Ren Share

Where does renewable electricity come from? You’re
probably thinking about wind turbines and solar panels. But in the
UK, that’s only half the story.

To find out why, join us for our third dive into the
government’s annual energy data,
, published last week. Parts one and two covered the

challenge of decarbonising the UK
changes in UK gas supply and demand

In part three we show – among other things – that rotting
rubbish tips generated more electricity in 2013 than hydropower or
solar panels. In a series of pictures we’ll show you the hidden
faces behind the past, present and future of UK renewable

UK renewable electricity is growing

Renewables generated 54 terawatt hours of electricity
in 2013, 15 per cent of the UK total. That’s enough to supply 11
million average homes with all their electricity for a year, almost
half of all UK homes.

Renewables’ share of electricity generation has
more than doubled since 2010, when 6.8 per cent came from
renewables. You can see how fast renewable electricity output
(purple line) is growing in the graph below. But fossil fuels (blue
lines) still made up 65 per cent of the total in 2013.

DUKES Table 5.5

So what makes up that 15 per cent

Wind is the king of UK renewables, now and in

First off, those familiar wind turbines
– supported by most of the public but hated by some. These are the
undisputed king of UK renewable electricity generation. Most of the
UK’s onshore capacity is on the hills of Scotland, including
Whitelees near Glasgow (pictured), the UK’s largest onshore
windfarm. It opened in 2009 and helped onshore wind electricity
output double in the five years to

Whitelee -550

CC2.0 Scottish Government

In 2013 windfarms were responsible for about
half of total renewable electricity output with 30 per cent coming
from onshore wind and another 20 from offshore wind, as the graph
below shows.

Ren Now

DUKES table 6.1.1

Offshore wind is a relatively recent phenomenon. It is
harder to build and connect to the grid, so it is about 50 per cent
more expensive than onshore wind. But it avoids some of the visual
impacts of turbines on hills and is being
by government.

Thanet -550

CC2.0 Wessex Archaeology

Thanet offshore windfarm (above) was completed
off the Kent coast in 2010. It’s one reason electricity output from
offshore wind is now more than six times higher than it was in

Biomass burning is big and growing

Burning biomass like wood or straw in
conventional power stations is the second biggest source of
renewable electricity today, after wind power. It is a huge,
industrial-scale activity. Not so much logs on the fire as
trainloads of woodchip replacing coal.

The UK’s largest coal-fired power station
Drax (pictured) is now also the UK’s single largest producer of
renewable electricity. It burns millions of tonnes of wood, mostly
sourced from North America.

Drax 550

CC2.0 FireStationKind

Drax plans to convert more of its capacity to
burn woodchips that it will store in huge, specially designed
domes. It has been in
with government over subsidies for
the conversion but will probably go ahead either way.

The environmental impacts of burning biomass are
disputed too. It may save large amounts of carbon, or it may be
worse than burning coal. It all depends
where the wood comes from. The lack of clarity over subsidies
and environmental impacts explains why there’s a large question
mark over how much biomass will be burnt for electricity in 2020
(see graph, below).

Renewable electricity from rotting rubbish is

Coming in third on the renewable electricity
league table is landfill gas. What’s that? When biodegradeable
material like food waste is buried in landfill sites it starts to
rot, releasing methane. This can be captured and used to generate
electricity in gas turbines like the ones at the top of the

This is probably the biggest surprise
entry on the renewables league table. But it won’t keep its podium
place for long. Almost all of the potential to capture landfill gas
is already being exploited. The amount of electricity generated
from landfill gas is expected to stagnate out to 2020 while other
sources surge ahead, as the graph below shows.

Ren Futures

DUKES table 6.1.1
, Carbon Brief analysis of DECC’s
renewable energy roadmap
and electricity market reform
delivery plan

That’s because we are sending less rubbish to
landfill as recycling increases. More councils are collecting food
waste too.

Hydopower, not running away with

The graph above shows that DECC expects
hydroelectric power – number four in the renewable electricity
league – to face a similar story of low or no growth.

Small-scale schemes on fast-flowing rivers
are becoming increasingly common around the UK, but contributed
less than 15 per cent of hydroelectricity in 2013. Most still comes
from massive dams like Sloy near Loch Lomond, pictured

Sloy Dam

CC2.0 Marc

Solar is surging ahead, but how

In 2013 solar power ranked below both hydro and
landfill gas, producing a measly 3.8 per cent of the UK’s renewable
electricity. But it won’t stay there for long. DECC expectations
for solar vary widely in 2020, as the graph above shows. Even on
the lowest trajectory solar should overtake hydro and landfill

Predicting the future of energy is
. Solar’s trajectory has proved
particularly difficult to plot. Deployment has consistently
outstripped government expectations because costs have fallen
faster than it thought they would.

Faster deployment means a rising subsidy
bill. DECC says that’s why it has cut subsidies for solar farms,
pictured below, though others claim the move was
politically motivated
. More solar farms are
likely to be built
despite the change
but it’s hard to say how

Toyota -550

CC2.0 Toyota UK

Different kinds of renewable electricity from

Another surprise entry in the renewables league
table is energy from waste, sneaking in just behind solar with 3.7
per cent of the total. Some waste in the UK is burnt in
incinerators, politely referred to in the industry as ‘energy from
waste plants’.

Burning the biodegradable portion of
household waste produces renewable electricity in the same way as
landfill gas is considered renewable. That’s because the trees that
made the paper and plants that made the food will grow back in
time. Here’s a space-age incinerator in Marchwood near


CC2.0 GrahamAndDairne

A growing number of incinerators have
in the pipeline
, but the technology remains
highly controversial. One long-planned plant in Norfolk was
recently cancelled
and the prospects for the industry are uncertain.

The future looks rosier for anaerobic digestion
(AD), even though it certainly doesn’t smell sweet. AD takes waste
– anything from sewage sludge to food scraps – and ferments it in
sealed, oxygen-free tanks to produce methane.

Electricity output from AD has grown as
fast as onshore wind over the past five years, though from a much
lower baseline. It could double again by 2020, the graph above
suggest. So plants like the one pictured below could become an
increasingly familiar sight.

Cassington -550

Source: Agrivert

Slipping below the waterline

Coming in last on the renewable electricity
league table are tidal and wave power. The UK is ideally placed to
exploit these with its long coastlines, large tidal ranges and
location on the rim of the Atlantic where waves are

Despite these natural advantages and DECC
claiming the UK is a world leader in the area, UK marine renewables
produced just six gigawatt hours of electricity in 2013 – enough
for 1,200 homes. Wave and tidal devices are at the experimental or
demonstration stage, like the Pelamis P2 pictured

Pelamis -550

CC2.0 Scottish Government

In 2020 DECC expects marine renewables to have
ramped up their output more than 15-fold to 100 gigawatt hours.
However, this remains an insignificant fraction of renewable
electricity as a glance at the graph above shows.

So there you have it. Wind is and will be the
UK’s number one renewable electricity supplier for the next few
years. Our waste supplies a surprising 16 per cent of the total
through landfill gas, incinerators and AD. And there are high hopes
for solar, but even at the very top of the range of expectations it
will contribute less than a fifth of the total in 2020.