In conversations about Britain's renewable energy resources, wind and solar get most of the attention.
People understand how they work and that they're essential for decarbonisation.
They also assume that wind and solar are our largest renewable resources.
In a way, that's true. In terms of simple capacity (how much electricity could be generated if we used all our renewables at full tilt), GB's renewable resources look like this (from UK Government stats):
In the above graph, wind (on and offshore) has nearly half of all GB renewable capacity. Solar offers 31.5% and bioenergy offers less than half that, at 14.9% of renewable capacity. Hyrdo power offers 4.6%.
But in the UK we get a lot of days that look like this, as shown by Drax's Electric Insights website on 17 December 2018:
In the above, you can see solar generating zero. Because it was pretty overcast and so solar couldn't be depended on to generate the right volumes.
That's why we end up with a graph like this, again taken from official UK energy stats, which shows actual generation figures, not capacity to generate:
In this graph, we see that bioenergy actually generated 32.1% of our renewable power, second only to wind's 51.4% (roughly proportionate to its capacity).
Solar generated 11.6% of renewable power, about a third of its capacity figure.
So, whilst biomass has a lower capacity compared to solar, it's actually our second biggest generator of renewable power.
The key lesson here isn't 'biomass good, solar bad'. The reality is that we need a full mix of renewables.
But what we do need to understand is that different renewables have different functions. Biomass is useful because it's very reliable - there when you need it. That makes it a great back-up on our energy system, ensuring security of supply as well as low-carbon power.
What we haven't shown here is all the extra services that biomass can provide to help balance the energy system. But that's for another blogpost.