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Tag Archives: imports

Greenpeace – 100% global renewables by 2050

By Dave Elliott

A new report from Greenpeace says the world can be 100% renewable in energy by 2050, and 65% renewable in electricity in just 15 years. The 2015 Energy [R]evolution report, the latest iteration in its global and local scenario series, says global CO2 emissions could be stabilized by 2020 and would approach zero in 2050. Fossil fuels would be phased out, beginning with the most carbon-intensive sources. (more…)

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In praise of wind power

By Dave Elliott

This year has seen yet more negativity on wind power, and proposals to cut support for on -land wind, despite this being the cheapest of the major new renewables. While overall public support for the use of wind energy remains high, in practice many new on-land projects are now opposed: two thirds of applications have been turned down in the last year. Much of this has been about visual intrusion, ‘Not In My Back Yard’ concerns relating to  treasured views and, more prosaically, possible impacts on house prices. (more…)

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Imported wood combustion? Some say it’s fine..others disagree

By Dave Elliott

Many environmentalists are not keen on using imported wood pellets in old inefficient converted fossil-fueled plants. They say there are better ways to use biomass and better sources- local anaerobic digestion of biomass wastes and residues, along with Combined Heat and Power (CHP). Large-scale biomass conversion, and even co-firing with coal, is sometimes portrayed as an interim option, getting biomass use established, but not everyone is convinced that this helps build up support for local sourcing of biomass. It’s just a way to keep old power plants going, so as to avoid having to write off some sunk costs.  There is also the wider debate about the extent to which large-scale combustion of grown biomass, especially from forests, is net low carbon, given that it takes time for new growths to absorb emitted CO2. It’s even been claimed that using wood from trees might lead to more emissions net than from using coal, depending on the source of the wood: http://www.rspb.org.uk/Image/biomass_report_tcm9-326672.pdf 

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Supergrid (2) – could it work?

By Dave Elliott

In my previous post I looked at the potential and problems of supergrids. The basic idea is that, since, in various parts of the EU, there will be times when there is excess electricity generated from wind etc. over and above local demand, this excess can be shunted to regions which are short and have high demand, using low-loss HVDC supergrids. Would it work on a large scale?

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Supergrids – a desert mirage?

By Dave Elliott

There have been reports that the Desertec Industrial Initiative (Dii) had abandoned its plan to help support the development of solar power in the Sahara and the export of some to Europe, since it looked as if the EU could meet most of its green energy needs indigenously, without significant imports. So is the desert CSP/supergrid idea dead? (more…)

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Water and Transportation Nexus: US Domestic Water for Imported Oil?

Energy and water are inextricably linked. If we consider food as energy, which we should since it is the substance that powers our bodies, then the energy-water nexus is perhaps the most important in the agricultural sector. When we use agriculture to grow crops for biomass that is later converted to liquid fuels, then the energy-water nexus is even more apparent. I calculated how much water is used for driving light duty vehicles (cars, vans, light trucks and sport utility vehicles) and published the results in Environmental Science and Technology (10.1021/es800367m). Results are also summarized in a commentary in Nature Geoscience volume 1.

The results vary from 0.1-0.4 gallons of water per mile (0.2 – 1 L H2O/km) for petroleum gasoline and diesel, non-irrigated corn for E85 vehicles, and non-irrigated soy for biodiesel. Additionally, driving on electricity from the US grid consumes near 0.2-0.3 gallons of water per mile (0.5 – 0.7 L H2O/km). The reason is that water is used to cool off the coal, natural gas, and nuclear power plants on the grid. However, if irrigated corn is used to make E85 ethanol in the United States, then the water consumption jumps by one to two orders of magnitude to 10-110 gallons of water per mile (23-260 L H2O/km), with an average of 28 gallons of water per mile driven. Keep in mind that only about 15-20% of corn bushes are irrigated to any extend in the US.

This information is only an introduction to the energy-water nexus, but the US government is looking at it more closely recently due to research showing how constraints on one side can create problems for the other. This is typified by potential legislation proposed by Senator Bingaman: The Energy and Water Integration Act of 2009. This bill use similar language as in my Env. Sci. and Tech. paper in measuring the life cycle impact of water for transportation in terms of water consumed per distance traveled. Hopefully, research, industry, and government efforts can minimize impacts on water resources and use them wisely for our energy future.

The concept of using water resources sustainably, especially for growing biomass for liquid fuels, makes one wonder about water embodied in imports and exports in general. Is it better for the US to import biofuels from Brazil that are grown from sugar cane that might not stress water resources as much as corn agriculture does in the US? The US has a tariff on imported ethanol, but not imported oil. If the US has an energy policy goal of reducing imports from the Middle East, then it seems like the tariffs would be switched since the US has friendly relations with the Brazilians. So it seems the current US energy policy is to literally trade domestic water for foreign oil. I guess it could be worse.

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