Members of the [NAE Engineering Grand Challenges] panel are "confident that we are not that far away from a tipping point where energy from solar will be [economically] competitive with fossil fuels," Kurzweil said, adding that it could happen within five years.
"We also see an exponential progression in the use of solar energy," he said. "It is doubling now every two years. Doubling every two years means multiplying by 1,000 in 20 years. At that rate we'll meet 100 percent of our energy needs in 20 years."
I reviewed the 14 21st century engineering grand challenges and MIT's ten emerging technologies for 2008
The National Academy of Engineering has a page that discusses the challenges for economical solar power.
The US DOE has an analysis of projected energy costs until 2030 The chart shown does not have the adjustment for operating load factors. It takes three times as much wind MW to generate the same as 1 MW of nuclear power.
The total fuel costs of a nuclear power plant in the OECD are typically about a third of those for a coal-fired plant and between a quarter and a fifth of those for a gas combined-cycle plant.
In January 2007, the approx. US $ cost to get 1 kg of uranium as UO2 reactor fuel at likely contract prices (about one third of current spot price):
Uranium: 8.9 kg U3O8 x $53 472
Conversion: 7.5 kg U x $12 90
Enrichment: 7.3 SWU x $135 985
Fuel fabrication: per kg 240
Total, approx: US$ 1787
At 45,000 MWd/t burn-up this gives 360,000 kWh electrical per kg, hence fuel cost: 0.50 c/kWh.
If assuming a higher uranium price, say two thirds of current spot price: 8.9 kg x 108 = 961, giving a total of $2286, or 0.635 c/kWh.
Fuel costs are one area of steadily increasing efficiency and cost reduction. For instance, in Spain nuclear electricity cost was reduced by 29% over 1995-2001. This involved boosting enrichment levels and burn-up to achieve 40% fuel cost reduction. Prospectively, a further 8% increase in burn-up will give another 5% reduction in fuel cost.
50 GWd/t standard burn up could go up to 65 GWd/t while still 5% enrichment Up to 100GWd/t burnup could be reached with existing reactors but would need 8-10% enrichment.
Accelerator enhanced constant reprocessing would enable Ultra high burnup of 700 GWd/t. [pg 96-102 discusses Possible Transmutation Strategies Based on Pebble Bed ADS (accelerator driven systems) Reactors for a Nuclear Fuel Cycle without Pu Recycling in Critical Reactors.]
There are many advanced fission reactor designs that are in development There are several possibilities for reducing the DOE estimated overnight construction cost in half and for reducing fueling and operating costs by four times by 2015-2020. It will take several completions of any new power plants and a few years of operations before cost reductions are recognized. China has ordered four AP1000 plants for $5.3 billion. However, until several are completed the new cost savings will not be recognized. Utilities are also continuing to order other plants which may be more expensive because Westinghouse is only able to build at a certain maximum rate.
South Africa's Pebble Bed Modular Reactor (PBMR) aims for a step change in safety, economics and proliferation resistance. Production units will be 165 MWe. They will have a direct-cycle gas turbine generator and thermal efficiency about 42%. Up to 450,000 fuel pebbles recycle through the reactor continuously (about six times each) until they are expended, giving an average enrichment in the fuel load of 4-5% and average burn-up of 90 GWday/t U (eventual target burn-ups are 200 GWd/t) [start two times as effiencient with fuel and then four times]. This means on-line refuelling as expended pebbles are replaced, giving high capacity factor.
Overnight construction cost (when in clusters of eight units) is expected to be US$ 1000/kW and generating cost below 3 US cents/kWh. A demonstration plant is due to be built in 2007 for commercial operation in 2010. A design certification application to the US Nuclear Regulatory Commission is expected in 2008, with approval expected in 2012, opening up world markets.
UPDATE: More recent estimates suggest that production costs could be US$2500-3500/kW for pebble bed reactors. Inflation in the cost of steel, cement and other materials is increasing the cost of all energy production.
According to Business Report, it could cost between $9.9 billion (R67 billion) and $13.8 billion to build 24 reactor installations, which together could generate 3,960 megawatts. That's expensive power coming in at $3,500/Kw at the upper end of the cost estimate.
A larger US design, the Modular Helium Reactor (MHR , formerly the GT-MHR), will be built as modules of up to 600 MWt. In its electrical application each would directly drive a gas turbine at 47% thermal efficiency, giving 280 MWe. It can also be used for hydrogen production (100,000 t/yr claimed) and other high temperature process heat applications. Half the core is replaced every 18 months. Burn-up is up to 220 GWd/t, and coolant outlet temperature is 850°C with a target of 1000°C.
The Westinghouse AP-1000 has received several design certifications. Overnight capital costs are projected at $1200 per kilowatt and modular design will reduce construction time to 36 months. The 1100 MWe AP-1000 generating costs are expected to be below US$ 3.5 cents/kWh and its has a 60 year operating life.
Another US-origin but international project which is a few years behind the AP-1000 is the International Reactor Innovative & Secure (IRIS). IRIS is a modular 335 MWe pressurised water reactor with integral steam generators and primary coolant system all within the pressure vessel. It is nominally 335 MWe but can be less, eg 100 MWe. Fuel is initially similar to present LWRs with 5% enrichment and burn-up of 60,000 MWd/t with fuelling interval of 3 to 3.5 years, but is designed ultimately for 10% enrichment and 80 GWd/t burn-up with an 8 year cycle, or equivalent MOX core. The core has low power density. IRIS could be deployed in the next decade (2015), and US design certification is at pre-application stage. Multiple modules are expected to cost US$ 1000-1200 per kW for power generation. They expect that construction of the first IRIS unit will be completed in three years, with subsequent reduction to only two years.
The Remote-Site Modular Helium Reactor (RS-MHR) of 10-25 MWe has been proposed by General Atomics. The fuel would be 20% enriched and refuelling interval would be 6-8 years.
Another full-size HTR design is Areva's Very High Temperature Reactor (VHTR) being put forward by Areva NP. It is based on the MHR and has also involved Fuji. Reference design is 600 MW (thermal) with prismatic block fuel like the MHR. HTRs can potentially use thorium-based fuels, such as HEU or LEU with Th, U-233 with Th, and Pu with Th. Most of the experience with thorium fuels has been in HTRs. General Atomics say that the MHR has a neutron spectrum is such and the TRISO fuel so stable that the reactor can be powered fully with separated transuranic wastes (neptunium, plutonium, americium and curium) from light water reactor used fuel. The fertile actinides enable reactivity control and very high burn-up can be achieved with it - over 500 GWd/t - the Deep Burn concept and hence DB-MHR design. Over 95% of the Pu-239 and 60% of other actinides are destroyed in a single pass.
Nuclear fusion success offers the possibility of $500/kw to $20/kw of installed power. However, there is still great uncertainty of any success with nuclear fusion.
Thermoelectrics could boost the efficiency and total power generated from high heat central power such as nuclear, coal and natural gas power plants Increasing the efficiency of power plant heat conversion to 150-200% of what they are now would greatly reduce the costs of existing plants and these types of plants. The thermoelectrics have many commonalities with advanced solar power. Broad success with solar power should also mean broad success with thermoelectronics for alternative power plants. Thermoelectronics could provide an across the board boost of 30-50% in cost efficiency for nuclear, coal and natural gas by 2020.
Kitegen offers the possibility of greatly reducing the cost and increasing the total power generated by wind while reducing the materials used in construction per MW
The Uranium hydride [nuclear battery] could be mass produced at factories starting with $1400/kw prices in 2012
So there are several possibilities getting into the range of $1000/kw overnight costs for new nuclear reactors. Advanced thermoelectronics and further advances in nuclear fuel and nuclear design could provide $500/kw prices in 2020-2030 and would have far lower variable and operating costs. Nuclear fusion could push off the day of solar power price supremacy indefinitely into the future. This will not matter if we are building nuclear fission with far less waste and no air pollution, or clean aneutronic nuclear fusion or efficient wind power. Any future with clean and abundant power would be a pretty good future.