Carbon-Pros Analyst Blog

Shortly after we installed solar PV, we bought a data monitor. Our system has a centralized inverter, typical of most installations. The inverter takes DC power generated by the solar array and converts it to AC power for use inside our home. The data monitor measures and records the kilowatt-hours (kWh) generated on the roof. The inverter a good place for monitoring because the solar power flows though it before joining the electrical service panel. Data logging occurs at frequent intervals whenever the sun is shining. Our inverter manufacturer, SMA, offered several options for receiving data feeds including direct-to-PC, wireless-to-countertop display, and Ethernet-to-Internet for capture on SMA's web portal. We chose the latter option because it was the most flexible approach. From the web portal, we can see real-time and cumulative statistics. And we can view it on any device from our PCs and Macs to our iPhones. Therefore we know what's going on whether we are at home or traveling. Data monitoring has been more valuable than we anticipated. If not for the data monitor, we'd have no idea how much power is coming off the roof. Solar PV is totally silent and because our panels are installed flat to the roof, they are virtually out of sight. The SMA web portal sends us a daily email with production statistics and provides web access to accumulated data. Last May, we had a defective breaker shut off the power feed from the roof. Fortunately, our installer receives the same daily emails, noticed that our production had dropped to zero, and quickly fixed the problem. Without monitoring, we may not have noticed the outage until our month-end utility statement. In the future, several components in the "smart grid" will perform a more complete monitoring function including energy production (if any) and energy consumption by circuit. Even though SMA's monitor only provides production data (not consumption) it has become a daily reminder of our electrical usage. This has led to an ongoing effort to reduce usage through better lighting, more efficient appliances, and reduction of phantom loads. With a year of minor tweaking behind us, we have shaved about 10% off our annual power use. This year, we estimate that our solar array will produce about 90% of our electricity. We last paid for electric usage in February 2009. With the meter running backwards every week of the summer, we don't expect to pay any more usage fees until November 2009 when the days are short and the snow is flying. Now that's a happy thought. --JCB

Start at the beginning with NZE step 1.

Posted by Carbon-Pros at 09:04 AM | Permalink | TrackBacks (0)

Transportation makes up a significant portion of the carbon footprint of every company and every employee (about about 22% globally, see IPCC). Making carbon-aware transportation choices can reduce your footprint and have a positive impact on your bottom line. For individual companies, the transportation footprint includes inbound and outbound shipping, business travel, and employee commuting. Carbon emissions from travel are directly related the mode of transport, the efficiency of fuel consumption, and the distance traveled. Assuming two persons in a mid-sized car, trains can be twice as efficient per passenger-mile than cars, and over short-distances cars can be twice as efficient than planes. Actual results vary because a single person driving a large SUV is less efficient than flying in a peak-loaded airplane. And because landing and take-off reduce airplane efficiency, trips shorter than 500 miles favor a car, whereas longer distances favor a plane. Peak-load buses and ferries are less efficient than trains but more efficient than cars. Peak-load is important because off-hour and rural buses (with few passengers on board) can be less efficient than a small car. Employee commuting via bus can be highly carbon-efficient since typical work hours coincide with peak-period travel. Ferries are a special case because fuel efficiencies vary all over the map. Slow moving ferries are much more efficient than high-speed ferries due to the tremendous drag involved. High-speed ferries can exceed plane travel in terms of carbon emissions per passenger-mile. We all know that car efficiencies vary greatly. Per 100 miles driven, hybrids and small cars emit about 50 pounds of CO2, mid-sized cars emit about 80 pounds, and SUVs and pickups emit about 120 pounds (EarthTrends). Van-pools and big SUVs are more carbon-efficient than small cars if fewer miles are driven and/or more passengers are on-board. In summary, trains and buses are usually less environmentally damaging than cars and planes but the best choice depends entirely on the circumstances. Living close to work, car-pooling, cycling, and telecommuting can radically reduce emissions from employee commuting. Phone, web, and video-conferencing can radically reduce emissions from business travel. Fuel-efficient fleets, ground-transport options, and reduced packaging can reduce emissions from shipping. Obviously, carbon-efficiency is only one part of business decision making about transportation. Time-to-market, employee efficiency, and customer requirements are usually more important. That said, the savings from reducing transportation requirements and making smart transport choices go directly to your bottom-line.

Posted by Carbon-Pros at 10:24 AM | Permalink | TrackBacks (0)