Off Grid DC Power
This is an interesting example of an off-grid zero-carbon community. Of particular note is their use of DC machinery powered directly from solar PV panels, with no intermediate storage.
I particularly like their use of robust Nickel-Iron cells for lighting.
Spotted, thanks to an article on No Tech Magazine.
Living Energy Farm (LEF) has developed two unique electrical technologies. The first is “daylight drive” whereby we power high-voltage DC motors during daylight hours. Early generations of off-grid energy systems used low-voltage DC electricity from PV panels. Increasingly, PV panels are tied together in strings that produce much higher voltages. At LEF, 90% of energy use is based on daylight drive application of high-voltage DC power from PV panels. This dramatically reduces the cost of providing basic services like pumping water, grinding grain, cutting wood, or accomplishing any of a myriad tasks that are needed in a village. Combined with thermal storage, daylight drive is a much cheaper, more durable method of suppling stationary power than AC power systems.
The second technology we have developed at LEF is the integration of nickel-iron (NiFe) batteries with LED lighting and charging systems. We are pursuing the deployment of this latter technology because it can be easily deployed to provide lighting and charging services for people all over the world who cannot afford grid power.
How is that LEF found these simple, cost-effective ways of using solar electricity while so many well-funded engineering organizations did not? Because we have been looking for answers that are simple, cheap, and durable, and they are looking for energy systems that mimic the AC grid power available to middle class consumers in industrial societies. The answer you get depends on the question you ask.
NiFe batteries are heavy and expensive. They were in significant use in industry 50 – 100 years ago. They faded out because the battery companies could not make enough money on them. But that predated both the arrival of both easily available photovoltaic (PV) solar electricity and LED light bulbs. (Incidentally, the old industrial NiFe batteries had high standby loss, modern ones do not. The price of NiFes is also coming down dramatically.) With the demise of NiFe batteries, the nascent off-grid movement of the 1970s and 1980s standardized around the use of short-lived lead-acid batteries. Off-grid technologies have been crippled by poor batteries.
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