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A week's supply of biofuels, given our current energy use of 101 quadrillion BTU/year, and assuming 100% efficiency, is 2 quadrillion BTU. At the peak of our pr

by xyzzyz 7y ago

A week's supply of biofuels, given our current energy use of 101 quadrillion BTU/year, and assuming 100% efficiency, is 2 quadrillion BTU. At the peak of our production, we produced around 0.2 quadrillion BTU worth of biodiesel. This means that a week's supply of biofuels is around 10 years of production. Of course, in practice, if you overbuild renewable energy generation to a large enough multiple that will greatly increase the average cost of produced kWh, and if you keep most of the fossil fuel infrastructure on standby, then at the immense expense, and greatly increased energy prices, you could reduce CO2 emissions by switching to renewables. The real question is, why would you do so, if it would be much, much cheaper to just build enough nuclear plants to cover your needs. France managed to do it in the 70s., why can't we do it 50 years later?

AnthonyMouse 7y ago
> A week's supply of biofuels, given our current energy use of 101 quadrillion BTU/year, and assuming 100% efficiency, is 2 quadrillion BTU. At the peak of our production, we produced around 0.2 quadrillion BTU worth of biodiesel. This means that a week's supply of biofuels is around 10 years of production. We produce around ten times as many gallons of ethanol as biodiesel. It has about half as many BTUs, which implies we would need around two years of production. Not really a problem if we only need that much once every two years. It's also assuming we couldn't produce more than we do now, or do something more efficient like convert existing coal fired plants to burn biomass from algae. > The real question is, why would you do so, if it would be much, much cheaper to just build enough nuclear plants to cover your needs. France managed to do it in the 70s., why can't we do it 50 years later? Because we do whatever costs less. Nuclear plants are expensive. On the other hand, so is storage. It's not actually clear which one is going to cost less in the long term, so what we should probably be doing is building both at the same time. Which has the additional advantage of replacing fossil fuels even faster, because the two technologies have very little overlap in terms of either labor expertise or materials use, and complement one another in that there is more electricity demand during the day when solar is generating but there is still non-trivial demand at night which can be handled by nuclear. They're not coming at the expense of one another, they're both coming at the expense of fossil fuels, so the more the merrier.
- xyzzyz 7y ago
  > Because we do whatever costs less. Nuclear plants are expensive. On the other hand, so is storage. It's not actually clear which one is going to cost less in the long term, Right. It's really worth asking why exactly nuclear plants are so expensive to build, and why they were so much cheaper in the past. The plants that French built in the 70s and 80s were produce much cheaper electricity than fossils and renewables, in terms of LCOE. Why is US so terrible at building things today? Would it even be possible to build, say, Hoover dam today? How many more times it would cost now than it did in the 1930s, in inflation adjusted dollars, despite great advancements in the available technology? > so what we should probably be doing is building both at the same time. If you build nuclear, there's no need to build storage, really. Energy storage is very expensive to build, per stored MWh, much more expensive than nuclear is today, even at today's greatly inflated prices.
  - AnthonyMouse 7y ago
    > Right. It's really worth asking why exactly nuclear plants are so expensive to build, and why they were so much cheaper in the past. I tend to think it's a combination of factors that mostly boil down to bureaucratic inefficiency and various forms of political corruption. The problem is there are multiple groups who profit from it being expensive. First you have the people actually receiving the money. Contractors and unions. If it costs ten times as much they get a ten times bigger contract with ten times more hours. Then you have the competitors. The fossil fuel industry is committed to ensuring that nuclear reactors are "sufficiently" regulated. And the problem is there's nobody on the other side. The people paying the money are the utility ratepayers. They're not organized. Maybe the key to fixing it is recognizing that the two groups in favor of higher costs aren't actually aligned. The contractors and unions want lucrative construction work, the competitors don't want construction at all. But if nobody's building then you don't get a big fat contract, you get a big fat nothing. But at the root it's a political problem. Existing laws make construction expensive. Either fix them or expect it to continue to be expensive. > If you build nuclear, there's no need to build storage, really. Solar is cheaper than anything when the sun is shining, and there are a lot of things -- charging electric vehicles is a big one -- that can be demand-shifted into that time period with price incentives. But as soon as you're using it you've got an issue. Sunlight doesn't perfectly align with demand. You need something to get you over the demand peak in the evening. But storage enough to cover the base to peak load differential for two or three hours a day is a whole lot cheaper than needing to cover the full load for the full night. Interestingly, some of the newer nuclear reactor designs have built-in storage. A molten salt reactor can use hot salt as thermal storage. Let solar handle more of the load during daylight while you put heat from the reactor into a vat of molten salt, then have the extra heat to spin more turbines during the load peak in the evening.

by xyzzyz 7y ago

AnthonyMouse 7y ago

> A week's supply of biofuels, given our current energy use of 101 quadrillion BTU/year, and assuming 100% efficiency, is 2 quadrillion BTU. At the peak of our production, we produced around 0.2 quadrillion BTU worth of biodiesel. This means that a week's supply of biofuels is around 10 years of production. We produce around ten times as many gallons of ethanol as biodiesel. It has about half as many BTUs, which implies we would need around two years of production. Not really a problem if we only need that much once every two years. It's also assuming we couldn't produce more than we do now, or do something more efficient like convert existing coal fired plants to burn biomass from algae. > The real question is, why would you do so, if it would be much, much cheaper to just build enough nuclear plants to cover your needs. France managed to do it in the 70s., why can't we do it 50 years later? Because we do whatever costs less. Nuclear plants are expensive. On the other hand, so is storage. It's not actually clear which one is going to cost less in the long term, so what we should probably be doing is building both at the same time. Which has the additional advantage of replacing fossil fuels even faster, because the two technologies have very little overlap in terms of either labor expertise or materials use, and complement one another in that there is more electricity demand during the day when solar is generating but there is still non-trivial demand at night which can be handled by nuclear. They're not coming at the expense of one another, they're both coming at the expense of fossil fuels, so the more the merrier.

xyzzyz 7y ago
> Because we do whatever costs less. Nuclear plants are expensive. On the other hand, so is storage. It's not actually clear which one is going to cost less in the long term, Right. It's really worth asking why exactly nuclear plants are so expensive to build, and why they were so much cheaper in the past. The plants that French built in the 70s and 80s were produce much cheaper electricity than fossils and renewables, in terms of LCOE. Why is US so terrible at building things today? Would it even be possible to build, say, Hoover dam today? How many more times it would cost now than it did in the 1930s, in inflation adjusted dollars, despite great advancements in the available technology? > so what we should probably be doing is building both at the same time. If you build nuclear, there's no need to build storage, really. Energy storage is very expensive to build, per stored MWh, much more expensive than nuclear is today, even at today's greatly inflated prices.
- AnthonyMouse 7y ago
  > Right. It's really worth asking why exactly nuclear plants are so expensive to build, and why they were so much cheaper in the past. I tend to think it's a combination of factors that mostly boil down to bureaucratic inefficiency and various forms of political corruption. The problem is there are multiple groups who profit from it being expensive. First you have the people actually receiving the money. Contractors and unions. If it costs ten times as much they get a ten times bigger contract with ten times more hours. Then you have the competitors. The fossil fuel industry is committed to ensuring that nuclear reactors are "sufficiently" regulated. And the problem is there's nobody on the other side. The people paying the money are the utility ratepayers. They're not organized. Maybe the key to fixing it is recognizing that the two groups in favor of higher costs aren't actually aligned. The contractors and unions want lucrative construction work, the competitors don't want construction at all. But if nobody's building then you don't get a big fat contract, you get a big fat nothing. But at the root it's a political problem. Existing laws make construction expensive. Either fix them or expect it to continue to be expensive. > If you build nuclear, there's no need to build storage, really. Solar is cheaper than anything when the sun is shining, and there are a lot of things -- charging electric vehicles is a big one -- that can be demand-shifted into that time period with price incentives. But as soon as you're using it you've got an issue. Sunlight doesn't perfectly align with demand. You need something to get you over the demand peak in the evening. But storage enough to cover the base to peak load differential for two or three hours a day is a whole lot cheaper than needing to cover the full load for the full night. Interestingly, some of the newer nuclear reactor designs have built-in storage. A molten salt reactor can use hot salt as thermal storage. Let solar handle more of the load during daylight while you put heat from the reactor into a vat of molten salt, then have the extra heat to spin more turbines during the load peak in the evening.