After learning that there would be oxygen problems, Chen Xin was particularly concerned about his own planting greenhouse.

It's not just a place to feed him, it's also a place to provide him with the oxygen he needs to survive.

If you don't eat, you will die in about seven days, and you can last about three days without drinking water.

But if you don't breathe, you will be gone in ten minutes.

The importance of oxygen needs not be emphasized, and the importance of growing greenhouses that can provide oxygen naturally increases considerably.

Fortunately, Chen Xin has upgraded the planting greenhouse once before, and now not only the planting area has increased, but the number and efficiency of the fill lights have also improved a lot.

As long as he can keep the greenhouse running, even if the outside world is really cut off, the greenhouse will be enough to provide him with the oxygen he needs to survive.

It's just that this is not without hidden dangers, and Chen Xin does not have no worries about planting greenhouses.

Relying only on plant photosynthesis to maintain oxygen circulation in confined spaces has been done for a long time, and even the Federation conducted a famous Biosphere 2 experiment to build a self-sustaining ecosystem.

Sadly, however, these experiments failed.

Plants can indeed provide enough oxygen in a confined environment, but only if there is enough light.

Once it is dark, photosynthesis stops, and the oxygen that plants themselves need to breathe, and the oxygen that humans need to breathe, will soon run out of the limited oxygen in the confined space.

Not only is the confined space unable to maintain such an oxygen cycle, but even the Biosphere 2 laboratory, which was built with hundreds of millions of dollars in federal investment and has a well-established artificial ecosystem, cannot do the same thing.

In the Biosphere 2 experiment, bacteria decompose organic matter in the soil and consume a large amount of oxygen, while the carbon dioxide released is absorbed by the cement in the building, breaking the oxygen cycle and reducing the oxygen content in the air to the needs of human survival.

Of course, the solution to this problem is also very simple.

Because of the difference between day and night in the natural environment, plants cannot maintain 24-hour uninterrupted photosynthesis, and plants themselves need to consume oxygen for respiration, so they naturally cannot maintain oxygen circulation in a confined space.

But in an unnatural environment, this problem is not difficult to solve, that is, the use of fill lights to provide 24 hours of uninterrupted light for plants, so that plants can maintain uninterrupted photosynthesis.

If a plant is photosynthesized 24 hours a day, it will provide oxygen for its own breathing and for the survival of the human beings who live together.

It's just that in this way, the consumption of energy increases considerably.

Now is not before the catastrophe, there is the sun, a super-sized sustainable energy source that is almost infinite, providing a steady stream of light and heat to the earth.

Before the dust cloud blocks the sunlight, people can rely on the sun to enjoy the abundant energy it brings, whether it is photosynthesis or solar power, without additional energy input.

But now that humanity has lost sunlight, we can only rely on the energy provided by the earth itself.

Coal and oil, the most precious resources that the earth provides to mankind, are also the main means of obtaining energy for mankind today.

For human beings in the last days, these two traditional energy sources have become the key to ensuring human survival.

In particular, coal resources, whether it is heating or power generation, and the convenient use of easy-to-mine coal has become the most important material indispensable for human beings.

However, for Chen Xin and his shelter, gasoline is still mainly used at present.

Just by maintaining 24 hours of uninterrupted light to ensure the oxygen production of the growing greenhouse, the consumption of gasoline used to generate electricity is greatly increased.

It's not that Chen Xin doesn't want to use more efficient and reliable diesel, but diesel will condense when the temperature is low to below zero, which is inconvenient to use.

Although high-grade diesel can solve this problem, the price of high-grade diesel is really a bit higher than that of ordinary gasoline.

After all, even -35 diesel can only be used from -14 °C to 29 °C, which is not significantly advantageous compared with the condensation point of -35 °C of ordinary gasoline.

As for the higher-grade -50 diesel, not to mention where to buy such a high-grade diesel, its price is much more expensive than ordinary gasoline.

When Chen Xin first entered the shelter, he only needed to consume 10 liters of gasoline a day to generate electricity to meet all the electricity consumption, but after upgrading the planting greenhouse, he now consumes 20 liters of fuel per day, and the light time is only about 12 hours a day because of the -10% light time provided by the system upgrade.

Now, if the greenhouse is kept lit 24 hours a day, then fuel consumption will soar to twice as much as it is now, which means that Chen Xin will consume 40 liters of gasoline a day.

In other words, the gasoline that Chen Xin prepared for one year is likely to be only enough for three months.

Moreover, the uninterrupted use of the generator for a long time will also cause wear and tear on the generator and accelerate the damage of the generator.

"It's time to upgrade the power generation system." Chen Xin rubbed his forehead and calculated his gas consumption, he was sure that he had to upgrade the power system of the shelter.

Otherwise, unless he can continue to get a lot of gas from the SWAT team to keep it burned, he will run out of gas.

But how do you upgrade your power system? It doesn't make sense to simply increase the output power of the generator, because energy is conserved, and increasing the output power only means consuming more fuel.

Improving the efficiency of generators, this is a feasible method, but it will not play a big role, after all, saving 5%-10% sounds like a lot, but when it comes to actual consumption, it is nothing more than a few days to delay the days when the fuel is exhausted.

Therefore, the most appropriate way is to make the shelter self-sustaining, and the energy consumption and the output of the shelter can be balanced, forming a cycle.

Thinking of this, Chen Xin naturally remembered the algae circulation oxygen concentrator he told Mo Qingyan.

The system produces oxygen and algae biomass, which can be used to produce not only oxygen, but also biogas for fuel cell power generation, which consumes electricity, water and carbon dioxide.

Water resources are no longer a problem after Chen Xin can pump groundwater, and the water consumption of algae is not large, and it can also be recycled, Chen Xin is not worried about water resources.

As for the problem of carbon dioxide, after the whole system is in operation, it is possible to collect the carbon dioxide produced during the combustion of biogas to supply the algae for photosynthesis consumption, if not enough, the carbon dioxide in the air is also a supplement.

After all, Chen Xin's shelter is not a completely enclosed ecological experiment cabin, and it can be replenished with the help of external resources.

The only problem is the consumption of electrical energy.