IT’S not news, but Scotland uses six times more energy for heating in winter than in summer. While the first priority should be to reduce seasonal fluctuations by improving energy efficiency and building insulation, we also need a form of energy storage that is charged during summer and discharged during winter. Interestingly, the most obvious of these is thousands of years old. Biomass – burning organic material like wood for warmth – provides a way of storing sunlight and releasing it later as heat. Another option is to use hydrogen generated from low-carbon electricity. The electricity is used to separate hydrogen from water, with the resulting gas then either injected into the mains gas grid to be burnt as normal, or pressurised and transported, as in Aberdeen, which recently deployed Europe’s largest fleet of hydrogen buses. The third option is seasonal thermal energy storage. Typically thi s would involve using the sun’s energy, converted with solar thermal panels, to heat water stored in large pits or underground. Seasonal thermal energy storage integrated with district heating systems – where a number of buildings are linked to one heat source by a network of pipes – is an effective way of shifting heat energy from summer to winter. The drawback is that around half of the energy is lost between charging and discharging. While this seems a lot, the alternative would be to pay for heat generation equipment to satisfy the demand in winter which would then lie idle in summer. Continental Europe leads the way on low-carbon heat, and we should look to countries like Denmark for best practice examples – but also be aware that directly adopting their solutions might not be appropriate. A recent study showed that the cost of solar district heating with seasonal storage for Scotland is significantly higher than for Denmark and Canada, simply bec ause Scotland doesn’t get as much sunlight. Scotland’s solution, then, must be a different one. Rather than using solar thermal panels – as in continental Europe – Scotland could use heat pumps (devices which use electricity to draw and upgrade warmth from the ground, water or air) to charge these enormous heat batteries during summer. This would mean using clean electricity, which would otherwise have been wasted, to warm homes and businesses months later when that heat is needed.
Herald 23rd April 2018 read more »