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Solar thermal tower and mirror field at Sandia National Labs in New Mexico
National Solar Thermal Test Facility at Sandia National Laboratories, near Albuquerque NM. Sunlight is focused on the tower, super-heating a working fluid that can be used to run an electrical generator.

Our Energy Future: The Whole Picture

Energy Construct author analyzes our long-term energy options

By Ben Cipiti

With the price of oil making headlines, looming economic problems, and debate about climate change, energy has been driven to the forefront of the problems we face as a country. But if we continue to only debate about energy alternatives, the result will be at best painfully slow progress and at worst business as usual. Meanwhile the rest of the world passes us by and we lose our chance to be leaders in developing better solutions. We need to look at the whole picture to develop a realistic strategy for achieving our goals.

What are the problems with our current approach? Top on our list of concerns is the effect our addiction to oil has on the economy and national security. Oil places our economic health and security in the hands of unstable countries. And with about 86% of our primary energy coming from fossil fuels, we need new technologies that will reduce emissions.

Our goals are to achieve a cleaner, economic, and domestic energy future. But getting there is not going to be easy. Even if we can develop economic alternatives and have the public and political support to make significant changes, there are limits to how quickly new plants can be built. It is useful to maintain a diverse energy portfolio specifically for this reason.

The following figure presents a roadmap for achieving our goals. The left of the graph shows our energy breakdown as of 2005. The right shows the expected increased energy demand by 2030 with a more diverse and clean energy portfolio. The middle shows what it will take to achieve this vision.

Oil

The three alternatives to oil for transportation are biofuels, hydrogen, and electric vehicles. It is becoming more clear that biofuels are not the solution due to the massive land requirements and the fact that they require as much energy to produce (mostly from fossil fuels) as the energy we get out of them. Recent food price increases due to ethanol use hint at the ethical concern about converting food into fuel.

The hydrogen economy would require years of technology development, but more importantly, it will be incredibly wasteful of energy resources. Many efficiency losses exist in the process of producing and distributing the hydrogen, only to see more efficiency losses in converting the hydrogen into electricity in a fuel cell. The net efficiency of the hydrogen economy will be about 15%.

The best solution for drastically reducing oil use, reducing emissions, and doing so in an economic and efficient manner is through the use of electric cars. The net efficiency of the electric vehicle economy will be about 30%, or twice that of hydrogen. And the hybrid and plug-in hybrid technologies provide a development path that is already pushing us in that direction. On a per mile basis, the cost of electricity is one fourth the price of gasoline, and rising gas prices will only increase that gap.

But plug-in hybrids still need to make progress on reducing the cost of batteries, and all-electric vehicles will not be attractive to the mainstream unless a rapid charge capability is developed. Fortunately, a number of companies are already working on these technology improvements.

How fast can we transition? Consider that the average car is on the road for 16 years, so even aggressively pushing plug-in hybrids, it will take about 16 years before a majority of the vehicles on the road convert to partial electricity. At best, we may be able to decrease oil consumption from 40% to 10% of our total energy use by 2030, but that will be an aggressive goal.

Nuclear

The transition to plug-in hybrids and electric vehicles will make it that much more important to expand clean sources of power generation. With very little net emissions and economics similar to new coal plants, nuclear energy needs to be part of the solution. But nuclear faces regulatory hurdles that will limit how quickly new plants can be built.

Initially, utilities are finding that it will be economic to build a new reactor at the site of an existing nuclear plant, but building at a completely new site will be more challenging. (Existing sites have already dealt with much of the preliminary regulatory issues). Plus, the country is only beginning to become more accepting of nuclear, so many areas of the country may for a while continue to be against expanding production.

The nuclear power industry is the safest of all the power generation technologies. (Consider deaths and injuries due to coal mining, gas and oil explosions, and even hydroelectric dam ruptures.) The excellent safety record is due to our tight regulations. New plant designs that take advantage of passive safety systems will further increase our confidence. Passive safety refers to systems that engage due to natural forces—eliminating the chance of mechanical, electrical, or human error.

Another hurdle of nuclear is our inability to make a decision on how best to manage the waste. With the opposition to the Yucca Mountain repository, it may make more sense to use above-ground dry cask storage of the waste. All commercial spent fuel generated to date, if placed in dry cask storage, would fit in an area about the size of a football field. In the future, reprocessing of nuclear fuel will allow for the long-lived species to be removed and recycled back into existing reactors. And in the far future it will be possible to transmute all long-lived wastes into stable species.

Renewable

Our main sources of renewable energy today are hydroelectric (2.7%) and biomass (3.2%). Most of the renewable energy options are constrained by poor economics, low reliability, or large land requirements. Wind is the one option that is getting competitive and that can be used in many areas around the country. But even wind will be limited to at most 10% before the reliability issue leads to detrimental affects to the power grid.

Solar and geothermal are still expensive, making them unlikely to expand significantly. Ocean energy sources like wave energy and ocean current converters are technologies to keep an eye on, but they are still relatively immature in development. Biomass will be limited by land requirements. Renewable energy portfolio standards will help to expand the use of all these options despite the economic issues. Utilities can absorb some higher costs for low percentages of renewable, but ultimately they need to rely on cheap coal and nuclear to subsidize the cost.

Achieving 20% renewable by 2030 is probably the highest we can realistically hope for. This could be achievable with 10% wind, the existing hydroelectric and biomass sources, and just a couple percent of all the others. Regardless of how much costs of the renewables improve, a strong majority of our grid needs to come from reliable, baseload power. Even 20% of our energy from renewables will be pushing the limits as to what our grid can handle.

Coal

Since coal provides 50% of our electricity today, and due to our abundant resources, coal will remain an important part of our energy portfolio. That being said, public opposition is likely to limit new plants. And the possibility of future carbon regulations is making coal more of an investment risk.

For all of these reasons, carbon sequestration will be one of the most important technologies to develop in the coming years. Carbon sequestration involves both the removal of CO2 from exhaust and the storage in the ground. The challenge is in the removal step since it will add cost to and decrease the net electrical output from the plant—the sequestering step will not affect the economics as much. But both steps will require significant research and development. In the end, it will only be through large-scale industrial use that the utilities will be able to minimize costs and power consumption.

It will likely take 5 years in the best possible scenario to begin to pass carbon sequestering legislation. Gradual regulations could give the industry time to build and optimize the technology. An initial regulation may require reducing emissions by 10%. Ten years later the regulation may be ready to be increased to a 30% reduction. After 30 years, we would be lucky to have coal plants producing half the carbon emissions. The goal is to structure the legislation to help optimize the costs to make zero emission plants a reality in the future.

Natural Gas

Natural gas will continue to satisfy a sizeable portion of our energy needs, and with half the emissions of coal, gas is not a priority for reducing emissions right now. Though, with limited gas resources in our country, gas use will probably not expand greatly in the coming years due to the high price and volatility in the market.

Natural gas makes the most sense as an efficient source for home and industrial heating. With the quick ramp-up of gas turbines, it also makes sense for supplying peaking power and helping to stabilize the grid to enable more renewable energy use. We will need to continue to find new sources of gas—biodigesters and landfills that produce gas from organic wastes are excellent ways for producing useful fuel from waste products.

Conclusion

Due to various constraints, no one energy option is going to be a clear winner in the future. It will be prudent to maintain a diverse energy mix in case of fuel shortages or other unforeseen future challenges.

Increasing use of plug-in hybrids and electric vehicles will help to wean us away from oil. The added electrical demand can be met by expanding renewable and nuclear energy. And we need to work toward achieving zero emissions coal plants.

I believe in our ability to move toward cleaner, economic, and domestic sources of energy, but we need a vision of where we are headed. We have spent the last 20 years debating the problems. Let us spend the next 20 building solutions.

Ben Cipiti is a researcher at at Sandia National Laboratories in Albuquerque, New Mexico. The first chapter of The Energy Construct is available free on his web site.

Times Article Viewed: 11831
Published: 02-Jul-2008

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