Can renewable energy sources power the world?
Can renewable energy sources power the world?

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Can renewable energy sources power the world?

1.1 UK electricity scenarios

In 2011 the World Wide Fund for Nature (WWF), published Positive Energy (WWF, 2011a), describing a range of UK electricity scenarios for 2030 based on detailed analysis by the specialist consultancy Germanischer Lloyd Garrad Hassan (GLGH). The report demonstrated that renewables could contribute some 60–80% of the UK’s electricity by 2030. GLGH created six scenarios for the UK electricity sector in 2030, with the first three ‘Central’ scenarios assuming only modest attempts to reduce UK electricity demand, whereas the second three involve more ambitious energy conservation measures.

The report comments:

In all cases, the scenarios make full provision for ambitious increases in electric vehicles (EVs) and electric heating. Energy efficiency and behavioral change lead to the reductions in demand in the ambitious demand scenarios.

The volume of renewable capacity installed by 2020 in all scenarios is similar to that set out in the government’s Renewable Energy Roadmap in July 2011. However, critically, the scenarios envisage installation continuing at a similar rate during the 2020s. This will avoid the risk of ‘boom and bust’ in the UK renewables sector [...] and mean renewables provide at least 60% of the UK’s electricity by 2030.

The amount of renewable capacity the UK can and should build is determined by economic constraints – not available resources or how fast infrastructure can be built. GLGH assumes that it is economic to supply around 60% of demand from renewables. Going beyond 60% depends on whether there’s a market in other countries for the excess electricity the UK would generate at times of high renewable energy production.

An even more ambitious scenario, envisaging the UK making a transition to a ‘Zero Carbon Britain’ (ZCB) powered entirely by renewables by 2030, was published by the environmental charity the Centre for Alternative Technology (CAT) in 2013 and 2018. This transition would be achieved through ‘Powering Down’ – reducing energy demand without reducing quality of life; and ‘Powering Up’ – deploying renewable energy on a large scale and very fast. (Zero Carbon Britain, 2018).

Figure 1 summarises how the ZCB scenario envisages energy flowing in 2030 from a variety of renewable energy sources, via various energy conversion processes, to supplying energy for heating, cooking, lighting & appliances, industry and transport.

Figure 1 ZCB scenario showing energy flows from renewable energy sources to supply energy demands in 2030

The ZCB scenario is based on a detailed hourly model of UK energy supply and demand. In it, the majority of renewable electricity comes from a very large capacity of on-shore and offshore wind power, and there will be many occasions when this supply exceeds electricity demand. The ZCB researchers propose a ‘power to gas’ process in which surplus renewable electricity is converted into hydrogen by electrolysis. This is then combined with carbon dioxide from biomass to produce methane, which can be distributed and stored in the existing UK gas grid and burned in the UK’s conventional backup power stations (which normally burn fossil methane) when there is a deficit of renewable electricity.

In addition, some of the hydrogen and carbon dioxide are instead converted to a synthetic liquid fuel, methanol, which can be used as a substitute for gasoline in many vehicles.

Watch the following video, which gives more information on the thinking behind the ZCB scenario.

Download this video clip.Video player: track_04_renewable_energy_and_the_uk_zero_carbon_britain.mp4
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The Zero Carbon Britain project is a research project at the Centre for Alternative Technology that, in some way or another, has been going on for almost 40 years because, even in the 1970s when most of the UK was just fascinated with a new boom in gas and oil, there were people actually looking at developing a new energy strategy for the United Kingdom.
Overall, the aim of Zero Carbon Britain is simply to create a scenario where the net greenhouse gas emissions are zeroes. A large focus is on energy. So there, we are looking at what we call the power down, which is in looking at how much can we reduce our energy consumption while still maintaining similar lifestyles to what we have today. The other component is the power up, where we then look at how can we produce the energy that we still need after savings through renewables.
When we looked at the power down in our scenario, how much we can reduce energy consumption by, we first of all looked at where are we actually using energy today. What are the things we do with energy in the UK? And we identified that heating and just keeping warm in winter is a big chunk of the picture, and another big chunk is transport.
So a lot of focus on the power down research, on reducing our energy consumption is simply on how can we improve our energy efficiency in those fields. So we're talking about, for example, insulation of the existing building stock. And the other part was looking at the transport sector, how can we make sure that people still get from A to B but using a lot less energy where electrification of transport and a bigger role of public transport. So these are the main components that allow us to overall bring down energy consumption by more than 50 percent.
And the other side, then, we still need to produce the other half in the power up from renewables, from non-carbon emitting sustainable energy sources. And there, we looked at what are the resources that the UK has a lot of, and it's quite obvious that the UK has a huge potential for wind power. So in approximate numbers, the amount of wind power, we would need would be around 140 gigawatts. So that's very large compared to what we have today, which is I think two or three gigawatt at the moment.
But at the same time, if we look at the area that we could potentially use for it, it's actually still only a small fraction of the total area that we have available for offshore wind. So definitely, the resource is there for it. If we look at solar PV, solar photovoltaics. We started out by saying, well, how much roof area is there in the UK? How much of that might be suitable? And we looked at what could we get out of covering 10% of the roof area in solar PV, and we arrived at around 60 gigawatts of solar photovoltaics. So you could say one kilowatt per person in the UK very roughly.
One of the big pieces of criticism that we got for previous reports that we had done was that, yes, you're showing that in overall terms there is more than enough wind power and solar power to provide the energy for the UK, but what happens on the day when it's cold and dark and the wind doesn't blow? How will you make sure that we stay warm and happy on days when the renewable energy output is poor?
So what we did is we took 10 years worth of data of all sorts of types- hourly data. So hour for hour, we got data for the solar radiation coming down on various places in the UK. We got through a NASA computer and satellite model data for hourly wind speeds for locations far out in the Atlantic and in the North Sea. So we were simulating hour for hour based on solar radiation, wind speeds, temperatures how the supply and the demand would meet.
And one of the findings was that it is a challenging issue. Some people believe that if you spread wind turbines around enough you always have a balanced-out supply. And we found no, that isn't true. There are, in fact, times when, even across the whole of the UK, you have comparably low output from wind power at times of very high energy demand.
So one of the technologies, for example, that we looked at for backup and storing energy when there is a surplus of energy and then using that energy at times when the demand outstrips the supply is synthetic gas. So we were looking into, how can we use surplus renewable energy to make methane gas, store it in existing gas fields that we have today, and then burn that in gas power stations on days when there isn't enough wind to keep us all warm?
And our model shows that we can make that work out pretty right with the technology that exists today. And the good thing is, because this is a synthetic gas made from carbon dioxide from the air and hydrogen and electricity, if we burn it, we're only putting as much carbon dioxide into the atmosphere as it would take out in the first place. So it's not only renewable energy, but it's also completely carbon neutral.
End transcript
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These proposals are extremely radical and ambitious, but the UK’s offshore renewable energy resource, from wind, wave and tidal sources, is huge. In 2010 the Offshore Valuation study (Offshore Valuation Group, 2010), backed by the Crown Estate, UK and Scottish government departments and some major companies, concluded that it is equivalent in size to the UK’s offshore oil and gas resources – but unlike these fossil resources, the renewable resources do not suffer from depletion and should be available for an indefinite period.

The study also showed that the majority of the wind resource is located far offshore, and could be harnessed using floating turbines moored in very deep waters. As shown in Week 6, a number of companies including the Norwegian company Statoil are developing floating wind turbines.

But what’s involved in balancing supply and demand? You’ll look at that in the next section.


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