As each clients power needs vary, there is no one cost answer. An open cycle system reduces energy costs on average at 30% from the cost of peak grid power. A co-generation & tri-generation system reduces energy cost on average by 75% from the cost of peak power and replaced heating costs. After the cost of capital is included, the total savings can range from 20% to over 50%, a full energy audit from Optimal will outline the potential costs & savings to each client.
Costs in recent years have been rising due to the investment that has been needed to upgrade and maintain the distribution network of electricity. This investment has been driven not by an increase of overall consumption of electricity, but rather peak demand. Peak demand refers to the maximum power required at any one time, often caused by an extreme weather event, for example on hot days where use of air conditioning would reach a maximum.
Natural gas is the lowest emitting fossil fuel, often up to 42% less than coal fired power. Using natural gas in a micro turbine (which is the cleanest burning engine) also emits much lower Nox’s and Sox’s. Also using the waste heat to replace fuel that would have been consumed in heating and cooling applications further increases the environmental benefits of natural gas over coal.
For each kW of electricity generated, only 1/3 of the cost of generation is the cost of gas. This means that if gas were to rise by 10% in one year, the cost of making electricity onsite only rises by 3.3%. In this way, even if gas and grid power were to rise by the same amount annually, the cost of grid power continues to rise faster than the cost of generated power.
Turndown refers to the minimum power output of a generator before it turns off, or stalls. For example, a 65kW generator that can ‘idle’ at 6.5kW is aid to have a turndown of 10%. This is important as a customers power use will not be constant, and a genset will have to load follow to ensure it is not over or under producing power. Typically an engine will be able to turn down to 40%, whereas a turbine can turndown to as low as 10%.
Modularity refers to the ability of multiple generators (gensets) to be paired in a single installation. Modularity allows a solution to be installed that is not over or undersized for each individual customer, and also very importantly, creates a redundancy in the event of hardware failure. That is, if you have multiple gensets and one is down, you still have generation capacity and enhanced opportunity for turndown.
Absorption chilling, uses a lithium bromide solution that absorbs water. The process of absorbing this water chills a separate water circuit by removing its latent heat. The waste heat from power generation is then used to ‘boil off’ the absorbed water from the lithium bromide solution, and the process continues. The fluids continue to flow in a sealed circuit making a very efficient closed circuit. Adsorption chilling uses a solid (often a gel or solid salt) in a similar process.
Peak demand is measured for each medium to large energy customer as the highest single use of power at any single metered period. Most customers are metered in 15 or 30 minute intervals, and the highest power consumption metered is set as your maximum demand. This is often kept as your maximum demand for at least the next 12 months, and you are billed for this monthly regardless of actual use. This charge is levied to ensure that the network in your area is sufficient to cover your maximum required load. Onsite generation is an effective method to insulate you from the often high costs of an excessive demand requirement.