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Tag Archives: sustainability

Sustainable Hydrogen from bio-waste

It is clear substituting fossil fuels with Hydrogen is not only efficient but also sustainable in the long run. While efforts are on to produce Hydrogen at a cost in par with Gasoline or less using various methods, sustainability is equally important. We have necessary technology to convert piped natural gas to Hydrogen to generate electricity on site to power our homes and fuel our cars using Fuelcell.But this will not be a sustainable solution because we can no longer depend on piped natural gas because its availability is limited; and it is also a potent greenhouse gas. The biogas or land fill gas has the same composition as that of a natural gas except the Methane content is lower than piped natural gas. The natural gas is produced by Nature and comes out along with number of impurities such as Carbon dioxide, moisture and Hydrogen sulfide etc.The impure natural gas is cleaned and purified to increase the Methane content up to 90%, before it is compressed and supplied to the customers. The gas is further purified so that it can be liquefied into LNF (liquefied natural gas) to be transported to long distances or exported to overseas.

When the natural gas is liquefied, the volume of gas is reduced about 600 times to its original volume, so that the energy density is increased substantially, to cut the cost of transportation. The LNG can be readily vaporized and used at any remote location, where there is no natural gas pipelines are in existence or in operation. Similarly Hydrogen too can be liquefied into liquid Hydrogen. Our current focus is to cut the cost of Hydrogen to the level of Gasoline or even less. Biogas and bio-organic materials are potential sources of Hydrogen and also they are sustianable.Our current production of wastes from industries business and domestic have increased substantially creating sustainability isues.These wastes are also major sources of greenhouse gases and also sources of many airborne diseses.They also cause depletion of valuable resources without a credible recycling mechanisms. For example, number of valuable materials including Gold, silver, platinum, Lead, Cadmium, Mercury and Lithium are thrown into municipal solid waste (MSW) and sewage. Major domestic wastes include food, paper, plastics and wood materials. Industrial wastes include many toxic chemicals including Mercury, Arsenic, tanning chemicals, photographic chemicals, toxic solvents and gases. The domestic and industrial effluents contain valuable materials such as potassium, Phosphorous and Nitrates. We get these valuable resources from Nature, convert them into useful products and then throw them away as a waste. These valuable materials remain as elements without any change irrespective of type of usages.Recyling waste materials and treatment of waste water and effluent is a very big business. Waste to wealth is a hot topic.

The waste materials both organic and inorganic are too valuable to be wasted for two simple reasons. First of all it pollutes our land, water and air; secondly we need fresh resources and these resources are limited while our needs are expanding exponentially. It is not an option but an absolute necessity to recycle them to support sustainability. For example, most of the countries do not have Phosphorous, a vital ingredient for plant growth and food production. Bulk of the Phosphorus and Nitrates are not recovered from municipal waste water and sewage plants. We simply discharge them into sea at far away distance while the public is in dark and EPA shows a blind eye to such activities. Toxic Methane gases are leaking from many land fill sites and some of these sites were even sold to gullible customers as potential housing sites. Many new residents in these locations find later that their houses have been built on abandoned landfill sites. They knew only when the tap water becomes highly inflammable when lighting with a match stick. The levels of Methane were above the threshold limit and these houses were not fit for living. We have to treat wastes because we can recover valuable nutrients and also generate energy without using fresh fossil fuels. It is a win situation for everybody involved in the business of ‘waste to wealth’.

These wastes have a potential to guarantee cheap and sustainable Hydrogen for the future. Biogas is a known technology that is generated from various municipal solid wastes and effluents. But current methods of biogas generation are not efficient and further cleaning and purifications are necessary. The low-grade methane 40-55% is not suitable for many industrial applications except for domestic heating. The biogas generated by anaerobic digestion has to be scrubbed free of Carbon dioxide and Hydrogen sulfide to get more than 90% Methane gas so that it can be used for power generation and even for steam reforming to Hydrogen generation. Fuel cell used for on site power generation and Fuel cell cars need high purity Hydrogen. Such Hydrogen is not possible without cleaning and purifying ‘ biogas’ much. Hydrogen generation from Biogas or from Bioethanol is a potential source of Hydrogen in the future.

Hydrogen-the key to sustainability

Renewable energy is one of the fastest growing energy sources of our times. But still there are many obstacles to overcome, before it can substitute current methods of electricity generation using fossil fuels, or substitute petrol in cars. The main obstacle is, the intermittent and unpredictable nature of renewable energy sources, such as wind and solar. Wind blows only certain seasons of the year and then wind velocity fluctuates widely in a day. Similarly sun shines only certain hours in a day and the intensity of radiation varies widely in a day. The wind velocity and sun’s radiation intensity are critical components in designing a reliable energy system. It is an anomalous situation, when we need power, there is no sun or wind; when sun shines or wind blows, we may not need any power. How to overcome this anomaly? That is the key, in successfully deploying renewable energy technologies.

Currently we are using batteries to store the energy. When there is a wind with reasonable velocity or sunshine with reasonable radiation intensity, we can generate power and store them in batteries. The wind velocity should be above certain threshold limit, say such as, a least wind velocity of 3mts/sec for amount of hours, while designing a wind based energy system. The same principle applies to solar energy and we need certain minimum solar   intensity and several hours. But in reality, we don’t get these minimum operating parameters, which make the design of a renewable system more complicated.

Batteries can accumulate these small energy generations by intermittent sources of wind and sun, and store them. But these batteries have certain life between 3-5 years and requires regular maintenance, replacements.They also have certain charging and discharging cycles and limitations. At the end of its life, it has to be disposed carefully because these batteries are made of lead and acid, which are toxic materials. Many companies are trying to introduce better technologies such as ‘flow batteries’. But experience shows that such batteries are confined to only smaller capacities. Large scale storage is expensive and sometimes it is not economically feasible. Lithium-ion batteries are more efficient than Lead-acid batteries, but they are more expensive so the renewable energy projects become expensive and cannot compete with conventional fossil fuels, in spite of higher tariffs offered by Government as incentives. Moreover the demand for Lithium-ion batteries will increase substantially in the future, as more and more Electric cars are produced. But lithium sources are limited and it is not sustainable.

The best option to develop renewable energy systems is to generate Hydrogen using renewable energy and store them, instead of storing them in batteries. We can use stored Hydrogen to generate power, or use as fuel for the car, as and when we need. There are no maintenance or disposal problems with Hydrogen storage, when comparing with batteries. Hydrogen generators (electrolyzers) can generate Hydrogen when the intermittent power flows from wind or sun. They can run from a range of capacities from 5 to 100% of rated capacity and they are more suitable for renewable energy sources. But there will be a loss of energy, because the amount of power required to generate Hydrogen, is more than the power generated from the resulting Hydrogen by a Fuelcell.The initial cost will be higher, but it will give operational flexibility with least maintenance, and even adoptable to remote sites. Technology is improving to cut the cost of fuel cells and electrolyzers so that Hydrogen based renewable energy will become a sustainable source of energy in the future. Hydrogen is the only solution that can solve both power generation and transportation problems the world is currently facing.

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