Water has a specific heat capacity of about 4 kJ per litre per degree C. 15 m^3 is 15000 litres. Thus the heat capacity of a 15 m^3 storage tank is 4*15000 = 60000 kJ per degree C, or in more useful units, about 17 kWh per degree C. Lets be optimistic and assume you are able to heat this tank up to 90 degrees C during the summer. Let’s also assume the tank is perfectly insulated so no heat escapes until you want to release it into your home. Thus you have about 70 degrees C of useful temperature drop with which to heat your home (after that the water drops to room temperature of about 20 degrees C it cannot be used to heat your home). So the total energy available is 70 degrees C * 17 kWh per degree C = about 1190 kWh. My heating requirement for December and January alone is about 4,600 kWh. Thus a 15 m^3 storage tank might heat my home for a few weeks at best. This is assuming no additional solar input during those weeks but that is what “annualized” storage is all about. It’s also the stark reality in Vancouver where a sunny day in winter is a rare exception.

Incidentally, even if your home were insulated and sealed well enough that 1190 kWh of annualized heat storage could get you through the winter, that is only about $85 worth of electricity at current BC hydro rates. A savings of $85/year is not much pay back for a $15,000 investment. You’d be much better off putting your money in the bank and using the interest to pay your electric bill.

I’m not disputing that there may be a positive return on investment in solar heating solutions, but where there is, it most likely does not result from “annualized storage” but from continual collection, storage and release of solar energy, year round.

The capital cost of 12 solar collectors (24m2) and a seasonal solar storage underground tank (15m3) is under $15,000. in Vancouver – to provide nearly all the domestic hot water for showers and cleaning, plus the radiant floor space heating. Once installed, the system is maintenance free for decades, plus the solar heat is clean and renewable.

I think once people know that the asymetrical solar supply/heat demand problem has been solved with annualized storage, and that it is reasonably cheap, it should become very popular in Canada, like it is in Austria.

We would have consumed less fossil fules, if everybody used gas to heat their houses with, let’s say, 90% efficient gas furnance and used all electricity from renewable resources for industry and comunications. What we do now, look something like this: we consume all renewable electricity for heating and burn gas with 35% efficiency to generate electricity to power industry.

You’re still lucky in Canada, because gas is generally cheaper than electricity, if you have 90% efficient furnance, and it’s nothing unusal to have such “high” efficiency – condensing boilers have efficiency arround 100%. Here in Slovenia, gas is so expensive that it’s cheaper to heat with coal generated electricity, even if you have 100% efficient oven, and heating oil is even more expensive, so that you can heat with electricity day-round (through low and high tariff) and you still save money.

For comparrison, electricity in our country costs 0.08€/kWh (0.11CAD) at low tariff (22:00 – 6:00) and 0.16€ (0,22CAD) throught the day. You are really lucky to have such low energy prices!

This is exactly the information and discussion I have been looking for. Any feed back on my situation would be helpful. I live south of Seattle but figure our fuel cost and winter temperatures are similar enough. We have been heating our 1944 800 sq feet. (74 sq meters) home with electric baseboards (2) and one wall fan heater. Most of the time it is only the main living baseboard heater is heating our home. The other two only heat the bedrooms when needed (turned up 20 min before retiring). Recently we have started to look into heating our the main areas home with a gas fireplace instead of the baseboard heat. The hope is to reduce our heating cost and make use of the empty and useless fireplace.

Any feedback is appreciated.

Incadescant light bulbs are considered inefficient. This is because there is so much heat generated by them. If your using electricity to heat your house anyways then all your “inefficient”electronics and lights become almost 100% efficient because any heat they put out takes load off of your electric heater. So by going the CFL Route, which contain mercury, your not doing anybody any favours. You said you live in BC. Our power is hydroelectric so there is even no CO2 released by combustion

By maxed out, I only meant over the period of a year – I assumed that short-term planned fluctuations would average out. I would not at all be surprised if they varied the hydro generation during the day for various reasons. Do you have any references that describe BC Hydro’s strategies for doing this? I’ve looked but cannot find anything.

Here are a couple of other relevant sites that you might find interesting:

BC Hydro has a graph of real-time flow data for their BC-Alberta and BC-US interties that can be found at: http://transmission.bchydro.com/transmission_system/actual_flow_data/. The BC-US flow bounces around quite a bit so it looks like some of the demand fluctuations during the day are handled from imports (oil and gas generation would be my guess).

The Canadian Electricity Association has an informative document called Power Generation in Canada which can be found at: http://www.electricity.ca/media/pdfs/backgrounders/HandBook.pdf. Figure 4 on page 8 shows how Ontario handles demand in terms of what order different power sources come online. In Ontario the order is Hydro, Nuclear, Coal, Oil, Gas, Peaking Hydro. I would really like to see similar data for BC.

1. I don’t believe it is true that fixed generation resources (wind, solar, hydro, nuclear) are always maxed out. BC Hydro, for example maxes out during peak demand, because they sell electricity to the US. During off-peak hours, BC Hydro basically shuts down their generators and instead buys back coal based electricity from the US. This is done because US coal fired power plants cannot adjust output fast enough to match changes in daily demand. The coal fired plants operate at a fixed output, buying hydro power from BC hydro during their peak demand and selling coal power back during off-peak hours. This is a somewhat moot point though since the net effect is the same: any additional electrical usage effectively results in more coal being burned, regardless of whether you live near a hydro plant in BC or a coal plant south of the border, and regardless of whether you consume electricity during peak hours or not.

2. For a complete analysis of carbon footprint, you must compare dollars to dollars, rather than just MWh to MWh. If you have options at your disposal that result in greater greenhouse gas emission reductions per dollar spent than installing a high efficiency gas furnace, then you may be better off installing cheap space heaters and spending the money you save on other carbon offset strategies. For example, removing my inefficient gas furnace and installing cheap space heaters saved me a significant amount of money which I chose to spend on additional insulation and other strategies for reducing my own energy consumption. I suspect the net effect has been a greater return (both in reduced carbon emissions and dollars saved) than if I had installed a high efficiency gas furnace.

I agree with the conclusion of your article… when it comes to reducing carbon emissions, it’s really all about the negawatts.