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100% renewable energy and zero emissions – can we do it

By 20th December 2016 Sustainability No Comments

After reading news of how Google expects to meet its 100% renewable energy target in 2017, we decided to examine how realistic this goal is in the UK. It doesn’t look like it is.

In recent years, there’s been a growing clamour for a move to a 100% renewable energy system, not just in the UK, but globally.

The trouble is, people overlook just how dependent on fossil fuels the world economy is, and not just in electricity generation but in road transport, aviation and shipping – all of which have grown as a result of globalisation and trade.

We’ve looked at this from several angles and concluded that it just isn’t realistic now or in the foreseeable future.

What would be the goal?

Wherever 100% renewable energy gets a mention, it’s usually linked to keeping fossil fuels in the ground for the sake of avoiding climate change, and so it’s a fair assumption that the goal would essentially be to decarbonise the economy. But that actually makes it trickier to achieve in practice for reasons that will become clearer in a minute…

Aviation, road freight and buses are the first hurdle to 100% renewable energy

Right now, there is no credible, proven alternative to the use of jet fuel in aviation. The Solar Impulse project affords a glimpse of what solar powered flight could look like in the future, but it’s hard to imagine an aircraft equivalent to the Airbus A380 that runs entirely on solar…ever. So, right away, you can see that 100% renewable energy just isn’t within reach and, truthfully, may never be because of this one important and continuing use of fossil fuel.

Then there’s road freight and buses. These are mostly run on diesel, which not only releases CO2 emissions when burned but other harmful air pollutants. The problem is that electrifying them isn’t as easy as it with cars, owing to the weight of the vehicles involved and the size of the batteries needed. Hydrogen fuel cells could have a promising future, but they are yet to be adopted at scale and are currently very costly. The idea of creating a network of hydrogen filling stations has also been proposed, but the only cost-effective technique for producing large quantities of hydrogen is steam methane reforming, where the carbon molecules are removed from natural gas to leave behind just hydrogen – but this is energy intensive and results in CO2 emissions.

Getting to 100% renewable energy

If we can’t do anything about aviation, road freight and buses, what could we do? Well, we could seek to stop using coal, oil and natural gas in homes, shops, offices and industry, and replace this with renewable electricity.

But this would present an enormous challenge.

For a start, based on a simple evaluation, it would quadruple the consumption of electricity. That’s a big leap.

Then consider that in order to achieve the simultaneous goal of zero emissions, it would be necessary to source 100% of this electricity from non-combustion sources – that would mean not using wood and plant biomass, liquid biofuels, biomethane from anaerobic digestion of food and farm waste, landfill gas, or energy-from-waste incineration, because these all produce emissions of their own, and using only hydro, wind and solar instead.

To put this into context, non-combustion renewables supplied approximately 4,969 Thousand Tonnes of Oil Equivalent (ktoe) of final electricity in 2014; to meet the predicted increase in electricity consumption that would result from ditching fossil fuels in all but aviation, road freight and buses, these non-combustion renewables would need to supply an additional 88,497 ktoe of electricity. In 2014, these non-combustion renewables had an installed capacity of 20.1 GW – crude arithmetic says that if output would need to grow by 17 times under this scenario, so would capacity (assuming capacity factors remain unchanged) – to over 340 GW.

Could we finance and build the extra generating capacity?

As far as financing such a massive expansion of non-combustion renewables is concerned, that would probably be decided by the market and whether or not there’s sufficient investor appetite for the level of risk involved – if government policy clearly set out the intention, sending the right signals, it’s possible that the capital would be made available.

But could we actually get it built? It’s very unlikely we could expand large-scale hydro much beyond its current contribution because we simply lack the space, geography and topography to do so, which would mean the bulk of the increase in capacity would have to come from wind and solar – but we’d be talking about potentially tens of thousands of onshore and offshore wind turbines, which it’s hard to see getting built without huge opposition, and we would most probably run out of suitable rooftops and field sites to build enough solar PV capacity too.

Download our handy cut-out-and-keep infographic for a summary

Would homeowners stump up for new electric heating systems?

Around 22 million UK homes that currently have gas central heating would need to have this ripped out and replaced by all-electric alternatives. It’s unlikely that ground and air-source heat pumps would be suitable in much of the UK’s present housing stock, and so night storage heaters or low-energy infrared panel space heating would probably be used in most cases – either way, even the most conservative of estimates puts the total cost at well over £150 billion. And if homeowners won’t fund this themselves, who would – government?

Could industry adapt?

It’s far from clear that UK industry could adapt to electrification in all sectors. Take cement production, for instance – many of the UK’s kilns still run on coal. Glass recycling relies on huge amounts of natural gas to run the melting furnaces. Fertiliser production is also heavily dependent on natural gas, both for process heat and as source of hydrogen. These and many others may simply not be able to achieve the temperatures needed using electrically-powered systems, and perhaps should not be expected to in any case – the productive use of energy is the best use. And at what cost? Unless the same industries in other countries moved in concert, there’s a real risk that UK businesses would find themselves at a massive competitive disadvantage to overseas rivals.

Other pressures it could create

Firstly, the costs of wind and solar PV have fallen considerably in recent years, but if demand for those technologies – and the raw materials they depend on – started to grow really significantly, there’s a chance that costs may actually rise as canny commodity suppliers choke off supplies to boost profits. You know, a bit like OPEC, but for rare earth metals or copper.

Then there’s the environmental damage that the extractive and chemical processes used to make renewables are responsible for, which would undoubtedly increase just as the environmental damage of fossil fuel extraction declines.

Now, take these two additional concerns and imagine what that could look like if every country simultaneously embarked on a quest for 100% renewable energy…

What’s the alternative to 100% renewable energy in the UK?

This really depends on what the goal is.

If it’s about achieving maximum decarbonisation of the economy, which means eradicating the use of fossil fuels in all sectors (excepting aviation, road freight and buses) then large-scale electrification is still the way to go but perhaps powered by a combination of nuclear and non-combustion renewables given that the energy density of nuclear is much greater (and it would therefore take up less space).

If the goal is simply to stop using fossil fuels in electricity generation, where it’s acceptable to still have some system emissions, then a combination of combustion-based and non-combustion renewables might be able to achieve that, though this would mean fossil fuels would still be used in home and industrial heating.

As with many other issues, this question exposes the tension that exists between achieving our climate goals on the one hand and our broader sustainability goals on the other.

The bottom line?

100% renewable energy in the UK seems implausible at best, and an expensive distraction at worst. A more credible aspiration would be to move to 100% renewable electricity. Here at Remsol, we happen to think that it would be best to pursue the development of an electricity generating system that simply excludes fossil fuels but is then otherwise technology neutral.

Download our handy cut-out-and-keep infographic for a summary

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