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RENEWABLES
25 January 2016 16:00

US could cut power emissions 78% by 2030 using existing technology, says study

Sophie Yeo

Sophie Yeo

01.25.16
The 'world's largest solar plant' is currently powering 140,000 homes in the US
© BrightSource/Splash News/Corbis
Sophie Yeo

Sophie Yeo

25.01.2016 | 4:00pm
RenewablesUS could cut power emissions 78% by 2030 using existing technology, says study

In their pursuit of a connected nation, Americans built transcontinental railroads in the nineteenth century and the interstate highway system in the twentieth century.

With a similar level of effort, the US could construct a nationwide energy infrastructure that cuts carbon dioxide (CO2) emissions by up to 80%, says a study in Nature Climate Change.

This could be achieved without increasing the cost of electricity, thus providing an economic incentive to tackle the problem of climate change.

Previous studies

Scientists have previously tried to model ways to increase the volume of renewables in the electricity sector, so that penetration reaches close to 100%.

But generating power through renewables poses one particular challenge that fossil fuels don’t.

As the weather is variable, solar and wind power stations cannot generate electricity on demand. They can only provide when the sun shines and the wind blows. This is seen as a problem, as the supply and demand for electricity need to be balanced.

Previous studies have tried to get around this by making certain assumptions — for example, the availability of low-cost electrical storage, to control the supply of power. However, energy storage is still a technology in its infancy.

More renewables

A group of academics at the National Oceanic and Atmospheric Administration (NOAA), a US federal agency, has taken a different approach.

They have modelled a future that only uses currently available technologies and excludes electrical storage.

“The model is simply trying to find the least cost combination of generators and transmission to supply power every single hour,” co-lead author Christopher Clack of the Cooperative Institute for Research in Environmental Sciences (CIRES) tells Carbon Brief, adding that the model was “agnostic with respect to technology”.

This requires the construction of a lot more renewable energy power stations.

Building a combination of 1,529GW of solar, wind, natural gas, nuclear and hydro would cover the power needs of the US while reducing CO2 emissions by 78% and keeping costs lower than current projections, the study says.

The additional power stations for requiring this additional capacity would take up 6,570 square-km of US land — around 0.07% of the country’s total area. Several constraints are applied, including not building solar and wind on protected lands.

Generation capacity for a low-cost renewables, high-cost gas scenario where emissions are reduced by 78% on 1990 levels by 2030.

Generation capacity for a low-cost renewables, high-cost gas scenario where emissions are reduced by 78% on 1990 levels by 2030. Source: Nature Climate Change. Chart by Carbon Brief.

These CO2 reductions are based on a scenario where the US achieves expected cost reductions for renewable energy and increased demand for natural gas, boosting its price. Other scenarios, including a high-cost renewables, low-cost gas scenario similar to 2012, still yielded emissions reductions, albeit less steep.

This is enough to power the whole of the US, even assuming that demand for electricity rises by 14% by 2030. What’s more, the model sees wind and solar substantially increase their share, displacing other fossil fuels and some natural gas, whose share also decreases.

The following two videos show the windiest and sunniest areas of the US, illustrating the US weather system as a whole.

Wind potential

The wind is always blowing somewhere in the United States, though in any given location, it may stall out periodically and there are some locations with better wind resources than others. A new analysis shows that by better matching the scale of the U.S. electricity system to the scale of weather, the country could keep energy costs low, put more wind and solar on the grid, and eliminate much of the sector’s greenhouse gas emissions. The study finds that combining wind and solar is important as they are complementary. This animation covers 10 days in January 2008. Visualization by Chris Clack/CIRES.

Solar potential

Solar resources vary across the country, with greater potential in the South (and during the day). A new analysis shows that by better matching the scale of the U.S. electricity system to the scale of weather, the country could keep energy costs low, put more wind and solar on the grid, and eliminate much of the sector’s greenhouse gas emissions. The study finds that combining wind and solar is important as they are complementary. This animation covers 10 days in January 2008. Visualization by Chris Clack/CIRES.

Transmitting electricity today

Increasing the number of power stations is not enough to create a reliable source of electricity. The problem of intermittency remains.

To resolve this, the model uses the variability of the weather as a strength, rather than a hindrance, by creating a single electrical power system across the US — a solution which the study says is cheaper than integrating energy storage.

Currently, the US electrical system is split into three areas. These areas are called “interconnections”, each of which operates largely independently, with very little electricity transferred between them.

These three areas are further split into smaller units called Balancing Authorities, which work to maintain the balance of supply and demand in their areas.

A US-wide system

However, the larger the area,  the more effective they can be at balancing the supply and demand of electricity. This is particularly true when it comes to integrating intermittent renewables into the grid.

Having a larger area means that there is a larger volume of potential resources.

It takes advantage of the fact that the variability of the weather decreases as geographical area increases — that is to say, if the wind is not blowing in one place, it is likely to be blowing some place else. The model is the first to “incorporate weather data at high resolution over continental scale and yearly time horizons,” Clack points out.

This means that, rather than abandoning households and businesses to the vagaries of the weather in their own area, a large electrical system provides access to a vast pool of places they can send their excess electricity on sunny or windy days, and from which they can import electricity when it is calm or cloudy.

The study connects up the whole of the US through a network of high-voltage direct-current (HVDC) transmission lines, which is capable of transporting electricity over long distances.

The study shows that a larger grid is better than a smaller grid when it comes to integrating renewables. It says:

As the size of the connected system grows, the amount of wind and solar PV generation increases. Moreover, the cost of electricity decreases as the area increases, because the system has access to more remote, rich resources and the correlation between connected sites weakens.

Cost

This system could save Americans $47.2bn every year, says the study. The scenario outlined above would reduce the costs to 10 cents per kWh.

The saving is relative to the predictions of the International Energy Agency (IEA) and the Energy Information Administration (EIA). They estimate that the cost of electricity in the US in 2030 will be 11.5 cents per kilowatt hour (kWh).

Would coal be cheaper? Yes, say the researchers. Including coal in their modelling reduced the cost of electricity to 8.5c/kWh, but CO2 emissions were 37% higher than 1990 levels.

This is incompatible with the US target to reduce emissions 26-28% by 2025 on 2005 levels. And, as the study points out, large numbers of coal plants in the US are already being retired for age, economic or environmental reasons.

Difficulties

The challenges involved in implementing a low-carbon, transcontinental system would be far from negligible, as the study point out. It cites barriers including the current regulatory, commercial and legal system, and the required investment in the new transmission system and power plants.

The paper says that the decarbonisation of the electricity sector is likely to encourage further decarbonisation across the entire energy sector.

Alexander MacDonald, co-lead author on the study and also from NOAA, tells Carbon Brief:

If electric energy is cheap, then other electric users, such as autos and heat pumps are more likely to use it. Right now electric car fuel costs are significantly less expensive than fossil fuel costs.

He adds:

There are industry estimates that the purchase cost and range of electric cars should improve a lot over the next few years, and if they do, then having an inexpensive source of electric energy as is shown in our study, would help decarbonize transportation. Cheap, low carbon electricity would therefore help decarbonize other energy sectors.

With widespread use of electrical storage still distant and coal in decline, the study gives a snapshot of what the US electricity system could look like in a decarbonised future.

Main image: The Ivanpah Solar Electric Generating System in the Mojave Desert.

MacDonald, A. E. et al. (2016) Future cost-competitive electricity systems and their impact on US CO2 emissions, Nature Climate Change, doi: 10.1038/nclimate2921.

Sharelines from this story
  • US could cut power emissions 78% by 2030 using existing technology, says study
  • Mark Ohe

    If carbon emissions were the actual dilemma this study would have more merit. However, it’s the reduction of all greenhouse gas (GHG) emissions that is needed. Methane in particular. Reducing carbon by relying on methane fired electric power plants is no solution. In fact, GHG emissions would only increase. As would fracking to supply the methane, toxic compressor stations to move the methane, and more frack-gas pipelines to feed methane power plants. Each of these components would add significant amounts of GHG to the atmosphere, and destroy communities in which this toxic infrastructure was located.

    • wydeeyde

      What I think you are saying is ‘do nothing’. I’m not sure what you mean by destroying communities. There are natural gas facilities all across the US. Other than the current disaster in Porter Ranch CA I have not heard that communities are being destroyed in the way that coal communities were destroyed in the past including both major urban areas and the mining communities in the South East. Currently CO2 is far outstripping methane in contributing to global warming. However I see that a large increase in methane will generate serious effects toward global warming. Given that the article presents a target amount of natural gas usage by 2030 and poses a 78% reduction of greenhouse gases I wonder if you could present the scenario you see such as the actual significant amount related to the reductions projected by the referenced study.

  • Bruce Parker

    The plan calls for replacing over 300 GW of existing coal, which has a cost of $30/MWH for electricity, with new renewables, which have an average levelized cost of well over $100/MWH (e.g., $196/MWH for offshore wind) – seems to me that this would greatly increase electricity costs, not save money. And significantly upgrading the power grid and building tens of thousands of miles of new transmission lines – from the Midwest and Southwest deserts (where most of the renewable energy is) to the major population centers in the East and California – almost certainly will not happen in the next 15 years. The “average” person reading this will likely think that the study’s conclusion (“US could cut power emissions 78% by 2030 using existing technology”) is “doable” and all that we need to make it happen are for politicians, regulators, and utility owners to “make the right decisions”. This is yet another example of a study touting what is technologically possible but politically and socially next to impossible.

    • Richard Reiss

      The problem is every answer (do nothing, do something, do everything) is impossible. So might as well do the one that has a future to it. Scroll to frame 15 of Michael Oppenheimer’s pdf on “When will climate change become dangerous?” — which is North America, under the RCP 8.5 scenario, the track we’re currently on, in 2150 and beyond.
      http://www.pace.edu/paaes/sites/pace.edu.paaes/files/PPT_Oppenheimer_PaceLawSchool_Nov2014.pdf

      • Bruce Parker

        Which option has a future? Almost all of the analyses use the carbon budget shown in frame 24 of the pdf. Feedbacks from a warming world will likely use up at least 1/2 of the budget and existing greenhouse gases could use up most of the rest.

        … “It’s certainly not much of a stretch of the imagination to think that over the coming decades, we could lose a couple of gigatons per year from thawing permafrost,” says Holmes…. But by 2100, the “mean” estimate for total emissions from permafrost right now is 120 gigatons [440 GTCO2], say Schaefer. http://www.washingtonpost.com/news/energy-environment/wp/2015/04/01/the-arctic-climate-threat-that-nobodys-even-talking-about-yet

        According to Dr. Michael Mann, since the burning of coal must be ended to meet any meaningful temperature increase target, a more realistic target of atmospheric CO2 is 405 PPM, which will be reached in a few years (http://ecowatch.com/2015/12/24/dangerous-planetary-warming/2/ )

  • Richard Reiss

    Saul Griffith does a good job explaining the same options in a short blackboard talk from 2012.
    https://youtu.be/9hVEimuv5xQ

    And in a longer, excellent talk from September 2015.
    longnow.org/seminars/02015/sep/21/infrastructure-and-climate-change/

  • Dave Anthony

    Promising trends shown here. It would be a nice supplement to show what the energy input (CO2 output) is to manufacture the panels and turbines and compare those values to the proposed CO2 output savings predicted with a decarbonized system in place. Surely as the production technologies improve simultaneously with increased demand, their implementation should become much more economically and environmentally feasible.

  • piyush2

    Any such analysis needs to consider how resilient it will be to an increasingly hostile climate. When monster storms (such as the one that recently hit the northeast) with high winds knock out poles and cause electrical outages (which are hard to fix quickly because of heavy snow accumulations) for several days in sub-freezing temps, it becomes a life and death problem and local storage helps. If we are going to rely even more on massive electric grids that span possibly continents, then their vulnerability to extreme weather (hurricanes, tornadoes, blizzards) needs to be considered, the alternative could be underground grid but that one is hard to repair when there is a fault. However you look at the problem, it is not easy. What is not often discussed is energy reduction, everyone wants to find substitutes for the extraordinarily extravagant energy consumptive lifestyles created by a fossil fuel bonanza, what we really need to question is the usage and think of building infrastructure that would require much less energy consumption (such as walkable/bikable communities, better insulation, more public transit, local agriculture, discouraging frequent long distance travel etc)

  • As the size of the connected system grows, the amount of wind and solar PV generation increases. Moreover, the cost of electricity decreases as the area increases, because the system has access to more remote, rich resources and the correlation between connected sites weakens. … This makes perfect sense.


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