Clean renewable home energy has an arch nemesis. It’s not (as some green narratives might suggest) powerful oil lobbies holding it back for the sake of profits though, it’s much more boring than that. The supervillain of clean energy is infrastructure: The electricity grids of the modern world are based on old fashioned technologies and ideas of how to ship electricity from power stations to your plug sockets at home.

But over the last couple of years a bit of lateral thinking to solve the grid problem has emerged from a surprising area. It’s not from city electrical engineers, or solar power research facilities… but from the automotive industry’s EV trailblazers, Nissan and Tesla. Helped along by DIY electric geeks. Plug your electric vehicle into your house to power it. Use home solar and wind generators to charge the car. Turn your car into a miniature home power station with clean energy. It’s not just wishful thinking either, it’s really happening.

Clean Energy Gridlock
All power grids need to deliver a baseload of electricity. The baseload rises and falls on a curve, with a daytime peak and an evening trough. At its most basic level, when everyone boils their kettle for coffee in the morning there’s got to be enough power on tap to meet high demand. At 2 a.m. when most power is seeping quietly into TVs on standby or keeping the streetlights lit, there’s lower demand.

Power stations can anticipate this predictable rise and fall in baseload to prevent brownouts. The grids that deliver this power evolved back at the end of the 19th century. Fossil fuel power was all that we had back then, producing consistent power output. So the grids were designed to be simple systems to handle constant power supply. But wind and sunlight aren’t as predictable, you can’t just shovel more of them into a furnace to meet peak demand. Variable renewable power sources need more efficient grid systems to replace predictable fossil fuel sources. Hence the 21st Century’s grid problem.

This has caused a big problem for a centralised, countrywide clean energy switchover. If it’s a cloudy morning with low wind, the millions of kettles boiling up for morning coffee might not work. As a result, despite creating large capacities of solar and wind power in Europe and America, the electricity suppliers have little choice but to keep the coal fires burning, just in case.

This means our electricity-generation carbon emissions are barely dropping and on days where solar and wind are supplying the grid, we’re wasting the excess power from CO2-producing fossil burners. If only we could store the power or manage multiple power sources more efficiently, we could reduce our reliance on fossils and attack rising CO2 emissions without risking commercial or political disaster.

Car-home power
Whilst engineers and boffins are working on super-efficient ‘smart grids’ to try and solve this baseload problem, home DIY geeks have inspired electric vehicle manufacturers to find a surprisingly simple solution. If you had a bunch of batteries in your home, linked to your own solar panels and wind turbines, you could generate and store your own power. Enter the likes of Nissan and Tesla with an automotive solution to renewable home energy.

The average (Japanese) household needs about 10-12KW of energy in a 24hr period. That’s half the charge on a Nissan LEAF, more like a fifth of the charge on a Tesla Model S. All it takes is the kit to plug your electric car into your home, plus some average wind and sun on your panels and rooftop turbine and (in theory at least) you can go off-grid.

This explains why Tesla has announced plans to launch a home battery pack and Nissan has revealed a home/car docking station, following on from rumours of geeks taking wrecked Nissan LEAFs and rigging up their own homemade solutions over the last couple of years. The wisdom of crowds, eh?

Nothing new but still a game changer
When you think about it, this isn’t a huge leap. You could power your home off a petrol or diesel generator, which is basically the same tech as a car engine. But the battery solution is also subtly different. It’s interoperable battery and charging tech migrating from one category of thing (transport) into another (the home) and in doing so, taking CO2 emissions reduction to a new level of thinking. The biggest source of CO2 emissions are (some experts say) homes and electrical power generation. The next largest source of emissions is transportation. Connecting the two might just kill two climate-changing birds with the same stone (or in this case, Li Ion battery).

To put that in perspective, even a zero-emissions electric vehicle still needs mains electricity to charge it, which means even the cleanest electric car causes CO2 emissions on a par with an economical diesel when you consider the power station emissions required to charge it. So turning your home into a charging station with solar and wind frees the EV up to be truly zero emissions.

At the same time, using an EV’s power capacity to watch TV and boil the kettle, (plus store energy in its battery pack so you can harvest when you don’t need it on a windy night at 2 a.m.) means the EV can free your home from the grid. And before you wonder what happens if you need power at home when you’re out in the EV, obviously, if these early experiments work (and Tesla launch a home battery pack) we should expect home batteries to become a default feature of future homes.

Combined with better insulation and sustainable building materials, the EV might not only reduce the CO2 emissions of transport but reduce them at home too. It’s a lightbulb moment without the grid… and that’s a first if the lightbulb in question is hanging from your bedroom ceiling.