to study local variability of air pollution Additional research is needed to further evaluate the potential of low cost air sensor systems 18