Thursday, February 28, 2013
Selling solar hot water or large scale pool heating into municipal facilities has always been a very difficult task. City people have to protect the interests of their taxpayers at all times. They are under tremendous scrutiny and every snake oil salesman out there is trying to dig his claws into municipal coffers. Cities tend to hire engineering companies in order to distance themselves from the sensitive decision making. They also tender projects to several bidders in efforts to ensure fairness but its not like 3 people could bid on a solar hot water heater for a municipal Aquatic Center. Someone would have to specify the whole system up front and that engineering company would need valid experience in order to do that. What has happened is systems have been done under grant programs with the intent to demonstrate solar energy and these demonstrations have become the accepted norms. In this gold rush of free money we've seen what has happened in some jurisdictions which is the application of what we like to call "the tried and proven untrue technologies of yesteryear". Let's look at hot water first. Domestic solar hot water heating systems use evacuated tubes or boxed and glazed collectors. These small scale systems don't have good economics because they are small scale. The cost of tanks and controls and plumbing and roofing is high compared to the area of collector exposed to the sun and the collector choice is naturally an expensive one because if you're going to all this trouble you'll want something that delivers maximum bang, not maximum bang for the collector buck. When we start looking at larger scale systems like preheating showers for Aquatic Centers we start to see much lower fixed costs per collector area. Solar gets a lot more viable a lot quicker. What happened of course is that engineers specified the old school boxed and glazed or evacuated tube collectors. They didn't even consider unglazed collectors like Powerstrip. When we look at these performance curves we see that unglazed collectors are affected by wind and as we move right on the x axis (water getting warmer relative to air temperature) we see why engineers like the evacuated tubes and boxed and glazed collectors. They retain their efficiency into marginal weather conditions and into the higher end of the heating range. What engineers failed to recognize or perhaps never thought to even look at was the fact that most hot water heating is done at the low end of the temperature range when Powerstrips are even more efficient per area than the other types and on top of better efficiency they are far less expensive. Finally an engineer recognized this in Canada post rebate era. Yes the conservative government abandoned the Eco Energy program for Renewable Heat in 2010 and as a result Associated Engineering was tasked not with spending the City of Richmond's money as fast as possible in the safest way possible. Instead Charlie Smeenk PEng was tasked with spending the city's money with the best return on investment in mind. The money had to be spent with the taxpayer's best interests in mind. Charlie and I met early in the process and he was the one who pushed me toward the idea that we needed to plaster low cost unglazed collectors all over the Aquatic Center roof and move the cold water through them on their way to the boilers. The system has been installed for a year now and we've monitored it with our web based monitoring . The monitoring is not internet connected so the data is not always up to date and we've lost some data but we've still proven that we've displaced more energy here with this system than we would have with more expensive technology. We've also proven that cost effective solar hot water is possible. Its possible to deliver solar at $100/GJ That's $100 in capital cost up front in exchange for 1 GJ of annual energy production. If energy costs $10/GJ after boiler efficiency is included (which is close even with today's low natural gas prices) then its a simple ten year payback period. Others will brag that they are doing better than 10 years. They are incorrect. There's no way to do better than this kind of economics against cheap natural gas .......or is there. In the last few months the cities of Sechelt, Esquimalt, and Kimberley have installed our solar panels at their municipal facilities. Coral Engineering is the engineering company behind these projects and Scott Graham of Renew Energy is the solar dealer. They have gone one step further with all this. They are using the Powerstrips to heat a tank of water and that tank of water is the source for a heat pump. Heat pumps utilize low grade heat. Ground source heat pumps for example might take ground heat at 10C and use it so the ground cools down to 5 degrees. That 10C to 5C drop in ground temperature is converted through the heat pump to heating water at 60C or air at 20C or a pool at 29C. Heat pumps take low temperature energy and pump it up to a higher temperature for use. Solar needs to operate at low temperature in order to be able to take advantage of unglazed collector cost efficiency. Heat pumps are the means by which we can utilize that low grade heat. We've known this in the solar industry for decades but we've been distracted by grants for the tried and true conventional approaches. Yes natural gas is cheaper than electricity and we can just burn fuel at will in many places and that is a problem but as we move to a sustainable energy future we'll need to use more electricity and less natural gas for reasons I won't delve into here. For now these particular cities have relatively high natural gas costs allowing them to take advantage of the improvements and demonstrations we can make to their electricity based infrastructure. In the future we will see district heating systems and ground source heat pumps working with unglazed solar integrated into roof tops, under driveways, under roadways, collecting heat wherever we can and releasing heat at night as needed. Heat pumps on their own are often not very effective. Ramp up their source temperatures with solar panels and the numbers start to look much better. Our web based controls and monitoring systems are perfectly suited to help quantify and control systems like these on large and small scale. This is the future of solar heat. This is viable solar thermal application. As usual its a very difficult road given the bias and status quo that is in place and more significantly just the fact that the alternative energy of 2013 is being sold to us as natural gas. Cheap natural gas is not a stepping stone on the road to an alternative energy future. It is a stumbling block but we're starting to see some progress. Just barely.