On-site Renewable Energy Technologies

In a net zero context this study focuses on electrical technologies. The primary reason is that during periods of excess generation, the utility grid can be used to ‘virtually’ store the excess energy. Non-electrical energy production requires on-site storage such as thermal storage. In consideration of the type of client non-electrical energy storage will likely prove to be costly and require significant maintenance.

There are multiple technologies that can offset site electricity use, from solar photovoltaic (PV) to wind to biogas generators. Other technologies such as solar water heating focus on reducing energy use from gas consumption. Because of the nature of retail building design, construction and leasing, many of these technologies become infeasible. For example, wind power is highly site specific; an adequate wind resource may be available at one location, and become insufficient only a short distance away. Biogas and other biofuels require a reliable fuel stock and sometime significant maintenance effort. Since most of Canada has a suitable solar resource, and once installed, PV is nearly maintenance free, solar PV will be the main technology discussed, as it works around the constraints of the building type best. Some consideration will also be given to wind based energy generation.

The Ontario Power Authority is responsible for governing the Feed-In-Tariff (FIT) program to provide incentive for groups who install electricity generating equipment to reduce the load on province energy plants. The contract price offered is summarized in the table below.

Table 1: Feed-In-Tarrif Contract Price

Wind energy sees several problems in an urban setting. First, the amount and speed of wind varies greatly by location; even within the same city. To determine if wind is appropriate at a specific site, an environmental assessment of the location must be done before a project should consider an installation. Secondly, payback is not attractive for local wind projects. On average (in Ontario), wind produces approximately 2,000 kWh of electricity for every kW of capacity installed. This means a 1kW turbine will produce enough electricity to achieve an approximate FIT incentive of $270 a year with an installation cost of approximately $6,000 for a simple payback of 22 years. Third, there is a large amount of uncertainty when it comes to potential maintenance costs, insurance or neighbourhood complaints. All of which could lead to increased costs. Most wind turbines installed in urban settings end up being more about a visual statement than about generation.

Solar energy rectifies many of the problems brought forth with wind. First, solar is consistent. Across Ontario, solar produces approximately 1,200 kWh of electricity per kW capacity installed, without a need for an environmental assessment. Secondly, payback is much more attractive for solar. Payback for solar projects can vary from 6.5 years for a rooftop mounted system to 13 years for a parking lot mounted system. Third, since a solar array has no moving parts, there is much more certainty regarding maintenance costs, insurance or complaints.