First, lets assume that they mean 12 kWh/day (unlikely since an average house uses 30 kWh/day, and the article states output is enough for several households). The article states the entire structure lasts 60 years (lets use 50 for simple math), and that components will need to be replaced every 10-15 years, and every 25 years, for different components. We can use the 10 year figures, again for easy math.
I live in Nevada, which has one of the cheapest electricity rates in the country. A flat-bill system runs me $.16/kWh, and a tiered structure can get as cheap as $0.125/kWh. Lets assume that I currently purchase all electricity at the cheapest possible rate (impossible since this is only available for 7 months out of the year, but whatever). Using the national average (I use a bit less due to no A/C and rely on better insulation in my home instead), that works out to $3.75/day, which is $112/month for just electricity. There are 600 months in 50 years. With no inflation, I could expect to spend $67200 on electricity over those 50 years. 12 kWh assumed to be produced per day provides 40% of my average usage. This gives me a total lifetime value for this project of $26880. Depending on the cost of the entire structure and maintenance, that leaves a lot of room to work with and still come out on the positive side, even with best estimates at making this device appear worthless. If the initial cost is anywhere near the $20,000 neighborhood and is legal to install in residential areas, I would strongly consider this for personal use. Electricity is probably going to get more expensive as oil and natural gas resources go down, and the actual value is likely to be significantly higher.