"Contemporary society requires reliable electricity; Galin engine generators ensure it."

(Adapted from here.)

The article: “Military Microgrids Steeply Cut Energy Costs Says New Study” (published 2017) recently set me into a rabbit hole looking into: the difference between microgrids and back up generators, and why the pricing in the article is in $/kWatt (cost per power unit) versus $/kWatt-hour (cost per energy unit - this is what you usually see on your electricity bill).

Here are my thoughts:

  • microgrids - supply electricity to site full-time, 

  • back up generators - supply electricity at times that the main grid goes down. 

A generator can be either a component in a microgrid, or just an electricity back up. It all depends on how it is used. The article states that using microgrids leads to cheaper “power” (kW). This is obvious, the reason that microgrids are inherently cheaper (compared with backup power generation) is because they offer centralisation of electrical supply across a site (say a military installation). Instead of each building having their own generator, they have 1 generator that is 10x more powerful. Obviously, this is a cost saving because of economies of scale. Generators are more efficient at larger power outputs, and you only need to service and maintain one (or two, in case the other one breaks) in one location, versus going around checking up on 10 generators (or maybe 20, if each site is also installed with a backup). This economy is reflected in the pricing presented with $30/kW for microgrids versus $80/kW for portable generators. It is even cheaper, in $/kW, for the 'main grid' electricity supplier! 

The point is, if you want energy independence/resilience from the main grid - you want to run a microgrid. The problem of course is, if that generator in your microgrid breaks, your whole site is stuffed. The business case here is how much you pay when the main grid goes down, versus when the microgrid goes down, versus how much you pay to maintain 10 generators for each site. 

An attractive feature of microgrids is that the technologies that produce energy in it can be varied and upgraded relatively easily. So for example, initially a given microgrid only has two massive generators (one for use, and another for backup). However, over time, a solar array is added into the microgrid, a battery is added, and as the generator comes to end-of-life it is replaced with a smaller version, because solar + battery are able supply over 50% of the required energy. You can see where this is going....The energy generation mix can be tailored for the specific site in question. One interesting side note here is that it may be useful for microgrids to generate and distribute energy in DC not AC form. This is because we mainly consume DC electricity, and would thereby save a lot on conversion costs. (Galin engine generates DC electricity.) The reason we have AC electricity is because it is more efficient to transmit electrical energy in AC form over large distances. 

It seems, just like in fashion, technology systems move in cycles. Initially, when electricity was starting to be rolled out, it was in the form of microgrids. Then, economies of scale caused coalescence of these microgrids, and the 'main grid' was born. Now (and interestingly, driven by increasing demand for electricity) microgrids are slowly coming back into fashion. Then....it will be back to main grids....etc etc.

This article makes a very good point about the importance of engines as backup electricity suppliers, as well as electricity generators in microgrids. The attractive features of engines are:

  • run on a range of fuels,

  • provide continuous energy (quickly rechargeable, i.e. refillable, unlike batteries),

  • start quickly.

These features make engines important for microgrids everywhere:

  • in developed regions like North America demand exceptional electric reliability to support their increasingly Internet-based economies,

  • in remote areas worldwide suffer from a lack of central grid access or inconsistent service, hindering basic health, well-being, and commerce,

  • and in cases when the push to integrate intermittent renewable energy sources like solar and wind necessitates stable companion technologies to ensure a consistent power flow.

The problem with existing engines is that they are designed to develop mechanical shaft power, an alternator is added on and the frequency of rotation for the engine is controlled within tight requirements to generate electricity at the required AC frequency (50/60 Hz). Under variable load, generator systems have very poor efficiency. Inverter generators attempt to improve on this by allowing the engine to rotate at a higher (more optimal for the engine) frequency and then use electronics to convert the electrical energy to the required frequency. These are all positive steps in the right direction.

We can do even better. The aim of hybrid propulsion is to combine an internal combustion engine and an electric motor efficiently. However, until we rethink the way we couple the engine to the motor we will not achieve maximum possible efficiency of the system designed to convert heat energy from chemical combustion to electrical energy. This is our focus at Galin Engine.

We are designing Galin engine for applications which want to do more with less. Maximise efficiency, get higher power output for the same weight, longer operating time, improved stealthiness.

What could you achieve with a generator or hybrid powertrain that is at least 15% more efficient, 4x lighter, and 4x smaller than what you are using now?

"Contemporary society requires reliable electricity; Galin engine generators ensure it."